Life Sciences Commons^™

Characterization Of Western Corn Rootworm (Coleoptera: Chrysomelidae) Susceptibility To Foliar Insecticides In Northeast Nebraska, Timothy B. Dang, Ana M. Vélez, Arnubio Valencia-Jiménez, Jordan Reinders, Emily E. Stricklin, Matthew W. Carroll, Clinton D. Pilcher, Jeffrey T. Krumm, Graham P. Head, Lance Meinke

Department of Entomology: Faculty Publications

Foliar-applied insecticides are commonly used for adult Western Corn Rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), control in Nebraska but little efficacy data is available. Anecdotal reports of reduced efficacy in areas of northeast Nebraska led to the conduct of this study. Objectives were to (i) evaluate the efficacy of commercial applications of commonly used formulated insecticides (bifenthrin, lambda-cyhalothrin, chlorpyrifos, or tank mixes) for WCR control in 7 northeast Nebraska counties during 2019 and 2020 and (ii) conduct adult WCR concentration-response vial bioassays with bifenthrin, chlorpyrifos, and dimethoate active ingredients on a subset of field populations. Whole plant counts …

Evidence Of Western Corn Rootworm (Diabrotica Virgifera Virgifera Leconte) Field-Evolved Resistance To Cry3bb1 + Cry34/ 35ab1 Maize In Nebraska, Jordan D. Reinders, Emily E. Reinders, Emily Robinson, Bryan W. French, Lance J. Meinke

Department of Entomology: Faculty Publications

BACKGROUND: Western corn rootworm (WCR; Diabrotica virgifera virgifera) field-evolved resistance to transgenic maize expressing the Cry3Bb1 protein derived from Bacillus thuringiensis (Bt) has been confirmed across the United States Corn Belt. Although use of pyramided hybrids expressing Cry3Bb1 + Cry34/35Ab1 has increased in recent years to mitigate existing WCR Bt resistance, susceptibility of Nebraska WCR populations to this rootworm–Bt pyramid has not been assessed. Plant-based bioassays were used to characterize the susceptibility of WCR populations to Cry3Bb1 and Cry3Bb1 + Cry34/35Ab1 maize. Populations were collected from areas of northeastern Nebraska with a history of planting Bt maize that expressed …

Characterizing The Relationship Between Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Survival On Cry3bb1-Expressing Corn And Larval Development Metrics, Jordan D. Reinders, David S. Wangila, Emily Robinson, B. Wade French, Lance Meinke

Department of Entomology: Faculty Publications

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a significant pest of field corn, Zea mays L. (Poales: Poaceae), across the United States Corn Belt. Widespread adoption and continuous use of corn hybrids expressing the Cry3Bb1 protein to manage the western corn rootworm has resulted in greater than expected injury to Cry3Bb1-expressing hybrids in multiple areas of Nebraska. Single-plant bioassays were conducted on larval western corn rootworm populations to determine the level of resistance present in various Nebraska counties. The results confirmed a mosaic of susceptibility to Cry3Bb1 across Nebraska. Larval development metrics, including head capsule width …

Field Efficacy Of Soil Insecticides On Pyrethroid-Resistant Western Corn Rootworms (Diabrotica Virgifera Virgifera Leconte), Dariane Souza, Julie A. Peterson, Robert Wright, Lance Meinke

Department of Entomology: Faculty Publications

Background: Field-evolved pyrethroid resistance has been confirmed in western corn rootworm (WCR) populations collected from the United States (US) western Corn Belt. Resistance levels of WCR adults estimated in lab bioassays were confirmed to significantly reduce the efficacy of foliar-applied bifenthrin. The objective of the present study was to investigate the impact of WCR pyrethroid resistance levels on the performance of common soil-applied insecticide formulations (23.4% tefluthrin, 17.15% bifenthrin, and 0.1% cyfluthrin+2.0% tebupirimphos). Field trials were conducted in 2016 and 2017 in three Nebraska, US, counties (Saunders, Clay, and Keith) where distinct levels of WCR susceptibility topyrethroids (susceptible, moderately resistant, …

Bifenthrin Baseline Susceptibility And Evaluation Of Simulated Aerial Applications In Striacosta Albicosta (Lepidoptera: Noctuidae), Débora G. Montezano, Thomas E. Hunt, Dariane Souza, Bruno C. Vieira, Ana M. Velez, Greg Kruger, Sarah N. Zukoff, Jeff D. Bradshaw, Julie A. Peterson

