monitoring of stink bugs in blackberry and life...
TRANSCRIPT
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MONITORING OF STINK BUGS IN BLACKBERRY AND LIFE HISTORY OF
EUSCHISTUS QUADRATOR ROLSTON
By
SARA ANN BRENNAN
A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
2012
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© 2012 Sara Brennan
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To my parents for their continued love and support
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ACKNOWLEDGMENTS
I would especially like to thank my major professor, Dr. Oscar Liburd, for having faith in
me, providing guidance and encouraging me throughout my studies. Thanks to other members of
my graduate committee, Dr. Joe Eger and Dr. Eileen Buss, for their continued support and
guidance. I deeply appreciate the assistance I received from the other members of the Small Fruit
and Vegetable IPM laboratory in Gainesville, FL, as well as the employees of the Plant Science
Research and Education Unit in Citra, FL. I would also like to thank Lyle Buss and Jane Medley
for their assistance with photography and graphics. Thanks goes to all faculty and students of the
Entomology and Nematology Department at the University of Florida, many of whom supported
me in various ways throughout this journey. Finally, I cannot thank my parents enough for their
moral support and encouragement throughout this process.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS ...............................................................................................................4
LIST OF TABLES ...........................................................................................................................7
LIST OF FIGURES .........................................................................................................................8
ABSTRACT .....................................................................................................................................9
CHAPTER
1 INTRODUCTION ..................................................................................................................11
2 LITERATURE REVIEW .......................................................................................................16
Stink Bugs ...............................................................................................................................16
Euschistus servus .............................................................................................................17
Euschistus quadrator .......................................................................................................18
Biology and Behavior .............................................................................................................19
Euschistus servus .............................................................................................................20
Euschistus quadrator .......................................................................................................20
Injury .......................................................................................................................................21
Monitoring and Management .................................................................................................23
Pheromones .....................................................................................................................23
Traps ................................................................................................................................24
Other Methods of Monitoring Stink Bug Populations ....................................................25
Chemical Control .............................................................................................................26
Cultural Control ...............................................................................................................27
Biological Control ...........................................................................................................28
Organic Control ...............................................................................................................29
Justification .............................................................................................................................30
Hypotheses ..............................................................................................................................31
Specific Objectives .................................................................................................................31
3 STINK BUG SPECIES SURVEY IN BLACKBERRIES .....................................................32
Materials and Methods ...........................................................................................................33
Results.....................................................................................................................................34
Discussion ...............................................................................................................................35
4 MONITORING STINK BUGS IN BLACKBERRY .............................................................44
Materials and Methods ...........................................................................................................46
Study Site .........................................................................................................................46
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Trap Comparison .............................................................................................................46
Pheromone Comparison ..................................................................................................47
Laboratory study ......................................................................................................47
Field study ................................................................................................................48
Pheromone Concentration Comparison ...........................................................................48
Data Analysis ...................................................................................................................49
Results.....................................................................................................................................49
Trap Comparison .............................................................................................................49
Pheromone Comparison ..................................................................................................50
Pheromone Concentration Comparison ...........................................................................50
Discussion ...............................................................................................................................51
5 LABORATORY REARING AND DESCRIPTIONS OF IMMATURE STAGES OF
EUSCHISTUS QUADRATOR ................................................................................................63
Materials and Methods ...........................................................................................................64
Laboratory Rearing ..........................................................................................................64
Life History Study ...........................................................................................................64
Descriptions of Immature Stages .....................................................................................65
Data Analysis ...................................................................................................................65
Results.....................................................................................................................................65
Laboratory Rearing ..........................................................................................................65
Immature Descriptions ....................................................................................................66
First instar .................................................................................................................66
Second instar ............................................................................................................67
Third instar ...............................................................................................................69
Fourth instar .............................................................................................................70
Fifth instar ................................................................................................................71
Discussion ...............................................................................................................................72
6 GENERAL CONCLUSIONS .................................................................................................80
Species Survey in Blackberries ..............................................................................................80
Monitoring in Blackberries .....................................................................................................81
Life History and Taxonomy of E. quadrator ..........................................................................81
LIST OF REFERENCES ...............................................................................................................83
BIOGRAPHICAL SKETCH .........................................................................................................93
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LIST OF TABLES
Table page
3-1 Species complex by sex in blackberries using the beating tray method ............................38
3-2 Numbers of each stink bug species collected by date ........................................................39
3-3 Numbers of stink bug species collected by blackberry variety (5/8/2010-6/19/2010) ......40
4-1 Species complex of stink bugs captured in trap comparison study ...................................54
4-2 Chi-square values for each treatment in Y-tube assays (n=60) .........................................54
4-3 Species complex of stink bugs captured in pheromone comparison study ........................55
4-4 Species complex of stink bugs captured in pheromone concentration comparison
study ...................................................................................................................................55
5-1 Duration (in days) of each immature stadium of E. quadrator under laboratory
conditions ...........................................................................................................................75
5-2 Head capsule (HC) length and width, and length of antennal segments (A#) of E.
quadrator .......................................................................................76
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LIST OF FIGURES
Figure page
1-1 Location and estimated number of blackberry farms in Florida in 2007 ...........................15
3-1 Blackberry field layout in Citra, FL ...................................................................................41
3-2 Species complex in blackberries using the beating tray method .......................................42
3-3 Total stink bug numbers correlated with mean percent fruit development in organic
and conventional blackberry plots .....................................................................................43
4-1 Yellow pyramid trap with screen top .................................................................................56
4-2 Tube trap ............................................................................................................................57
4-3 Y-tube olfactometer set up .................................................................................................58
4-4 Mean number of stink bugs captured in yellow pyramid traps (YP) or tube traps with
(B) or without (UB) pheromone lures. Means followed by the same letter are not
significantly different according to ANOVA (F=4.93, df=5, P=0.0021). .........................59
4-5 Mean number of stink bugs captured in yellow pyramid traps baited with Trécé or
Suterra pheromone lures or without lures (UB). Means were not significantly
different according to ANOVA (F=1.80, df=5, P=0.1339). ..............................................60
4-6 Mean number of stink bugs captured in yellow pyramid traps baited with one, two or
three Trécé lures or unbaited (UB). Means were not significantly different according
to ANOVA (F=2.23, df=5, P=0.0772). .............................................................................61
4-7 Percent stink bugs captured per species in field experiments (n=78) ................................62
5-1 Adult and nymph cage examples .......................................................................................77
5-2 Dorsal and ventral view of immature stages of Euschistus quadrator ..............................78
5-3 Number of nymphs per instar that molted into each subsequent instar during the
experiment..........................................................................................................................79
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Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science
MONITORING OF STINK BUGS IN BLACKBERRY AND LIFE HISTORY OF
EUSCHISTUS QUADRATOR ROLSTON
By
Sara Ann Brennan
August 2012
Chair: Oscar Liburd
Major: Entomology and Nematology
Blackberry production in Florida has increased more than 100% within the last two
decades and several insect pests, including stink bugs, have been feeding on this crop. Euschistus
quadrator Rolston is a relatively new stink bug pest to Florida, and has spread throughout the
state. The objectives for this study were to determine the stink bug species present in blackberry,
to develop monitoring tools for stink bugs and to describe the life history and immature stages of
E. quadrator. In a field survey, E. quadrator was the most abundant stink bug species, followed
by E. servus Say, E. obscurus (Palisot de Beauvois), Thyanta custator (F.), Proxys punctulatus
(Palisot de Beauvois) and Podisus maculiventris Say.
In my monitoring studies, yellow pyramid traps were more effective than tube traps in
catching stink bugs, with or without the addition of the Euschistus spp. pheromone. In a
pheromone comparison experiment, there were no statistical differences between traps baited
with a Trécé Pherocon Centrum lure, a Suterra Scenturion lure, and an unbaited trap. These
results were supported by a Y-tube olfactometer assay where there were no differences between
the lures and a control.
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Experiments to determine duration of immature stages of E. quadrator were conducted in
the laboratory at 25 ± 0.5 C and 50 ± 5% RH. I found that the duration of the six stadia of E.
quadrator, egg through fifth instar, averaged 8.3, 6.1, 7.8, 6.8, 7.6 and 11.2 days, respectively.
We found relatively low numbers of stink bugs in blackberries during the course of this
study. However, under optimum conditions, stink bugs may warrant the development of pest
management programs in blackberries to prevent them from reaching damaging levels.
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CHAPTER 1
INTRODUCTION
Commercial blackberry, Rubus (Rubus), production worldwide increased 45% from 1995
to 2005, producing 127,270 mt on 20,035 ha. During the same time, U.S. production increased
34% to 28.884 mt on 4,818 ha, the highest production in the world in 2005 (Strik et al. 2007).
Much of this increase in blackberry production is due to more efficient breeding of blackberry
plants and an increase in consumer demand for more fruits and vegetables. In addition,
blackberries are rich sources of antioxidants (polyphenols), which are believed to boost the
bod ’ i u e te a d la i orta t role i reduci g eart di ea e, ca cer a d diabete
(Moyer et al. 2002, Bowen-Forbes et al. 2008). As the U.S. population becomes more health
conscious, fruits high in antioxidants including blackberries are becoming increasingly popular.
Blackberries were not a popular commercial crop until the 1990s due to the low quality
and poor storage characteristics of the berries (Clark 1992). The development of thornless
varieties has probably enabled blackberries to move from a primarily local crop to a nationwide
retail crop. Although blackberries are mainly grown in the Pacific Northwest, production in the
southeastern U.S. is increasing. Georgia alone has tripled its production in the last 10 years (Strik
et al. 2007). The USDA Plant Hardiness Zone Map shows that Georgia, Arkansas and Florida
have overlapping plant hardiness zones, classified by average extreme minimum temperature
(USDA 2012). Georgia and Arkansas, which harvested 122 and 159 ha of blackberries in 2007
(USDA 2009b), respectively, have a humid subtropical climate (Kottek et al. 2006). Although
northern Florida has a similar climate and plant hardiness zone, blackberry harvest in 2007 was
limited to 40 ha, suggesting that there is room to increase production (USDA 2009b, USDA
2012).
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Blackberries have been grown on several small farms in Florida dating back to 1920
(USBC 1952). Blackberry harvest has slowly but steadily increased in the state and in the last
two decades there has been >100% increase to 40 ha of blackberries harvested in the state of
Florida (USDA 1994-2009a). Production in Florida occurs in 30 counties, with most farms
concentrated in northern Florida (Anderson et al. 2011, Figure 1-1).
Earlier ripening of blackberries in Florida may enable growers to meet a market window
not currently being filled by other southern states. A similar case is seen in southern highbush
blueberrie , w ic were bred i t e 1970 to grow well i Florida’ cli ate a d ri e earlier t a
other states (Williamson and Lyrene 2004). Recently, the University of Florida Institute of Food
and Agriculture (IFAS), through the Small Fruit and Vegetable IPM program, has established its
first blackberry research site in Citra, Florida and had their first on-far “blackberr field da ”
in 2010.
Blackberries and raspberries are members of the genus Rubus. They have flowers with five
petals, perennial roots and biennial shoots called canes (Crandall 1995). The canes do not
produce flowers in the first year of growth, and are known as primocanes. In the second year, the
canes produce fruit, and are known as floricanes (Jennings et al. 1991). The flowers are produced
in late spring or early summer, and fruits ripen within a couple of weeks. The canes die after they
produce fruit, and new canes develop each year. The plants must be pruned to remove floricanes
after harvest to provide room for the new primocanes, which will fruit the following year.
Blackberries typically grow best in temperate climates and commercial varieties have historically
required low winter temperatures to stimulate flower bud development, limiting production to
northern states (Jennings et al. 1991).
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In recent years, several lower-chill and disease resistant blackberry cultivars have been
developed, making them possible for commercial production in Florida (Jennings et al. 1991,
Moore 1997, Clark 2005). The University of Arkansas, in particular, has released several
varieties of blackberries that exhibit favorable characteristics for commercial production in
Florida.
o e of t e ewer varietie t at were relea ed i clude ‘Ara a o’, ‘C icka aw’,
‘C octaw’, ‘Kiowa’, ‘Natc ez’ a d ‘Ouac ita’. ‘Ara a o’ i a t or le , erect variet t at ri e
early, has good fruit quality, and fruits are of average size (Moore and Clark 1993). The
‘C icka aw’ variet i t or a d erect. It roduce a large fruit of good qualit a d a igh yield
Clark a d Moore 1999 . ‘C octaw’ i a t or , erect variet t at ri e earl i t e ea o , a
a medium- ized, good qualit fruit a d roduce well Moore a d Clark 1989 . ‘Kiowa’ i a
thorny, erect variety. Its fruit size is consistently large and its yields are similar to that of
‘C octaw’ Moore a d Clark 1996 . ‘Natc ez’ i a t or le , erect to e i-erect variety with a
large fruit ize a d ig ield Clark a d Moore 2008 . ‘Ouac ita’ la t are t or le , erect a d
perform especially well in the South. This variety has a medium-large fruit size and produces
consistently high yields (Clark and Moore 2005).
