Multiple Assays Indicate Varying Levels of Cross Resistance in Cry3Bb1-Selected Field Populations of the Western Corn Rootworm to mCry3A, eCry3.1Ab, and Cry34/35Ab1

This study describes three closely related proteins, cloned from Brevibacillus laterosporus strains, that are lethal upon feeding to Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR). Mpp75Aa1, Mpp75Aa2 and Mpp75Aa3 were toxic to WCR larvae when fed purified protein. Transgenic plants expressing each mMpp75Aa protein were protected from feeding damage and showed significant reduction in adult emergence from infested plants by both susceptible and Cry3Bb1 and Cry34Ab1/Cry35Ab1-resistant WCR. These results demonstrate that proteins from B. laterosporus are as efficacious as the well-known Bacillus thuringiensis (Bt) insecticidal proteins in controlling major insect pests such as WCR. The deployment of transgenic maize expressing mMpp75Aa along with other active molecules lacking cross-resistance have the potential to be a useful tool for control of WCR populations resistant to current Bt traits. IMPORTANCE Insects feeding on roots of crops can damage the plant roots resulting in yield loss due to poor water and nutrient uptake and plant lodging. In maize the western corn rootworm (WCR) can cause severe damage to the roots resulting in significant economic loss for farmers. Genetically modified (GM) expressing Bacillus thuringiensis (Bt) insect control proteins, has provided a solution for control of these pests. In recent years populations of WCR resistant to the Bt proteins in commercial GM maize have emerged. There is a need to develop new insecticidal traits for the control of WCR populations resistant to current commercial traits. New proteins with commercial level efficacy on WCR from sources other than Bt are becoming more critical. The Mpp75Aa proteins, from B. laterosporus, when expressed in maize, are efficacious against the resistant populations of WCR and have the potential to provide solutions for control of resistant WCR.

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The Use of Insecticides to Manage the Western Corn Rootworm, Diabrotica virgifera virgifera, LeConte: History, Field-Evolved Resistance, and Associated Mechanisms

Insects ◽

10.3390/insects12020112 ◽

2021 ◽

Vol 12 (2) ◽

pp. 112 ◽

Cited By ~ 1

Author(s):

Lance J. Meinke ◽

Dariane Souza ◽

Blair D. Siegfried

Keyword(s):

Diabrotica Virgifera Virgifera ◽

The United States ◽

Western Corn Rootworm ◽

Cross Resistance ◽

Corn Rootworm ◽

Diabrotica Virgifera ◽

Mechanisms Of Resistance ◽

Pyrethroid Insecticides ◽

Diabrotica Virgifera Virgifera Leconte ◽

Over Time

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Dvv) is a significant insect pest of maize in the United States (U.S.). This paper reviews the history of insecticide use in Dvv management programs, Dvv adaptation to insecticides, i.e., field-evolved resistance and associated mechanisms of resistance, plus the current role of insecticides in the transgenic era. In the western U.S. Corn Belt where continuous maize is commonly grown in large irrigated monocultures, broadcast-applied soil or foliar insecticides have been extensively used over time to manage annual densities of Dvv and other secondary insect pests. This has contributed to the sequential occurrence of Dvv resistance evolution to cyclodiene, organophosphate, carbamate, and pyrethroid insecticides since the 1950s. Mechanisms of resistance are complex, but both oxidative and hydrolytic metabolism contribute to organophosphate, carbamate, and pyrethroid resistance facilitating cross-resistance between insecticide classes. History shows that Dvv insecticide resistance can evolve quickly and may persist in field populations even in the absence of selection. This suggests minimal fitness costs associated with Dvv resistance. In the transgenic era, insecticides function primarily as complementary tools with other Dvv management tactics to manage annual Dvv densities/crop injury and resistance over time.

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Field and Laboratory Studies of Resistance to Bt Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae)

Journal of Economic Entomology ◽

10.1093/jee/toz151 ◽

2019 ◽

Vol 112 (5) ◽

pp. 2324-2334 ◽

Cited By ~ 2

Author(s):

Ram B Shrestha ◽

Aaron J Gassmann

Keyword(s):

Field Experiments ◽

Diabrotica Virgifera Virgifera ◽

Western Corn Rootworm ◽

Cross Resistance ◽

Corn Rootworm ◽

Insecticidal Toxin ◽

Susceptible Population ◽

History Of ◽

Bacterium Bacillus

Abstract Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), has developed resistance to transgenic corn that produces the insecticidal toxin Cry3Bb1 derived from the bacterium Bacillus thuringiensis (Bacillales: Bacillaceae) (Bt), with cross-resistance extending to corn with Bt toxins mCry3A and eCry3.1Ab. Additionally, some populations of western corn rootworm have evolved resistance to Cry34/35Ab1 corn. We conducted a 2-yr field and laboratory study that included three field locations: 1) Bt-susceptible population, 2) field with a recent history of Cry3Bb1 resistance, and 3) field with a long-term history of Cry3Bb1 resistance. The population with recently evolved Cry3Bb1 resistance showed resistance to Cry3Bb1 corn in both laboratory bioassays and field evaluations; by contrast, the population with a long-term history of Cry3Bb1 resistance showed resistance, in both laboratory and field experiments to Cry3Bb1 corn and corn with a pyramid of mCry3A plus eCry3.1Ab corn. Field-based evaluations also showed that the field population with a long-term history of Cry3Bb1 resistance imposed higher root injury to Cry3Bb1 corn and the pyramid of mCry3A plus eCry3.1Ab compared with the susceptible control. The results of this study are discussed in the context of developing strategies to manage western corn rootworm in areas where populations have evolved resistance to Cry3Bb1 corn.

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