Browsing by Author "Turner, E. Craig Jr."

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    Adrenal steroid, blocking agent, and social stress effects on northern fowl mite population development on Leghorn chickens and toxicological evaluation of selected acaricides (Acarina: macronyssidae)
    Hall, Robert Dickinson (Virginia Tech, 1977-07-15)
    Administration of adrenal steroids or blocking agents at optimum doses influenced northern fowl mite development on chickens. Corticosterone at 20 ppm or desoxycorticosterone at 30 ppm in feed were most effective in inhibiting mite infestations. High levels of social stress increased resistance of chickens to mites in a manner similar to but more effective than steroid administration. The mechanism of resistance was a decrease in capillary density at the skin surface. Commercial laying hens caged alone had lower plasma corticosterone levels and supported more mites than hens caged in groups. Stress-induced, steroid initiated, or inbred mite resistance was incompatible with maximum production from chickens. Resistant chickens produced poorer weight gains and testes mass than did susceptible birds. Sex hormones were shown to play a supplementary, and antibody a minor role in mite resistance. Carbaryl was shown to be the compound most toxic to northern fowl mites of those registered in Virginia for application to poultry. Malathien resistance was noted in mites from a commercial poultry house. The synthetic pyrethroid permethrin was effective against these mites.
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    The armored scale insects of Venezuela (Homoptera: Coccoidea: Diaspididae)
    D'Ascoli, Alfredo (Virginia Tech, 1971-04-05)
    Scale insects are among the most serious plant pests throughout the world. The Diaspididae is the largest scale insect family and probably the most important economically. No comprehensive taxonomic study dealing with the scale insects of Venezuela has been conducted in the past. Forty-nine species are described and illustrated in this study, of which 2 are new species. Twenty-seven additional species are recorded from Venezuela for the first time. Keys are provided for determination of the 49 species. The material studied was borrowed from several institutions. Mounting techniques are given. The description of each species is based on females, since males and nymphs were available only in a few species. While this is essentially a taxonomic and faunistic study, the hosts on which the scale insects were found are listed. It is hoped that this study would be used as basis for future research in Venezuela. More collections need to be made throughout the many ecologically different areas of the country; especially from non-cultivated plants. The accumulation of additional distributional and biological records, and will lead to a better understanding of the Venezuelan armored scale insect fauna.
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    Aspects of dispersal and population structure of Blattella germanica (L.) in field habitats and attitudes concerning aesthetic injury levels
    Zungoli, Patricia A. (Virginia Polytechnic Institute and State University, 1982)
    Movement behavior of Blattella germanica (L.) was investigated using two mark-recapture techniques 1) marking field collected populations of adult German cockroaches with a unique number, and 2) releasing strains of genetically marked German cockroaches to observe nymphal movement. Movement by adult cockroaches was studied by marking 3299 field collected German cockroaches in eight apartments. allowed for population. Adults were marked with Liquid Paper'. This recognition of specific individuals in the After marking, cockroaches were released at their original site of capture. Biological data was recorded on both nymphs and adults. Results indicate that movement of adult German cockroaches between apartments is minimal. Movement within apartments is greater, but not substantial. Movement appears to be linked to carrying capacity of the habitat (=apartment). When a vital resource -- food, water, or harborage -- becomes limited, adult movement can be detected when populations are large. Trapped populations in focus and non-focus apartments are spatially distributed in different ways. German cockroaches in non-focus apartments are trapped predominately in traditional sites of infestation kitchen and bathroom areas, with 90% of the collections occurring in these sites. In focus apartments trap collections indicate that one-third of the population is found in areas traditionally identified as non-preferred sites of infestation. Movement of German cockroach nymphs was investigated using releases of genetically marked strains of cockroaches. Collections of marked individuals were limited, suggesting that the strains used, especially eye color mutants, were not competitive in field environments. Results of this study were inconclusive. The feasibility of applying the aesthetic injury level concept to control programs within the urban environment rather than to pests occurring on the exterior was investigated. A random survey was conducted in non-elderly public housing projects in Roanoke, VA, Norfolk, VA, and Baltimore, MD. One hundred surveys were taken in each of the cities. The results of the survey indicate that the aesthetic injury level concept can not be successfully applied to control programs for insect pests occurring inside the home. are dependent upon the Tolerances extent of are variable, and the infestation experienced by each resident. It is speculated that as infestation levels decline, tolerance of the pest would also decline.