As blackberry production expands, pests and disease problems are expected to increase.
Therefore, it is important to develop pest management strategies to address potential threats.
Flower thrips, Frankliniella spp., midges, Dasineura spp., and stink bugs (Pentatomidae) have
been problematic in Georgia and Florida (Mizell 2007, O. E. Liburd, personal communication).
These pests differ from the traditional northern pests of blackberries, which include aphids
(Aphis spp.), Japanese beetles (Popillia japonica Newman), green June beetles (Cotinis nitida
(L.)), weevils (Otiorhynchus spp.)), crown borers (Pennisetia marginata (Harris)), cane borers
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(Oberea bimaculata (Olivier), Agrilus spp.), leaf rollers (Argyrotaenia franciscana
(Walsingham), Choristoneura rosaceana (Harris)) and mites (Phyllocoptes gracilis (Nalepa),
Tetranychus urticae Koch) (Crandall 1995, Johnson and Lewis 2003). This new pest complex
may exist because of host shifts of insects onto the newer warm season varieties, expanded
blackberry production into new areas, and the use of reduced-risk pesticides targeted for other
key pests. Nevertheless, integrated pest management tactics are needed to address this new pest
complex.
In 2008 and 2009, large numbers of stink bugs were observed in blackberries and were
suspected of injuring the fruit (O. E. Liburd, personal communication). The purpose of this
research was to characterize the key stink bug species complex present in Florida blackberries. In
addition, I compared and evaluated monitoring tools for key stink bugs [Euschistus spp.] in
blackberries and described the life history and immature stages of E. quadrator Rolston. My goal
was to establish effective monitoring strategies that are environmentally friendly and
economically practical for growers. There is little, if any research on stink bugs in blackberries,
especially in the southeastern United States. With the new potential for stink bugs to cause injury
to blackberries by feeding on the fruit and interfering with the quality of marketable yield,
developing effective monitoring tools and understanding their biology will be important aspects
of agricultural stink bug management.
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Figure 1-1. Location and estimated number of blackberry farms in Florida in 2007
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CHAPTER 2
LITERATURE REVIEW
Stink Bugs
Stink bugs belong to the family Pentatomidae, which is the third largest family in the order
Heteroptera, with over 4,000 known species (Schaefer and Panizzi 2000). Many phytophagous
stink bugs are important pests, causing severe economic losses on a variety of plants (McPherson
and McPherson 2000). Most stink bug species that are pests of crops belong to the subfamily
Pentatominae (Schuh and Slater 1995).
Stink bugs are highly polyphagous and mobile, often moving quickly through various
crops and host plants. When crops are not fruiting, stink bugs may feed on wild hosts until crops
become available (McPherson and McPherson 2000). This makes detection and management
difficult. In addition, several stink bug species may form a species complex that attack various
crops, increasing management difficulty (McPherson et al. 1979a). The most common stink bugs
in this complex are the southern green stink bug, Nezara viridula (L.), the green stink bug,
Chinavia hilaris (Say), and the brown stink bug, Euschistus servus (Say) (McPherson and
McPherson 2000).
The genus Euschistus not only contains E. servus, but also other pest species in the
continental United States such as Euschistus variolarius (Palisot de Beauvois), Euschistus
tristigmus (Say), Euschistus ictericus (L.), Euschistus quadrator Rolston and Euschistus
conspersus (Uhler). Euschistus quadrator and smaller species in the genus, such as E. obscurus
Pali ot de Beauvoi , are o eti e referred to a t e ‘Le er Brow ti k Bug co le ’ due to
their increasing pest status (Hopkins et al. 2005).
Members of the genus Euschistus have been observed feeding on many cultivated crops
including corn, Zea mays L., cotton, Gossypium hirsutum (L.), alfalfa, Medicago sativa L.,
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soybean, Glycine max L., and various fruits (McPherson and McPherson 2000). These species
have migrated south, and increased in pest status in the southeastern United States in recent
years.
Most of the information gathered on the increasing pest status of Euschistus spp. is from
Louisiana and Georgia. It is important to note that these states have a humid subtropical climate,
with humid and hot summers and mild winters (Kottek et al. 2006). Since Florida is
characterized in the same climate zone, it is possible that these stink bugs will become more of a
problem in Florida, as they have in other southeastern states.
Euschistus servus
The brown stink bug has two subspecies, E. s. euschistoides (Vollenhoven) and E. s. servus
(Say). Euschistus servus servus occurs from Florida to California along the southern states, and
E. s. euschistoides is in the northern half of the United States (McPherson 1982). The brown
stink bug feeds primarily on soybean, cotton, corn and various fruits (McPherson and McPherson
2000, Schaefer and Panizzi 2000). Historically, the brown stink bug has been the most
economically significant pest in this genus (McPherson and McPherson 2000). It is one of the
most commonly collected stink bugs in many crops, along with the southern green stink bug and
the green stink bug.
Euschistus servus was recorded in Florida as early as 1886 in corn, although it was thought
to be a predatory bug on the corn earworm, Helicoverpa (Heliothis) armigera (Hübner)
(Ashmead 1887). In 1908 and 1914, E. servus was commonly found all over Florida (Van Duzee
1909, Barber 1914). T i ti k bug a bee fou d i everal of Florida’ cro , i cludi g cor ,
pecan, cotton and rice (Ashmead 1887, Hill 1938, Sprenkel 2008, Nuessly et al. 2010, Wright et
al. 2011).
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Euschistus quadrator
Euschistus quadrator is found across the southeastern U.S., and has been reported from
Texas to Florida and north to Louisiana and Arkansas. It is most prominent in Georgia soybean
and cotton crops (McPherson et al. 1993).
Euschistus quadrator was not described until 1974, much later than E. servus, which was
described in 1832 (Henry and Froeschner 1998). Euschistus quadrator was described from
insects found in Mexico, Texas and Louisiana (Rolston 1974), and was not found in Florida until
1992 (J. E. Eger, personal communication). It has since spread throughout the state and has
become an agricultural pest of many fruit, vegetable and nut crops in the southeastern United
States. Euschistus quadrator had previously been a secondary or tertiary pest, often found in
very low numbers if at all.
Euschistus quadrator has recently become a more prominent pest with the introduction of
crops such as Bt cotton, which does not control stink bugs, and reduced application of broad-
spectrum insecticides. The first record of E. quadrator on cotton was in 1998 in southern
Georgia (Bundy and McPherson 2000b). It was listed as a pest of concern for the southeastern
United States in 2007 (Brambila 2007). In addition to Bt cotton, reduced use of broad-spectrum
insecticides may have led to a resurgence of stink bugs as agricultural pests (Greene et al. 2001).
Euschistus quadrator has been noted in several different crops, sometimes as prominent as E.
servus (Hopkins et al. 2010). It has recently been a key pest listed in soybean and corn (Ruberson
et al. 2009, Hopkins et al. 2010, Tillman 2010b, Olson et al. 2011). This suggests that the pest
species complex may be changing, with E. quadrator increasing in pest status. Within 10 years
of its discovery in cotton, E. quadrator was listed as a common pest and increasingly abundant in
southern Georgia (Ruberson et al. 2009, Tillman et al. 2009a).
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Biology and Behavior
Stink bugs in southeastern crops are characterized by having a shield-shaped body, ranging
in size from approximately 9 to 15 mm in length, depending on the species (McPherson 1982,
Schaefer and Panizzi 2000). They have a segmented beak arising from the front of the head, five-
segmented antennae, three-segmented tarsi, membranous hind wings, and forewings (hemelytra)
that are leathery basally and membranous distally (McPherson and McPherson 2000). The
scutellum is usually triangle-shaped. They garner their common name from their ability to
secrete a foul-smelling liquid from glands on their thorax when threatened. These scent glands
occur dorsally on nymphs and adults (Schuh and Slater 1995, McPherson and McPherson 2000).
Mating begins in the spring and eggs are laid in clusters with tight rows. Eggs are cylinder-
a ed, a d u uall located o t e u der ide of a la t’ leave or o te . gg of Euschistus
spp. range in length from approximately 0.88 to 1.15 mm, and diameter from approximately 0.71
to 1.03 mm (Bundy and McPherson 2000a). Egg clusters are usually geometrically or irregularly
shaped. The incubation period for eggs can be anywhere from 3 days to 3 weeks depending on
the species and environmental conditions. There are five nymphal instars. First instars remain on
or near the eggs in clusters, and disperse to find water and food sources around the time of the
first molt (McPherson and McPherson 2000). Development from egg to adult ranges from 23 to
58 days, depending on the species and environmental conditions (Schaefer and Panizzi 2000).
Adults commonly overwinter beneath leaf litter or mulch. Overwintering adults become active in
spring, which is usually when the first generation appears. Overwintering adults typically
colonize spring vegetables, mullein, Verbascum thapsus (L.), white clover and other wild hosts
(McPherson and McPherson 2000). Euschistus servus and E. quadrator are both bivoltine in the
southern United States (McPherson 1982, Munyaneza and McPherson 1994, Herbert and Toews
2011). Most species in the genus Euschistus have very similar life histories.
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Euschistus servus
Euschistus servus is most often between 11 and 15 mm long (McPherson 1982). It usually
overwinters under crop residues and weeds, especially common mullein and winter wheat,
Triticum aestivum L. (Rolston and Kendrick 1961, Buntin and Greene 2004,). These hosts may
provide an environment for E. servus to build up and subsequently move into important cash
crops.
The egg masses of E. servus are semi-translucent and light yellow, and range between 28
to 55 eggs per cluster. Bundy and McPherson (2000a) found a maximum of 35 eggs per cluster
for E. servus (Esselbaugh 1946, Woodside 1946). Earlier, Rolston and Kendrick (1961) recorded
that E. servus eggs have an incubation period ranging from 3 to 14 days, with an average of 5.5
days, while Munyaneza and McPherson (1994) found a range of 5 to 7 days with an average of
5.8 days. Euschistus servus nymphs complete their development in approximately 23 to 63 days,
averaging around 33 days according to Rolston and Kendrick (1961) and 44.3 days according to
Munyaneza and McPherson (1994) at 23 C.
Euschistus quadrator
Adults are shield-shaped and light to dark brown in color. They are smaller than many
other members of the genus, generally around 9 mm in length and approximately 5 mm wide
across the abdomen (Esquivel et al. 2009). Euschistus quadrator lacks dark spots in the
membranous area of the hemelytra, a characteristic present in other species of Euschistus
commonly found in southeastern crops (Esquivel et al. 2009).
The eggs of E. quadrator are semi-translucent and light yellow, and become more red as
the eggs mature (S. A. Brennan, personal observation). The micropylar processes (fan like
projections around the top of the egg) are longest in this species compared with other Euschistus
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spp. (Bundy and McPherson 2000a). Bundy and McPherson (2000a) found a maximum of 25
eggs per cluster in their research. Little is known about E. quadrator nymphs.
Injury
Stink bugs have piercing-sucking mouthparts and most feed primarily on fruits and seeds,
causing injury to various fruits and vegetables, and resulting in significant quality and yield loss
(Schaefer and Panizzi 2000, Panizzi 1997). Stink bugs pierce plant tissues with their stylets,
causing physical injury that resembles a pinprick. They also inject digestive enzymes to aid in
e tracti g t e la t’ fluid Mile 1972, McP er o a d McP er o 2000 . T i re ult i
injury in the form of discolored spots on the fruit or deformed areas, rendering the fruit
unmarketable. Stink bugs can also transmit various microorganisms, which cause plant diseases,
such as yeast-spot disease in soybeans (Daugherty 1967). A stylet sheath is often left behind at
the feeding site (Bowling 1979, 1980).
Due to the relatively new pest status of stink bugs in blackberries, very little to no research
has been conducted in this area. Morrill (1910) first reported an observation of E. servus feeding
on Rubus sp. Stink bugs feed between or on the drupelets of bramble berries and this can result
in collapsed or leaky drupelets that render the fruit unmarketable for commercial growers (D. G.
Pfeiffer, personal communication). Furthermore, stink bug feeding can alter the taste of the fruit,
which can negatively affect its marketability (S. A. Brennan, personal observation). For instance,
when a bug is disturbed, it releases its defensive chemicals onto the fruit, which causes the fruit
to have a distinctive taste. This is especially important in mechanically harvested berries where
stink bugs are continuously disturbed with the mechanical harvester (DeFrancesco et al. 2002).
Stink bugs in other crops. Stink bugs were first reported on cotton in the early 20th
century (Cassidy and Barber 1939). They have historically been a secondary pest of cotton, but
are increasing in pest status (Greene et al. 2001). This is most likely due to the transition from
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growing conventional cotton dominated by broad-spectrum insecticide applications to transgenic
cotton for control of the lepidopteran complex (McPherson and McPherson 2000).
