The straw itch mite, Pyemotes tritici (LaGreze-Fossat and Montagne) was proposed by Bruce and LeCato (1980) as a potential biological control agent for the red imported fire ant, Solenopsis invicta Buren

Jouvenaz, D. P.

Lofgren, C. S.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Entomology Papers from Other Sources Entomology Collections, Miscellaneous 1986 An Evaluation of the Straw Itch Mite, Pyemotes Tritici, for Control of the Red Imported Fire Ant D. P. Jouvenaz USDA C. S. Lofgren USDA Follow this and additional works at: https://digitalcommons.unl.edu/entomologyother  Part of the Entomology Commons Jouvenaz, D. P. and Lofgren, C. S., "An Evaluation of the Straw Itch Mite, Pyemotes Tritici, for Control of the Red Imported Fire Ant" (1986). Entomology Papers from Other Sources. 34. https://digitalcommons.unl.edu/entomologyother/34 This Article is brought to you for free and open access by the Entomology Collections, Miscellaneous at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Entomology Papers from Other Sources by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Scientific Notes record of a long-winged mole cricket on St. Croix, either S. vicinus or S. didactylus (as suggested by Nickle and Castner 1984) is best dropped. This note is a contribution from the Agric. Exp. Stn., Montana State University, Bozeman, MT and is published as Journal Series No. J-1773. We would like to thank W. B. Muchmore for contributing the St. John specimen, and J. W. Brewer for review- ing an earlier version of the manuscript. REFERENCES CITED BEATTY, H. S. 1944. The insects of St. Croix, V. I. J. Agric. Univ. P. R. 28: 114-172. CANTELO, W. W., J. L. GOODENOUGH, A. H. BAUMHOVER, J. S. SMITH, JR., J. M. STANLEY, AND T. J. HENNEBERRY. 1974. Mass trapping with blacklight: effects on isolated populations of insects. Environ. Entomol. 3: 389-395. MISKIMEN G. W., AND R. M. BOND. 1970. The insect fauna of St. Croix, U.S.V.I. Scientific Survey of Puerto Rico and the Virgin Islands 13(1): 1-114. New York Academy of Sciences. NICKLE, D. A., AND J. L. CASTNER. 1984. Introduced species of mole crickets in the United States, Puerto Rico, and the Virgin Islands. Ann. Entomol. Soc. America 77: 450-465. AN EVALUATION OF THE STRAW ITCH MITE, PYEMOTES TRITICI (ACARI: PYEMOTIDAE) FOR CONTROL OF THE RED IMPORTED FIRE ANT, SOLENOPSIS INVICTA (HYMENOPTERA: FORMICIDAE) D. P. JOUVENAZ AND C. S. LOFGREN U. S. Department of Agriculture Agricultural Research Service Insects Affecting Man and Animals Research Laboratory Gainesville, Florida 32604 The straw itch mite, Pyemotes tritici (LaGreze-Fossat and Montagne) was proposed by Bruce and LeCato (1980) as a potential biological control agent for the red imported fire ant, Solenopsis invicta Buren. Although P. tritici may be regarded as a pest species (a cause of dermatitis in man and animals), it is an effective parasite of stored product insects (Bruce and LeCato 1979). In their 1980 paper, Bruce and LeCato reviewed the desirable characteristics of this mite, and reported success in preliminary tests against individual S. invicta colonies sufficient to warrant further evaluation. We are aware of only one other reference to attempted ant control with P. tritici, and that was on leaf-cutting ants (species not specified) in Brazil (Vilela 1986). He reported that the ant nests became inactive after 2 or 3 days but recovered within 16 days. Jouvenaz et al. (1981) reviewed the status of biological control of imported fire ants and concluded that non-specific predators, such as P. tritici, might be useful if they could be applied without danger to the user or environment. While the goal of our USDA-ARS research program on biological control of fire ants is to establish a complex 761 The Florida Entomologist, Vol. 69, No. 4 (Dec., 1986), pp. 761-763Published by Florida Entomological SocietyFlorida Entomologist 69(4) of specific natural enemies in the United States, we still believe that non-specific agents could be useful. Thus, we conducted additional evaluations that are reported here. The mites were reared by Dr. W. A. Bruce on pupae of the cigarette beetle (CBP), Lasioderma serricorne (F.), at the Stored Products Insects Research and Development Laboratory, USDA, ARS, Savannah, Georgia, by the methods of Bruce and LeCato (1980). Single-mound doses of mite-infested CBP were dispensed into individual contain- ers and transported in a cool styrofoam chest to Gainesville, Florida, for application to S. invicta mounds just as the adult progeny were emerging from the gravid females. Each 25 ml of CBP contained several thousand gravid female mites, each of which produced ca. 250 progeny (conservatively, 5-7.5 X 105 mites/25 ml). The viability of the mites was confirmed visually at the time of application. Three widely separated (> 5 km apart) test sites with large numbers of mature, queen-right (worker brood present) colonies of S. invicta were selected in Alachua County, Florida. We have not observed polygynous colonies in the test areas. The test colonies at site #1 were located along a fence on the edge of a pasture and in a stand of young (ca. 12 cm diameter) pine trees. Sites #2 and #3 were in open pastures. At each site, 40 mature, widely separated (> 4 m) colonies (10 for each of 3 dosages, plus 10 controls) were selected and rated before and at intervals of 1, 2, 4, and 8 weeks after treatment by the population index method of Lofgren and