Department of Entomology: Faculty Publications

Striacosta albicosta (Smith) is a maize pest that has recently expanded its geographical range into the eastern United States and southeastern Canada. Aerial application of pyrethroids, such as bifenthrin, has been a major practice adopted to manage this pest. Reports of field failure of pyrethroids have increased since 2013. Striacosta albicosta populations were collected in 2016 and 2017 from maize fields in Nebraska, Kansas, and Canada and screened with bifenthrin active ingredient in larval contact dose-response bioassays. Resistance ratios estimated were generally low in 2016 (1.04- to 1.32-fold) with the highest LC50 in North Platte, NE (66.10 ng/cm²) …

Optimizing Egg Recovery From Wild Northern Corn Rootworm Beetles (Coleoptera: Chrysomelidae), Adriano E. Pereira, Dalton C. Ludwick, Julie Barry, Lance J. Meinke, Daniel J. Moellenbeck, Mark R. Ellersieck, Jordan D. Reinders, Ryan W. Geisert, Keiran Hyte, Amanda Ernwall, Kyle J. Paddock, Bruce E. Hibbard

Department of Entomology: Faculty Publications

The northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae), is one of the most important insect pests in the U.S. Corn Belt. Efforts to obtain eggs from wild northern corn rootworm populations using techniques developed for other rootworm species have been unsuccessful due to lack of oviposition. In 2016, we evaluated four oviposition media in choice tests within each of three female densities in 30.5 × 30.5 × 30.5 cm BugDorm cages. The number of eggs laid per female was significantly affected by female density and the interaction of female density × oviposition media, but oviposition was relatively …

Spatial Variation In Western Corn Rootworm (Coleoptera: Chrysomelidae) Susceptibility To Bacillus Thuringiensis Corn Events In Nebraska, Jordan D. Reinders

Department of Entomology: Dissertations, Theses, and Student Research

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an economically important pest species of field corn (Zea mays L.) in the U.S. Corn Belt. Yield losses and control costs exceed greater than $1 billion annually. Over the past 10+ years, growers have adopted transgenic corn hybrids expressing rootworm-active Bacillus thuringiensis (Bt) proteins as a primary WCR management tactic. Field-evolved resistance to Cry3Bb1 and mCry3A proteins expressed in single-trait Bt hybrids has been confirmed in some areas of Nebraska. Growers have used different tactics as needed to prevent or mitigate resistance, resulting in a mosaic of selection pressure placed …

Farmers’ Perspectives On Resistance In Western Corn Rootworm To Crw-Bt Corn In Midwest Usa, David A. Andow, Robert Wright, Erin W. Hodgson, Thomas E. Hunt, Ken Ostlie

Department of Entomology: Faculty Publications

Resistance in western corn rootworm to transgenic corn hybrids was first confirmed in 2011 in Midwestern USA, and threatens their continued use. Farmers are often the first line of resistance detection, so their understanding and attitudes toward this issue are critical for improving resistance management. We conducted telephone focus groups during 2013 with farmers who had experienced rootworm resistance. There were four stages in dealing with unexpected rootworm injury: Awareness of a problem, diagnosis, confirmation, and recommendations. Most farmers discovered the problem themselves, but this usually happened too late in the growing season to limit yield loss. Once aware of …

Sublethal Effects Of Vatpase-A And Snf7 Dsrnas On Biology Of Southern Corn Rootworm, Diabrotica Undecimpunctata Howardi Barber, Adriano E. Pereira, Ana María Vélez, Lance J. Meinke, Blair D. Siegfried

Department of Entomology: Faculty Publications

RNA interference is a powerful tool against corn rootworm. Adults and neonates of southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae), were exposed to the LC₅₀ of vATPase-A and Snf7 double-stranded RNAs (dsRNAs), and the effects on female fecundity, egg viability, male fitness as measured by sperm viability and mating capacity, larval recovery along with dry weight, and instar determination 10 d after exposure to dsRNA, were determined. Significant reductions were observed for a number of parameters in dsRNA-exposed rootworms relative to control treatments. Female fecundity and larval recovery were significantly reduced after exposure to both dsRNAs. In …

Assessing The Risk Of Resistance Evolution, Adult And Larval Susceptibility, And Sublethal Effects After Exposure Of Corn Rootworms To Vacuolar Atpase-A And Snf7 Dsrnas, Adriano Elias Pereira

Department of Entomology: Dissertations, Theses, and Student Research

Corn rootworms are Diabroticite beetles from the genus Diabrotica and include the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, and the northern corn rootworm, D. barberi Smith & Lawrence, as the most important pests in the U.S. Corn Belt. The southern corn rootworm (SCR), D. undecimpunctata howardi Barber, is considered a polyphagous plant pest and feeds in a wide variety of plants including peanuts, cucurbits, soybeans, and especially corn. Resistance to control methods including behavioral resistance to crop rotation and to corn hybrids expressing Bacillus thuringiensis Berliner toxins in WCR has frequently been reported. SCR has been considered a …

