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Akbar W.,Louisiana State University | Showler A.T.,Knipling Bushland Us Livestock Insects Research Laboratory | Reagan T.E.,Louisiana State University | Davis J.A.,Louisiana State University | Beuzelin J.M.,Louisiana State University
Entomologia Experimentalis et Applicata

Feeding behavior of Melanaphis sacchari Zehntner (Hemiptera: Aphididae) was studied on sugarcane, Saccharum spp. (Poaceae), cultivars HoCP 91-555 (resistant), LCP 85-384 (moderately resistant), and L 97-128 (susceptible) using the electrical penetration graph (EPG) technique. Constitutive concentrations of total phenolics and available carbohydrates, water potential at the whole-leaf tissue level, and free amino acids (FAAs) in phloem sap extracts, and in honeydew produced by aphids fed on L 97-128 and HoCP 91-555 were determined. Cultivar did not influence time for M. sacchari to access phloem sieve elements. Total time in sieve elements was ca. two-fold greater on L 97-128 than on HoCP 91-555, whereas it did not differ from LCP 85-384 in either cultivar. The mean duration of individual events associated with phloem sap ingestion was ca. 50% shorter on both HoCP 91-555 and LCP 85-384 than on L 97-128. Although cultivar effects were not detected for levels of total phenolics, available carbohydrates, and water potential, two free essential amino acids, histidine and arginine, were absent from phloem sap in HoCP 91-555. Two free essential amino acids, leucine and isoleucine, and two free non-essential amino acids, tyrosine and proline, were absent from honeydew of aphids fed on HoCP 91-555. These results suggest that despite apparent biosynthesis of some FAAs, the absence of important FAAs in the phloem sap of HoCP 91-555 and the inability of M. sacchari and its endosymbionts (e.g., Buchnera) to derive specific free essential and non-essential amino acids from other ingested molecules, possibly along with other unidentified factors, underlie the pest's decreased phloem sap ingestion and consequently reduced growth potential on HoCP 91-555. © 2013 The Netherlands Entomological Society. Source

Lindroth E.,WRAIR | Hunt T.E.,Haskell Agricultural Laboratory | Skoda S.R.,Knipling Bushland Us Livestock Insects Research Laboratory | Culy M.D.,Dow AgroSciences | And 2 more authors.
Annals of the Entomological Society of America

The western bean cutworm, Striacosta albicosta (Smith), is a secondary pest of maize (Zea mays L.) and dry beans (Phaseolus vulgaris L.) in the western United States. Recently, this insect has undergone a major territory expansion into the eastern United States and has become a pest throughout much of the Corn Belt. This study was instigated to examine the population genetics of this pest to facilitate control and resistance management, as well as to shed light on the current habitat expansion. S. albicosta individuals were collected from 24 different locations across the traditional and expanded range and amplified fragment length polymorphism analysis was conducted to assess genetic variability. In total, 90 markers were analyzed, encompassing >90% of genetic variation. Gst across all locations was moderately high (Gst = 0.5032). AMOVA analysis revealed that the majority of genetic variation was within locations (54%) and among locations within groups (45%) indicating genetic differentiation of subpopulations. The Mantel test revealed no correlation between geographic and genetic distance (n = 548; r = 0.0045; P = 0.4350). Locations sampled in the eastern United States did not exhibit any reduction in genetic variation in comparison to locations sampled in the western United States, so we conclude that no bottleneck event has occurred with this territory expansion. © 2012 Entomological Society of America. Source

Irvine R.J.,James Hutton Institute | Moseley M.H.,Dukes Veterinary Practice | Moseley M.H.,University of Pretoria | Leckie F.,Natural Research Projects Ltd | And 6 more authors.
European Journal of Wildlife Research

