evaluation of the nematode steinernema carpocapsae to control fire ants in nursery stock

Evaluation of the Nematode Steinernema carpocapsae to Control Fire Ants in Nursery StockAuthor(s): Donald P. Jouvenaz and W. Randy MartinSource: The Florida Entomologist, Vol. 75, No. 1 (Mar., 1992), pp. 148-151Published by: Florida Entomological SocietyStable URL: http://www.jstor.org/stable/3495494 .Accessed: 12/06/2014 16:03

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148 Florida Entomologist 75(1) March, 1992

EVALUATION OF THE NEMATODE STEINERNEMA CARPOCAPSAE

TO CONTROL FIRE ANTS IN NURSERY STOCK

DONALD P. JOUVENAZ' AND W. RANDY MARTIN2 1USDA, ARS, Medical & Veterinary Entomology Research Laboratory,

1600 S.W. 23rd Drive, Gainesville, FL 32608

2Biosys, Inc. 1 Progress Blvd., Box 26, Alachua, FL 32615

Recent developments in low-cost, large scale production of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis (Bedding 1984) have facilitated large-scale field testing against various soil-infesting insects (Kaya 1985, Poinar 1986), with good potential for control in some applications. Early research by Poole (1976) and Quattlebaum (1980) indicated that the potential included fire ants. Citrus growers in Florida using nematodes (BioVectorg; Biosys, Inc.) for control of soil insects have reported fewer problems with fire ants (personal communications to W. R. Martin). Jouvenaz et al. (1990), however, did not achieve significant control of red imported fire ants, Solenopsis invicta Buren, in field trials of nematodes (Biosys, Inc.) conducted in Florida.

Steinernematid nematodes may be moderately effective against fire ants in irrigated soil. Morris et al. (1990) reported 47% control with Steinernema carpocapsae versus 39% control with the Amdro standard at sites containing irrigated turf. This level of control is far below normal for Amdro (Williams et al. 1987; Jouvenaz et al. 1990), indicating that it may have been broadcast on wet soil (personal communication, D. F. Williams, USDA, ARS). Unmarked mounds found outside the blocks after treatment were not included in the assessment for activity; thus, control by nematodes may have been overestimated due to mound relocation. Considerable relocation of fire ant nests occurred in the tests conducted by Jouvenaz et al. (1990). Had not mound movement been taken into consideration (Poole and Quattlebaum scored all mounds uninhabited after treatment as dead), the apparent control would have been over 77% (of 44 treated mounds, 34 were inactive). We subsequently confirmed the aversion of fire ants to nematodes by controlling the movement of small laboratory colonies between containers of sandy soil with single applications of BioSafe? Lawn and Garden Insect Control (Steinernema carpocapsae; Biosys, Inc., Palo Alto, CA).

The readiness with which fire ants relocated their nests in the field and vacated soil in containers to avoid nematodes prompted us to evaluate the potential of these parasites to eliminate fire ants from nursery stock. The early spread of fire ants in the southeastern United States was greatly facilitated by the shipment of infested nursery stock (Lofgren 1986). Recently these pests have been transported to Arizona and California; if they become established in the West, their range will increase substantially.

Currently, federal certification of nursery stock for shipment through quarantine is based solely on incorporation of chlorpyrifos. Granular chlorpyrifos is not as effective as previously believed, drenching poses problems of worker exposure, and both treat- ments are expensive (personal communication, H. Collins, USDA, APHIS). The improve- ment of methods for control of fire ants is a critical need of the nursery industry (Regel- brugge 1991).

In the present study, three sequential tests were conducted using BioSafe against fire ants nesting in nursery pots containing Pittosporum sp. shrubs. A colony of S. invicta consisting of five queens, 3,000-5,000 workers and about 1.5 g brood was intro- duced into each of 50 1 gal pots containing shrubs 20-35 cm in height. The ants were


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Scientific Notes 149

maintained on honey agar, boiled eggs, and Lepidoptera larvae, and were allowed 48 h for acclimation before treatment with nematodes. The fire ant-infested potted shrubs were held individually in plastic trays, the inner walls of which were coated with Fluon? (ICI America) to prevent migration of the colonies. The trays were arranged in a grid on the cement floor of a shed and treated in a randomized complete block design. Daily soil temperatures in the pots ranged from 16-32?C at a depth of three inches. Soil moisture was monitored and the plants were watered as deemed necessary. Suspensions of nematodes were prepared according to label directions and kept agitated; viability was confirmed microscopically immediately before use.