The first record of E. quadrator in cotton was in 1998 in southern Georgia (Bundy and
McPherson 2000b). By 2004 and later in 2007, E. quadrator was listed as a common pest in
cotton in southernmost Georgia (Ruberson et al. 2009, Tillman et al. 2009a).
Stink bugs, including E. servus, occur in most regions where soybean is grown in the
United States (Turnipseed and Kogan 1976). Members of the genus Euschistus commonly found
in soybean include E. servus, E. obscurus E. quadrator, E. tristigmus, and E. ictericus (Todd
1982, Orr et al. 1986). In the mid-1970s, E. quadrator was rare in soybean in Louisiana
(McPherson 1982). Observations by Orr et al. (1986), however, in the early 1980s show a
significant increase in numbers of E. quadrator also in Louisiana. In Georgia, McPherson et al.
(1993) found low numbers of E. quadrator in soybean during a five-year study in the late 1980s.
However, increasing reports of E. quadrator in other crops in southern Georgia may lead to an
increased pest status of E. quadrator in southern grown soybean (Ruberson et al. 2009).
Cotton, soybean and other crops are often grown in close proximity. Olson et al. (2011)
determined that E. servus in southwestern Georgia strongly preferred soybean over Bt cotton,
non-Bt cotton, and peanut. This supports the earlier work of Bundy and McPherson (2000b),
who found higher numbers of E. servus in soybean than in cotton. Similarly, Herbert and Toews
(2011) and Olson et al. (2011) found soybean to be a more suitable host for reproduction of E.
servus than cotton, peanut and corn. Since some varieties of soybean have a long bloom and fruit
set period, they may support populations of stink bugs for long periods of time, allowing them to
move into other near-by crops (Toews and Shurley 2009).
23
Stink bug pest status has also been increasing in corn. Townsend and Sedlacek (1986)
attributed some of this increase into cultural control changes in the production of corn and
adoption of Bt corn as an alternative strategy for management of lepidopteran pests as opposed
to the use of broad spectrum insecticides. Tillman (2010b) found all developmental stages of E.
quadrator and E. servus in Georgia corn fields, suggesting that corn is a reproductive host for
these stink bug species (Tillman 2010b).
Monitoring and Management
Stink bugs are mobile, polyphagous pests, making monitoring and management difficult
(McPherson and McPherson 2000). There are only a few commercial methods that have been
used for monitoring stink bugs in blackberry (DeFrancesco et al. 2002, Johnson and Lewis
2003). Most monitoring information comes from crops such as cotton, pecan, peaches and
soybean. Since stink bugs are polyphagous, monitoring methods may differ between crops.
Visual searches, ground cloths, blacklight traps, fruit injury, beating and sweep net samples have
historically been used to determine stink bug infestation levels (Todd and Herzog 1980). Many
of these methods are labor intensive and can be biased against catching nymphs or adults. Sweep
netting, for example is inefficient in some crops, such as corn and cotton, and can catch more late
instar nymphs and adults (Toews and Shurley 2009).
Pheromones
Several species of stink bugs produce pheromones that attract other stink bugs and aid in
the aggregation of stink bugs in the field (Todd and Herzog 1980, Krupke et al. 2001). It is
believed that these male-produced pheromones are aggregation pheromones, as both sexes are
attracted to the pheromones in field studies (Aldrich et al. 1991, Millar et al. 2002, Leskey and
Hogmire 2005). Pheromones can be used to improve monitoring efficiency in the field.
24
Aldrich et al. (1991) trapped volatiles from male and female Euschistus spp. using gas
chromatography, they found a sex-specific component, methyl (2E,4Z)-decadienoate, produced
by males. This pheromone attracts males, females and nymphs of several Euschistus spp. and is a
major component for E. servus, E. politus (Uhler), E. ictericus, E. conspersus and E. tristigmus
(Aldrich et al. 1991). Although direct studies of volatile secretions of E. quadrator have not been
conducted, this species is caught in traps baited with the Euschistus spp. pheromone (Tillman
and Cottrell 2012, S. A. Brennan, personal observation).
Traps
Mizell and Tedders (1995) modified a pyramid trap initially developed by Tedders and
Wood (1994) to monitor for the pecan weevil, Curculio caryae (Horn). The modified pyramid
trap is used extensively in pecan and peach orchards. These pyramid traps are most effective
when painted with industrial safety yellow paint as opposed to other colors, indicating that the
color yellow may be an attractive visual stimulus for stink bugs (Mizell and Tedders 1995,
Leskey and Hogmire 2005). Yellow pyramid traps have increased attraction when paired with
the Euschistus spp. pheromone, methyl (2E,4Z)-decadienoate, offering a more convenient and
efficient method of sampling compared to visual searches, sweep netting or insecticidal sprays
(Aldrich et al. 1991, Cottrell 2001, Leskey and Hogmire 2005). This trap has detected stink bug
migration into peach and blackberry, with and without the addition of the pheromone (Mizell
2008b). However, the rate of escape from these traps depends on the cage used on top of the trap.
Cottrell (2001) found the rate of escape decreases when using an insecticidal ear tag inside the
trap, which did not decrease attraction of Euschistus spp. to the trap in pecan orchards. Hogmire
and Leskey (2006) were able to significantly reduce escape of Euschistus spp. by reducing the
cone opening inside the trap, and increasing jar size, with or without an insecticidal ear tag in
apple and peach orchards.
25
Tube traps made from clear plastic tubes with wire mesh cones on the ends have been used
in several studies with varying results, and are still commercially available for monitoring stink
bugs. Krupke et al. (2001) caught very few stink bugs using two variations of the tube trap in
mullein, while Aldrich et al. (1991) used these traps to test their Euschistus spp. pheromone in
weedy areas or blackberry patches, and caught a large numbers of stink bugs.
Other Methods of Monitoring Stink Bug Populations
A relatively new method of detection involves monitoring for the vibrational signals of
stink bugs using accelerometers. Many types of insects use plants as a type of transmission
channel for vibrational songs, which can be used for courtship, rivalry songs and female
acceptance songs (Michelsen et al. 1982). Stink bugs communicate at short range by generating
vibrational signals through a plant using a tymbal organ located underneath the elytra. These
vibrations are transmitted and detected through the legs. These signals have been characterized
for C. hilaris and N. viridula (Millar et al. 2002). Lampson et al. (2010) found four different
songs for males and two different songs for females in cotton, the same number of songs
previously reported for E. conspersus and E. heros (F.). These songs are species-specific,
allowing for discrimination between species for monitoring. Although this method is new, there
seems to be promise in providing information on stink bugs in the field. However, additional
costs of labor and materials may render this method impractical.
Regardless of the sampling method, it should be noted that stink bugs have a pronounced
edge effect in most field crops. In cotton, stink bug damage and colonization are associated
mostly within crop edges (Tillman et al. 2009b, Toews and Shurley 2009). Edge effects have
also been noted in corn, peanut and wheat (Reay-Jones 2010, Tillman 2010b, 2011a). Thus, to
improve sampling efficiency and reduce costs, sampling should occur on the edges of fields,
depending on the crop.
26
Chemical Control
Stink bugs can be tolerant to some insecticides, and the use of insecticides can kill
beneficial insects, cause harm to the environment and repeated use may cause insecticide
resistance (Crandall 1995). Historically, recommendations for stink bug control included broad
spectrum pesticides such as dichlorodiphenyltrichloroethane (DDT), parathion, lindane and
dieldrin (Borden et. al. 1952).
Organophosphates, such as methyl parathion, dicrotophos and acephate, are used
extensively to control stink bug pests in soybean and cotton (McPherson et al. 1979b, Chyen et
al. 1992, Willrich et al. 2003, Tillman and Mullinix 2004, Snodgrass et al. 2005). Methyl
parathion and dicrotophos are listed as Category 1 insecticides by the Environmental Protection
Agency (EPA). This is the most toxic out of four categories of insecticides (EPA 1991, Chyen et
al. 1992). These insecticides have demonstrated negative effects on parasitoids and predators of
stink bugs, such as Trissolcus basalis (Wollaston), Telenomus podisi Ashmead and Podisus
maculiventris (Say) (Orr et al. 1989, Sudarsono et al. 1992, Tillman and Mullinix 2004).
Alternatives to methyl parathion are pyrethroids (Chyen et al. 1992, Greene et al. 2001).
Pyrethroids, including bifenthrin (Category 2), λ-cyhalothrin (Category 2), cyfluthrin
(Category 3), and cypermethrin (Category 3) have also shown some efficacy against stink bugs.
Generally, Euschistus spp. are less susceptible to these insecticides than other stink bug species
(Willrich et al. 2003, Snodgrass et al. 2005). Cyfluthrin is more toxic to beneficial insects than E.
servus (Tillman and Mullinix 2004). Willrich et al. (2003) and Snodgrass et al. (2005) found that
brown stink bugs were more susceptible to bifenthrin compared with other pyrethroids that are
effective against other stink bug species. To achieve significant bug mortality using other
ret roid , ig rate ad to be a lied Willric et al. 2003 . λ-cyhalothrin and cypermethrin
27
had the least effect on E. servus, a d λ-cyhalothrin exhibited similar effects on E. quadrator
(Willrich et al. 2003).
Intra-species differences in susceptibility to insecticides have been shown for Euschistus
spp., N. viridula and C. hilaris (Snodgrass et al. 2005). Variation within life stages of a species
has also been demonstrated to show varying levels of susceptibility. Generally, fewer
insecticides are effective against Euschistus spp. than other pest species. In addition, late instar
nymphs of Euschistus spp. can be more susceptible to different insecticides than adults of the
same species (Willrich et al. 2003). Methyl parathion, even at a higher rate, does not provide
adequate control of E. servus fifth instars (McPherson et al. 1979b). This reiterates the fact that
effective and accurate monitoring tools must be implemented to ensure that plot management
tactics including insecticides target the proper species and life stages.
Cultural Control
Trap crops. Trap crops are used to attract and keep pest species away from the cash crop,
prevent them from entering the cash crop mechanically or to enhance natural enemy populations
(Hokkanen 1991). Trap crops are planted at a specific space and time, depending on the pest
species and cash crop. Utilizing a trap cropping system can reduce insecticide applications to the
main crop, preserve more natural enemies, and combat other issues such as pest insecticide
resistance (Hokkanen 1991). In some cases, the trap crop can be treated with insecticides to
further reduce pest pressure.
Trap crops are especially efficient considering that stink bugs prefer field borders, as well
as their tendency to aggregate as nymphs (McPherson and McPherson 2000). In many instances,
stink bug infestations are closely related to the phenology of the cash crop. This can be exploited
by planting trap crops at particular times to attract stink bugs away from the cash crop
(Hokkanen 1991, McPherson and McPherson 2000). Early-maturing soybean varieties have
28
shown promise as a trap crop for conventional soybean (McPherson et al. 2001). Stink bugs
typically colonize these early-maturing varieties before moving into conventional soybean as the
early varieties senesce. This temporal difference would enable the grower to minimize
insecticide treatments in the conventional soybean, and predict stink bug infestations based on
crop phenology (Smith et al. 2009).
Many different species of plants are recommended for trap cropping of stink bugs,
depending on the cash crop. Triticale [Triticale hexaploide Lart.], sorghum [Sorghum bicolor
(L.)], millet [Pennisetum glaucum (L.)], buckwheat [Fagopyrum sagittatum Gilib], sunflower
[Helianthus annus L.], soybean, field peas [Phaseolus vulgaris L.], okra [Abelmoschus
esculentum Moench] and others have been evaluated as potential trap crops for stink bugs
(Bundy and McPherson 2000b, Mizell 2008a, Olson et al. 2011, Tillman 2011b).
Biological Control
Parasitoids. Biological control methods do exist, as most Euschistus spp. are susceptible
to parasitoids and predators (McPherson and McPherson 2000). Stink bugs are attacked by
several different parasitoids and predators at both the immature and adult stages. Telenomus
podisi is a common egg parasitoid of E. servus, along with Trissolcus euschisti Ashmead, T.
basalis, T. brochymenae (Ashmead) T. thyantae Ashmead, Ooencyrtus spp. and Trissolcus
edessae Fouts (Yeargan 1979, Orr et al. 1986, Koppel et al. 2009, Tillman 2010a).
In addition to egg parasitoids, several parasitoids attack adult Euschistus spp., with
Gymnoclytia immaculata (Macquart), Cylindromyia euchenor (Walker), and Euthera tentatrix
Loew attacking E. quadrator, and Trichopoda pennipes (F.), Gymnoclytia occidua (Walker), C.
euchenor, E. tentatrix, and Gymnosoma fuliginosum Robineau-Desvoidy attacking E. servus
(Eger and Ables 1981, McPherson et al. 1982). Ruberson et al. (2009) found the first record in
29
the Americas of the braconid wasp, Aridelus rufotestaceus Tobias parasitizing E. servus in
Georgia soybean.