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    Aspects of the biology, behavior, bionomics, and control of immature stages of the cat flea Ctenocephalides felis felis (Bouche) (Siphonaptera: Pulicidae) in the domiciliary environment
    Byron, David W. (Virginia Polytechnic Institute and State University, 1987)
    The larval stage of the cat flea, Ctenocephalides felis felis (Bouche), was found to exhibit behaviors that were conducive to its security in carpet. Larvae exhibited positive geotactic, and negative phototactic behaviors. This resulted in the larvae spending greater than 80% of their time at the base of the carpet pile. Cat flea larvae also exhibited a positive hydrotaxis, and appeared to exhibit undirected movements when foraging. Larva were observed to respond to disturbances by coiling their body longitudinally. Cat flea hatched and unhatched eggs, and larval exuviae were found to be dispersed in a contagious fashion within carpet. The spatial pattern of the immature stages and remains was influenced by the habits of the pet host within a given room. First-instar larvae do not move far, if at all, from the location of eclosion. The movement of the larval stage is influenced by biotic and abiotic factors in the environment. Areas of high pedestrian or pet traffic are not conducive to successful eclosion from the egg or for successful larval development. Various methods of control exist for controlling an indoor infestation including both non-chemical and chemical tactics. A method for the physical control of immature stages in carpet is vacuuming. A beater-bar vacuum removes about 50% of the eggs but less than 30% of the larvae from a carpet. Chemical control tactics indoors are normally conducted using a compressed-air sprayer. Pressure within the application system is critical for creating spray patterns which can be overlapped to allow even insecticide coverage of the substrate. A compressed-air application system is not capable of delivering pesticides in a manner that will completely penetrate the carpet substrate to reach the base of the carpet. No significant differences in carpet penetration were observed over a range of 20 to 70 psi. Regardless of pressure, more than 93% of the solution applied to carpet was deposited in the upper third (6 mm) of the carpet. Pet owners were surveyed about their knowledge and perceptions of household infestations of the cat flea, and also about financial expenditures and their willingness to pay for a flea-free environment. The importance and the pest status of flea infestations were determined to be based on physical, psychological, and economic impacts on homeowners. Respondents' perceptions of infestations on their pet were associated with infestation levels in the house. The respondents were willing to pay more for flea control in July, the onset of the flea season, than they were at the peak or decline of the season. They were also willing to pay more as their perception of the intensity of the problem on the pet or in the home increased. Household income was not shown to affect a respondent's actual financial expenditures or his willingness to pay for flea control on the pet or in the home.
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    Biological and ecological studies of Hydrotaea aenescens (Wiedemann) (Diptera: Muscidae), and other arthropods of high-rise cage layer poultry houses
    Dillon, Perian Lenore (Virginia Tech, 1994-05-15)
    Laboratory and field studies of Hydrotaea aenescens were undertaken to provide information on this predator's biology and ecology under differing conditions, and to promote its use as a biocontrol agent for controlling house flies in poultry houses. Taxonomic diversity of arthropods in a new high-rise cage layer poultry house was determined from manure samples collected from different manure moisture categories. Stabilization of taxonomic diversity and taxonomic evenness of manure-inhabiting arthropods occurred after the house had been operating for eight months. In contrast, overall diversity in high-rise poultry houses at a well managed, longer established farm was significantly higher than that observed at the new farm, even after 1 1/2 years of operation. When the densities of selected manure-inhabiting predatory arthropods collected from the manure samples (including Carcinops pumilio, pseudoscorpions, a dermapteran species, an anthocorid species, and H. aenescens) were correlated with percent manure moisture, the results showed that, of these predators, only H. aenescens was positively correlated with both manure moisture and with densities of house fly larvae. This information emphasized that although predators such as C. pumilio may exhibit high predation rates on house fly eggs and first instars, their effectiveness 1s reduced by their spatial separation from their supposed prey. This contrasts greatly with H. aenescens performance. Decreases in survival of house fly larvae occurred when the larvae were exposed to H. aenescens of higher larval stadia. This was dramatically demonstrated when 100 first instar house flies were exposed to 100 second instar H. aenescens. No house fly larvae survived. Developmental times were determined at constant temperatures for egg, and larval H. aenescens. Developmental times decreased as temperature increased. Median time for egg and larval development ranged from 1.3 and 14.6 days at 22.2°C to 0.5 and 8.3 days at 35.0°C, for the respective stages. All of this information, together with developmental times and mortality of H. aenescens immatures gathered in a study of temperature dependent development has enhanced understanding of the biotic interactions in accumulated poultry manure. These data will be invaluable in designing integrated pest management programs especially in the area of computer-aided decision making.