In the first test, 50 ml of water containing 30,000 nematodes (about 1,000 per square inch of soil surface) were poured into each of 20 pots, 50 ml of water containing 300,000 nematodes was poured into each of 20 other pots, and the remaining 10 pots received 50 ml of water only. At the time of treatment, an additional pot of watered potting soil (but without a plant) was placed in each tray to provide the ants with untreated soil in which to relocate their nests. Without "escape pots", ants cluster around the bases of evacuated containers (personal observation), and evaluation is difficult due to the open drainage holes. Also, this represents a more natural situation, since ants are free to relocate in untreated soil in nurseries. Three days after treatment, 10 pots treated with each dose of nematodes (total of 20) were examined for the presence of living ants by spreading the soil on a 1 x 1.5 m white plastic cloth. The remaining 20 treated pots and the 10 control pots were examined similarly 14 days after treatment. The number of worker ants was estimated and categorized as none, fewer than 100, 100-1,000, or over 1,000.

The second test was conducted using replanted shrubs, new ant colonies, a new and different lot of BioSafe?, and a different brand of potting soil (Hyponex Professional Mix?; Hyponex Corp., Atlanta, Ga. in lieu of Pennington Potting Mix?; Pennington Lawn & Garden Supplies, Orlando, Fla.). The same procedures used for the first test were employed except that 50 ml of water containing the nematodes were sprayed onto the soil surface with a Solo #485 backpack sprayer.

The third test consisted of 30 pots infested with new fire ant colonies, of which 20 were sprayed (same sprayer) with a single dose of 75,000 nematodes (about 2,500 nematodes per square inch of soil surface) in 50 ml water. The remaining 10 pots received water only. The batch of BioSafes, method of application, and potting soil were as in the second test; however, escape pots were not provided. Instead, all 30 pots were arranged and treated in a random pattern on the ground, which was covered with short grass and shaded by two oak trees. Thus, the ants were free to relocate in field soil (fine sand). This test was evaluated four days after treatment.

We found that fire ants were not eliminated from 1 gal pots containing Pittosporum shrubs treated with either 30,000 or 300,000 nematodes (1,000 or 10,000 per square inch of soil surface). The numbers of cadavers in the refuse piles did not indicate elevated mortality in treated colonies.

In the first and second tests, queens and brood remained in all 80 treated pots and all 20 control pots; neither was found in the escape pots three or 14 days after treatment. Most of the worker ants also remained in the treated pots.

In the first test, fewer than 100 workers were found in each of the 20 escape pots examined three days after treatment. Fewer than 100 workers per pot were found in 18 of the 20 escape pots examined 14 days after treatment; the remaining two escape pots harbored 100-1000 workers each. Fewer than 100 workers were found in each of the 10 control escape pots, all of which were examined 14 days after treatment.

In the second test, fewer than 100 workers per pot were found in 18 of the 20 escape pots examined three days after treatment; the remaining two escape pots harbored 100-1000 workers each. Of the 20 escape pots examined 14 days after treatment, 10



150 Florida Entomologist 75(1) March, 1992

harbored fewer than 100 workers and 10 harbored 100-1000 workers each. Of the 10 control pots, five harbored fewer than 100 workers and five harbored 100-1000 workers each.

In the third test, queens, brood and workers remained in 11 (55%) of the 20 treated colonies and five (50%) of the 10 control colonies four days after treatment. Brood was absent from nine (45%) and queens from seven (35%) of the treated pots. However, brood was absent also from five (50%) and queens from three (30%) of the 10 control pots. Four of the treated pots and two of the control pots (20% each) also were free of worker ants.

After completion of the above tests, a bioassay using wax moth, Galleria melonella, larvae was conducted to assess the distribution of nematodes in treated potting soil. Ten pots containing shrubs, but without ants, were sprayed with 300,000 nematodes each. Five pots were bioassayed after 48 h and the remaining five after 72 h. Soil samples were taken from the periphery of the upper part of the root ball (about one inch below the surface), the periphery of the lower part of the root ball, the interior of the root ball, and from below the root ball. Each soil sample was packed loosely in a separate petri dish, to which five G. mellonella larvae were added. The larvae were examined for nematode parasitization after one week incubation at 28?C.

The bioassay with larvae of G. melonella indicated that distribution of nematodes was not uniform. Of the 50 larvae (10 treated pots) exposed to soil from the periphery of the upper root ball, the periphery of the lower root ball, the interior of the root ball, or below the root ball, 48 (96%), 42 (84%), 34 (68%), and 20 (40%), respectively, became parasitized. Since one or very few nematodes are required to initiate parasitization of G. melonella larvae, it also appears that few active nematodes were present.