Williams (1982). Colonies of S. invicta often relocate their nests spontaneously or in response to disturbance (ineffec- tive control measures or repeated examinations). This is a common problem in fire ant population studies (Williams and Lofgren 1983). Therefore, we assumed that new mounds within ca. 4 m of abandoned test mounds were the result of nest relocation. Tests were initiated at sites #2 and #3 two and four weeks, respectively, after treatment of site #1. Thus, different generations of mites were applied to the mounds at each site. Ambient (shade) temperatures ranged from ca. 29-33?C during the study period (May-June). Mite-infested CBP were applied in dosages of 25, 50, or 100 ml per mound by scraping soil from the top of the tumulus and sprinkling CBP on the exposed tunnel system. Assuming an average of 105 ants per colony (Lofgren and Williams 1985) these dosages equal 5-7.5, 10-15, and 20-30 mites per ant, respectively. Due to a limited supply of CBP, control mounds were opened for examination but did not receive CBP. The CBP were attacked immediately by the excited worker ants and quickly taken into the nest. Our test results (Table 1) show that a single application of P. tritici at any of the three doses did not reduce the S. invicta population significantly (Newman-Keuls mul- tiple range test). Even discounting movement of colonies (scoring all unoccupied mounds as dead, even if a new mound was found within 4 m), P. tritici did not reduce the population when applied at the two lower dosages. Ten of the 30 check colonies relocated at least once during the evaluation period, whereas nine of 30 colonies treated with 25 ml, and 11 of 30 colonies treated with 50 ml of mite-infested CBP relocated. Seventeen of the 30 colonies treated with 100 ml of CBP relocated; thus, high concentrations of mites may prove sufficiently irritating to stimulate colony movement. Since there was no reduction of the S. invicta population index, we felt that further tests were not warranted. Even if adequate control of fire ants were possible through repeated applications of P. tritici, such repetitious treatments do not seem to us to be practical. Formicidal baits and drench treatments approved by the U. S. Environmental Protection agency for single-mound treatments are available and may be safer, since pyemotid mites present a hazard of dermatitis which may be severe enough to require medical treatment and even hospitalization (Baggett et al. 1981, Moser 1975). We thank Mr. Henry Beauchamp for excellent technical assistance. Dr. William A. Bruce, USDA, ARS, Savannah, Georgia, kindly supplied the mites and helpful advice. 762 December, 1986 Scientific Notes TABLE 1. RESULTS OF FIELD TRIALS WITH PYEMOTES TRITICI FOR CONTROL OF RED IMPORTED FIRE ANTS, SOLENOPSIS INVICTA. (ONE APPLICATION OF MITE-INFESTED CIGARETTE BEETLE PUPAE (CBP) MADE TO EACH OF 10 MOUNDS AT RATE INDICATED). Percent reduction in population index after Application rate indicated weeksb (ml mite-infested Application rate CBP/mound) (mites/ant)a 1 2 4 8 25 5-7.5 9 22 37 43 50 10-15 22 27 33 38 100 20-30 18 25 39 45 Check -11 18 23 35 "Mites conservatively estimated at 5-7.5 X 10 /25 ml CBP. Assumes 105 ants/colony. bMean of 3 replicates. No significant difference between treatments at a given post-treatment time (Newman- Keuls multiple range test). REFERENCES CITED BAGGETT, D. A., B. L., DAVIS, L. B. ELLIOT, P. V. FOURNIER, S. J. LERRO, J. A. RAWLINGS, AND C. R. WEBB, JR. 1981. Occupational dermatitis associated with grain itch mites-Texas. Centers for Disease Control Morbid. Mortal. Re- port 30: 590-2. BRUCE, W. A., AND G. L. LECATO. 1979. Pyemotes tritici: Potential biological con- trol agent of stored-product insects, pp. 213-220. In J. G. Rodriguez (ed.), Recent advances in acarol. Academic Press, New York. BRUCE, W. A., AND G. L. LECATO. 1980. Pyemotes tritici: A potential new agent for biological control of the red imported fire ant, Solenopsis invicta (Acari: Pyemotidae). Internat. J. Acarol. 6: 271-4. JOUVENAZ, D. P., C. S. LOFGREN, AND W. A. BANKS. 1981. Biological control of imported fire ants: A review of current knowledge. Bull. Entomol. Soc. Amer. 27: 203-8. LOFGREN, C. S., AND D. F. WILLIAMS. 1982. Avermectin Bla: A highly potent inhibitor of reproduction by queens of the red imported fire ant (Hymenoptera: Formicidae). J. Econ. Entomol. 75: 798-803. LOFGREN, C. S., AND D. F. WILLIAMS. 1985. Red imported fire ants (Hymenoptera: Formicidae): Population dynamics following treatment with insecticidal baits. J. Econ. Entomol. 78: 863-7. MOSER, J. C. 1975. Biosystematics of the straw itch mite with special reference to nomenclature and dermatology. Trans. R. Entomol. Soc. London 127: 185-91. VILELA, E. F. 1986. Status of leaf-cutting ant control in forest plantations in Brazil. In C. S. Lofgren and R. K. Vander Meer (eds.), Fire ants and leaf-cutting ants: Biology and management. Westview Press, Boulder, Colorado. WILLIAMS, D. F., AND C. S. LOFGREN. 1983. Imported fire ant (Hymenoptera: Formicidae) control: Evaluation of several chemicals for individual mound treat- ments. J. Econ. Entomol. 76: 1201-5. 763 

An Evaluation of the Straw Itch Mite, Pyemotes Tritici, for Control of the Red Imported Fire Ant

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An Evaluation of the Straw Itch Mite, Pyemotes Tritici, for Control of the Red Imported Fire Ant

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