Volume 19(3), 26- 31, 2015 JOURNAL of Horticulture, Forestry and Biotechnology www.journal-hfb.usab-tm.ro
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Cydalima perspectalis Walk. (Lepidoptera: Crambidae), a dangerous pest of Buxus sempervirens in Timis County, Romania
Fora C.G.1, Poşta D.S.1
1Faculty of Horticulture and Forestry Timişoara
*Corresponding author. Email: [email protected] Abstract Cydalima perspectalis Walk. (Lepidoptera: Crambidae) is, in present, a dangerous pest on species of Buxus sempervirens in Europe to. The importance of this pest result from his spread on almost entire continent, spread realized in less than one decade, and from damages which can produce it on host plants, damages which can contributes to drying of defoliated individuals. In Romania this pest is present to, in special in Timis County, where has been observed in 90% of localities targeted by our research, and where seems to found good climatic condition to multiplying. In all 10 localities, both in urban and rural area of county, defoliation oscillated from 0 to 100%, damage levels being very different even in the same locality. Thus, it was determined that 19.35% from analyzed box tree individuals were not damaged, 50.00% from individuals had a weak damage level, 8.06% had middle damage level, 6.45% had strong damage level and 16.14% very strong damage level. In general has been observed that the damage level of box tree individuals was weak to middle. If on effects of defoliation produced by C. perspectalis overlap the effect of dry summers, with very high temperatures, lake that from summer of 2015, the risk that individuals of box tree to dry is more accentuated.
Key words Cydalima perspectalis, damage level, Buxus sempervirens, Timis County, Romania
In Romania the most prevalent species of
Genus Buxus is Buxus sempervirens. To us, Buxus
sempervirens is one of the most cultivated wood
species in parks and gardens (Şofletea and Curtu,
2007). In Europe, as in our country, the species of
Buxus are threatened in last years by a dangerous pest
Cydalima perspectalis Walk., found for the first time in
Germany in 2007 (Krüger, 2008). In Romania has been
found for the first time in 2010, in 3 different locations
from Bucharest (Iamandei, 2010), respectively in 2011,
in North-West part of the city and in a yard of a
kindergarten (Szekely et al., 20011). In Timişoara we
found him for the first time in larva stage in summer of
2013 on few individuals of Buxus from Young
Naturalists Park. From first report to present, the
species widespread continuously and very much, which
suggest the high mobility of it. Therefore, it can be
observed in Switzerland (Billen, 2007), Holland (Muus
et al., 2009), England (Mitchell, 2009), France
(Feldtrauer et al., 2009), Austria (Rodeland, 2009),
Liechtenstein (Slamka, 2010), Belgium (Casteels et al.,
2011), Italy (Biondi, 2010), Hungary (Sáfián and
Horváth, 2011), Czech Republic (Šumpich, 2011),
Turkey (Hizal et al., 2012), Slovenia (Seljak, 2012),
Croatia (Matošević, 2013), Slovakia (Pastorális et al.,
2013), Denmark (Hobern, 2013). The box tree moth, C.
perspectalis, is a crambid moth native to eastern Asia
(Leraut, 2012). It was most probably introduced to
Europe with containered Buxus seedlings (Mally and
Nuss, 2010). The importance to studying of this species
derive from the very large area of spreading, from
injuries which can cause it, sometimes the injuries can
be a total defoliation, from the fact that in Europe is a
pest mainly on Buxus sempervirens, recently
introduced in our region and therefore with predators
and parasitoids almost unknown.
Our paper follow on the one side to establish
the spreading of this pest in Timis County, the
westernmost county of Romania, and on the other side
to appreciate the damage level produced on analyzed
box trees, fact with a high significance for practice. All
of these elements are a first step in order to studying
the biology of the pest in conditions of our country,
which is almost unknown in present.
Material and Method
The spread study of defoliator C. perspectalis,
on individuals of B. sempervirens, was conducted in
summertime of 2015, in parks and gardens from urban
and rural places of Timis County, 10 localities being
covered: Buzias, Carpinis, Cenad, Comlosu Mic, Deta,
Jimbolia, Lovrin, Lugoj, Sannicolau-Mare and
Timisoara. It has been done visual assessments on a
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number of 62 individuals of B. sempervirens, box trees
(25 individuals) and hedges (37 pieces). It was
followed, in principal, the appreciation of defoliation
percentage done by pest caterpillars on host plants.