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    Biology and natural control of the white pine weevil, Pissodes strobi (Peck), in Virginia
    Harman, Dan M. (Virginia Tech, 1966-06-05)
    Ovariole development and termination of diapause in the white pine weevil were studied by dissecting weevils at various intervals throughout the winter. Old-generation adults brought into the laboratory November produced viable eggs within 5 days. New generation adults brought into the laboratory on November 4 produced viable eggs during November. Viable eggs were deposited by other new-generation adults after 10 to 15 day. at room temperature in winter. On each of the 3 collection date studied, new generation adult produced viable eggs without copulating after collection from hibernation indicating that capulation occurs in the fall. There was no evidence of progressive ovariole development throughout the winter. New generation adults which were isolated as soon as they emerged from the shoots and maintained at constant room temperature had poorly developed ovarioles by November 20 and produced no eggs. Weevil flight and dispersal through a white pine plantation was studied by releasing 409 marked weevils at a central point within a l431-tree plantation and checking every tree at 5-day intervals. Weevils flew readily at the time of re1ease. Marked weevils were recorded throughout the plantation. which extended as far as 330 feet from the release point. A few weevils were observed on scattered white pines 200-300 yards from the release point beyond a hardwood barrier. Total numbers of weevils present on the leaders increased from April 26 to May 5, after which numbers steadily decreased. By June 15, only 20 weevils were observed on the leaders.
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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.
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    A contribution to the knowledge of the odonata
    Carle, Frank Louis (Virginia Tech, 1982-06-16)
    Theories concerning the origin of insect wings and flight are reviewed and a new scenario for their origin proposed. It is suggested that environmental conditions of the small stream were responsible for the evolution of insect flight, and that thermoregulation as well as respiration was important in the preadaptation of wings. The possibility that the five paired convex-concave vein systems each represented a dorsal-ventral blood channel is suggested. Odonate wing vein homology and nomenclatural systems, and phylogeny are reviewed. The process of vein loss is evaluated in the Palaeoptera and a new system of odonate wing vein homologies proposed. The odonate wing mechanism is analyzed and the heretofore overlooked discal nodus characterized. Reevaluation of the comparative morphology of fossil and recent Odonata indicates that Protozygoptera and Protanisoptera represent evolutionary side branches, that the Anisozygoptera is polyphyletic, and that Isophlebiidae and Calopterygoidea are the most generalized Odonata known. Previous scenarios explaining evolution of the unique odonate copulatory process are reviewed. Considering the copulatory behavior of the Calopterygoidea generalized supports evolutionary trends toward male domination and in-flight completion of the process. Assuming direct sperm transfer the original odonate mode requires that originally oviposition be in tandem and that sperm transfer to and from male anterior abdominal sterna be accidental. In contrast, assuming an original indirect transfer of sperm leads to a copulatory sequence similar to that of the Odonata. The proposed scenario differs from others in that extraordinary postures are not envisioned, the process is completed at rest, and the odonate tandem hold is developed prior to copulation. Anisopteran morphology and phylogeny are reviewed and reliable dentification keys developed for North American families and genera, and for 180 anisopteran species collected in Virginia and vicinity. Each species is described and photographed, including seven new species. The biogeography of Virginia Anisoptera is best explained by overlapping biotic regions, the fauna being a mixture of eastern North American, boreal, and tropical elements. New efficient methods for collecting, preserving, and rearing Odonata are described.