Effect Of Cry1f Maize On The Behavior Of Susceptible And Resistant Spodoptera Frugiperda And Ostrinia Nubilalis, Ana María Vélez, Analiza P. Alves, Erin E. Blankenship, Blair Siegfried

Department of Entomology: Faculty Publications

Understanding the behavior of pests targeted with Bacillus thuringiensis Berliner (Bt) crops is important to define resistance management strategies. Particularly the study of larval movement between plants is important to determine the feasibility of refuge configurations. Exposure to Bt maize, Zea mays L. (Poaceae), has been suggested to increase larval movement in lepidopteran species but few studies have examined the potential for resistance to interact with behavioral responses to Bt toxins. Choice and no-choice experiments were conducted with Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) and Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) to determine whether Cry1F resistance influences neonate movement. Leaf discs …

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 …

Susceptibility Of Nebraska Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations To Bt Corn Events, David S. Wangila, Aaron J. Gassmann, Jennifer L. Petzold-Maxwell, B. Wade French, Lance J. Meinke

Department of Entomology: Faculty Publications

Transgenic plants have been widely adopted by growers to manage the western corn rootworm, Diabrotica virgifera virgifera LeConte, in field corn. Because of reduced efficacy in some Nebraska fields after repeated use of Cry3Bb1-expressing hybrids, single plant bioassays were conducted in 2012 and 2013 to characterize the susceptibility of western corn rootworm populations to the rootwormactive proteins Cry3Bb1, mCry3A, and Cry34/35Ab1. Results demonstrate that there are heritable differences in susceptibility of Nebraska western corn rootworm populations to rootworm-active Bt traits. Proportional survival and corrected survival data coupled with field histories collectively support the conclusion that a level of field resistance …

Effect Of Maize Lines On Larval Fitness Costs Of Cry1f Resistance In The European Corn Borer (Lepidoptera: Crambidae), Jennifer L. Petzold-Maxwell, Blair D. Siegfried, Richard L. Hellmich, Craig A. Abel, Brad S. Coates, Terrence A. Spencer, Aaron J. Gassmann

Department of Entomology: Faculty Publications

Crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted and enable management of key insect pests while reducing the use of conventional insecticides. However, the evolution of Bt resistance could diminish these benefits. Fitness costs of Bt resistance occur in the absence of Bt toxin when individuals with resistance alleles show a reduction in fitness relative to susceptible individuals, and they can delay the evolution of resistance. Ecological factors including host-plant variety can affect the magnitude of fitness costs, and consequently, the degree to which fitness costs delay resistance. In this study, we measured fitness costs …

Inheritance Of Cry1f Resistance, Crossresistance And Frequency Of Resistant Alleles In Spodoptera Frugiperda (Lepidoptera: Noctuidae), A. M. Vélez, T. A. Spencer, A. P. Alves, D. Moellenbeck, R. L. Meagher, H. Chirakkal, B. D. Siegfried

Department of Entomology: Faculty Publications

Transgenic maize, Zea maize L., expressing the Cry1F protein from Bacillus thuringiensis has been registered for Spodoptera frugiperda ( J. E. Smith) control since 2003. Unexpected damage to Cry1F maize was reported in 2006 in Puerto Rico and Cry1F resistance in S. frugiperda was documented. The inheritance of Cry1F resistance was characterized in a S. frugiperda resistant strain originating from Puerto Rico, which displayed >289-fold resistance to purified Cry1F. Concentration–response bioassays of reciprocal crosses of resistant and susceptible parental populations indicated that resistance is recessive and autosomal. Bioassays of the backcross of the F1 generation crossed with the resistant parental …

Larval Survival And Plant Injury Of Cry1ab-Susceptible, -Resistant, And -Heterozygous Genotypes Of The Sugarcane Borer On Transgenic Corn Containing Single Or Pyramided Bt Genes, David S. Wangila, B. Rogers Leonard, Yaoyu Bai, Graham P. Head, Fangneng Huang

Department of Entomology: Faculty Publications

Transgenic corn (Zea mays L.) products expressing multiple Bt proteins targeting a same group of insect pests have become commercially available in the U.S. The first commercialized pyramided Bt corn technologies for managing lepidopteran pests include Genuity® VT Triple Pro™ and Genuity® SmartStax™. In this study, larval survival and plant injury of Cry1Ab-susceptible (Cry1Ab-SS), -resistant (Cry1Ab-RR), and -heterozygous (Cry1Ab-RS) genotypes of the sugarcane borer, Diatraea saccharalis F., on five commercial corn hybrids were evaluated in a leaf tissue bioassay and two greenhouse trials during 2010–2011. The five hybrids included two non-Bt corn and three Bt corn hybrids representing three …