Tillman et al. (2010) discovered that a common tachinid parasitoid of E. servus,
Cylindromyia sp., was attracted to the aggregation pheromone, methyl (2E,4Z)-decadienoate,
used for monitoring Euschistus spp. in the field. Other parasitoids that use this pheromone as a
host finding kairomone are Gymnosoma spp. and Euthera spp. (Aldrich et al. 1991).
Many chewing and sucking predators attack stink bug eggs. These include minute pirate
bugs (Orius spp.), the cotton fleahopper, (Pseudatomoscelis seriatus (Reuter)), a plant bug
(Spanagonicus sp.), the spined soldier bug, (Podisus maculiventris), the big-eyed bugs (Geocoris
uliginosus (Say) and G. punctipes (Say)) and several species of ants and lady beetles (Yeargan
1979, Ruberson et al. 2009, Tillman 2010a, 2011b). Stink bugs also feed on their own eggs in the
field and laboratory (Ruberson et al. 2009, S. A. Brennan, personal observation).
Ruberson et al. (2009) also discovered the first record of fungal infection of E. servus.
They were unable to identify the fungus because it was not sporulating, but determined that it
belonged the fungal order Entomophthorales, a group of entomopathogenic fungi.
Organic Control
Relatively few products are effective for stink bug control in organic crops. With a
growi g tre d toward i ecticide reductio via IPM tec ique , a d co u er ’ de ire for
organic produce, only a few insecticides have been labeled for organic pest control. Three
organic insecticides that have been used for stink bugs are azadirachtin (Neem), pyrethrins
(PyGanic) and spinosad (Entrust).
Azadirachtin is derived from the neem tree, Azadirachta indica (A. Juss), and exhibits
feeding deterrency and growth disruptive properties (Mordue and Blackwell 1993). It is effective
against other insects, such as Japanese beetles and locusts as a feeding deterrent (Butterworth
30
and Morgan 1971, Ladd et al. 1978). Kamminga et al. (2009) found that E. servus adults were
susceptible to azadirachtin when mixed with spinosad or pyrethrins. Azadirachtin-treated
tomatoes had fewer stylet sheaths than untreated tomatoes, however azadirachtin had no effect
on stink bugs in a filter paper repellency test (Kamminga et al. 2009).
Pyrethrins are derived from plants in the family Compositae, such as Chrysanthemum
cinerariifolium (Trev.), and can cause rapid knockdown and eventual death of insects by
effecting nerve function (Casida 1980). Pyrethrins were used in the early 1800s to control body
lice and many other household and agricultural pests (Casida 1980). Kamminga et al. (2009)
found that E. servus adults and nymphs were only susceptible to pyrethrins when mixed with
spinosad. They were effective, however, in repelling stink bugs when applied to tomatoes and
filter paper (Kamminga et al. 2009).
Spinosad is from a class of insecticides, spinosyns, which are derived from a soil
microorganism, Saccharopolyspora spinosa (Mertz and Yao) (Sparks et al. 1998). Spinosad acts
as a contact poison and is effective against many different pests, including thrips and
lepidopteran pests, and is less toxic to beneficial predators (Boyd and Boethel 1998, Sparks et al.
1998, Kamminga et al. 2009). Euschistus servus adults are susceptible to spinosad, alone or tank
mixed with azadirachtin or pyrethrins, but nymphs are not affected (Kamminga et al. 2009).
However, spinosad-treated tomatoes had no effect on E. servus and insects were attracted to it in
filter paper repellency tests (Kamminga et al. 2009).
Justification
Stink bugs have the potential to cause injury to blackberry as well as other fruit crops by
feeding on the fruit and reducing the marketable yield. They are highly polyphagous and several
techniques, including use of sweep nets, fruit injury, in situ counts and pheromone baited traps,
have been used to monitor stink bugs. For instance, pheromone baited traps painted with
31
industrial safety yellow enamel paint have been used successfully to monitor brown stink bugs,
E. servus, the dusky stink bug, E, tristigmus, and the green stink bug C. hilaris (Leskey and
Hogmire 1995). Developing an effective monitoring protocol may reduce reliance on routine
pesticide applications and give growers time to respond to increasing populations.
Correct identification is important to select the most appropriate pest management tools.
Pest management tools, including pesticides, are only effective against certain species (Flint and
Gouveia 2001). To facilitate correct identification of E. quadrator, detailed descriptions of the
immatures were reported herein. Adults were not described since they were described by Rolston
(1974).
Hypotheses
H0: Stink bugs are present in blackberry.
HA: Stink bugs are not present in blackberry.
H0: The yellow pyramid trap will be more effective than the tube trap for
monitoring stink bugs in blackberry.
HA: There are no differences between the yellow pyramid trap and tube trap for
monitoring stink bugs in blackberry.
H0: The addition of pheromone lures will increase trap captures of stink bugs.
HA: Pheromone lures do not increase trap captures for stink bugs.
Specific Objectives
1. To identify key stink bug species in blackberry.
2. To describe the immature stages of Euschistus quadrator.
3. To evaluate traps and pheromone lures in the subsequent categories for monitoring stink
bug species: a) trap comparison in blackberry field test, b) pheromone lure comparison in
blackberry field tests and laboratory bioassays.
32
CHAPTER 3
STINK BUG SPECIES SURVEY IN BLACKBERRIES
Since blackberries are a relatively new crop for the southeast, most of the recommended
pest management information applies to the northwestern United States where blackberries have
been an important crop for decades. However, many pest species present in other areas affect
blackberries in the southeast. Thrips, spider mites, stink bugs and beetles have been listed as
pests of concern for Florida, and these pests are also present in the northwest (Ellis et al. 1991,
Mizell 2007, O. E. Liburd, personal communication). Euschistus spp., the southern green stink
bug, Nezara viridula (L.) and the green stink bug, Chinavia hilaris (Say), have been reported as
pests of blackberries (Johnson and Lewis 2003, Anonymous 2008, Mizell 2008a), and the brown
stink bug, Euschistus servus (Say), causes injury to other Rubus spp. crops (Maxey 2011). With a
southern shift in blackberry production, it is likely that stink bugs will become more of an issue
in blackberry crops.
Historically, the most commonly collected stink bugs in many crops are the brown stink
bug, E. servus, the southern green stink bug and the green stink bug (McPherson and McPherson
2000). In recent years, E. quadrator Rolston and other minor species in the genus are increasing
i e t tatu , a d are ow referred to a t e ‘Le er Brow ti k Bug co le ’ Ho ki et al.
2005). Members of the genus Euschistus have been found in corn, cotton, rice, soybean, pecan
and peach in Florida (Ashmead 1887, Hill 1938, Temerak and Whitcomb 1984, Mizell 2008b,
Sprenkel 2008, Nuessly et al. 2010, Wright et al. 2011). In 2008 and 2009, large numbers of
stink bugs (several species) were observed in blackberries in Citra, Florida (O. E. Liburd,
personal communication). With the changing pest complex and potential future increases in
blackberry production in the southeast, it is necessary to identify and survey any new pest
species, including stink bugs, which may pose a threat to increasing production. Here, we used a
33
knockdown technique to monitor the species complex in blackberries. This technique involves
placing a collecting device on the ground at the base of the plant. The plant is then shaken
vigorously until the pest species is dislodged from its host and falls into the collecting device.
Insects are then placed into a collecting jar and later identified to species. The specific objective
for this study was to identify stink bug species present in blackberry.
Materials and Methods
Research was conducted at the University of Florida, Plant Science Research and
Education Unit in Citra, Florida, and at the Small Fruit and Vegetable IPM laboratory in
Gainesville. The experimental site in Citra consists of two 0.12 ha sites, each composed of six
blackberr varietie , ‘Kiowa’, ‘Ouac ita’, ‘Ara a o’, ‘C icka aw’, ‘C octaw’ a d ‘Natc ez’
(Figure 3-1). Each row is approximately 38 m long with 30 blackberry plants, and rows are
spaced approximately 4.5 m apart. Half of the site is managed as a traditional conventional site
and the other is managed as an organic site. Blackberry plants were approximately 3 years old
and 1.5 meters tall.
Each site was watered using a hard line with in-line emitters as needed, not exceeding
2500-3000 gallons/acre/day. Drip irrigation was placed in middle of each row. The organic plot
received half the amount of water as the conventional plot. Organic plots were covered with
DeWitt landscaping tarp [DeWitt Company, Sikeston, MO]. Hydrosource water-gathering
crystals [Castle International Resources, Sedona, Arizona] in various sizes (medium and
standard) were added to the soil in the organic plots for water retention (Figure 3-1). After
fruiting, floricanes were pruned to allow room for the primocanes. Blackberries were grown on a
moving arm shift trellis (Stiles 1999).
Both conventional and organic plots were sprayed with copper sulfate as a fungicide.
Conventional plots also received t e fu gicide ‘Pri ti e’ [BA F, Co., Research Triangle Park,
34
NC], w erea orga ic lot were ra ed wit t e fu gicide ‘ ere ade’ [AgraQuest, Inc., Davis,
CA]. With respect to nutrition, conventional plots were fertilized with 10-10-10 and the organic
plots were fertilized with Nature Safe 10-2-8 [Nature Safe Cold Spring, KY]. Weed control in
t e co ve tio al lot wa acco li ed wit t e erbicide ‘Rou d U ’ [Mo a to, t. Loui ,
MO], whereas weeds were hand-pulled from the organic plot.
Sampling was conducted on four randomly chosen blackberry plants of each variety in
both blackberry plots. A harvest tray (~ 1 x 0.6 m) [Wal-Mart, Gainesville, FL] was placed on
the ground at the base of the blackberry bush. Bushes were shaken vigorously 3-4 times over the
tray and the cover of the tray replaced immediately. Sampling occurred once every 2 wk for 8
wk. All stink bug species that fell into the tray were collected. In 2010, stink bugs were sampled
from May 8th
to June 19th
when bushes were more than 50% fruiting. Stink bugs from each
sample were transferred to collecting jars and labeled by date, sample and variety. All jars were
brought back to the Small Fruit and Vegetable IPM laboratory at the University of Florida in
Gainesville, FL. All stink bugs were counted, mounted, pinned and identified to species using a
key to the Florida families of Pentatomidae developed by Dr. J. Eger.
Data Analysis. All information is presented as raw data (total counts) due to low numbers
of stink bugs found in the field.
Results
A total of 54 stink bugs were collected in the blackberry plot throughout the sampling
period. Table 3-1 represents the species collected including E. quadrator, which was the most
abundant, followed by E. servus, E. obscurus (Palisot de Beauvois), Thyanta custator (F.),
Proxys punctulatus (Palisot de Beauvois) and the spined soldier bug, Podisus maculiventris Say
(Figure 3-2). Both males and females of most species were found in the field (Table 3-1). Only
35
adults were collected, which may mean that blackberries are not a reproductive host for these
stink bugs.
Other insects collected included ants (Hymenoptera: Formicidae), spiders (Arachnida:
Araneae: Salticidae; Arachnida: Araneae: Oxyopidae), grasshoppers (Insecta: Orthoptera:
Acrididae), plant bugs (Insecta: Hemiptera: Miridae), katydids (Insecta: Orthoptera:
Tettigoniidae), leaffooted bugs (Insecta: Hemiptera: Coreidae), lady beetles (Insecta: Coleoptera:
Coccinellidae) and flower beetles, Euphoria sepulcralis (F.) (Coleoptera: Scarabaeidae).
Discussion
The first visual sighting of stink bugs was of E. servus on 28 April 2010 in the organic
plot. The organic plot began fruiting after the conventional, but fruit became riper faster in the
organic plot, which may have been more attractive to stink bugs. Although overall stink bug
numbers were low, there is a general correlation between the number of stink bugs found on each
sampling date with the amount of ripe fruit in each plot. As the percent of ripe fruit increased in
both the organic and conventional plots, the number of stink bugs also increased (Figure 3-3).
During sampling, most stink bugs were found on the third sampling date (6/5/2010), when most
berries were ripe (Table 3-2). An approximately equal number of stink bugs were found in the
organic plot (28) and the conventional plot (26) (Table 3-3). The Chickasaw variety produced the
most stink bugs across both the conventional and organic plots. This variety ripens
approximately 1 wk later than Kiowa and Natchez varieties.
Several new pest records for blackberries were found. This is the first known record of E.
quadrator, E. obscurus, T. custator, P. punctulatus and P. maculiventris in blackberry. Little, if
any, information has been published in journals on the stink bug complex in blackberries. The
limited information available is on websites, which state that green stink bugs, southern green
stink bugs and brown stink bugs are most prominent.