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    Contributions to the autecology and ecosystematics of immature ceratopogonidae (Diptera), with emphasis on the tribes heteromyiini and sphaeromiini in the middle atlantic United States
    Knausenberger, Walter Ingolf (Virginia Tech, 1986-12-05)
    Biological and systematic study of the immature stages of the biting midges (Diptera: Ceratopogonidae) has been infrequent, although the family is one of the largest in the order, with over 4,000 species worldwide, and is ubiquitous among aquatic/semiaquatic environments. An ecosystematic analysis is presented here of the Ceratopogonidae in Virginia and contiguous states based mainly on a diversified biological field survey, with particular attention to associating immature stages with adults, and acquisition of ecological data. I emphasized (a) extraction of larvae and pupae; (b) two methods of rearing, developed for this study: individual rearing(IR) with an agar-nematode technique, and collective rearing from the habitat substrate in rearing cartons(RC); and (c) field trapping of adults at the habitats. In Section I, a faunistic assessment - the first of its sort - is provided of the total Virginia-region ceratopogonid fauna, in all developmental stages, with a focus on Culicoides, including a comparative evaluation of the relative abundance of the ceratopogonid genera with respect to methods of collecting and extracting. High taxonomic richness of the ceratopogonid fauna in the Middle Atlantic states is reflected in the 150 described and 42 undescribed (new) species recovered. A detailed geographic checklist for the 222 species of Virginia and the five contiguous states is presented and interpreted. At least 54 Culicoides species are present in the Middle Atlantic u.s. About half of the larval species can be determined in Virginia. With the results of this study, 93% of breeding sites for the genus are known in Virginia, more than for any other state. Section II assembles and synopsizes data on the autecology, life history, habitat, morphology, systematics, as well as geographic and seasonal occurrence of 28 species (3 new) and 10 genera in two related tribes of predaceous biting midges, Heteromyiini and Sphaeromiini (subfamily Ceratopogoninae). Shorelines are the "archetypical arena" in which these larvae thrive, typically above and below the water line. Their habitats and substrates are characterized in detail. The greatest diversity of larvae in these tribes consistently occurs in and along mid-reach streams{Order: 3 to 5). Mechanisms of ecological partitioning by sympatric species, and the differential adaptive significance of larval, pupal and adult morphological characters are evaluated. Taxonomic and ecological diversity in these groups are clearly related.
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    Determination of the possible role of arthropods as vectors for "Potomac Horse Fever" in equines
    Fletcher, Michael Gordon (Virginia Polytechnic Institute and State University, 1987)
    Potomac Horse Fever (PHF) is a disease of great concern to many horse owners in the Potomac River area of Maryland and Virginia. It is caused by a rickettsia, Ehrlichia risticii. The involvement of an arthropod vector has been suspected because of the seasonal epidemiology of the disease. This research was an attempt to identify and evaluate potential arthropod vectors. A seasonal activity study of biting arthropods attacking horses in endemic areas of Maryland and Virginia identified five potential vectors: (1) Simulium jenningsi (Diptera: Simuliidae), (2) Stomoxys calcitrans (Diptera: Muscidae), (3) Culicoides obsoletus (Diptera: Ceratopogonidae), (4) C. variipennis, and (5) Dermacentor variabilis (Acari: Ixodidae). These five arthropod species were given status as potential vectors because they were collected feeding on horses just prior to and throughout the PHF season. Simulium jenningsi and D. variabilis have the closest seasonal association with the occurrence of PHF as presented in this study. D. variabilis was determined to have the greatest potential due to its reported association with other rickettsial diseases. A series of laboratory and field studies were designed to examine the potential role of D. variabilis in the transmission of E. risticii. We first attempted to transmit E. risticii by feeding adult D. variabilis collected from an endemic farm on susceptible horses. Other laboratory studies included mouse to horse and mouse to mouse transmission attempts using ticks fed on mice inoculated with E. risticii. A serological survey of 105 trapped field rodents (host of immature D. variabilis) on endemic farms in Maryland showed all specimens collected to be negative for PHF antibodies. These studies and others gave no indication of D. variabilis's involvement in the transmission of the disease in nature. The other species mentioned above were not examined.
