Life Sciences Commons^™

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 …

Molecular Characterization Of Western Corn Rootworm Pyrethroid Resistance, Dariane Souza, Blair D. Siegfried, Lance Meinke, Nicholas J. Miller

Department of Entomology: Faculty Publications

Background: Western corn rootworm (WCR) pyrethroid resistance has been confirmed in the western US Corn Belt. Toxicological and biochemical studies indicated that multiple mechanisms of resistance might be involved in the resistance trait, such as enhanced metabolism and/or kdr target-site mutation(s) in the voltage-gated sodium channels. To characterize the mechanisms of WCR pyrethroid resistance at the molecular level, pairwise comparisons were made between RNA-Seq data collected from pyrethroid-resistant and -susceptible WCR populations. Gene expression levels and sodium channel sequences were evaluated.

Results: Seven transcripts exhibited significantly different expression (q ≤ 0.05) when comparing field-collected pyrethroidresistant (R-Field) and -susceptible (S-Field) WCR …

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, …

Enhanced Metabolism And Selection Of Pyrethroid-Resistant Western Corn Rootworms (Diabrotica Virgifera Virgifera Leconte), Dariane Souza, Arnubio V. Jiménez, Gautam Sarath, Lance J. Meinke, Nicholas J. Miller, Blair D. Siegfried

Department of Entomology: Faculty Publications

Western corn rootworm (WCR) pyrethroid resistance has been previously reported in the United States (US) western Corn Belt, and cross-resistance and synergism studies suggested that both target site insensitivity and enhanced metabolism may be conferring WCR resistance to pyrethroids. The present study aimed to investigate the potential mechanisms of WCR pyrethroid resistance and to estimate the heritability of the resistance trait. Biochemical assays using model substrates and spectrophotometry revealed 2–4-fold higher activity of P450s and esterases in pyrethroid-resistant WCR populations, whereas the biological activity of glutathione S-trans- ferase was similar between populations tested. No mutation in the voltage-gated sodium channel …

Molecular Gut-Content Analysis Of Adult Ground Beetles (Coleoptera: Carabidae) Provides No Evidence Of Predation Of Western Corn Rootworm (Coleoptera: Chrysomelidae) In A Nebraska Corn Agroecosystem, Camila Oliveira-Hofman, Vinícius S. Victor, Lance Meinke, Julie A. Peterson

Department of Entomology: Faculty Publications

This study was conducted to characterize the ground beetle (Coleoptera: Carabidae) community in Nebraska continuous cornfields and investigate the potential for predation of the western corn rootworm, Diabrotica virgifera virgifera LeConte, a key rootfeeding insect pest that is an annual management challenge in this system. Seven collection dates were conducted at five commercial cornfields in west central Nebraska during the growing season of 2014. In each field, carabids were sampled using five 24-h pitfall traps. Carabid specimens were placed in 95% ethanol in the field and stored at –20 °C to preserve DNA. After identification to the species level, DNA …

Characterization Of Pyrethroid Resistance In The Western Corn Rootworm Diabrotica Virgifera Virgifera Leconte, Dariane Sagaseta De Oliveira Souza

Department of Entomology: Dissertations, Theses, and Student Research

The western corn rootworm (WCR), Diabrotica virgifera virgifera Le Conte (Coleoptera: Chrysomelidae), is a major pest of maize (Zea mays L.) in the United States and has continuously challenged our ability to develop sustainable pest management solutions. Resistance to chemical insecticides, crop rotation, and most recently transgenic plants that express toxins derived from Bacillus thuringiensis Berliner (Bt) have been well documented among WCR populations. Furthermore, US regulatory insecticide prohibitions and the lack of new active ingredients have reduced the options for WCR control. Pyrethroid insecticides are one of the few remaining chemical options. Therefore, the recent confirmation …

Characterization Of The Natural Enemy Community, With Emphasis On Entomopathogens, For Management Of Western Corn Rootworm (Diabrotica Virgifera Virgifera) In West Central Nebraska, Camila Oliveira-Hofman

Department of Entomology: Dissertations, Theses, and Student Research

Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae),the western corn rootworm (WCR), is a major pest of corn (Zea mays L.) in the United States and Europe. WCR management options comprise mainly transgenic hybrids, insecticide applications and crop rotation. WCR is highly adaptable to management practices and field-evolved resistance to transgenic corn, insecticides and crop rotation in the United States Corn Belt has been reported. Therefore, the motivation for this project was to look into alternative options for WCR management. The goal of this dissertation is to characterize the natural enemies from irrigated commercial cornfields in Nebraska and examine their …