Susceptibility Of Cry1ab Maize-Resistant And -Susceptible Strains Of Sugarcane Borer (Lepidoptera: Crambidae) To Four Individual Cry Proteins, Liping Zhang, Fangneng Huang, B. Rogers Leonard, Mao Chen, Thomas Clark, Yu Cheng Zhu, David S. Wangila, Fei Yang, Ying Niu

Department of Entomology: Faculty Publications

Sugarcane borer, Diatraea saccharalis (F.), is a major target of Bt maize in South America and many areas of the US mid-south region. Six laboratory strains of D. saccharalis were established from six single-pair F2 families possessing major resistance alleles to Cry1Ab maize hybrids. Susceptibility of the six strains was evaluated on diet treated with each of four purified trypsin-activated Bt proteins, Cry1Ab, Cry1Aa, Cry1Ac, and Cry1F. Bt susceptibility of the six strains was compared with that of known Cry1Ab-susceptible and -resistant strains of D. saccharalis. At least two of the six strains demonstrated a similar level (>526-fold) …

Modeling Evolution Of Diabrotica Virgifera Virgifera (Coleoptera: Chrysomelidae) To Transgenic Corn With Two Insecticidal Traits, David W. Onstad, Lance J. Meinke

Department of Entomology: Faculty Publications

Asimulation model of the population dynamics and genetics of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), was created to evaluate the use of refuges in the management of resistance to transgenic insecticidal corn, Zea mays L., expressing one or two toxin traits. Hypothetical scenarios and a case study of a corn hybrid pyramided with existing toxins are simulated. In the hypothetical situations, results demonstrated that evolution is generally delayed by pyramids compared with deployment of a single-toxin corn hybrid. However, soil insecticide use in the refuge reduced this delay and quickened the evolution of resistance. Results were sensitive …

Video-Tracking And On-Plant Tests Show Cry1ab Resistance Influences Behavior And Survival Of Neonate Ostrinia Nubilalis Following Exposure To Bt Maize, Jarrad R. Prasifka, Richard L. Hellmich, Andre L. B. Crespo, Blair Siegfried, David W. Onstad

Department of Entomology: Faculty Publications

To examine how resistance to Bacillus thuringiensis (Bt) toxins influences movement and survival of European corn borer (Ostrinia nubilalis [Hübner]) neonates, the responses of Cry1Ab-resistant , -susceptible, and hybrid (F1) larvae were examined using two different techniques. First, using an automated videotracking system, aspects of O. nubilalis movement were quantified in the presence of artificial diet incorporating 50% non-Bt or insect-resistant Cry1Ab maize tissue. Second, O. nubilalis dispersal and survival were measured 48–72 h after hatching on a Cry1Ab maize plant surrounded by two non-Bt maize plants. Video tracking indicated the presence of Cry1Ab tissue increased the total distance …

Inheritance Of Cry1f Resistance In Laboratory-Selected European Corn Borer And Its Survival On Transgenic Corn Expressing The Cry1f Toxin, E. J. G. Pereira, N. P. Storer, Blair D. Siegfried

Department of Entomology: Faculty Publications

A major assumption of the high-dose/refuge strategy proposed for insect resistance management strategies for transgenic crop plants that express toxins from Bacillus thuringiensis is that resistance traits that evolve in pest species will be recessive. The inheritance of Cry1F resistance and larval survival on commercially available Cry1F corn hybrids were determined in a laboratory-selected strain of European corn borer, Ostrinia nubilalis (Hu¨ bner), displaying more than 3000-fold resistance to Cry1F. Concentration-response bioassays of reciprocal parental crosses indicated that the resistance is autosomal and recessive. Bioassays of the backcross of the F₁ generation with the selected strain were consistent with …

Genetic Structure And Molecular Variability Of Spodoptera Frugiperda (Lepidoptera: Noctuidae) Collected In Maize And Cotton Fields In Brazil, S. Martinelli, P. L. Clark, M. I. Zucchi, M. C. Silva-Filho, John E. Foster, C. Omoto