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    The effect of eight tensides on the toxicity of diazinon topically applied to the male German cockroach
    Candler, William H Jr. (Virginia Tech, 1976-09-08)
    The effect of 8 tensides on the toxicity of diazinon were investigated by means of topical dose applications to male adult German cockroaches, Blattella germanica (L.). Other diazinon formulations were evaluated for comparison. These were Diazinon 4E, Diazinon 4E plus Igepal CO-630, Oiazinon 4E plus Multi-Film X-77, diazinon in OMSO, diazinon in Stoddard's Solvent, and diazinon in Stoddard's Solvent plus piperonyl butoxide. Five of the tensides formed emulsions that were similar in toxicity to diazinon in Stoddard's Solvent. These were, in order of decreasing L050 's, Bio Film, Tween 80, hexadecyltrimethyl ammonium bromide (HAB), Multi-Film X-77, and Triton X-100. All of the tenside emulsions were more effective than Oiazinon 4E. Emulsions formed with Triton X-100 and Multi-Film X-77 had L050 's significantly lower than the Oiazinon 4E formulation. The two tensides added to Oiazinon 4E seemed to decrease effectiveness. OMSO and piperonyl butoxide were the two most effective additives to diazinon. Both were synergistic with respect to diazinon in Stoddard's Solvent. The results from this investigation indicate that several of the tested formulations may prove effective in cockroach control. Additional studies of these preparations under practical conditions need to be made.
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    Evaluation of methods to protect poultry house insulation from infestations by lesser mealworm (Coleoptera: Tenebrionidae)
    Despins, Joseph L.; Turner, E. Craig Jr.; Pfeiffer, Douglas G. (1991)
    Insecticide sprays Bnd paint barriers Applied to the surface of extruded polystyrene, and different types of insulation, were evaluated for prevention of lesser melllwonn, Alphitobius diapcn"nlls (Panzer), infestations. In a lahoratOly study, tetrachlOlvinphos 50 ¥lP and pirimiphosmethyl 7E on extruded polystyrene produced> 90% mortality in larval and adult lesser mealwonn populations 71 wk after application. These insecticide spray treatments, however, were not effective under conditions found in the manure pit of a high rise cage layer house. Our field study showed that Styrofoam SS"" and Ethafoarn 220''', were resistant. to lesser mealwonn infestations. Super IQ'" paint., a latex paint impregnated with chlorpyrifos, was also effective in protecting extruded polystyrene from infestations under field conditions.
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    Feeding activity, a study of control measures, and a survey of black fly pests (Dipterai Simuliidae) of horses in Virginia
    Townsend, Lee Hill (Virginia Tech, 1975)
    The feeding activity of female black flies may cause considerable annoyance to saddle horses. Horses under attack become head-shy and difficult to manage, posing a potential hazard to riders. Stabling horses offers a means of protection against black fly feeding, but most horse owners cannot or will not stable their animals to prevent disturbance by noxious flies. Because stabling is an unsatisfactory control measure, I will evaluate various ear protectants to find easily applied materials of suitable effectiveness and duration on pastured animals to be of practical value to the owners.