Dietary Risk Assessment Of V-Atpase A Dsrnas On Monarch Butterfly Larvae, Huipeng Pan, Xiaowei Yang, Keith Bidne, Richard L. Hellmich, Blair Siegfried, Xuguo Zhou

Department of Entomology: Faculty Publications

By suppressing the expression of genes with essential biological functions, in planta RNAi can negatively affect the development and survival of target pests. As a part of a concerted effort to assess the risks of RNAi transgenic crops on non-target organisms, we developed an in vivo toxicity assay to examine the impacts of ingested dsRNAs incurred to the monarch butterfly, Danaus plexippus (L.), an iconic eco-indicator in North America. To create the worst case scenario, the full-length v-ATPase A cDNAs from the target pest, western corn rootworm, Diabrotica virgifera virgifera, and the non-target D. plexippus were respectively cloned. A 400 …

Dietary Risk Assessment Of V-Atpase A Dsrnas On Monarch Butterfly Larvae, Huipeng Pan, Xiaowei Yang, Keith Bidne, Richard L. Hellmich, Blair D. Siegfried, Xuguo Zhou

Entomology Faculty Publications

By suppressing the expression of genes with essential biological functions, in plantaRNAi can negatively affect the development and survival of target pests. As a part of a concerted effort to assess the risks of RNAi transgenic crops on non-target organisms, we developed an in vivo toxicity assay to examine the impacts of ingested dsRNAs incurred to the monarch butterfly, Danaus plexippus (L.), an iconic eco-indicator in North America. To create the worst case scenario, the full-length v-ATPase A cDNAs from the target pest, western corn rootworm, Diabrotica virgifera virgifera, and the non-target D. plexippus were respectively cloned. A …

Rnai Induced Knockdown Of A Cadherin-Like Protein (Ef531715) Does Not Affect Toxicity Of Cry34/35ab1 Or Cry3aa To Diabrotica Virgifera Virgifera Larvae (Coleoptera: Chrysomelidae), Sek Yee Tan, Murugesan Rangasamy, Haichuan Wang, Ana Maria Vélez, James Hasler, David Mccaskill, Tao Xu, Hong Chen, Jessica Jurzenski, Matthew Kelker, Xiaoping Xu, Kenneth E. Narva, Blair D. Siegfried

Department of Entomology: Faculty Publications

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important maize pest throughout most of the U.S. Corn Belt. Bacillus thuringiensis (Bt) insecticidal proteins including modified Cry3Aa and Cry34/35Ab1 have been expressed in transgenic maize to protect against WCR feeding damage. To date, there is limited information regarding the WCR midgut target sites for these proteins. In this study, we examined whether a cadherin-like gene from Diabrotica virgifera virgifera (DvvCad; Gen-Bank accession # EF531715) associated with WCR larval midgut tissue is necessary for Cry3Aa or Cry34/ 35Ab1 toxicity. Experiments were designed to examine the sensitivity of WCR to …

Developing An In Vivo Toxicity Assay For Rnai Risk Assessment In Honey Bees, Apis Mellifera L, Ana María Vélez, Jessica Jurzenski, Natalie Matz, Xuguo Zhou, Haichuan Wang, Marion D. Ellis, Blair Siegfried

Department of Entomology: Faculty Publications

Maize plants expressing dsRNA for the management of Diabrotica virgifera virgifera are likely to be commercially available by the end of this decade. Honey bees, Apis mellifera, can potentially be exposed to pollen from transformed maize expressing dsRNA. Consequently, evaluation of the biological impacts of RNAi in honey bees is a fundamental component for ecological risk assessment. The insecticidal activity of a known lethal dsRNA target for D. v. virgifera, the vATPase subunit A, was evaluated in larval and adult honey bees. Activity of both D. v. virgifera (Dvv)- and A. mellifera (Am)-specific dsRNA was tested by dietary …

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 …

Early Detection And Mitigation Of Resistance To Bt Maize By Western Corn Rootworm (Coleoptera: Chrysomelidae), David A. Andow, Steven G. Pueppke, Arthur W. Schaafsma, Aaron J. Gassmann, Thomas W. Sappington, Lance Meinke, Paul D. Mitchell, Terrance M. Hurley, Richard L. Hellmich, R. Pat Porter