Ticks and their pathogens cause significant disease and economic loss in many animal populations. Despite this, experiments that test the impact of ticks and tick-borne diseases on wild animal populations are rare. Here, we report on an experiment assessing the effect of ticks on red grouse productivity and chick growth in relation to other causes of poor recruitment at two sites in the Scottish uplands during 2005. Treated hens received two leg bands impregnated with the acaricide permethrin, while controls hens were untreated. Chicks were captured at c.2 weeks of age and fitted with a metal patagial tag, and chicks from treated hens also received a permethrin-impregnated strip. Mean tick burdens in treated chicks were close to zero compared with a mean of around 12 in the control group. Although treatment reduced tick infestations, it did not increase brood size. Growth rates in chicks from control and treated hens were similar during the first 10 days and comparable with chicks fed an ad-lib invertebrate-based diet. These results suggest that in this case, neither ticks (and the tick transmitted louping-ill virus) nor food shortages was the main cause of chick mortality. However, mortality in the adult hens was around 35 %, and predation accounted for 62 % of these losses before broods fledged. Our results indicate that on our study sites, predation may have a more important impact on grouse population dynamics than ticks and tick-borne disease. We suggest that it may be more cost effective to determine the causes of poor grouse population performance before implementing popular but expensive tick control measures such as the culling of alternative hosts and running acaracide treated sheep 'tick-mop' flocks. © 2013 Springer-Verlag Berlin Heidelberg. Source

Rochon K.,University of Manitoba | Baker R.B.,Iowa State University | Almond G.W.,North Carolina State University | Gimeno I.M.,North Carolina State University | And 2 more authors.
Journal of Medical Entomology

We investigated the acquisition of porcine reproductive and respiratory syndrome (PRRS) virus by the stable fly (Diptera: Muscidae; Stomoxys calcitrans (L.)) through a bloodmeal, and virus persistence in the digestive organs of the fly using virus isolation and quantitative reverse-transcription PCR (qRT-PCR). Stable flies were fed blood containing live virus, modified live vaccine virus, chemically inactivated virus, or no virus. Stable flies acquired PRRSV from the bloodmeal and the amount of virus in the flies declined with time, indicating virus did not replicate in fly digestive tissues. Virus RNA was recovered from the flies fed live virus up to 24 h postfeeding using virus isolation techniques and 96 h using qRT-PCR.We further examined the fate of PRRSV in the hemolymph of the flies following intrathoracic injection to bypass the midgut barrier. PRRSV was detected in intrathoracically inoculated adult stable flies for 10 d using qRT-PCR. In contrast to what we observed in the digestive tract, detectable virus quantities in the intrathoracically inoculated stable flies followed an exponential decay curve. The amount of virus decreased fourfold in the first 3 d and remained stable thereafter, up to 10 d. © The Authors 2015. Source

Lohmeyer K.H.,Knipling Bushland Us Livestock Insects Research Laboratory | Pound J.M.,Knipling Bushland Us Livestock Insects Research Laboratory
Journal of Medical Entomology

A granular formulation of novaluron (Novaluron 0.2G, 0.2% [AI]), a newer benzoylphenyl urea insecticide, was evaluated for its efficacy in controlling the larval stage of horn flies, Haematobia irritans (L.); house flies, Musca domestica L.; and stable flies, Stomoxys calcitrans (L.), in cow manure. Various rates and insecticide placement locations (top, middle, and bottom of manure) were evaluated in this study and all combinations of these variables reduced adult emergence of all three species when compared with the untreated controls. The presence of deformed pupae indicated that novaluron had an insect growth regulator effect on the developing fly larvae. Top, middle, or bottom application rates of 0.125, 0.195, 0.25, and 0.375 g novaluron onto manure samples, reduced adult horn fly emergence by >90%. Middle and bottom application rates of 0.195, 0.25, and 0.375 g novaluron reduced adult house fly emergence >93%. All rates and placement combinations resulted in >98% reduction of adult stable fly emergence. The level of control efficacy observed against these three fly species along with the ease of use of a granular formulation, make this product an ideal candidate for use in an integrated livestock pest management program. © 2012 Entomological Society of America. Source

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