Entomology Commons^™

Method Development For Monitoring Bean Leaf Beetle, Cerotoma Trifurcata (Forster) (Coleoptera: Chrysomelidae), Susceptibility To Thiamethoxam Seed Treatments On Soybeans, Chelsea L. Tietjen, Thomas Hunt, Daniel D. Snow, David A. Cassada, Blair D. Siegfried

Department of Entomology: Faculty Publications

The increased use of thiamethoxam seed treatments for controlling pests such as the bean leaf beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), suggests the need for methods to measure and monitor the development of resistance to thiamethoxam. The objectives of this study were to develop a bioassay method that can be used to monitor bean leaf beetle susceptibility to thiamethoxam, and to quantify the relative concentrations of thiamethoxam and clothianidin in early growth stage soybean tissue treated with thiamethoxam as a seed treatment. Overwintered and F1 bean leaf beetles were collected from alfalfa and soybean fields and used in excised soybean …

Assessment Of Variation In Susceptibility Of The Fall Armyworm, Spodoptera Frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), To Bacillus Thuringiensis Toxins, Karen Ferreira Da Silva

Department of Entomology: Dissertations, Theses, and Student Research

The fall armyworm, Spodoptera frugiperda, is a polyphagous insect pest affecting multiple crops. Fall armyworm is managed with insecticides and corn hybrids expressing insecticidal proteins derived from Bacillus thuringiensis. The early detection of insect resistance is important for making appropriate management decisions informs IPM and IRM recommendations.

The objective of the first study was to establish baseline susceptibility of fall armyworm populations to the Cry1F Bt insecticidal protein, emphasizing collections from locations where fall armyworm overwinters in the U.S. Fall armyworm neonates were exposed to artificial diet treated with increasing Cry1F concentrations, and mortality and growth inhibition were …

Impact Of Spodoptera Frugiperda Neonate Pretreatment Conditions On Vip3aa19 Insecticidal Protein Activity And Laboratory Bioassay Variation, Karen F. Da Silva, Terence A. Spencer, Carolina Camargo Gil, Blair D. Siegfried, Frederick S. Walters

Department of Entomology: Faculty Publications

BACKGROUND: Variation in response to insecticidal proteins is common upon repetition of insect bioassays. Understanding this variation is a prerequisite to detecting biologically important differences.We tracked neonate Spodoptera frugiperda (J.E. Smith) susceptibility to Vip3Aa19 over 17 generations using standardized bioassay methods. Five larval pretreatment conditions and one bioassay condition were tested to determine whether susceptibility was affected. These included: storage time; prefeeding; storage at reduced temperature; storage at reduced humidity; colony introgression of field-collected individuals. Extremes of photoperiod during the bioassay itself were also examined.

RESULTS: LC₅₀ values for two strains of S. frugiperda varied 6.6-fold or 8.8-fold over …

Responses Of Amblyomma Americanum And Dermacentor Variabilis To Odorants That Attract Haematophagous Insects, A. L. Carr, R. M. Roe, C. Arellano, D. E. Sonenshine, C. Schal, C. S. Apperson

Biological Sciences Faculty Publications

Carbon dioxide (CO₂), 1-octen-3-ol, acetone, ammonium hydroxide, L-lactic-acid, dimethyl trisulphide and isobutyric acid were tested as attractants for two tick species, Amblyomma americanum and Dermacentor variabilis (Acari: Ixodidae), in doseresponse bioassays using Y-tube olfactometers. Only CO₂, acetone, 1-octen-3-ol and ammonium hydroxide elicited significant preferences from adult A. americanum, and only CO₂ was attractive to adult D. variabilis. Acetone, 1-octen-3-ol and ammonium hydroxide were separately evaluated at three doses against CO₂ (from dry ice) at a field site supporting a natural population of A. americanum nymphs and adults. Carbon dioxide consistently attracted the …

Insecticidal Control Of Bemisia Tabaci (Hemiptera: Aleyrodidae) Transmitting Carlavirus On Soybeans And Detection Of The Virus In Alternate Hosts, Difabachew K. Belay, Randy M. Huckaba, Axel M. Ramirez, Jose C. V. Rodrigues, John E. Foster