Department of Entomology: Faculty Publications

Transgenic Bt maize that produces less than a high-dose has been widely adopted and presents considerable insect resistance management (IRM) challenges.Western corn rootworm, Diabrotica virgifera virgifera LeConte, has rapidly evolved resistance to Bt maize in the field, leading to local loss of efficacy for some corn rootworm Bt maize events. Documenting and responding to this resistance has been complicated by a lack of rapid diagnostic bioassays and by regulatory triggers that hinder timely and effective management responses. These failures are of great concern to the scientific and agricultural community. Specific challenges posed by western corn rootworm resistance to Bt maize, …

Effect Of Seed Blends And Soil-Insecticide On Western And Northern Corn Rootworm Emergence From Mcry3a1+ Ecry3.1ab Bt Maize, Daniel L. Frank, Ryan Kurtz, N A. Tinsley, Aaron J. Gassmann, Lance J. Meinke, Daniel Moellenbeck, Michael E. Gray, Larry W. Bledsoe, Christan H. Krupke, Ronald E. Estes, Patrick Weber, Bruce E. Hibbard

Department of Entomology: Faculty Publications

Seed blends containing various ratios of transgenic Bt maize (Zea mays L.) expressing the mCry3A+eCry3.1Ab proteins and non-Bt maize (near-isoline maize) were deployed alone and in combination with a soil applied pyrethroid insecticide (Force CS) to evaluate the emergence of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in a total of nine field environments across the Midwestern United States in 2010 and 2011. Northern corn rootworm, Diabrotica barberi Smith & Lawrence emergence was also evaluated in four of these environments. Both western and northern corn rootworm beetle emergence from all Bt treatments was significantly reduced when compared with beetle …

Genetic Differentiation Of Western Corn Rootworm Populations (Coleoptera: Chrysomelidae) Relative To Insecticide Resistance, Hong Chen, Haichuan Wang, Blair D. Siegfried

Department of Entomology: Faculty Publications

Abstract

As the single most important pest of field corn, Zea mays L., throughout most of the Corn Belt, the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), has undergone repeated selection for resistance to a variety of insecticides that persist widely among Nebraska populations. In this study, we used 11 microsatellite markers to genotype two populations with high levels of resistance to methyl-parathion and aldrin (Polk and Stromsburg), two populations with low and intermediate levels of resistance (Mead and Clay Center) from Nebraska, and one population from outside the Corn Belt (Safford, Arizona). The genetic diversity measured by …

Mortality Impact Of Mon863 Transgenic Maize Roots On Western Corn Rootworm Larvae In The Field, T. L. Clark, D. L. Frank, B. W. French, Lance J. Meinke, D. Moellenbeck, T. T. Vaughn, B. E. Hibbard

Department of Entomology: Faculty Publications

Mortality of western corn rootworm (Diabrotica virgifera virgifera LeConte) due to feeding on MON863 transgenic maize (Zea mays L.) expressing the Cry3Bb1 protein was evaluated at three Missouri sites in both 2003 and 2004 and at one site each in South Dakota, Nebraska, and Iowa in 2004. To do this, survivorship relative to survivorship on isoline maize (i.e., the same genetic background, but without Cry3Bb1) was evaluated. Comparisons were made using low (1650–2500 eggs/m) and high (3300–3500 eggs/m) western corn rootworm egg densities. Significantly fewer beetles were recovered from MON863 than from isoline maize. Emergence from MON863 as …

The Prospects For Sequencing The Western Corn Rootworm Genome, Nicholas Miller, S. Richards, T. W. Sappington

Department of Entomology: Faculty Publications

Historically, obtaining the complete sequence of eukaryotic genomes has been an expensive and complex task. For this reason, efforts to sequence insect genomes have largely been confined to model organisms, species that are important to human health and representative species from a few insect orders. This situation is set to change as a number of ‘next generation’ sequencing technologies are making largescale DNA sequencing both affordable and accessible. Sequencing the genome of the western corn rootworm, Diabrotica virgifera virgifera, is likely to become a realistic proposition within the next 2 years. In the meantime, there is an active community …

Western Corn Rootworm ( Diabrotica Virgifera Virgifera Leconte) Population Dynamics, Lance Meinke, Thomas W. Sappington, David W. Onstad, Thomas Guillemaud, Nicholas Miller, Judit Komáromi, Nora Levay, Lorenzo Furlan, József Kiss, Ferenc Toth

Department of Entomology: Faculty Publications

1 The western corn rootworm Diabrotica virgifera virgifera LeConte is a major insect pest of field maize, Zea mays L. Larvae can cause substantial injury by feeding on maize roots. Larval feeding may destroy individual roots or root nodes, and reduce plant growth, stability, and yield. Costs associated with managing corn rootworms in continuous maize are annually one of the largest expenditures for insect management in the United States Corn Belt.