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    Hymenopterous parasites of lps spp. bark beetles (Coleoptera:Scolytidae) in Virginia
    Berisford, C. Wayne (Virginia Tech, 1968-06-19)
    The pine engraver beetles (~ spp.:Coleoptera:Scolytidae) may be serious pests depending on certain prerequisite conditions. In their secondary or "normal" role they breed in slash and damaged, dying, and dead trees. The broods emerging from these sources normally attack similar material. When such material is scarce due to cessation of cutting operations in mid-season or when conditions are especially favorable for brood development, an excess of beetles is often produced which, due to the lack of more suitable material, attack healthy trees. Repeated attacks cause these trees to succumb and die. When normally healthy trees are weakened by fire, flood, defoliation, drought, stagnation, etc., then they become more acceptable host material for successful engraver attacks. When the production of a very large number of beetles in "normal" breeding material coincides with physiological stress in "healthy" trees, then population explosions can occur. When large numbers of beetles and low host vigor do not coincide, spot kills cornnon1y occur. According to Thatcher (32), spot kills, although not conspicuous, add up to large volumes of timber loss each year.
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    Influence of flight activity and octopamine on hemolymph trehalose titers in Heliothis zea (Boddie) (Lepidoptera: Noctuidae)
    Davidson, Deborah Ann (Virginia Tech, 1990-04-05)
    Hemolymph trehalose concentrations of male and female Heliothis zea were quantitated by high performance thin-layer chromatography (HPTLC) at various ages and times of the day and related to flight activity. Effects of octopamine injection or stress on trehalose levels were also quantified. Flight activity was measured with a 32-channel computerized actograph that simulated sunrise at 0300 EST (Eastern Standard Time) and sunset at 1700. Males exhibited greater flight activity than females at all ages examined. Flight began near sunset, continuing through the night and ending around sunrise. Females flew continuously throughout the night, whereas males exhibited two peaks in activity: the first between 1700 and 1900, followed by a second peak between 2000 and 2400. Flight activity peaked on days 3-4 in males and days 4- 5 in females. Trehalose was the predominant hemolymph sugar, comprising 82-100% of total hemolymph sugars. Glucose was the second most frequently observed sugar. Trehalose concentrations were variable, ranging from < 1 ug/ul to 37 ug/ul. Lab-reared moths had higher and more variable trehalose concentrations than field collected (wild) moths. Trehalose levels were relatively constant several days after emergence in both sexes but decreased significantly by day 6 in males. When examined over a 24 hour period, trehalose concentrations gradually increased throughout the day in day 4 males and females, peaking one hour before sunset at approximately 18 ug/ul. This peak is hypothesized to be related to flight preparation. Females showed a second peak in trehalose levels at 1800, but males’ trehalose levels continued to decline until 1900. Males and females exhibited more similar patterns in trehalose concentrations when sampled every 15 minutes over the sunset period (1500-1900) than when sampled at hour intervals. Injections of octopamine, reputed to induce hyperglycemia in other insects, failed to elicit significant increases in trehalose levels in either fed or starved moths. Starved moths had lower trehalose concentrations than fed moths. Method of analysis (HPLC, HPTLC and anthrone) produced no differences in measured levels of trehalose or glucose. Various forms of stress (handling, shaking), also reported to induce hyperglycemia in other insects, similarly did not significantly increase trehalose titers in moths.
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    Inheritance of resistance to lindane in the German cockroach, Blattella germanica (L.)
    Barker, John Grove (Virginia Tech, 1957-05-04)
    1. The inheritance mechanism or resistance to lindane in the German cockroach, Blattella germanica (L.) was studied by determining the toxicity of lindane to the following populations ot cockroaches: a) lindane.resistant and non-resistant strains, b) the F1 and F2 progeny of reciprocal crosses between the two parental strains, c) the F1 and F2 progeny of backcrosses between the reciprocal cross F1 males. and resistant and non-resistant strain females, d) the progeny of pair matings within resistant and non-resistant strains and e) eight successive generation of a resistant strain isolated from further insecticide selection. 2. The method. employed in rearing the cockroaches and obtaining toxicological data on the different populations, as well as the genetical and statistical procedures, are described. 3. The toxicological data tor the mass matings are presented 1n the form of regression lines fitted by appropriate statistical analyses. 4. The toxicological data. for the pair matings, transformed into "indices of resistance," are presented in tabular form. 5.. Appropriate conclusions are drawn from the data to explain the inheritance mechanism of lindane resistance in the German cockroach.