A practical treatment for eliminating fire ants from nursery stock must be essentially 100% effective in all types of potting soil, and also be quite persistent. Unfortunately, fire ant colonies living in nursery stock were unaffected by steinernematid nematode drenches. Also, the G. melonella bioassay indicated that premixing nematodes in potting soil would not be effective. Thus, it appears unlikely that these parasites can be manipu- lated to reliably eliminate fire ants from nursery stock.

We thank Lloyd R. Davis, Jr., for his excellent assistance in this study. The potted plants were provided by the Florida Department of Agriculture and Consumer Services, Division of Plant Industry, through Mr. Richard A. Clark. Mention of a commercial product does not constitute indorsement by the USDA.

REFERENCES CITED

BEDDING, R. A. 1984. Large scale production, storage, and transport of the insect- parasitic nematodes Neoaplectana spp. and Heterorhabditis spp. Ann. Appl. Biol. 104: 117-120.

JOUVENAZ, D. P., C. S. LOFGREN, AND R. W. MILLER. 1990. Steinernematid nematode drenches for control of fire ants, Solenopsis invicta, in Florida. Florida Entomol. 73: 190-193.

KAYA, H. K. 1985. Entomogenous nematodes for insect control in IPM systems, pp. 282-302, in M. A. Hoy & D. C. Herzog [eds.], Biological control in agricultural IPM systems, Academic Press, New York.

LOFGREN, C. S. 1986. History of the imported fire ants in the United States, pp. 36-47 in C. S. Lofgren & R. K. Vander Meer [eds.], Fire ants and leaf-cutting ants, biology and management, Westview Press, Boulder CO.

MORRIS, J. R., K. W. STEWART, AND R. L. HASSAGE. 1990. Use of the nematode Steinernema carpocapsae for control of the red imported fire ant (Hymenoptera: Formicidae). Florida Entomol. 73: 675-677.

POINAR, G. 0. JR. 1986. Entomophagus nematodes, pp. 95-122, in J. M. Franz [ed.], Biological plant and health protection. Gustav Fisher Verlag, New York.



Scientific Notes 151

POOLE, M. A. 1976. Survey and control efficacy of endoparasites of Solenopsis richteri Forel and S. invicta Buren in Mississippi. Ph.D. Dissertation, Mississippi State University, Mississippi State. 92 pp. [Dissert. Abstr. Int. B, 37: 3254].

QUATTLEBAUM, E. C. 1980. Evaluation of fungal and nematode pathogens to control the red imported fire ant, Solenopsis invicta Buren. Ph.D. Dissertation, Clemson University, Clemson, S. C. 54 pp. [Dissert. Abstr. Int. B, 41: 16421].

REGELBRUGGE, C. 1991. The impact of imported fire ants on interstate shipment of nursery stock and sod. Attachment 3, Minutes of the Imported Fire Ant Technical Work Group. Available through Amer. Asso. Nurserymen, 1250 I Street, N.W., Suite 500, Washington, D.C. 20005.

WILLIAMS, D. F., C. S. LOFGREN, AND R. K. VANDER MEER. 1987. The red imported fire ant, Solenopsis invicta: control with fluoroaliphatic sulfone bait toxicants. J. Agric. Entomol. 4: 41-47.

MOVEMENT OF IMMATURE BEMISIA TABACI (HOMOPTERA: ALEYRODIDAE) ON POINSETTIA LEAVES

JAMES F. PRICE AND DAGMAR TABORSKY University of Florida

Gulf Coast Research and Education Center 5007 60th Street East

Bradenton, Florida 34203

Little is known about the movement of the first instar (crawler) Bemisia tabaci (Gennadius), sweetpotato whitefly, on host crops. Lopez-Avila (1986) stated that first instar B. tabaci crawls about the leaf surface from the insect's eclosion until it finds a suitable place to feed. The crawler of a similar insect, the greenhouse whitefly (Trialeurodes vaporariorum (Westwood)), often moves from one leaf to another before feeding (Larson et al. 1978).

Understanding the movement of immature B. tabaci within and among hosts is important because crawlers incite disease (Hoelmer et al. 1991, Schuster et al. 1991), other abnormalities (Hoelmer et al. 1991, Yokomi et al. 1990) and reduce crop value simply by their presence (Price & Poe 1991). Pest management options also are affected by the movement of crawlers. Crawlers that move greater distances and over a longer period more likely will contact entomopathogenic (Fransen 1990) or insecticidal (Schuster et al. 1989) residues. Crawler movement onto toxic residues was important for sweetpotato whitefly control on poinsettias when oils, oxamyl, phosalone and pyrethroids alone and in combination with certain other insecticides were applied (Schuster et al. 1989). This study was performed to determine the distance travelled by immature sweetpotato whitefly on poinsettias, and the period during which the travel occurs in order to assess the potential damage of the pest and tactics for its control on poinsettias.