36
The majority of stink bug information in Florida, especially for Euschistus spp., is from the
early 20th
century. A review of the literature shows that, historically, the pest status of stink bugs
in Florida is debatable. The most commonly mentioned stink bugs in the state are N. viridula, E.
servus and E. ictericus (L.). Nezara viridula is commonly found in rice, soybean, faba bean and
various weeds in southern Florida (Buschman and Whitcomb 1980, Temerak and Whitcomb
1984, Jones and Cherry 1986, Nuessly et al. 2004, Cherry and Wilson 2011). Euschistus servus
is usually seen in pecans, soybean, elderberry and goldenrods in Florida (Hill 1938, Frost 1979,
Fontes et al. 1994). Euschistus ictericus is found in rice and faba bean (Temerak and Whitcomb
1984, Jones and Cherry 1986,Nuessly et al. 2004, Cherry and Wilson 2011). There is no doubt
that these pests occur in other Florida crops, but literature with this information was not found.
Other documented occurrences of Euschistus spp. in Florida include E. obscurus in elderberry
and goldenrod, and E. quadrator in faba bean (Frost 1979, Fontes et al. 1994, Nuessly et al.
2004). Given this information, we expected to find mostly green stink bugs and E. servus in field
trials.
When using any monitoring device, care should be taken in identifying the stink bug
species present. Euschistus servus is relatively easy to identify versus other Euschistus spp., but
E. ictericus, E. tristigmus (Say) and P. maculiventris look very similar, and the smaller brown
stink bugs of the ‘Le er Brow ti k Bug co le ’ are easily confused. Predatory stink bugs,
such as the spined soldier bug, may be mistaken as pests. Podisus maculiventris is a beneficial
predatory stink bug that mostly feeds on lepidopteran and coleopteran larvae, but has been
shown to feed on phytophagous stink bugs (McPherson et al. 1980, McPherson and McPherson
2000). Predatory stink bugs can be differentiated from phytophagous stink bugs most easily by
the mouthparts. Predatory stink bugs have a short and thick first rostral segment, which is free
37
from the body. Phytophagous stink bugs have a slender first rostral segment that appears to
attach at the anterior tip of the head ventrally (Mizell 2008b). The yellow pyramid traps capture
both predatory and pest species using the Euschistus spp. pheromone (Mizell 2008a).
Of the other insects found, several beneficials were collected including ants (Formicidae),
spiders (Salticidae and Oxyopidae), and lady beetles (Coccinellidae). Other pest species included
grasshoppers (Acrididae), plant bugs (Miridae), katydids (Tettigoniidae), leaffooted bugs
(Coreidae) and flower beetles, Euphoria sepulcralis (F.). This species of beetle is common in
Florida and known for feeding on flowers and ripe fruit (Frost 1979, Turner and Liburd 2007).
Overall, blackberries in Florida seem to have a different stink bug complex than that of
other production areas. While we found several Euschistus spp. that are commonly mentioned in
other areas, we did not find either the green stink bug or the southern green stink bug. It is also
interesting to note that so many different Euschistus spp. were found on the blackberries at the
same time, and that E. quadrator was the dominant species.
38
Table 3-1. Species complex by sex in blackberries using the beating tray method
Species Male Female Unknown Total
E. quadrator 11 10 21
E. servus 7 5 12
E. obscurus 5 4 9
T. custator 3 3 6
P. punctulatus 0 2 1 3
P. maculiventris 0 3 3
Total 54
39
Table 3-2. Numbers of each stink bug species collected by date
Date E. quadrator E. servus E. obscurus P. maculiventris T. custator P. punctulatus Total
5/8/2010 3 0 1 2 0 0 6
5/22/2010 4 2 3 1 1 0 11
6/5/2010 9 4 5 0 3 2 23
6/19/2010 5 6 0 0 2 1 14
Total 21 12 9 3 6 3 54
40
Table 3-3. Numbers of stink bug species collected by blackberry variety (5/8/2010-6/19/2010)
Blackberry # of Stink Bugs
Variety Organic Conventional
Kiowa 3 7
Ouachita 7 3
Arapaho 3 1
Choctaw 3 1
Chickasaw 10 8
Natchez 2 6
Total 28 26
41
Figure 3-1. Blackberry field layout in Citra, FL
42
Figure 3-2. Species complex in blackberries using the beating tray method
43
Figure 3-3. Total stink bug numbers correlated with mean percent fruit development in organic
and conventional blackberry plots
44
CHAPTER 4
MONITORING STINK BUGS IN BLACKBERRY
Blackberry production in the southeastern United States is increasing. Georgia has tripled
its production in the last 10 years and harvested 122 ha of blackberries in 2007 (Strik et al. 2007,
USDA 2009). Similarly, blackberry production has increased fivefold in Florida (O. E. Liburd,
personal communication). Traditionally, blackberry production in Florida only involved small
backyard operations and small (<0.3) ha u-pick operations. Now, growers are experimenting
with larger acreage (3-5 ha). Currently total production in Florida is estimated between 5-75 ha
and increasing. Florida, along with much of the southeast, has a humid subtropical climate,
which is likely to support good blackberry yield (Kottek et al. 2006). Earlier ripening of
blackberries in Florida may enable growers to meet a market window not currently being filled
by other southern states.
In recent years, several blackberry cultivars have been developed to be more tolerant to the
climatic conditions of the southern United Sates, making these states a candidate for commercial
blackberry production (Jennings et al. 1991, Moore 1997). Pest and disease problems are
expected to increase as blackberry production expands into these states. Recent sightings of large
numbers of stink bugs and other hetero tera i Florida’ berrie ju tifie tudie to evaluate
their roles in blackberry production in these non-traditional states. It is possible that stink bugs
will become more of a problem in blackberries as they have in other southeastern crops.
Very little research has been conducted on stink bugs in blackberries. Stink bugs cause
feeding injury in blackberries in the form of collapsed or leaky drupelets that render the fruit
unmarketable for growers (D. G. Pfeiffer, personal communication). Moreover, stink bug feeding
can alter the taste of the fruit, which can also negatively affect its marketability (S. A. Brennan,
personal observation).
45
Stink bugs are highly mobile and polyphagous pests, which makes monitoring difficult
(McPherson and McPherson 2000). Visual searches, ground cloths, blacklight traps, fruit injury,
beating and sweep net samples have typically been used to determine stink bug infestation levels
(Todd and Herzog 1980). Many of these methods are labor intensive and can be biased against
catching nymphs or adults (Toews and Shurley 2009). The addition of pheromones can be used
to improve monitoring efficiency in the field.
Aldrich et al. (1991) trapped volatiles from male and female Euschistus spp., and using gas
chromatography, found that the major component produced by males is methyl (2E,4Z)-
decadienoate. This pheromone attracts males, females and nymphs of several Euschistus spp.
(Aldrich et al. 1991). Euschistus quadrator Rolston was also caught in yellow pyramid traps
baited with the Euschistus spp. pheromone (Tillman and Cottrell 2012, S. A. Brennan, personal
observation).
A commonly used trap for stink bugs, the yellow pyramid trap, was developed by Mizell
and Tedders (1995). These pyramid traps are most effective when painted with industrial safety
yellow as opposed to other colors (Leskey and Hogmire 2005, Mizell and Tedders 1995). Yellow
pyramid traps have been shown to increase attraction of stink bugs when paired with the
Euschistus spp. pheromone [methyl (2E,4Z)-decadienoate], offering a more convenient and
efficient method of sampling for stink bugs compared to other methods (Aldrich et al. 1991,
Cottrell 2001, Leskey and Hogmire 2005). This trap has detected stink bug migration into
blackberry, with and without the addition of the pheromone (Mizell 2008a).
Tube traps made from clear plastic tubes with wire mesh cones on the ends have been used
in several studies with varying results, and are commercially available for monitoring stink bugs.
Krupke et al. (2001) caught very few stink bugs using two variations of the tube trap. However,
46
Aldrich et al. (1991) used these traps to test their Euschistus spp. pheromone and caught large
numbers of stink bugs.
With the increase in blackberry production in and around Florida, as well as the apparent
elevation in pest status of stink bugs, determining an effective monitoring tool for selected stink
bug species is essential for growers. The specific objectives of this study were:
1. To compare commercial traps for monitoring stink bugs in blackberries
2. To compare pheromone lures for captures of stink bug species in a Y-tube assay and field
deployment experiments.
Materials and Methods
Study Site
Research was conducted at the University of Florida, Plant Science Research and
Education Unit in Citra, Florida, and at the Small Fruit and Vegetable IPM laboratory in
Gainesville, Florida.
Trap Comparison
Two different types of commercially available stink bug traps, 1) Yellow Pyramid trap [R.
Mizell, Quincy, FL] and 2) Trécé tube trap [Great Lakes IPM, Vestaburg, MI], were compared
with and without pheromone lures. Pyramid traps were constructed as recommended by Dr.
Russell F. Mizell (Mizell 2008a). Both the Trécé Pherocon Centrum lure [Trécé Inc., Adair, OK]
and Suterra Scenturion lure [Suterra Corporate, Bend, OR] were used in each baited trap since
information on the lure that performs the best was unavailable.
Four treatments were evaluated as follows: 1) Pyramid trap baited, 2) Pyramid trap
unbaited, 3) Trécé trap baited, and 4) Trécé trap unbaited. The experiment was a completely
randomized block design with three replicates. Blackberry bushes were approximately 3 years
old a d 1.5 tall. Varietie co i ted of ‘Kiowa’, ‘Ouac ita’, ‘Ara a o’, ‘C icka aw’,
47
‘C octaw’ a d ‘Natc ez’. The yellow pyramid trap was placed just east of the row
approximately 0.5 m from the bushes (Figure 4-1). The Trécé tube trap was hung from the trellis
inside the bush approximately 1 m from the ground (Figure 4-2). Traps were spaced a minimum
of 15 m apart and were blocked by variety (row). Traps were placed on the first, third and fifth
rows. Trap contents were emptied into collecting jars and rotated weekly for three weeks. All
stink bug species were brought back to the Small Fruit and Vegetable IPM laboratory at the
University of Florida to be counted, mounted, pinned and identified.
Pheromone Comparison
Laboratory study
A bioassay was conducted in a glass Y-tube olfactometer [Chemglass Life Sciences,
Vineland, NJ]. Humidified airflow was maintained at 1,000 ml/min using a 2-channel air
delivery system, with two glass flowmeters, an acrylic chassis, two charcoal filters, and two gas
bubblers [Analytical Research Systems, Gainesville, FL]. The glass Y-tube (150 mm main tube,
80 mm arms, 35 mm internal diameter, 40/35 joints) was held at a 30 angle inside a cardboard
box (44 × 30 × 23 cm) on a piece of foam core set at a 5% incline (Figure 4-3). Preliminary
studies indicated that E. quadrator responded better at a 5% incline as opposed to a horizontal
surface. Foam core and interior of box were white. A hole was cut into the side of the box at the
end of the Y-tube so that pheromones did not collect and pool inside the box. Two mason jars,
located outside of the box, were modified to house the lures during the assay (Figure 4-3). Holes
were drilled into the lids, and valves were secured to the lids that were connected to the plastic
tubing attached to the filtration system.
Two commercially available aggregation pheromone lures for monitoring Euschistus spp.,
1) Trécé Pherocon Centrum lure and 2) Suterra Scenturion lure, were compared in the Y-tube
bioassay. Treatments were compared as follows: 1) Trécé Pherocon Centrum lure against a blank
48
control, 2) Suterra Scenturion lure against a blank control, and 3) Trécé Pherocon Centrum lure
versus Suterra Scenturion lure. Stink bugs were placed in the Y-tube base and allowed to
acclimate for 3 min before attaching the Y-tube arms and airflow. Stink bugs were evaluated to
determine their preference, and the time it took them to make a decision was recorded. A choice
was considered made after the insect remained in one of the arms for 1 min. Stink bugs were
considered unresponsive after staying in the Y-tube for 15 min without making a choice. Adult
stink bugs > 1 month old were used in the assay. A total of 20 responding stink bugs per
treatment were evaluated, with the jars being rotated after 10 stink bugs to prevent positional
bias.
Field study
Two different aggregation pheromone lures marketed commercially for stink bug
monitoring were evaluated, 1) Trécé Pherocon Centrum lure and 2) Suterra Scenturion lure.
Yellow pyramid traps were used because my preliminary trap comparison research indicated that
these traps performed better than tube traps. Three treatments were compared as follows: 1)
Trécé Pherocon Centrum lure, 2) Suterra Scenturion lure and 3) unbaited trap. Experimental
design was a completely randomized block with four replicates. Traps were placed just east of
the row approximately 0.5 m from the bushes. Traps were spaced a minimum of 15 m apart and
were blocked by variety (row). Traps were placed in the first, third, fifth and sixth rows. Trap
contents were emptied into collecting jars and traps were rotated weekly. All stink bug species
were brought back to the Small Fruit and Vegetable IPM laboratory at the University of Florida
to be counted, mounted, pinned and identified.