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    Interactions between the rust fungus Puccinia carduorum Jacky and the musk thistle herbivores Trichosirocalus horridus (Panzer), Rhinocyllus conicus Froelich (Curculionidae: Coleoptera), and Cassida rubiginosa Muller (Coleoptera; Chrysomelidae)
    Abad, Reynaldo Gallego (Virginia Tech, 1990-12-01)
    The compatibility of the rust fungus Puccinia carduorum Jacky with three biological control agents, Trichosirocalus horridus (Panzer), rhinocvllus conicus Froelich, and Cassida rubiginosa Müller and their combined impact on must thistle, Carduus thoermeri Weinmann were studied.
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    Investigations of the destructive behavior, and method for control of the lesser mealworm, Alphitobius diaperinus (Panzer), (Coleoptera: Tenebrionidae)
    Despins, Joseph L. (Virginia Polytechnic Institute and State University, 1986)
    The relationship between the types of construction of high rise caged layer houses and insulation damage produced by the lesser mealworm was examined. Polyurethane insulation which had heavy-weight paper glued to its surface and was installed with tape to seal off the seam between the insulation boards had no infestations. Structures with concrete block pit walls had lower insulation infestations than those houses with wooden walls forming the pits. Houses with a support structure set on top of the concrete block pit wall had lower infestations than houses built with the support structure set directly into the earth. The insulation installed nearest the pit was the most severely infested, and infestation intensity was inversely proportional to insulation height above the manure pit. Damage in extruded polystyrene insulation resulted in a substantial loss of volume of material in the corner areas of the insulation panels, and caused a significant reduction in insulating quality. Observations were made on the effect of manure moisture and poultry house construction materials on lesser mealworm dispersal behavior. Larvae and adults preferred manure habitats of 30 and 40% moisture, and dispersal from the manure significantly increased when manure moisture was increased to levels of 50 and 60%. Larvae climbed a significantly greater distance up a vertical wooden surface than up a vertical concrete block surface under field conditions. Results indicate that structures built with wood pit walls are predisposed to infestations, and that fluctuating manure moisture levels in these houses can indirectly contribute to accelerated infestation by driving the larvae from the manure pits into the insulation. Insecticide sprays, plastic films, paint barriers applied to the surface of extruded polystyrene, and different types of insulation were evaluated for lesser mealworm resistance. In a laboratory study, tetrachlorvinphos and pirimiphos-methyl sprayed on extruded polystyrene produced greater than 90% mortality in larval and adult populations up to 71 weeks postapplication. Larvae were unable to penetrate either chlorpyrifos-impregnated or non-insecticidal polyethylene films. Infestation intensity was inversely proportional to insulation cell size. Effective treatments identified under field conditions were permethrin and pirimiphos-methyl sprays, and two formulations of chlorpyrifos-impregnated latex paint. Insulation materials with a cell size of 1.5 mm were resistant to lesser mealworm field populations.
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    Life history studies of the old house borer, Hylotrupes bajulus (L.) (Coleoptera: Cerambycidae)
    Cannon, Kevin Francis (Virginia Tech, 1982-03-05)
    A North American biotype of the old house borer, Hylotrupes bajulus (L.) was established from field and laboratory data. This biotype is based on differences in size and longevity of the life stages and on adult fecundity. N. A. females were observed to oviposit a mean of 165.1 ± 15.5 eggs in comparison to 119.4 (South African) and 105.2 (European). Oviposition period was 5.2 ± 0.5 days for the N. A. biotype and 3.9 and 12 days for the South African and European, respectively. Eggs of the N. A. biotype were smaller than those of the South African and incubation period (8.5 ± 0.3) shorter than both South African (14.0) and European (9-12). Development and comparisons of the pupal and larval stages are presented and discussed. Comparisons of the N. A. and European biotypes under similar temperature, humidity and nutritional conditions found no significant differences between biotypes. These results indicate that the biotypes have undergone little genetic change since their separation over 200 years ago. The old house borer is quite responsive to environmental conditions and the biological variation noted in field populations is attributed to non-genetic modifications of the phenotype. The high degree of biological flexibility noted in this species allows the OHB to inhabit marginal habitats and explains its present world-wide distribution. The OHB was successfully reared from egg to adult in 9-11 months on an artificial diet. An oligidic diet was developed and was composed of ground host tissue (southern yellow