After establishing of the defoliation percentage, it was
appreciated the damage level using our own scale of
interpretation (table 1), scale established taking into
account the injuries that caterpillars can do on host
plants and the effects that the defoliation had on host
plants, knowing that the species of Buxus have a very
slow growing, the recovery of foliage is in many times
difficult and can cause, in some cases, the drying of
defoliated individuals.
Table 1
Injury scale of defoliation percentage at Cydalima perspectalis Walk.
Crt. no. Defoliation (%) Damage level Damage significance
1. 0 0 undamaged
2. 1-20 1 weak
3. 21-40 2 middle
4. 41-60 3 strong
5. >60 4 very strong
Results and Discussions
The obtained results show that the defoliator
C. perspectalis was present in the majority of studied
localities, with exception of village Comlosu Mic
where has been identify, in garden from a front of one
house, just 2 box trees of B. sempervirens, these being
unattacked. The percentages of defoliation oscillated
from 0 to 100%, more than 80% from analyzed
individuals of B. sempervirens presenting different
percentages of defoliation.
Using our injury scale of interpretation of
defoliation percentage at C. perspectalis it can be
observed that 19.35% of individuals were not
defoliated, 50.00% from all individuals had a low level
damage, 8.06% middle damage, 6.45% strong damage
and 16.14% very strong damage (figure 1). In general
it can be observed that the damage level was low to
middle that underline the necessity of detailed studies
of biology and dynamic of species in conditions of our
country in order to apply of control measures correct
and in time.
Fig. 1. C. perspectalis damage level in Timis County, Romania (2015)
Adults of C. perspectalis have a wingspan of
around 4 cm (Leuthardt and Baur, 2013), white color
slightly iridescent wings with a large dark brown band
at the outer margin and a characteristic white spot on
the forewing, in the discoidal cell (figure 2). Hind
wings are white with the same band at the outer margin
as in the forewings (Mally and Nuss, 2010). In a less
common color variant, the adults are completely
brown, but still show a white forewing spot. The moths
are good flyers and can reach a lifespan of up to two
weeks. After mating the females laid eggs on the leaves
of the host plant in groups of 5-20, coated with a
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translucent jelly (Leuthardt and Baur, 2013). At
beginning the eggs are pale yellow, but close to
hatching, the black heads of the larvae are visible. The
light green larvae are characterized by black stripes
with white dots and hairs and a shiny black head and in
the last larval stage they can reach a length of up to 4
cm (figure 2). The pupae are between 1.5 and 2.0 cm
long (figure 2), initially are green with dark stripes on
the dorsal surface, towards the end of pupation they
turn brown with a dark pattern corresponding to the
brown wing borders of the adult. They are concealed in
a cocoon of white silk spun among the leaves and twigs
(Korycinska and Eyre, 2009).
The caterpillars of C. perspectalis feed on
leaves of Buxus spp. (B. sempervirens, B. microphylla,
B. sinica and B. colchica), Ilex purpurea, Euonymus
alata and Euonymus japonicus and are considered to be
serious defoliators (Korycinska and Eyre, 2009).
Recent study investigated the oviposition choice and
larval food preference and performance on five
commonly used European box-tree varieties: B.
sempervirens ‘Sempervirens’, B. s. ‘Rotundifolia’, B. s.
‘Argenteo - variegata’, B. s. ‘Aureovariegata’ and B.
microphylla ‘Faulkner’. The study showed that females
prefer the variety ‘Rotundifolia’ for oviposition, but
revealed no differences in larval growth rate and
survival on the five varieties. However, a strong
seasonal variation in larval performance was found, the
spring generation growing faster than the autumn
generation (Leuthardt and Baur, 2013).
Larvae feed mainly on leaves but may also
attack the bark. Young larvae prefer leaves containing
a high concentration of alkaloids (older leaves).
Indeed, under natural conditions, young larvae tend to
feed on old leaves at the bottom of box tree plants
(Leuthardt and Baur, 2013). This behavior permits a
fast uptake of large amounts of alkaloids within a short
time to increase protection against predators, before
maximizing the larval growth rate. Young larvae feed
at beginning with superior part of leaves and after that
with entire leaf. Total defoliation is common (figure 2)
and usually results in the death of the trees. One
possibility to stimulate the recovery of box tree leaves
is irrigation in summertime, in period when usually the
dryness is present.