2 Even though D. virgifera virgifera has been studied intensively for over 50 years, there is renewed interest in the biology, ecology, and genetics of this species because of …

Adaptation And Invasiveness Of Western Corn Rootworm: Intensifying Research On A Worsening Pest, Michael E. Gray, Thomas W. Sappington, Nicholas Miller, Joachim Moeser, Martin O. Bohn

Department of Entomology: Faculty Publications

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is an established insect pest of maize (Zea mays L.) in North America. The rotation of maize with another crop, principally soybeans, Glycine max (L.), was the primary management strategy utilized by North American producers and remained highly effective until the mid-1990s. In 1995, widespread and severe root injury occurred in east-central Illinois and northern Indiana maize fields that had been annually rotated with soybeans on a regular basis for several decades. The failure of this cultural tactic from a pest management perspective was attributed to a behavioral adaptation by a …

Assessing Risk Of Resistance To Aerial Applications Of Methyl-Parathion In Western Corn Rootworm (Coleoptera: Chrysomelidae), Michael A. Caprio, Tim Nowatski, Blair Siegfried, Lance J. Meinke, Robert J. Wright, Larry D. Chandler

Department of Entomology: Faculty Publications

We validated a stochastic model of the evolution of resistance to adulticidal sprays of methyl-parathion in western corn rootworm, Diabrotica virgifera virgifera LeConte, populations in Nebraska. The population dynamics predicted by the model resembled that reported for field populations, and time until control failures occurred closely matched reports by commercial crop consultants. We incorporated uncertainty about the values used for 18 model parameters by replacing default values with random draws taken from a normal distribution. One parameter, the initial resistance allele frequency, was no longer measurable because of the evolution of resistance. We therefore proposed five candidate initial allele frequencies …

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 …

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 …

Characterization Of General Esterases From Methyl Parathion-Resistant And -Susceptible Populations Of Western Corn Rootworm (Coleoptera: Chrysomelidae), Xuguo Zhou, Michael E. Scharf, Lance J. Meinke, Laurence D. Chandler, Blair D. Siegfried

Department of Entomology: Faculty Publications

A consistent correlation between elevated esterase activity and methyl parathion resistance among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations has previously been documented. Characterization of general esterase activity using naphtholic esters as model substrates indicated that differences between resistant and susceptible strains could be maximized by optimizing assay conditions. The optimal conditions identified here were similar to those reported for other insect species. The majority of general esterase activity was found in the cytosolic fractions of resistant populations, whereas the activity was more evenly distributed between cytosolic and mitochondrial/nuclear fractions in the susceptible population. General esterase activity was …

Does Landscape Diversity Slow The Spread Of Rotation-Resistant Western Corn Rootworm (Coleoptera: Chrysomelidae)?, D. W. Onstad, D. W. Crwoder, S. A. Isard, E. Levine, J. L. Spencer, Matthew E. O'Neal, S. T. Ratcliffe, M. E. Gray, L. W. Bledsoe, C. D. Di Fonzo, J. B. Eisley, C. R. Edwards

Matthew E. O'Neal

A behavioral change in some western corn rootworm (Diabrotica virgifera virgifera LeConte) populations is threatening the effectiveness of crop rotation, a successful management strategy for controlling this pest. We created a set of simple meteorologic and behavioral models that can be used to predict the spread of the beetle infesting soybean (Glycine max (L.)) throughout the midwestern United States. We used data collected in Illinois, IN, MI, and Ohio to create maps of observations to evaluate the model. We displayed data on the maps using detection thresholds for western corn rootworm in soybean fields of 10 or 20 beetles per …