pine, Pinus spp.), purified cellulose, agar, and basic nutrients. This diet provided an adequate physical and nutritional environment as noted in the reduction in larval mortality and developmental period when compared to conventional rearing methods. Comparative nutritional, physiological and behavioral studies are now possible between larvae feeding on artificial diets and conventional wooden blocks. Observations of the adult mating behavior, fecundity, oviposition period and egg viability were reported under two mating regimes: single and multiple. Fecundity and egg viability were not significantly different between regimes. However, the number of egg batches, length of oviposition period and the longevity of adult females were significantly different. Adult behavior between regimes was not noticeably different. Males actively compete for females when other males are present and aggressive interactions are common. The practical and evolutionary significance of single and multiple matings is discussed. Consumption, growth, utilization and respiration by three weight classes of old house borer larvae, under 5 constant temperatures and relative humidity were studied. Wood consumption in all larval weight classes was greatest in the temperature range of 20° to 30°C and significantly reduced below and above these temperatures. Growth rates for small larvae were not significantly different among temperatures. Medium and large larvae recorded negative growth rates at 15° and 35°C. Wood utilization was greatest at temperatures of 20° and 25°C. Respiration rates were highest for small larvae. Small larvae were apparently more efficient at converting wood ingested to biomass at all temperatures.
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    The macrobenthos of a new reservoir, Lake Anna, Louisa County, Virginia
    Voshell, J. Reese Jr. (Virginia Polytechnic Institute and State University, 1976)
    The macrobenthos of a new reservoir in central Virginia, Lake Anna, was studied for the first three years after impoundment, 1972-1975. Prior to this, extensive macrobenthic collections had been made in the river destined for impoundment, the North Anna River. The biota of this river had been seriously affected by acid mine drainage for over 100 years. Macrobenthos consists of the organisms living on the bottom or the solid-liquid interface. The occurrence of these organisms is significant, because they are major items in the diet of many fish, and are thus important in the flow of energy through an ecosystem. The basic objectives of this study were to determine the changes in macrobenthic community structure brought about by impoundment, and then to observe the successional changes which occurred in the following years. This information was then compared to a hypothetical model predicting the productivity of new reservoirs. It was discovered that traditional grab sampling was not reliable in new reservoirs because of the abundant submerged terrestrial vegetation. An original sampling method was developed which involved the use of SCUBA to place and retrieve artificial substrate samplers. This SCUBA method was compared to grab sampling, and found to more reliably estimate macrobenthic community structure. Following impoundment, there was an immediate change in macrobenthic community structure. Colonization of the new reservoir occurred very quickly, especially during the first summer period. The acid mine drainage did not affect the distribution of macrobenthos in the new reservoir, probably because of dilution. Identification of over 525,000 organisms revealed that they could be classified into three groups: first colonizers, omnipresent species, and second colonizers. A review of the food habits of these organisms indicated that there were four trophic functional groups: micropredators, macropredators, collector-microgatherers, and collector-microfilterers. The first colonizers consisted of three species, one of which was completely dominant in each of the first three functional groups the first year. The second colonizers consisted of many additional species, several of which shared dominance in each of the same three functional groups the second and third years. The omnipresent group consisted of midge larvae which were dominant in the fourth functional group, collector-microfilterers, in all three years. This information, in conjunction with analysis of the horizontal, vertical, and temporal distribution, indicated that the development of macrobenthic community structure in Lake Anna followed the general trends expected in ecological succession. These trends are increased number of species, increased equitability of species composition, and better organization of distribution. A comparison of the development of macrobenthos in new reservoirs with a model of expected productivity indicated that the abundance of macrobenthos. may also exhibit the same trends as productivity. These trends are an initial increase in productivity for several years, followed by a sharp decline for several years, to be finally followed by a small increase and stabilization. This sequence of events probably requires at least 15 years for macrobenthos.