Pheromone Concentration Comparison
The Trécé Pherocon Centrum lure was evaluated in three different concentrations
(treatments) as follows: 1) one lure, 2) two lures and 3) three lures. These treatments were
49
compared to an unbaited control. The Trécé Pherocon Centrum lure was used because it
performed numerically better than the Suterra Scenturion lure in previous field experiments. All
treatments were used with the yellow pyramid trap. Experimental design was a completely
randomized block with three replicates. Traps were placed just east of the row approximately 0.5
m from the bushes. Traps were spaced a minimum of 15 meters apart and were blocked by
variety (row). Traps were placed in the first, third and fifth rows. Traps were sampled once per
week for 4 weeks. All stink bug species were brought back to the Small Fruit and Vegetable IPM
laboratory at the University of Florida to be counted, mounted, pinned and identified.
Data Analysis
Field experiments were arranged in a randomized complete block design. Resulting data
were analyzed using analysis of variance (ANOVA) and differences among means were
determined using a least significant difference (LSD) mean separation test (0.05) (PROC GLM,
SAS Institute 2008). The Y-tube assay data were analyzed using a chi-square analysis with an
expected probability of 0.5. A t-test was used to determine any significant differences between
sexes of Euschistus spp. caught in traps (0.05) (PROC TTEST, SAS Institute 2008).
Results
Trap Comparison
There was a significant difference between trap types, with the yellow pyramid trap
catching more stink bugs than the tube trap (Figure 4-4; F=4.93, df=5, P=0.0021). However,
there were no significant differences between a baited and unbaited pyramid or tube trap. Both
males and females were caught in the traps, but there were no statistical differences between
sexes (t=0.49, P=0.6526).
50
The species recorded for this experiment, in order of abundance, consisted of Euschistus
servus (Say) being the most common, followed by E. quadrator, Podisus maculiventris Say, E.
obscurus (Palisot de Beauvois), Euschistus ictericus (L) and Thyanta custator (F.) (Table 4-1).
Pheromone Comparison
In the Y-tube assays, there were no statistical differences between any of the treatments
(Table 4-2). In the Trécé lure versus a blank control, 12 stink bugs chose the lure and 8 chose the
blank control (χ2= 0.8, df=1, P=0.3711). In the Suterra lure versus a blank control, 10 stink bugs
each chose the lure or the blank control (χ2= 0.0, df=1, P=1.00). In the Trécé lure versus the
Suterra lure, 13 stink bugs chose the Trécé lure and 7 chose the Suterra lure (χ2= 1.8, df=1,
P=0.1797). There were a total of 12 non-responders, distributed fairly evenly across all
treatments.
Similar to my Y-tube assays, no significant differences were found in the field tests that
compared pheromone baited pyramid traps with and unbaited pyramid traps (Figure 4-5; F=1.80,
df=5, P=0.1339). Numerically, traps baited with the Trécé lure caught more stink bugs (n=10),
but not enough to be significantly more effective than the Suterra lure or unbaited traps. The
unbaited traps captured five stink bugs, and the Suterra lure caught seven. The species
composition for this experiment consisted of E. servus being the most common, followed by T.
custator, E. quadrator and E. ictericus (Table 4-3). Both males and females were caught in the
traps, but there were no statistical differences between sexes (t=0.18, P=0.8648).
Pheromone Concentration Comparison
There were no significant differences between traps baited with any pheromone load rates
and unbaited traps (Figure 4-6; F=2.23, df=5, P=0.0772).
The species composition for this experiment consisted of E. servus being the most
common, followed by E. quadrator, T. custator E. ictericus and P. maculiventris (Table 4-4).
51
Both males and females were caught in the traps, but there were no statistical differences
between sexes (t=-0.88, P=0.4309).
Discussion
In the trap comparison experiment, no stink bugs were caught in the tube traps. This is
similar to the observations of Krupke et al. (2001), where very low numbers of stink bugs were
captured when comparing two different sizes of tube trap. However, Aldrich et al. (1991) caught
a significant number of stink bugs in the genus Euschistus using the tube trap in a deciduous
forest. This indicates that tube traps may not be effective in blackberry crops but may have
potential uses in other crops. This may be due to the fact that stink bugs may rely more on the
visual cues of the pyramid trap, or that they may tend to remain on or near berry clusters and not
in the foliage of the plant. The pyramid traps were effective in catching stink bugs, either with or
without the addition of the Euschistus spp. pheromone. Overall, stink bug numbers were
relatively low, so there were no statistical differences between a baited and an unbaited trap.
Most studies using the pyramid trap find that the addition of the Euschistus spp. pheromone
increases the efficacy of the trap (Leskey and Hogmire 2005).
In the pheromone comparison experiment, there were no statistical differences between the
Trécé Pherocon Centrum lure, the Suterra Scenturion lure and an unbaited trap. Again, stink bug
numbers were low, which may account for the observed non-significant differences and the
obvious similarities in effectiveness. However, these results were supported by the Y-tube
olfactometer assay where there were no statistical differences between the lures and a control,
although higher numerical values were recorded with the Trécé lure when using E. quadrator.
One of the reasons why the Y-tube assay did not show differences might be related to the
fact that stink bugs can be overwhelmed by the presence of a large amount of pheromones. This
has also been hypothesized by Krupke et al. (2001). The Y-tube used in this experiment was
52
modified with mason jars to possibly counteract this effect. The composition of these
commercial lures was unknown since this was proprietary information that the companies would
not disclose. Since there were no statistical differences between lures, both in the field and in the
Y-tube bioassay, there are a number of factors that may merit further study. These factors
include the ratio of pheromone components of the lure, the previous experience of the insects,
food or mate availability and the release rates of the lures.
Species found in field experiments include E. quadrator, E. servus, E. obscurus, T.
custator, E. ictericus and P. maculiventris (Figure 4.7). Only adult stink bugs were caught in
monitoring traps, and both males and females were caught. Since no statistical differences
between sexes were found, it can be determined that this trap attracts both males and females.
Stink bugs appear to colonize blackberry when berries are mid-ripe to fully ripe. In the trap
comparison experiment, a total of 35 total stink bugs were found, with the majority found in
traps located in the Kiowa variety. Kiowa ripens earlier than most varieties in early June, and
fruiting extends for six weeks (Moore and Clark 1996). The peak in stink bug numbers occurred
during the week of 5/5/2010, when berries were mid-ripe. In the pheromone comparison
experiment, most stink bugs were found during the week of 5/26/2010 in Kiowa and Natchez
when berries were beginning to ripen. Natchez also ripens early in June, and fruiting extends for
four weeks (Clark and Moore 2008). In the pheromone concentration experiment, most stink
bugs were found in Kiowa in the week of 7/7/2010 when berries were ripe.
Proxys punctulatus (Palisot de Beauvois) was not caught in traps during field studies, but
was found in the species survey experiment (Chapter 5). This stink bug has been found
previously in the pyramid trap (Mizell 2008a). It has been suspected of being predaceous but is
also known to feed on plants and weeds, such as cotton, Gossypium hirsutum (L.), and zigzag
53
spiderwort, Tradescantia subaspera Ker (Vangeison and McPherson 1975, Gomez and Mizell
2009). These stink bugs are not thought to cause significant economic damage (Schaefer and
Panizzi 2000).
With the pyramid trap, several different tops can be used with the yellow pyramid base.
Although rate of escape was not calculated during the experiments, observations between
sampling dates indicated that stink bugs are able to escape when using the screen top. Cottrell
(2001) found a high rate of escape when using 2.8 L jar tops and that Euschistus spp. have a high
rate of escape within 24 hours of being put in the trap when using a jar top. Later, Hogmire and
Leskey (2006) found that by decreasing the jar opening and increasing the jar size, the rate of
escape can be reduced. The plans followed for these experiments include a 2.5 inch opening on
the screen top, which may have accounted for a few escapes. If using a screen top, the addition
of an insecticidal ear tag may help prevent escape. Based on findings from other studies, it may
be more effective to use a jar top on the trap as opposed to a screen top, although this may be
more costly for growers.
Overall, the yellow pyramid trap was more effective than the tube trap for monitoring stink
bugs in blackberry. The pheromone lures were no more effective than an unbaited trap, however
this may be a result of low stink bug numbers in the field. In both field studies and the Y-tube
assay, the Trécé Pherocon Centrum lure performed better numerically than the Suterra
Scenturion lure or an unbaited trap but there were no significant differences. The screen top may
have a higher rate of escape than other tops, but the addition of an insecticidal ear tag may
counteract this effect. This research may provide information for growers who are considering
the purchase of available lures as to which lure is more practical and whether a lure is needed for
their field setting.
54
Table 4-1. Species complex of stink bugs captured in trap comparison study
Species Male Female Total
E. quadrator 5 1 6
E. servus 5 10 15
E. obscurus 1 3 4
T. custator 1 0 1
E. ictericus 1 3 4
P. maculiventris 0 5 5
Total 35
Table 4-2. Chi-square values for each treatment in Y-tube assays (n=60)
Treatment χ2 P
Trécé vs. Control 0.8 0.3711
Suterra vs. Control 0 1
Suterra vs. Trécé 1.8 0.1797
55
Table 4-3. Species complex of stink bugs captured in pheromone comparison study
Species Male Female Unknown Total
E. quadrator 2 1 3
E. servus 2 6 1 9
E. obscurus 0 0 0
T. custator 3 3 2 8
P. punctulatus 0 0 0
E. ictericus 2 0 2
E. tristigmus 0 0 0
Total 22
Table 4-4. Species complex of stink bugs captured in pheromone concentration comparison
study
Species Male Female Total
E. quadrator 2 3 5
E. servus 8 2 10
T. custator 1 3 4
E. ictericus 1 0 1
P. maculiventris 0 1 1
Total 21
56
Figure 4-1. Yellow pyramid trap with screen top (Photo credit by: Sara Brennan)
57
Figure 4-2. Tube trap (Photo credit by: Sara Brennan)
58
Figure 4-3. Y-tube olfactometer set up. A) jar 1, B) jar 2, C) air filtration system, D) modified
cardboard box, E) aeration hole, F) foam board
59
Figure 4-4. Mean number of stink bugs captured in yellow pyramid traps (YP) or tube traps with
(B) or without (UB) pheromone lures. Means followed by the same letter are not
significantly different according to ANOVA (F=4.93, df=5, P=0.0021).
60
Figure 4-5. Mean number of stink bugs captured in yellow pyramid traps baited with Trécé or
Suterra pheromone lures or without lures (UB). Means were not significantly
different according to ANOVA (F=1.80, df=5, P=0.1339).
61
Figure 4-6. Mean number of stink bugs captured in yellow pyramid traps baited with one, two or
three Trécé lures or unbaited (UB). Means were not significantly different according
to ANOVA (F=2.23, df=5, P=0.0772).
62
43.59%
17.95%
16.67%
8.97%
7.69%
5.13%
E. servus
E. quadrator
T. custator
E. ictericus
P. maculiventris
E. obscurus
Figure 4-7. Percent stink bugs captured per species in field experiments (n=78)
63
CHAPTER 5
LABORATORY REARING AND DESCRIPTIONS OF IMMATURE STAGES OF
EUSCHISTUS QUADRATOR
Adults of Euschistus quadrator Rolston were not described until 1974, and its pest status
remained very low until the mid-1990s. Adults were described from insects found in Mexico,
Texas and Louisiana (Rolston 1974), but nymphal stages have not been described. Descriptions
of immature stages of occasional or secondary pests are important especially if pest status is
likely to change in the future.
Euschistus quadrator is abundant in Georgia soybean and cotton (McPherson et al. 1993).
However, the first record of E. quadrator in Florida occurred in 1992, and it has since spread
throughout the state (J. E. Eger, personal communication). It was listed as a pest of concern in
the southeastern United States in 2007 (Brambila 2007).
Euschistus quadrator has been noted in several different crops, where it is as abundant as
Euschistus servus (Say) (Hopkins et al. 2010). It was recently listed as a key pest in cotton,
soybean and corn (Ruberson et al. 2009, Hopkins et al. 2010, Tillman 2010b, Olson et al. 2011).
This suggests that the pest species complex may be changing, with E. quadrator increasing in
pest status. Tillman (2010b) found all developmental stages of E. quadrator in Georgia corn
fields. Since E. quadrator caused similar cotton boll damage as E. servus in cage studies, this
may indicate that E. quadrator has the potential to cause as much injury as E. servus to crops
(Hopkins et al. 2005).
Since E. quadrator is often found in same habitats as E. servus, there is potential for
confusion when trying to identify the stink bug species present. Differences in insecticide
susceptibility have been shown for E. servus and E. quadrator, as well as intra-species
differences (McPherson et al. 1979b, Willrich et al. 2003, Snodgrass et al. 2005). With the
potential for damage by stink bugs, including the ‘Le er Brow ti k Bug co le ’, correct
64
identification is the key for developing appropriate IPM tools for managing these pests. Since
adults have already been described (Rolston 1974), describing the immature stages of E.
quadrator to allow identification of this species would be of significant help to growers and
extension personnel who are trying to identify the stink bug species present in their crops. The
specific objective of this study was to establish rearing protocol to: a) determine the duration of
immature life stages of Euschistus quadrator, b) describe the immature stages of Euschistus
quadrator.