Fig. 2. Larva (up left); Pupa (up right); Pupa and Adult (down left);
Defoliation (down right); of C. perspectalis.
(Photo: Fora Ciprian George)
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The effect of the moth is often aggravated by
the occurrence of the box blight, caused by the fungal
pathogen Cylindrocladium buxicola Henricot, another
invasive species that arrived in Europe a few years
before C. perspectalis. In infested areas, it has become
impossible to maintain healthy box trees without
chemical treatment or laborious mechanical removal of
larvae (Kenis et al., 2013). Infestation symptoms
include feeding damage on the leaves of the shoot
edges by the larvae, which can leave only leaf
skeletons and the epidermis behind them (Leuthardt
and Baur, 2013).
Other associated symptoms are webbing of
the branches, frass and residues of molting such as
black capsules of different sizes. Heavy infestation
leads to dry plants and their defoliation, which
combined with the subsequent attack of the bark results
in the death of the plant. Box trees with a low level of
damage are often able to recover if they do not suffer
from renewed attacks (Strachinis et al., 2015). If heavy
defoliation overlaps on dry condition with lake of
precipitation in summertime increase the risk that
individuals of box tree to die. This species has up to three generations per
year in Asia, as well as in Europe (Korycinska and
Eyre, 2009), and overwinters in the caterpillar stage
(Zhou et al., 2005). The first flight occurred from late
May to mid June; the second one from mid July to mid
August and the third from early September to early
October. Males may be attracted by long distance
(Santi et al., 2015).
Young larvae overwinter in diapause in a
cocoon built between leaves. Diapause is induced by
day length and temperature experienced by young
larvae (Maruyama and Shinkaji 1993). Larval feeding
continues in spring and pupation also occurs in the
foliage (Kenis et al., 2013).
No natural enemies have been recorded in
Europe so far (Nacambo et al., 2013) while it is neither
attacked by predators (birds) because of the toxicity of
the host plant (Leuthardt et al., 2010). Given all these
circumstances this invasive pest has very favorable
conditions (no natural enemies, favorable climate,
widely available host plant) for spreading and
establishing in new areas. In Europe larval parasitism
was less than 1% and represented by a single tachinid
parasitoid, Pseudoperichaeta nigrolineata Walk. while
no egg or pupal parasitoids were found (Nacambo,
2012). Predators were not commonly observed either,
possibly due to the sequestration of toxic alkaloids
from their host-plant (Leuthardt et al. 2013).
Today, there are several possibilities to
control C. perspectalis. Besides the periodic
mechanical removal of larvae at low infestations levels,
chemical insecticides like deltamethrin or
diflubenzuron as well as Bacillus thuringiensis
preparations should be effective against the box tree
moth (Korycinska and Eyre, 2011; ). Furthermore,
there are promising investigations with application of
Trichogramma (Zimmermann et al., 2009) and
entomopathogenic nematodes (Choo et al., 1991).
Natural enemies of the pest include polyphagous
parasitoids (Nacambo et al., 2014) and birds exhibiting
low predation, probably due to the high levels of toxic
alkaloids sequestered by its larvae (Leuthardt and Baur,
2013). Recently, laboratory experiments have indicated
the susceptibility of C. perspectalis larvae to
baculovirus Anagrapha falcifera nucleopolyhedrovirus
(AnfaNPV) as a new opportunity to control this pest
(ROSE et al., 2013). Caterpillars of C. perspectalis are
more sensitive at chemical insecticides is young stages
(L1-L3). Because of that the control measures had to
be applied in spring as soon as possible, in our
conditions early in March. The treatments must be
repeated after that moment every 7 to 10 days until the
caterpillars disappears because the pest has two-three
generation per year and in some moments it can be
found in the same time eggs, larva and pupa on box
trees. A mechanical control measure can be applied in
autumn, before winter, when the caterpillars stay
together in overwinter places through cutting of
infested steams. Particular attention should be taken
regarding monitoring and control of this dangerous
pest because can contribute at destroying of important
ornamental species from parks and gardens.
Conclusions
Analyzing of our results obtained from
researches performed on spread of species C.
perspectalis and assessment of damage level on host
plant B. sempervirens, can be formulated next
conclusions:
- In Timis County the pest is present in majority of
localities targeted by our research;
- Damage levels has been from undamaged to very
strong damaged and can be observed a general
tendency of damage from weak to middle;
- It is required to continue to study biology and pest
dynamics in order to correct application and in
time of control measures.
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