Browsing by Author "Vaughan, Jefferson Archer"

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    Biology and control of the lesser mealworm: Alphitobius diaperinus, a structural pest in poultry houses
    Vaughan, Jefferson Archer (Virginia Polytechnic Institute and State University, 1982)
    Late instar larval Alphitobius diaperinus initiated tunneling damage to polystyrene insulation in search of protected pupation sites. Adult females oviposited upon the surface of the styrofoam but early instar larvae left the styrofoam soon after hatching. Within twenty days, large numbers of adults moved into the styrofoam, expanding the tunnels and depreciating the panels' suitability as pupation sites for the late instar larvae. No oviposition occurred within the tunnels. All lifestages of Alphitobius diaperinus were found to be cannibalistic. Although preliminary tests show that adult mealworms will consume house fly late instar larvae and prepupae, no significant predation of the house fly by A. diaperinus could be detected under simulated natural conditions at the population density tested. Wettable powder formulations of permethrin and carbaryl when sprayed upon styrofoam were comparable in residual activity. Residual activity of both compounds was less when applied to unpainted plywood. The emulsifiable concentrate formulation of permethrin proved to be ineffective. Regression slopes from topical application studies reveal that tetrachlorvinphos may be the material of choice against A. diaperinus because there is less chance of the lesser mealworm developing resistance to tetrachlorvinphos than with either permethrin or carbaryl. Tetrachlorvinphos also showed longer residual effectiveness against A. diaperinus as a surface spray on styrofoam and plywood than did permethrin or carbaryl.
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    Biology of immature Culicoides variipennis ssp. australis (Coq.) (Diptera:Ceratopogonidae) at Saltville, VA
    Vaughan, Jefferson Archer (Virginia Polytechnic Institute and State University, 1985)
    The larval and pupal biology of a unique population of gulicoides variipennis inhabiting the brine ponds of Saltville, VA was studied. Developmental threshold temperatures (OC) and thermal constants (Odays) for larvae and pupae were 9.6OC and 387Odays (larval stage) and 9.6OC and 3OOdays (pupal stage) respectively. Accumulated heat units recorded in the field ranged from 366—376Odays between successive generations in the summer. Heat accumulations required for completion of immature development of Q. variipennis were found to be much greater (83lOdays) for the overwintering generation. During the summer, larval/pupal distribution within the littoral zone of a brine pond was confined to the surface cm of mud at or near the shoreline. Insects overwintered farther offshore, mostly as 3rd instars. In ear1y' March, most larvae had xnolted to 4th instars and migrated above shoreline to pupate. Adult emergence occurred in April. Three summer generations were documented for 1983-1984 at Saltville._ Life tables and survivorship curves were calculated for the overwintering generation and the first summer generations for 1983 and 1984. For the overwintering generation, there was a relatively constant mortality rate between successive ageclasses (Type II survivorship curve). During the summer, there was relatively little mortality between successive larval age—classes but a dramatic increase in mortality was evident at the pupal stage (Type I survivorship curve). Late instar larvae were found to migrate from the shoreline onto the exposed mudflats to pupate, thus becoming vulnerable to predation by ants and carabid beetles. Excellent survival rates of the larvae during the summer was attributed to habitat stability, the paucity of predators and parasites and abundant microfloral content (i.e. food} of the pond water. Intra-specific competition for food resources appeared to be alleviated somewhat by partitioning of those resources on a diurnal cycle.