Materials and Methods
Laboratory Rearing
A laboratory colony was established and maintained for several months from wild caught
E. quadrator adults from a variety of host plants. Adults were caged in groups of 8-10 males and
females. Cages (15 × 15 × 18 cm) were made from plastic food storage containers [Target,
Minneapolis, MN] with holes in the lids ( ~ 4 × 5 cm) and sides covered with 0.3 mm mesh
screens for aeration (Figure 5-1). Each cage contained a 59.2 mL Solo soufflé cup with lid [Solo
Cup Company, Lake Forest, IL] with a cotton roll [1 cm diameter, cut to 5 cm length, Richmond
Dental, Charlotte, NC] inserted into a hole cut into the lid for a water source (Figure 5-1). Adults
were reared on organic green beans, roma beans and cherry tomatoes. A strip of cheesecloth was
taped to the inside of the cage for oviposition. Cages were kept in a rearing incubator on a
16L:8D photoperiod at 25 ± 0.5C and 50 ± 5% relative humidity (RH).
Life History Study
The life history study began on 1/31/2012. All egg clusters were removed daily, the
number of eggs laid per cluster was counted, then egg clusters were placed into individual 5.5 cm
Petri dishes for 7 days. Although egg clusters were laid all over each cage, only clusters laid on
the cheesecloth were used. Clusters were checked daily between 1400 and 1500 hours for any
65
molting activity. Nymphs were counted by instar per egg cluster. When nymphs reached the
second instar, they were transferred to a 473.18 ml clear plastic container with lid [Solo Cup
Company, Lake Forest, IL] with filter paper in the bottom to provide extra room (Figure 5-1).
Nymphs were fed organic green beans only, which were changed every 2-3 days as needed. The
number of eggs that hatched were calculated to determine % survival. The stadium for each
instar in days and incubation period for eggs in days were also determined.
Descriptions of Immature Stages
Ten live nymphs of each instar were photographed and measured using Auto-Montage Pro
software [version 5.02, Syncroscopy, Frederick, MD] and a Leica MZ12.5 stereomicroscope.
Length was measured from the tip of the tylus to the tip of the abdomen, and width was
measured at the second abdominal segment on first through third instars, and just below wing
pads on fourth and fifth instars. Head capsule width was measured across the compound eyes,
and head capsule length was measured from the tip of the tylus to the back of the head.
Data Analysis
Means and standard errors were reported for the number of days required for development
from egg to 1st instar, as well as other immature stages (2
nd, 3
rd, 4
th, and 5
th instars). Cumulative
mean age and the number of days required to complete each stadium were also calculated. Data
were analyzed using Microsoft Excel [Microsoft Office Professional Plus 2010, Redmond, WA]
where appropriate.
Results
Laboratory Rearing
In this study, eggs were laid in clusters of 2 to 39, averaging 15.01 eggs per cluster (n=54).
A total of 812 eggs were laid on cheesecloth over the 7 day period. 754 of these eggs were
viable, and 425 hatched. The incubation period averaged 8.3 days (Table 5-1). The first through
66
fifth stadia averaged 6.1, 7.8, 6.8, 7.6 and 11.2 days, respectively. The total developmental time
from egg to adult averaged 47.7 days (Table 5-1). Of the insects that molted into adults, 51%
were male (137 insects) and 49% were female (133 insects), placing the sex ratio at
approximately 1:1.
Immature Descriptions
First instar
Figure 5-2A. Length 1.06 ± 0.01 mm; width 1.00 ± 0.01 mm. Form ovoid to nearly
circular, convex dorsally, usually longer than broad, greatest width at abdominal segments 2-3.
No or few visible punctures on dark brown areas.
Head declivent, narrowly rounded anteriorly, anterolateral margins slightly sinuate,
posterior margin broadly convex; yellowish brown to brown dorsally, with vertex often more
yellow medially and tylus yellowish brown; tylus surpassing juga; apical half of head sparsely
setose, white line extending from each eye posteromedially and disappearing beneath pronotum.
Eyes red. Antennae 4-segmented; segments 1-2 brown to red; segment 3 yellowish red to brown;
segment 4 longest, fusiform, reddish brown to brown, incisures lighter, distinct constrictions at
junctures of 2-3 and 3-4, ratio of segment length approximately 2:3:3:7; segments 2 and 3
sparsely setose, setae moderately dense on 4th
segment. Ventral surface of head yellowish brown.
Rostrum 4-segmented; yellowish brown basally, becoming darker brown distally.
Thoracic nota brown, yellowish brown medially, yellow mediolongitudinal line extending
from anterior margin of pronotum to posterior margin of metanotum; lateral margins entire and
slightly explanate. Thoracic nota with posterior margins broadly arcuate. Thoracic pleura dark
brown, pro- and mesopleura fused to respective nota; metapleuron separated from metanotal
plate by membranous area. Spiracles on posterior margins of pro- and mesopleura. Sterna
yellowish red, concolorous with ventral surface of abdomen. Coxae and trochanters yellowish
67
brown, coxae with brown spot on lateral surface; femora brownish red to red; tibiae reddish
brown to yellow, legs sparsely setose; tarsi, tarsal claws and pulvilli yellowish; tarsi 2-segmented
and darker at apex.
Dorsum of abdomen yellow with red markings, markings variable in density. Yellowish
brown-to-brown medial and lateral plates present. Eight medial plates present; plates 1 and 2 on
corresponding abdominal segments, small and transversely linear, plate 3 traversing segments 3
and 4, transversely linear and slightly constricted medially; plate 4 traversing segments 4 and 5,
subrectangular with irregular margins, slightly more narrow than and 3-4 times medial length of
plate 3, yellowish-red anchor-shaped marking present; plate 5 traversing segments 5 and 6,
subtrapezoidal with irregular margins, same width or slightly more narrow than plate 4, narrower
posteriorly, 4-5 times medial length of plate 3, yellowish anchor-shaped marking present; plate 6
located on segment 7, approximately same width as posterior third of plate 5, variable in shape,
often split or partially split medially; plate 7 located on segment 8, often similar in size and shape
to plate 6, but not split medially, plate 9 fused to lateral plates on segment 9. Paired ostioles of
scent glands located near intersegmental suture laterally on plates 2, 3, 4. Nine lateral plates
present, triangular in shape dorsally, rounded to subquadrate ventrally, plate 1 smaller, plates 2-7
largest and similar in size, plate 7 occasionally slightly smaller, plate 8 decreasing in size
posteriorly, plate 9 fused to medial plate 8. Spiracles located on segments 2-7, each located in
dark brown macule. Single trichobothrium located posteromesad to each spiracle on segments 3-
7, small dark macule usually present at base of trichobothria.
Second instar
Figure 5-2B. Length 1.90 ± 0.05 mm; width 1.27 ± 0.02 mm. Form broadly pyriform;
dorsum of head and thorax with numerous punctate brown spots; ventral punctures minute or
absent.
68
Similar to previous instar except as follows, head slightly declivent, lateral margins of juga
slightly sinuate; yellowish red dorsally with dark brown band posteriorly, oval brown spot
medial to each eye, vertex concolorous with remainder of dorsal surface. Antennal segment 1
dark brown to black proximally and reddish yellow distally, segment 2 reddish, segment 3 white,
incisures reddish brown, segment 4 brown, setae increasing in density distally; ratio of segment
lengths approximately 4:7:6:10. Ventral surface of head dark brown except for ventral surface of
juga and white markings around base of antennae. First two rostral segments paler than last two
segments.
Thoracic nota yellowish white; lateral margins explanate, dentate, occasionally with sparse
brown spots. Posterior margins of mesonotum angulate; intersegmental lines between segments
darker brown from either side of midline to at least half-way between lateral margin and midline
of body; pronotum with black marking within cicatrices, mesonotum with two pairs, metanotum
with one pair, of irregular brown markings. Pleura whitish yellow, with irregular brown bands
and scattered punctures. Coxae white to brown, usually with darker margins and brown central
spot; trochanters white; femora white basally, proximal one-third to one-half brown and slightly
setose; tibiae reddish brown to brown, often reddish basally, more setose than femora; tarsi
brown and setose, tarsal claws and pulvilli yellowish to yellowish brown.
Dorsum of abdomen white to yellow with numerous, short, longitudinal, red markings.
Medial plates 1 and 2 absent; plates 3-5 very similar to first instar except markings more yellow
and better defined, plate 6 reduced to transverse band, traversing segments 6 and 7, plates 7 and
8 similar to first instar but each with pale medial spot. Nine lateral plates white with brown
margins, sometimes one to three faint brown spots in white areas. Sterna concolorous with
dorsum, red lines and spots slightly less dense medially; medial plates brown with minute
69
punctures, plates on segments 4-9. Brown markings as follows: circular area surrounding
spiracles and base of trichobothria, crescent-shaped markings laterally on each segment
corresponding to borders of lateral plates on dorsum; medial plates solid brown and shaped as
follows, rounded spot on segment 4, subquadrate markings on segments 5-8 occupying most of
segment mesially, that on segment 5 about half as broad as other plates, plate on segment 9 U-
shaped. Spiracles on segments 2-7. Two trichobothria posterior to each spiracle on segments 3-7.
Third instar
Figure 5-2C. Length 3.66 ± 0.14 mm; width 2.36 ± 0.08 mm. Form pyriform to slightly
ovoid; brownish black punctures and spots on head and thoracic nota more numerous than
second instar.
Dorsal surface of head similar to that of second instar except as follows, antennal segment
1 white, dark brown to black band proximally; segment 2 white, brown to reddish brown distally,
segments 1 and 2 moderately setose with setal insertions sometimes marked with brown;
segment 3 white, reddish brown proximally and distally; segment 4 brown, often reddish brown
proximally and sometimes distally; ratio of segment lengths approximately 3:6:5:7. Ventral
surface of head brown except for yellow-gray transverse band reaching from anterad of
antennifers nearly to anterior margins of eyes, this band spotted with brown.
Thoracic nota similar to that of second instar except brown areas along posterior margins
reduced, particularly on metanotum and mesonotum; mesonotum with medial area more
produced posteriorly; metanotum reduced in size. Punctures on pleura more numerous than in
second instar. Femora each with proximal two-thirds white, distal one-third dark brown; tibiae
brown, somewhat lighter proximally.
Dorsum of abdomen grayish, becoming more green as insects approach ecdysis, with
numerous short, longitudinal red markings; medial plates 3-5 with markings similar to second
70
instar, often split medially, plate 6 very small, plates 7 and 8 reduced and less defined with paler
markings. Lateral plates similar to those of second instar, but with crescent shaped margins
thinner and with 1-6 small brown punctures. Sterna with medial plates on segments 4-9 varying
from similar to those of second instar to almost transparent with brown spots.
Fourth instar
Figure 5-2D. Length 5.40 ± 0.19 mm; width 3.56 ± 0.13 mm. Form ovoid, yellowish green
dorsally.
Similar to third instar except as follows, head with tylus and juga subequal in length; oval
spot mediad of eye brown; ocellar spots now usually evident, but partially obscured by brown
band on posterior margin of head. Antennal segment 1 yellowish white to yellowish green with
brown spots, often brown proximally; segment 2 yellow to reddish yellow with brown spots;
segment 3 white proximally and more yellowish red distally, with faint brown to red spots;
segment 4 dark brown, often yellowish brown proximally; ratio of segment lengths
approximately 2:7:5:7. Ventral surface of head yellowish except for brown stripe extending from
eye to near tip of juga and broad dark band along posterior margin which is interrupted mesially.
Rostrum with segment 1 yellowish green; segment 2 yellow to brown; segments 3-4 yellowish
brown to brown.
Thoracic nota with brown borders along posterior margins reduced or absent; humeri with
brown punctures more numerous; cicatrices yellowish, often with brown marking mesially.
Brown spots on meso- and metanotum similar to third instar or reduced. Meso- and metanotal
wing pads approximately the same length, extending onto first abdominal segment. Pleura with
dark brown spots, lateral half also with dark brown longitudinal vittae. Sterna yellow. Coxae
yellow, each with brown band on lateral edge and sometimes central brown spot reduced or
absent; trochanters yellow; femora yellow with brown spots at insertions of setae, apices
71
brownish; tibiae yellowish with red to brown spots at insertions of setae, brown distally; tarsi
brown, lighter proximally.
Dorsum of abdomen yellowish green with dark yellow to green or red markings
throughout. Medial plates 2-4 with red to dark brown punctations and brown spots; plates 3-5
similar to third instar, plates 6, 7 and 8 with brown markings reduced to small spots. Lateral
plates 2-7 yellowish, each with crescent-shaped brown markings thinner; small brown punctures
often more numerous (7-12 per segment). Sterna yellowish green. Medial plates reduced to small
spots on segments 6, 7, 8, and 9.