Diagnostic Assays Based On Esterase-Mediated Resistance Mechanisms In Western Corn Rootworms (Coleoptera: Chrysomelidae), Xuguo Zhou, Michael E. Scharf, Srinivas Parimi, Lance J. Meinke, Robert J. Wright, Laurence D. Chandler, Blair D. Siegfried

Department of Entomology: Faculty Publications

Resistance to methyl-parathion among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations is associated with increased hydrolytic metabolism of an organophosphate insecticide substrate. An electrophoretic method to identify resistant individuals based on the staining intensity of esterase isozymes on nondenaturing polyacrylamide gels was developed. Three groups of esterases (I, II, and III) were visible on the gels, but only group II esterase isozymes were intensified in resistant populations. A total of 26 and 31 field populations of western corn rootworms from Nebraska (in 1998 and 1999, respectively) were assessed with nondenaturing polyacrylamide gel electrophoresis (PAGE) assays and diagnostic concentration …

Influence Of Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Injury On Yield Of Different Types Of Maize, Mario A. Urías-López, Lance J. Meinke

Department of Entomology: Faculty Publications

Two field experiments were conducted in 1995-1996 to determine if there are common yield responses among maize hybrids to larval western corn rootworm, Diabrotica virgifera virgifera LeConte injury. Three yellow dent hybrids, five white food grade dent hybrids, and a popcorn hybrid were included in the study. The minimum level of rootworm injury as measured by root damage ratings (3.2-4.2) that significantly reduced yield was similar across the hybrids included in the study. However, the pattern of yield response to different rootworm injury levels varied among hybrids. This suggests that maize hybrids may inherently differ in their ability to tolerate …

Larval Susceptibility Of An Insecticide-Resistant Western Corn Rootworm (Coleoptera: Chrysomelidae) Population To Soil Insecticides: Laboratory Bioassays, Assays Of Detoxification Enzymes, And Field Performance, Robert J. Wright, Michael E. Scharf, Lance J. Meinke, Xuguo Zhou, Blair D. Siegfried, Laurence D. Chandler

Department of Entomology: Faculty Publications

Soil insecticides were evaluated in laboratory and field studies against larvae of an insecticide resistant population (Phelps County, NE) of western corn rootworm, Diabrotica virgifera virgifera LeConte. Insecticide toxicity was evaluated by topical application of technical insecticides to 3rd instars from Saunders County, NE (susceptible) and Phelps County populations. Resistance ratios (LD₅₀ Phelps County/LD₅₀ Saunders County) for the insecticides methyl parathion, tefluthrin, carbofuran, terbufos, and chlorpyrifos were 28.0, 9.3, 8.7, 2.6 and 1.3, respectively. Biochemical investigation of suspected enzymatic resistance mechanisms in 3rd instars identified significant elevation of esterase activity (alpha and beta naphthyl acetate hydrolysis [3.8- and …

Influence Of Corn Phenology On Adult Western Corn Rootworm (Coleoptera: Chrysomelidae) Distribution, Stephanie J. Darnell, Lance J. Meinke, Linda J. Young

Department of Entomology: Faculty Publications

Field studies were designed to more clearly determine how adult western corn rootworm, Diabrotica virgifera virgifera LeConte, population distribution patterns are altered over time by changes and contrasts in corn (Zea mays L.) plant phenology using whole-plant beetle counts as the sampling tool. In 1994, studies were conducted in a model system consisting of a late-planted corn strip placed in the middle of an early-planted cornfield. The system was replicated over three fields. Large-scale variation was modeled using trend-surface regression analysis to describe the relationship between beetle counts and distance from the center of the late-planted strip. In each …

Influence Of Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Injury On Photosynthetic Rate And Vegetative Growth Of Different Types Of Maize, Mario A. Urías-López, Lance J. Meinke, Leon G. Higley, Fikru J. Haile

Department of Entomology: Faculty Publications

Two field experiments were conducted in 1995-1996 to determine if there are common photosynthetic and vegetative growth responses among genotypes of maize, Zea mays L., to larval western corn rootworm, Diabrotica virgifera virgifera LeConte injury. Specific variables measured from rootworm infested and noninfested plants were midday leaf photosynthetic rate, plant growth stage, and plant height during 9-18 leaf growth stages. Three yellow-dent hybrids, five white food-grade dent hybrids, and a popcorn hybrid were included in the study. Results suggest that there may be a common negative photosynthetic response within maize to larval injury during vegetative growth stages. Transient reductions in …