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Brandl M.A.,University of Gottingen | Schumann M.,University of Gottingen | French B.W.,North Central Agricultural Research Laboratory | Vidal S.,University of Gottingen
Journal of Insect Behavior | Year: 2016

The ability of western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) to develop resistance to various management practices requires the development of new management options. Repellent extracts can act as efficacy enhancing agents in WCR control. The present study investigated the potential repellence of garlic (Allium sativum L.), pepper (Capsicum sp. L), cape aloe (Aloe ferox Mill.), neem (Azadirachta indica A. Juss) and turmeric (Curcuma longa L.) derived extracts against WCR larvae in a no-choice bioassays. In initial screenings garlic and turmeric were evaluated as the most promising extracts as WCR larvae avoided garlic / turmeric treated soil. Turmeric was further evaluated in a rhizotron set up to quantify larval distribution and behavioral changes over time. WCR larvae avoided turmeric treated soil up to 0.05 m from its application in the root system, resulting in an increased dispersal and the formation of multiple clusters in the rhizotron. The proportion of larvae actively moving in the soil subsequently increased, whereas larval feeding significantly decreased. The spatial and behavioral alterations in the soil lead to the conclusion that turmeric is a repellent extract for WCR larvae. Turmeric repellence might further be exploited for WCR management through a synergy with insecticidal substances or microbial antagonists. © 2016 Springer Science+Business Media New York Source

Lundgren J.G.,North Central Agricultural Research Laboratory | Harwood J.D.,University of Kentucky
Journal of Entomological Science | Year: 2012

We examined how diverse communities of carabid beetles and crickets in a perennial hayfield respond to seed availability numerically and in their feeding behavior. Although there were 3 distinct insect communities identified over the diel cycle, these communities were similar in plots supplemented with Setaria viridis (L.) R Beauv. seeds and untreated plots. Gryllus pennsylvanicus Burmeister consumed plant material more frequently and ate more food in the fields with greater seed availability. However, they consumed prey with equal frequency in the 2 treatments. Allonemobius sp. consumed food less frequently than G. pennsylvanicus, and their diet was unaffected by seed availability. Availability of nonprey food resources may not affect soil insect communities in the short term, but some omnivores are quick to alter their diet to exploit nonprey resources. Source

Freydier L.,Agrocampus Ouest | Lundgren J.G.,North Central Agricultural Research Laboratory
Ecotoxicology | Year: 2016

Weed resistance to glyphosate and development of new GM crops tolerant to 2,4-dichlorophenoxyacetic acid (2,4-D) and dicamba is expected to lead to increased use of these herbicides in cropland. The lady beetle, Coleomegilla maculata is an important beneficial insect in cropland that is commonly used as an indicator species in safety evaluations of pesticides. Here, we examined the lethal and non-lethal effects of 2,4-D and dicamba active ingredients and commercial formulations to this lady beetle species, and tested for synergistic effects of the herbicides. Second instars of lady beetles were exposed to an experimental treatment, and their mortality, development, weight, sex ratio, fecundity, and mobility was evaluated. Using similar methods, a dose–response study was conducted on 2,4-D with and without dicamba. The commercial formulation of 2,4-D was highly lethal to lady beetle larvae; the LC90 of this herbicide was 13 % of the label rate. In this case, the “inactive” ingredients were a key driver of the toxicity. Dicamba active ingredient significantly increased lady beetle mortality and reduced their body weight. The commercial formulations of both herbicides reduced the proportion of males in the lady beetle population. The herbicides when used together did not act synergistically in their toxicity toward lady beetles versus when the chemistries were used independently. Our work shows that herbicide formulations can cause both lethal and sublethal effects on non-target, beneficial insects, and these effects are sometimes driven by the “inactive” ingredients. The field-level implications of shifts in weed management practices on insect management programs should receive further attention. © 2016 Springer Science+Business Media New York Source

Petzold-Maxwell J.L.,Iowa State University | Cibils-Stewart X.,Iowa State University | Cibils-Stewart X.,Kansas State University | French B.W.,North Central Agricultural Research Laboratory | Gassmann A.J.,Iowa State University
Journal of Economic Entomology | Year: 2012

We examined inheritance of resistance, feeding behavior, and fitness costs for a laboratory-selected strain of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), with resistance to maize (Zea maize L.) producing the Bacillus thuringiensis Berliner (Bt) toxin Cry3Bb1. The resistant strain developed faster and had increased survival on Bt maize relative to a susceptible strain. Results from reciprocal crosses of the resistant and susceptible strains indicated that inheritance of resistance was nonrecessive. No fitness costs were associated with resistance alleles in the presence of two entomopathogenic nematode species, Steinernema carpocapsae Weiser and Heterorhabditis bacteriophora Poinar. Larval feeding studies indicated that the susceptible and resistant strains did not differ in preference for Bt and non-Bt root tissue in choice assays. © 2012 Entomological Society of America. Source

Hitchon A.J.,University of Guelph | Smith J.L.,University of Guelph | French B.W.,North Central Agricultural Research Laboratory | Schaafsma A.W.,University of Guelph
Journal of Economic Entomology | Year: 2015

Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a major pest of corn, Zea mays L. The effect of the Bt proteins Cry34/35Ab1 and Cry3Bb1, alone or pyramided in corn hybrids on D. v. virgifera adult emergence was evaluated in field experiments for 3 yr. Experiments were infested artificially with 2,500 viable D. v. virgifera eggs per row meter of corn. The reduction in beetle emergence compared with non-Bt controls, from Cry34/35Ab1, Cry3Bb1, and the pyramided hybrids ranged from 64.3 to 97.4%, 91.1 to 95.2%, and 98.1 to 99.6%, respectively. The sex ratio of emerged beetles was usually female-biased from the Cry3Bb1 and pyramided treatments, but not from Cry34/35Ab1 treatment alone. Emergence from all Bt hybrids was delayed compared with the control, with the delay longest from the pyramided hybrid. In 2013, three egg infestation levels were tested, with densitydependent mortality observed at 1,250 viable eggs per row meter. The effect of Bt proteins on the emergence timing and sex ratio of D. v. virgifera may impact the suitability of resistance management plans, specifically the effectiveness of the refuge strategy. Susceptible males emerging from refuge might not be synchronized to mate with potentially resistant females emerging later from Bt corn hybrids. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. Source

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