Fifth instar
Figure 5-2E. Length 7.35 ± 0.19 mm; width 4.60 ± 0.13 mm. Form ovoid, dorsum of head,
thorax and abdomen laterally with relatively dense brown punctures, these larger and more
distinct than in fourth instar.
Similar to previous instar except as follows, head yellowish green; ocelli evident, reddish.
Antennal segments 1-2 yellow with brown spots at setal insertions; segments 3-4 yellow to
yellowish red, apex of segment 4 becoming brown; ratio of segment lengths approximately
2:7:5:6. Ventral surface of head yellowish green with sparse brown punctures apically; brown
supra-antennal vitta distinct.
Thoracic nota densely punctured, brown areas surrounding punctures enlarged laterally.
Meso- and metanotal wing pads subequal in length, extending onto third abdominal segment.
Pleura yellow, brown markings reduced compared to previous instar, most punctures almost
concolorous with pleural surface, dark spot present at base of each coxa and apex of supracoxal
cleft. Coxae and trochanters yellowish-green; both femora and tibiae yellowish-green proximally
and yellowish-red distally, both with brown spots mostly at setal insertions, those on femora
72
becoming more numerous distally; tarsal segments yellowish red, segment 2 with apex dark
brown.
Dorsum of abdomen yellowish green; medial plates 3-5 with white markings more distinct
and with red to brown spots, plates 6, 7, and 8 greatly reduced. Lateral plates with numerous
brown punctures. Sterna as in previous instar, except for red to brown spots reduced or absent,
mostly limited to area surrounding spiracles and base of trichobothria; crescent-shaped markings
greatly reduced.
Discussion
Based on observations, only 56.4% of the eggs laid hatched into the first instar. Incomplete
emergence may have attributed to this low percentage of eggs hatching. Some eggs appeared to
have been eaten by adults in the cage within 24 hours of being laid. This was obvious because of
the egg casings that were recorded in the cages during daily inspection. Euschistus spp. are
known to be cannibalistic (Ruberson et al. 2009). Nymphal survival decreased during each
stadium. Most insects died in the first, second, and fifth instars. Based on observations, most of
these losses resulted from incomplete ecdysis. Overall percentage of offspring that reached the
adult stage was 33% of the total eggs laid.
Nymphs of E. quadrator and E. servus were similar in both their life history and physical
appearance (Munyaneza and McPherson 1994). The duration of the egg and nymphal stages are
almost identical between species, with slight variations (Table 5.1). Munyaneza and McPherson
(1994) observed that E. servus averages 5.8 ± 0.04 days in the egg stage, whereas I found E.
quadrator to remain in the egg stage for 8.3 ± 0.05 days. Euschistus quadrator remained in the
first and second instar for 1.1 and 1.8 days longer than E. servus, respectively. However, the
third and fifth instars were identical considering the standard errors. The fourth instar for E.
quadrator was 1.7 days shorter than that for E. servus. The same variations are seen in the range
73
of days for each stage. Euschistus quadrator had a range of 6-11 days in the egg stage, compared
to 5-7 days for E. servus. The first and third instars were very similar, with 4-8 days and 5-16
days, respectively, for E. quadrator and 4-7 and 5-13 days, respectively, for E. servus. The
second, fourth and fifth instars had a slightly larger range of 6-12, 6-17 and 9-26 days for E.
quadrator, compared to 5-8, 7-14 and 8-20 days for E. servus. Munyaneza and McPherson
(1994) used similar rearing conditions (16L:8D at 23 C), so it is likely that these are species
specific differences. The minimum days required for E. quadrator to develop from egg to adult
was 36 days, and the maximum was 67 days (Figure 5-3). The overall life cycle is similar for
both species.
Euschistus servus nymphs are slightly larger than E. quadrator nymphs, though these size
differences are only apparent by microscope. Euschistus servus is approximately 0.50 mm longer
than E. quadrator in the first, second and third instars, and approximately 3.10 mm longer in the
fourth and fifth instars. Width for the first, second and third instars of E. servus was 0.14, 0.26
and 0.50 mm greater, respectively, than that of E. quadrator, and approximately 2.10 mm for the
fourth and fifth instars. Antennal segment lengths and head capsule length and width of E.
quadrator nymphs were measured for future aid in identification (Table 5-2). Some notable
differences are that in the first through third instar of E. quadrator, the third antennal segment is
white whereas it is brownish red in first through third instars of E. servus. The antennal segments
are dark in first, second and third instars of E. servus, and the incisures are white (Munyaneza
and McPherson 1994). Fourth instars of E. quadrator have dark brown to black tarsi, while in E.
servus, the tarsi are yellow and brown in the fourth instar. There are two sets of dark spots on the
head of fourth instar E. quadrator, and only one set of spots on fourth instar E. servus. In fifth
instars, E. servus has one set of dark spots on the head, which seem to be absent in E. quadrator
74
fifth instars. The dorso-medial abdominal plates in fifth instars of E. quadrator are more defined
than those of fifth instar E. servus. The lateral edges of the head and thorax are a darker brown in
E. servus fifth instars. The tip of the fourth antennal segment of fifth instar E. quadrator is darker
than that of fifth instar E. servus. The lateral plate borders are lighter or absent in E. servus
fourth and fifth instars, and a distinct black border is present in fourth and fifth instars of E.
quadrator. The white line across the eyes of fifth instar E. servus is very well defined, and less
defined or absent in E. quadrator fifth instars. The differences described above can be used to
distinguish E. quadrator from E. servus, allowing specific pest management tactics to be
developed for both species.
75
Table 5-1. Duration (in days) of each immature stadium of E. quadrator under laboratory
conditions
Stage
Number
completing
stadium
Range Average
days**
Cumulative
mean
age
Egg 425* 6-11 8.3 ± 0.05 8.3
1st instar 385 4-8 6.1 ± 0.05 14.3
2nd
instar 343 6-12 7.8 ± 0.07 22.1
3rd
instar 330 5-16 6.8 ± 0.07 28.9
4th
instar 304 6-17 7.6 ± 0.07 36.5
5th
instar 270 9-26 11.2 ± 0.11 47.7
* 754 eggs were laid
** Means are rounded to the nearest tenth; (
76
Table 5-2. Head capsule (HC) length and width, and length of antennal segments (A#) of E. quadrator
Instar HC Length HC width A1* A2* A3* A4*
1st 0.38 ± 0.01 0.57 ± 0.01 0.06 ± 0.01 0.13 ± 0.01 0.14 ± 0.01 0.31 ± 0.01
2nd
0.57 ± 0.02 0.75 ± 0.01 0.10 ± 0.01 0.26 ± 0.01 0.23 ± 0.01 0.46 ± 0.01
3rd
0.87 ± 0.01 1.04 ± 0.01 0.15 ± 0.01 0.50 ± 0.02 0.38 ± 0.02 0.65 ± 0.01
4th
1.22 ± 0.03 1.41 ± 0.01 0.25 ± 0.01 0.87 ± 0.03 0.66 ± 0.02 0.88 ± 0.02
5th
1.57 ± 0.03 1.81 ± 0.01 0.39 ± 0.01 1.41 ± 0.03 1.05 ± 0.02 1.17 ± 0.02
*A1=distal antennal segment
77
A B C
Figure 5-1. Adult and nymph cage examples. A) water source, B) adult stink bug colony cage, and C) nymph cage example (Photo
credit by: Sara Brennan)
78
Figure 5-2. Dorsal (left) and ventral (right) view of immature stages of Euschistus quadrator, A)
first instar, B) second instar, C) third instar, D) fourth instar, E) fifth instar
79
0
50
100
150
200
250
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69
# o
f n
ym
ph
s
Days
1st
2nd
3rd
4th
5th
adult
Figure 5-3. Number of nymphs per instar that molted into each subsequent instar during the experiment
80
CHAPTER 6
GENERAL CONCLUSIONS
Blackberry production is increasing in the southeast (Strik et al. 2007). Since blackberries
are a relatively new crop to this area, it is expected that the pest complex will be slightly
different than the more traditional production areas, such as the northeast and northwest United
States. This research focused on stink bug pests of blackberries in Citra, FL. Euschistus
quadrator Rolston was one of the most common stink bug species found in blackberries, and is
also relatively new to Florida compared to other stink bug species (J. E. Eger, personal
communication). There is little information available about E. quadrator. Therefore, descriptions
of the immature stages of E. quadrator and a life history study were completed to assist with
identification of this species in the field. We also assessed monitoring techniques in the field, and
attempted to refine laboratory techniques to evaluate pheromone lures used for monitoring stink
bugs in blackberry. Finally, a species survey of the stink bug species present in blackberry was
completed. The results from these studies will help in developing an effective pest management
program for stink bugs in commercial blackberry production.
Species Survey in Blackberries
Euschistus quadrator was the most abundant stink bug found, followed by E. servus, E.
obscurus, T. custator, Proxys punctulatus (Palisot de Beauvois) and the spined soldier bug, P.
maculiventris. There was a general correlation between the number of stink bugs found on each
sampling date with the amount of fruit in each plot. As the percent of ripe fruit increased in both
the organic and conventional plots, the number of stink bugs also increased.
This is the first known record of E. quadrator, E. obscurus, T. custator, P. punctulatus and
P. maculiventris in blackberry. While we found several Euschistus spp. that are commonly
mentioned in other areas, we did not find either the green stink bug or the southern green stink
81
bug. It is also interesting to note that E. quadrator was the most abundant stink bug species
found, and that so many different Euschistus spp. were found on the blackberries at the same
time.
Monitoring in Blackberries
In the trap comparison experiment, no stink bugs were caught in the tube traps. This
indicates that tube traps may not be effective in blackberry crops. The pyramid trap was more
effective in catching stink bugs than the tube trap, either with or without the addition of the
Euschistus spp. pheromone. Furthermore, there were no statistical differences between a baited
and an unbaited pyramid trap.
In the pheromone comparison experiment, there were no statistical differences in the
number of stink bugs caught between the pyramid trap baited with the Trécé Pherocon Centrum
lure, the Suterra Scenturion lure and an unbaited trap. These results were supported by results
from a Y-tube olfactometer assay where there were no statistical differences between either lures
and a control, although higher numerical values were recorded with the Trécé lure. This indicates
that both lures are most likely ineffective in the field. This research may provide information for
growers who are considering the purchase of available lures as to which lure is more practical
and whether a lure is needed for their field setting.
Species found in field experiments include E. quadrator, E. servus, E. obscurus (Palisot
de Beauvois), Thyanta custator (F.), E. ictericus (L.) and Podisus maculiventris Say. Stink bugs
appear to colonize in blackberry bushes when berries are mid-ripe to fully ripe.
Life History and Taxonomy of E. quadrator
Only 56.4% of the eggs laid hatched into the first instar, and 33% of the total eggs laid
reached the adult stage. Incomplete emergence from eggs and incomplete ecdysis between
instars may have attributed to this low percentage of survival. The overall life history and
82
physical appearance of E. quadrator nymphs are very similar to the brown stink bug, Euschistus
servus (Say), an economically important pest (Munyaneza and McPherson 1994). Euschistus
quadrator remained in the egg stage for approximately 2.5 days longer than E. servus. The first
and second instars for E. quadrator were 1.1 and 1.8 days longer, respectively, than E. servus.
However, the duration of the third and fifth instars was identical between species. The fourth
instar for E. quadrator was 1.7 days shorter than that for E. servus. The same small variations are
seen in the range of days for each stage. At 25 C, the minimum duration from egg to adult for E.
quadrator was 36 days, and the maximum was 67 days.
Euschistus servus nymphs are slightly larger than E. quadrator nymphs. Some of the more
notable differences are that in the first through third instar of E. quadrator, the third antennal
segment is white whereas it is brownish red in first through third instars of E. servus. Fourth
instar nymphs of E. quadrator have dark brown to black tarsi, while in fourth instar E. servus,
the tarsi are yellow and brown. There are two sets of dark spots on the head of fourth instar E.
quadrator, and only one set of spots on fourth instar E. servus. In fifth instar nymphs, E. servus
has one set of dark spots on the head, which seem to be absent in E. quadrator fifth instars. The
white line across the eyes of the fifth instars of E. servus is very well defined, and less defined or
absent in fifth instar E. quadrator. The differences described above can be used to distinguish E.
quadrator from E. servus, allowing specific pest management tactics to be developed for
individual species.
83
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BIOGRAPHICAL SKETCH
Sara A. Brennan was born in Camden, New Jersey in 1984. She was raised in Vero Beach,
Florida, and attended the University of Florida in 2002. She earned a Bachelor of Arts in 2006
where she majored in classical studies. In 2009, she changed her career focus and began her
a ter’ degree i e to olog at t e U iver it of Florida u der t e u ervi io of Dr. O car .
Liburd. After graduating, she hopes to take six months to a year off before beginning her Ph.D.
Her future study and career interests include sustainable urban agriculture, with a sub focus on
the social, economic and government policy aspects of agriculture.