Department of Entomology: Faculty Publications

The purpose of this research was to evaluate the genetic similarity and structure of the fall armyworm, Spodoptera frugiperda (J.E. Smith), populations associated with maize and cotton crops in Brazil using amplified fragment length polymorphisms. Mean genetic similarity among populations was 0.45. The unweighted pair group method with arithmetic mean analysis dendrograms did not separate populations of S. frugiperda into clusters related to the host plant in which the insects were collected. No genetic variation was observed among maize and cotton populations of S. frugiperda, suggesting that the same populations are injuring both crops in Brazil. This research validates …

Oil-Soluble Dyes For Marking Spodoptera Frugiperda (Lepidoptera: Noctuidae), Elis Christine Vilarinho, Odair Aparecido Fernandes, Celso Omoto, Thomas E. Hunt

Department of Entomology: Faculty Publications

Although various biological aspects of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) have been examined, adult movement and dispersal of this insect pest is not well understood. Release-recapture techniques by using marked insects is a useful approach for dispersal studies; however, the marking technique should not significantly affect insect biology or behavior. Therefore, the effect of different concentrations of oil-soluble dyes (Solvent Blue 35 [C.I. 61554], Sudan Red 7B [C.I. 26050], Sudan Black B [26150], Sudan Orange G [C.I. 11920], and Sudan I 103624 [C.I. 12055]) on development, mortality, and fecundity of S. frugiperda was evaluated. Dyes were added to artificial …

Flight Behavior Of Methyl-Parathion-Resistant And –Susceptible Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations From Nebraska, Jenny A. Stebbing, Lance J. Meinke, Steve E. Naranjo, Blair Siegfried, Robert J. Wright, Laurence D. Chandler

Department of Entomology: Faculty Publications

Relative flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm, Diabrotica virgifera virgifera LeConte populations, was studied as part of a larger effort to characterize the potential impact of insecticide resistance on adult life history traits and to understand the evolution and spread of resistance. A computer interfaced autograph was used to compare flight of resistant and susceptible individuals, and flight of resistant individuals with and without prior exposure to methyl-parathion. In each case, mean trivial and sustained flight durations were compared among treatments. In general, there were few differences in trivial or sustained flight characteristics as affected by beetle …

Development Of European Corn Borer Larvae On Event 176 Bt Corn: Influence On Survival And Fitness, Blair D. Siegfried, Amelia C. Zoerb, Terrence A. Spencer

Department of Entomology: Faculty Publications

European corn borer larvae, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) that have completed development on Event 176 Bt corn hybrids have survived exposure to sublethal doses of the Cry1Ab Bt toxin or are exploiting plant tissues that do not express the toxin. To evaluate the impact of such exposure, diapausing larvae were collected from Event 176 and conventional hybrids and compared for rates of pupation, parasitism, fitness (pupal weight, longevity, and fecundity) and susceptibility to the Cry1Ab toxin. Larvae completing development on Event 176 corn exhibited approximately 10% higher survival rates and correspondingly lower parasitism rates than larvae completing development on …

Dispersal Of Adult European Corn Borer (Lepidoptera: Crambidae) Within And Proximal To Irrigated And Non–Irrigated Corn, Thomas E. Hunt, Leon G. Higley, John F. Witkowski, Linda J. Young, Richard L. Hellmich

Department of Entomology: Faculty Publications

The European corn borer, Ostrinia nubilalis (Hübner), causes economic damage to corn, Zea mays L., throughout the Corn Belt. Because this insect has become the primary target of Bacillus thuringiensis Berliner (Bt) transgenic corn, current efforts addressing the management of O. nubilalis resistance to Bt corn require information on adult European corn borer dispersal and factors affecting its dispersal. In 1998 we conducted mark-release-recapture, release-recapture, and caged-mating studies to directly measure and compare local dispersal patterns of O. nubilalis adults within and proximal to irrigated and non-irrigated cornfields. Releases of marked adults were made corresponding to the first and second …

Oviposition By European Corn Borer (Lepidoptera: Crambidae) In Response To Various Transgenic Corn Events, Richard L. Hellmich, L. S. Higgins, John F. Witkowski, J. E. Campbell, L. C. Lewis

Haskell Agricultural Laboratory (Northeast Research and Extension Center)

Oviposition preference by European corn borers, Ostrinia nubilalis (Hübner), for or against transgenic corn would influence amounts of refuge required for resistance management. The objective of this research was to determine if various Bacillus thuringiensis (Bt) corn transgenic events influence O. nubilalis oviposition. All commercially available events (currently 5) were evaluated, plus 1 experimental event. Results from 3 independent studies are reported, including 3 field-cage experiments with vegetative corn, 2 field-cage experiments with reproductive corn, and 2 field experiments with natural O. nubilalis on reproductive corn. In each case, Bt corn hybrids are compared with their near isogenic hybrids by …