Scholarly Works, Entomology
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- Postemergence growth of the ovarian follicles of Aedes aegyptiHagedorn, H. H.; Turner, Sarah; Hagedorn, E. A.; Pontecorvo, David; Greenbaum, Paula; Wheelock, Geofrey; Flanagan, T. R. (1977)Growth of the ultimate follicle to the resting stage in Aedes aegypti is linear and reaches maximum development about 6Ohr after emergence. Decapitations and ligations at various times after emergence indicate that growth of the follicles is under the control of factors from the head and thorax. Release of head factor occurs within one day after emergence and is relatively sudden. The thoracic factor is released gradually over a 2 to 3 day period. Near normal growth of follicles in isolated abdomens after topical application of juvenile hormone (JH) indicates that the thoracic factor is JH from the corpora allata and demonstrates the feasibility of using this system as a JH assay. When ecdysone was injected simultaneously with JH the follicles failed to grow.
- Cucumber pollen germination and tube elongation inhibited or reduced by pesticides and adjuvantsGentile, A. G.; Vaughan, A. W.; Pfeiffer, Douglas G. (1978)
- Coleoptera of poultry manure in caged-layer houses in North CarolinaPfeiffer, Douglas G. (1980)
- Effect of tree fertilization on numbers and development of pear psylla (Homoptera: Psyllidae), and on fruit damagePfeiffer, Douglas G.; Burts, E. C. (1983)
- Effect of tree fertilization on protein and free amino acid content and feeding rate of pear psylla (Homoptera: Psyllidae)Pfeiffer, Douglas G.; Burts, E. C. (1984)
- Effects of field applications of paraquat on densities of Panonychus ulmi (Koch) and Neoseiulus fallacis (Garman)Pfeiffer, Douglas G. (1986)Neoseiulus fallacis (Garman) is the most important acarine predator of the European red mite, Panonychus ulmi (Koch), in sprayed apple orchards in the eastern United States [Poe, S. L., and W. R. Enns. 1969. Predaceous mites (Acarina: Phytoseiidae) associated with Missouri orchards. Trans. Missouri Acad. Sci. 3: 69-82; Berkett, L. P., and H. Y. Forsythe. 1980. Predaceous mites (Acari) associated with apple foliage in Maine. Can. Entomol. 112: 497-502]. Populations of this predator are often present only at very low densities in Virginia orchards, however. The herbicide paraquat has been shown to be toxic to N. fallacis using slide-dip bioassays [Rock, G. C., and D. R. Yeargan. 1973. Toxicity of apple orchard herbicides and growth-regulating chcmicnls to Neoseiulus fallacis and twospotted spider mite. J. Econ. Entomol. 66: 1342-1343; Hislop, R. G., and R. J. Prokopy. 1981 . Integrated management of phytophagous mites in Massachusetts (U.S.A.) apple orchards. 2. Influence of pesticides on the predator Amblyseius fallacis (Acarina: Phytoseiidae) under laboratory field conditions. Protect. Ecol. 3: 157-1721. Paraquat is commonly applied in Virginia apple orchards in early spring while N. fallacis is still in its overwintering site in the orchard ground cover. The purpose of this study was to determine if field applications of paraquat affect densities of P. ulmi and its predator, N. fallacis, in the tree canopy. Slide-dip bioassay data, while very useful for comparing toxicity from topical applications of pesticides, are highly artificial and do not reflect other factors in mortality (contact with dried residues, behavioral responses, habitat modification). Other methods should be employed to complement slide-dip data (Dennehey, T. J., J. Granett, and T. F. Leigh. 1983. Relevance of slide-dip and residual bioassay comparisons to detection of resistance in spider mites. J. Econ. Entomol. 76: 1225-1230).
- Relative susceptibility to slide-dip application of cyhexatin in three populations of Panonychus ulmi (Koch) in Virginia apple orchardsPfeiffer, Douglas G.; Pfeiffer, S. W. (1986)
- Disruption of olfactory communication in oriental fruit moth and lesser appleworm in a Virginia peach orchardPfeiffer, Douglas G.; Killian, J. C. (1988)
- 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.