Department of Entomology: Faculty Publications

A Carlavirus transmitted by Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an important disease of soybean nurseries in Puerto Rico causing substantial germplasm losses. Insecticide bioassay experiments were conducted at Dow AgroSciences (DAS) Research Station, Santa Isabel, Puerto Rico, either by spraying insecticides on B. tabaci infested soybean leaves or introducing B. tabaci adults onto insecticide-sprayed soybean leaves. Moreover, host plants were surveyed to detect the virus in overwintering hosts that serve as a source of inoculums. The direct spray experiment showed that Nuprid 2F (Imidacloprid), Capture 2 EC (Bifenthrin), Thionex (Endosulfan), Lannate LV (Methomyl), and Dimethoate gave good level ( …

Oxalic Acid: A Prospective Tool For Reducing Varroa Mite Populations In Package Bees, Nicholas P. Aliano, Marion D. Ellis

Department of Entomology: Faculty Publications

Abstract Numerous studies have investigated using oxalic acid (OA) to control Varroa mites in honey bee colonies. In contrast, techniques for treating package bees with OA have not been investigated. The goal of this study was to develop a protocol for using OA to reduce mite infestation in package bees. We made 97 mini packages of Varroa-infested adult bees. Each package contained 1,613 ± 18 bees and 92 ± 3 mites, and represented an experimental unit. We prepared a 2.8% solution of OA by mixing 35 g OA with 1 l of sugar water (sugar:water = 1:1; w:w). Eight treatments …

Development Of Methods To Evaluate Susceptibility Of Soybean Aphid To Imidacloprid And Thiamethoxam At Lethal And Sublethal Concentrations, Leonardo C. Magalhaes, Thomas E. Hunt, Blair D. Siegfried

Department of Entomology: Faculty Publications

The soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae), is a recent introduction (2000) from Asia and has become a serious soybean [Glycine max (L.) Merr. (Fabaceae)] pest in North America. Seed treatments using the neonicotinoid insecticides, imidacloprid and thiamethoxam, have been suggested as a method of control, and the use of these insecticides is becoming widespread. As a consequence, there is increased potential to select for resistance to these compounds. In the case of soybean aphids, baseline susceptibility to neonicotinoid insecticides and standardized methods for bioassay are lacking. A bioassay technique that uses excised soybean leaves immersed in an …

Acute Contact Toxicity Of Oxalic Acid To Varroa Destructor (Acari: Varroidae) And Their Apis Mellifera (Hymenoptera: Apidae) Hosts In Laboratory Bioassays, Nicholas P. Aliano, Marion D. Ellis, Blair D. Siegfried

Department of Entomology: Faculty Publications

Laboratory bioassays were performed to characterize the acute contact toxicity of oxalic acid (OA) to Varroa destructor (Anderson & Trueman) and their honey bee hosts (Apis mellifera L.). Specifically, glass-vial residual bioassays were conducted to determine the lethal concentration of OA for V. destructor, and topical applications of OA in acetone were conducted to determine the lethal dose for honey bees. The results indicate that OA has a low acute toxicity to honey bees and a high acute toxicity to mites. The toxicity data will help guide scientists in delivering optimum dosages of OA to the parasite and …

Baseline Susceptibility Of Western Corn Rootworm (Coleoptera: Crysomelidae) To Cry3bb1 Bacillus Thuringiensis Toxin, Blair D. Siegfried, Ty T. Vaughn, Terrence A. Spencer

Department of Entomology: Faculty Publications

Susceptibility to Cry3Bb1 toxin from Bacillus thuringiensis (Bt) was determined for western corn rootworm, Diabrotica virgifera virgifera LeConte, neonates from both laboratory and field populations collected from across the Corn Belt. Rootworm larvae were exposed to artificial diet treated with increasing Cry3Bb1 concentrations, and mortality and growth inhibition were evaluated after 4Ð7 d. The range of variation in Bt susceptibility indicated by growth inhibition was similar to that indicated by mortality. Although interpopulation variation in susceptibility was observed, the magnitude of the differences was comparable with the variability observed between generations of the same population. In general, the toxin was …

Resistance Status Of House Flies (Diptera: Muscidae) From Southeastern Nebraska Beef Cattle Feedlots To Selected Insecticides, Paula C.R.G. Marcon, Gustave D. Thomas, Blair D. Siegfried, John B. Campbell, Steven R. Skoda