Fifty, 6-wk-old 'Gutbier V-14 Glory' poinsettias grown in 15 cm pots were pruned to two mature leaves each. A female sweetpotato whitefly in a 3-cm clip cage was allowed to oviposit for one night on a leaf of each plant. One egg was permitted to remain on each leaf and plants were placed into a greenhouse and maintained at 26 ? 5? C. Three days after the eggs hatched and the insects had developed to the sessile second instar, a microscope micrometer was used to measure the distances between the attached, hatched eggs and the sessile second instars. Averages were calculated from the 50 observations.



Article Contentsp. 148p. 149p. 150p. 151

Issue Table of ContentsThe Florida Entomologist, Vol. 75, No. 1 (Mar., 1992), pp. i-ii+1-170Front Matter [pp. i-ii]Symposium: Insect Behavioral Ecology '91Introduction to the Behavioral Ecology of Immigration. The Immigration of Insects to Florida, with a Tabulation of Records Published Since 1970 [pp. 1-28]Escapees and Accomplices: The Naturalization of Exotic Ficus and Their Associated Faunas in Florida [pp. 29-38]Plants with Extrafloral Nectaries and Ants in Everglades Habitats [pp. 38-50]DNA Studies Reveal Processes Involved in the Spread of New World African Honeybees [pp. 51-59]Potential and Limitations of Predicting Invasion Rates [pp. 60-72]Functional Response, Reproductive Function and Movement Rate of a Grazing Herbivore: The Citrus Rust Mite on the Orange [pp. 72-83]

A New Genus of Psyllid (Homoptera: Psylloidea: Aphalaridae) from Florida [pp. 84-89]Feeding on Non-Host Plants by Partially Maxillectomized Tobacco Hornworms (Manduca sexta: Lepidoptera: Sphingidae) [pp. 89-93]New Records and Synonymy in Patagonian Atrichopogon (Diptera: Ceratopogonidae) [pp. 93-96]Two New Species of Moth-Flies, Genus Psychoda Latreille, from Northern Puebla, Mexico (Diptera: Psychodidae) [pp. 97-103]Survey of Termites in Guadeloupe, Lesser Antilles (Isoptera: Kalotermitidae, Rhinotermitidae, Termitidae) [pp. 104-109]Two Neotropical Cockroaches of the Genus Ischnoptera (Dictyoptera: Blattellidae) Established in Florida [pp. 109-115]Seedling Feeding Damage and Preference of Scapteriscus spp. Mole Crickets (Orthoptera: Gryllotalpidae) Associated with Horticultural Crops in West-Central Florida [pp. 115-119]Management of Insects on Pepper and Tomato with UV-Reflective Mulches [pp. 119-129]Life History and Parasites of Asphondylia borrichiae (Diptera: Cecidomyiidae), a Gall Maker on Borrichia frutescens [pp. 130-137]Field Evidence for an Attractant Produced by the Male Pepper Weevil (Coleoptera: Curculionidae) [pp. 138-144]Scientific NotesInfection of Mononychellus tanajoa (Acari: Tetranychidae) by the Fungus Neozygites sp. (Entomophthorales) in Northeastern Brazil [pp. 145-147]Evaluation of the Nematode Steinernema carpocapsae to Control Fire Ants in Nursery Stock [pp. 148-151]Movement of Immature Bemisia tabaci (Homoptera: Aleyrodidae) on Poinsettia Leaves [pp. 151-153]New Distribution Records for Polytes lineolatus (Heteroptera: Scutelleridae) with Description of Female Genitalia [pp. 154-155]New Distribution Records for the Assassin Bugs, Pnirontis brimleyi and Ctenotrachelus shermani (Heteroptera: Reduviidae) [pp. 155-160]Confirmation of the Brown Citrus Aphid, Toxoptera citricidus, in Costa Rica [pp. 161-162]Hyperparasitism of Liriomyza trifolii (Burgess) on Tomato [p. 162]Infection of Sound-Trapped Mole Crickets, Scapteriscus spp., by Steinernema scapterisci [pp. 163-165]

Book ReviewsReview: untitled [pp. 166-167]Review: untitled [pp. 167-168]

Back Matter [pp. 169-170]

evaluation of the nematode steinernema carpocapsae to control fire ants in nursery stock

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