- Compositions and methods for controlling pest insects(United States Patent and Trademark Office, 1996-05-07)Compositions of a purine, a xanthine oxidase inhibitor and/or a dihydrofolate reductase inhibitor, and methods of using same, for controlling the growth of pest insects which salvage, store, or excrete their nitrogenous wastes via the purine metabolic pathway.
- Bioeconomics of managing the spread of exotic pest species with barrier zonesSharov, A. A.; Liebhold, A. M. (Ecological Society of America, 1998-08)Exotic pests are serious threats to North American ecosystems; thus, economic analysis of decisions about eradication, stopping, or slowing their spread may be critical to ecosystem management. We present a model to analyze costs and benefits of altering the spread rates of invading organisms. The target rate of population expansion (which may be positive or negative) is considered as a control function, and the present value of net benefits from managing population spread is the criterion that is maximized. Two local maxima of the present value of net benefits are possible: one for eradication and another for slowing the spread. If both maxima are present, their heights are compared, and the strategy that corresponds to a higher value is selected. The optimal strategy changes from eradication to slowing the spread to finally doing nothing, as the area occupied by the species increases, the negative impact of the pest per unit area decreases, or the discount rate increases. The model shows that slowing population spread is a viable strategy of pest control even when a relatively small area remains uninfested. Stopping population spread is not an optimal strategy unless natural barriers to population spread exist. The model is applied to managing the spread of gypsy moth (Lymantria dispar) populations in the United States.
- Model of slowing the spread of gypsy moth (Lepidoptera : Lymantriidae) with a barrier zoneSharov, A. A.; Liebhold, A. M. (Ecological Society of America, 1998-11)When attempts to eradicate an introduced pest species fail and it becomes: established, barrier zones are often used to stop or to slow the spread of the population into uninfested areas. The U.S. Forest Service is currently conducting a Slow-the-Spread (STS) pilot project to evaluate the feasibility of slowing the spread of the gypsy moth (Lymantria dispar L.) in several areas along the population front. To predict the effect of barrier zones on the rate of gypsy moth spread we developed a model that assumes establishment of isolated colonies beyond the expanding population front. These colonies grow, coalesce, and thereby contribute to the movement of the population front. The model estimates the rate of spread from two functions: (1) colonization rate as a function of the distance from the population front and (2) population numbers in a colony as a function of colony age. Eradication of isolated colonies in a barrier zone was simulated by truncating the colonization rate function beyond a specific distance from the population front. The model predicts that eradication of isolated colonies in the STS project will result in a 54% reduction of spread rate. The actual rate of spread in the Appalachian Mountains has declined by 59% since 1990 when eradication of isolated colonies started. Thus, model predictions were close to the observed reduction in the rate of population spread.
- La Crosse encephalitis virus habitat associations in Nicholas County, West VirginiaNasci, Roger S.; Moore, Chester G.; Biggerstaff, Brad J.; Panella, Nicholas A.; Liu, H. Q.; Karabatsos, Nick; Davis, Brent S.; Brannon, E. S. (Oxford University Press, 2000-07-01)Aedes triseriatus (Say) population density patterns and La Crosse encephalitis virus infection rates were evaluated in relation to a variety of habitat parameters over a 14-wk period. Ovitraps and landing collections were used in a La Crosse virus-enzootic area in Nicholas County, WV. Studs sites were divided into categories by habitat type and by proximity to the residences of known La Crosse encephalitis cases. Results demonstrated that Ae. triseriatus population densities were higher in sugar maple/red maple habitats than in hemlock/mixed hardwood habitats or in a site characterized by a large number of small red maple trees. Sites containing artificial containers had higher population densities than those without. La Crosse virus minimum infection rates in mosquitoes collected as eggs ranged from 0.4/1,000 to 7.5/1,000 in the 12 study sites, but did not differ significantly among sites regardless of habitat type or proximity to human case residences. La Crosse virus infection rates in landing Ae. triseriatus mosquitoes ranged from 0.0/1,000 to 27.0/1,000. La Crosse virus was also isolated from host-seeking Ae. canadensis (Theobald) in two study sites, at rates similar to those found in the Ae. triseriatus populations. The Ae. triseriatus oviposition patterns and La Crosse virus infection rates suggest that this mosquito species disperses readily in the large woodlands of central West Virginia. The La Crosse enzootic habitats in Nicholas County, WV, are contrasted with those studied in other geographic regions where La Crosse virus is found.