Department of Entomology: Faculty Publications

The status of resistance to three insecticides (permethrin, stirofos, and methoxychlor), relative to a laboratory-susceptible colony, was evaluated in Þeld populations of house flies, Musca domestica L., collected from two beef cattle feedlots in southeastern Nebraska. Topical application and residual exposure to treated glass surfaces were suitable methods for determining the resistance status of house flies to permethrin, stirofos, or methoxychlor. However, in most cases, residual exposure was more sensitive in resistance detection (i.e., higher resistance ratios). The field populations tested were moderately resistant to permethrin (RR = 4.9-fold and RR = 7.3-fold, for topical application and residual exposure, respectively) …

Baseline Susceptibility Of The Corn Earworm (Lepidoptera: Noctuidae) To The Cry1ab Toxin From Bacillus Thuringiensis, Blair D. Siegfried, Terrence A. Spencer, Jessica Nearman

Department of Entomology: Faculty Publications

Susceptibility to Cry1Ab toxin from Bacillus thuringiensis (Bt) was determined for 12 field populations of neonate corn earworm, Helicoverpa zea (Boddie), from the United States. Earworm larvae were exposed to artificial diet treated with increasing Bt concentrations, and mortality and growth inhibition were evaluated after 7 d. The range of variation in Bt susceptibility indicated by growth inhibition was very similar to that indicated by mortality. Although interpopulation variation in susceptibility to both proteins was observed, the magnitude of the differences was small (less than or equal to fivefold). These results suggest that the observed susceptibility differences reflect natural variation …

Baseline Susceptibility Of European Corn Borer (Lepidoptera: Crambidae) To Bacillus Thuringiensis Toxins, Paula C. R. G. Macron, Linda J. Young, Kevin L. Steffey, Blair Siegfried

Department of Entomology: Faculty Publications

Susceptibility to CrylAb and CrylAc toxins from Bacillus thuringiensis was determined for 11 populations of neonate European corn borer, Ostrinia nubilalis (Hiibner), from the United States and 1 from northern Italy. Corn borer larvae were exposed to artificial diet treated with increasing B. thuringiensis concentrations, and mortality and growth inhibition were evaluated after 7 d. The range of variation in B. thuringiensis susceptibility indicated by growth inhibition was very similar to that indicated by mortality. Although interpopulation variation in susceptibility to both proteins was observed, the magnitude of the differences was small (54-fold) and comparable to the variability observed among …

Susceptibility Of Stable Flies (Diptera: Muscidae) From Southeastern Nebraska Beef Cattle Feedlots To Selected Insecticides And Comparison Of 3 Bioassay Techniques, Paula C. R. G. Marcon, Gustave D. Thomas, Blair Siegfried, John B. Campbell

Department of Entomology: Faculty Publications

Insecticide susceptibility of field populations of stable flies, tomoxys calcitrans (L.), was assayed using 3 exposure techniques: treated filter papers, treated glass petri dishes, and topical applications. Both topical applications and residual exposure to treated glass surfaces were suitable for testing susceptibility of stable flies to permethrin, stirofos, or methoxychlor. Residues on filter papers yielded inconsistent results with stirofos and methoxychlor. Significant concentration-mortality regression lines were generated with permethrin residues on filter papers, but ~1,000 times more insecticide was required to produce a toxic response when compared with permethrin residues on glass. Because of higher variability in response and the …

Oviposition Pheromone In The Simulium Damnosum Complex: Biological Activity Of Chemical Fractions From Gravid Ovaries, P. J. Mccall, R. R. Heath, B. D. Dueben, M. D. Wilson

Entomology Papers from Other Sources

Communal oviposition in the Afrotropical blackfly species complex Simulium damnosum Theobald (Diptera: Simuliidae) is mediated by a pheromone emitted by freshly laid eggs. Previously, two compounds (designated peaks A and B) emanating from fresh eggs were shown to be associated with attractiveness to gravid blackflies in bioassay. The present study investigated the role of these compounds by testing the responses of wild-caught Simulium yahense in Ghana to fractionated hexane extracts of gravid ovaries prepared by gas chromatography (GC). Although the fractions were prepared from Sierra Leonean Simulium teonense, GC analysis of the emissions from fresh S. yahense eggs showed …