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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #304520
Title: Larval mortality and development for rotation-resistant and rotation-susceptible populations of the western corn rootworm on Bt corn

Author
item TINSLEY, NICHOLAS - University Of Illinois
item SPENCER, JOSEPH - University Of Illinois
item ESTES, RONALD - University Of Illinois
item Prasifka, Jarrad
item SCHRADER, PRESTON - University Of Illinois
item French, Bryan
item GRAY, MICHAEL - University Of Illinois

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2014
Publication Date: 2/2/2015
Citation: Tinsley, N.A., Spencer, J.L., Estes, R.E., Prasifka, J.R., Schrader, P.M., French, B.W., Gray, M.E. 2015. Larval mortality and development for rotation-resistant and rotation-susceptible populations of the western corn rootworm on Bt corn. Journal of Applied Entomology. 139:46-54.

Interpretive Summary: The western corn rootworm is one of the most economically important insect pests of corn in the United States. Throughout its history as a pest of corn, this insect has adapted to variety of management tactics, including the cultural practice of crop rotation. Rotation-resistant western corn rootworms are more likely to lay eggs in non-corn habitats. Since first reported in Illinois in the late 1980s, populations of the rotation-resistant western corn rootworm have spread over a wide area of the eastern Corn Belt. Little information is available concerning the interaction of rotation-resistance with the use of Bt corn, a widely popular tactic for preventing larval injury and its associated yield loss. A greenhouse experiment was used to determine if rotation-resistant and rotation-susceptible western corn rootworm larvae differ with respect to survival or development when exposed to single- or dual-toxin (pyramided) Bt corn. Western corn rootworm eggs were placed in the root zone of young corn plants and removed from the soil 17 days later. Rotation-resistant and rotation-susceptible larvae showed similar survival and size when exposed to both single-toxin and pyramided (multiple-toxin) Bt corn. Results suggest that these two populations do not differ with respect to survival or development when exposed to Bt corn. Additionally, the similar survival for larvae exposed to single-toxin and pyramided Bt corn suggests that pyramided Bt hybrids containing the Cry3Bb1 and Cry34/35Ab1 toxins may not result in additive mortality for western corn rootworm larvae.

Technical Abstract: The western corn rootworm, Diabrotica virgifera virgifera LeConte, is one of the most economically important insect pests threatening the production of corn, Zea mays (L.), in the United States. Throughout its history, this insect has displayed considerable adaptability by overcoming a variety of pest management tactics, including the cultural practice of annual crop rotation. Since first reported in Illinois in the late 1980s, populations of the rotation-resistant western corn rootworm have spread to cover a wide area of the eastern Corn Belt. Currently, little information is available concerning the interaction of rotation-resistance with the use of Bt corn, a widely popular tactic for preventing larval injury and its associated yield loss. The goal of this greenhouse experiment was to determine if rotation-resistant and rotation-susceptible western corn rootworm larvae differ with respect to survival or development when exposed to single- or dual-toxin (pyramided) Bt corn. Individual corn plants were infested with 225 near-hatch eggs at the V5 (five leaf collar) growth stage. Larvae developed undisturbed on the root systems for 17 d, after which they were recovered using Berlese funnels. Surviving larvae were counted to estimate mortality, and head capsule widths were measured to assess development. Rotation-resistant and rotation-susceptible larvae had statistically similar mean levels of mortality and head capsule widths when exposed to both single-toxin (Cry3Bb1 or Cry34/35Ab1) and pyramided (Cry3Bb1 + Cry34/35Ab1) Bt corn. Our results suggest that these two populations do not differ with respect to survival or development when exposed to Bt corn. Additionally, the statistically similar mean levels of mortality for larvae exposed to single-toxin and pyramided Bt corn suggest that pyramided Bt hybrids containing the Cry3Bb1 and Cry34/35Ab1 toxins do not result in additive mortality for western corn rootworm larvae. Implications of our findings for management of this economically important pest are discussed.