- A method for harvesting and shipping live citrus rust mites (Acari : Eriophyidae)Bergh, J. Christopher; French, J. V. (Florida Entomological Society, 2000-09)
- Habitat preferences and phenology of Ochlerotatus triseriatus and Aedes albopictus (Diptera : Culicidae) in southwestern VirginiaBarker, Christopher M.; Paulson, Sally L.; Cantrell, Sue; Davis, Brent S. (Oxford University Press, 2003-07-01)Recently, the number of reported human cases of La Crosse encephalitis, an illness caused by mosquito-borne La Crosse virus (LAC), has increased in southwestern Virginia, resulting in a need for better understanding of the virus cycle and the biology of its vectors in the region. This study examined the spatial and temporal distributions of the primary vector of LAC, Ochlerotatus triseriatus (Say), and a potential secondary vector, Aedes albopictits (Skuse). Ovitrapping surveys were conducted in 1998 and 1999 to determine distributions and oviposition habitat preferences of the two species in southwestern Virginia. Mosquitoes also were collected for virus assay from a tire dump and a human La Crosse encephalitis case site between 1998 and 2000. Oc. triseriatus and Ae. albopictus were collected from all ovitrap sites surveyed, and numbers of Oc. triseriatus eggs generally were higher than those of Ae. albopictus. Numbers of Oc. triseriatus remained high during most of the summer, while Ae. albopictus numbers increased gradually, reaching a peak in late August and declining thereafter. In Wise County, relative Ae. albopictus abundance was highest in sites with traps placed in open residential areas. Lowest numbers of both species were found in densely forested areas. Ovitrapping during consecutive years revealed that Ae. albopictus was well established and overwintering in the area. An oviposition comparison between the yard and adjacent forest at a human LaCrosse encephalitis case site in 1999 showed that Ae. albopictus preferentially oviposited in the yard surrounding the home, but Oc. triseriatus showed no preference. LAC isolations from larval and adult collections of Oc. triseriatus females from the same case site indicated the occurrence of transovarial transmission.
- A simple character for sex differentiation of pupae and pupal exuviae of the dogwood borer (Lepidoptera : Sesiidae)Leskey, Tracy C.; Bergh, J. Christopher (Florida Entomological Society, 2003-09)
- The Minute Pirate Bug (Orius)Andrews, Heather; Kuhar, Thomas P. (Virginia Cooperative Extension, 2003-10-08)This publication reviews the minute pirate bug (Orius) including a description, lifecycle, feeding habits, habitat, and control.
- Green Peach Aphid on Vegetables: Homoptera: Aphididae, Myzus persicaeKuhar, Thomas P.; Reiter, Sara; Doughty, Hélène (Virginia Cooperative Extension, 2005-09-01)Describes the Green Peach Aphid (Myzus persicae), its life cycle, and its damage to crops. Also lists a few of the crop plants that it feeds on.
- Fall Armyworm in Vegetable CropsBarlow, Vonny M.; Kuhar, Thomas P. (Virginia Cooperative Extension, 2005-09-01)Describes Fall Armyworm (Spodoptera frugiperda), its life history, caterpillar damage to crops, and methods of control. Also provides an extensive list of host crops, grasses, and weeds.
- Colorado Potato BeetleKuhar, Thomas P.; Speese, John; Day, Eric R.; Cordero, Roberto J. (Virginia Cooperative Extension, 2005-09-01)Describes the Colorado Potato Beetle, its life cycle, and notes the kinds of plants it eats, and describes the damage and methods of control.