Tuesday, December 12, 2006

Oviposition and behavior of rotation-resistant and wild type western corn rootworm, Diabrotica virgifera virgifera

Lisa M. Knolhoff, lknolhof@uiuc.edu, University of Illinois - Urbana/Champaign, Entomology, 505 S. Goodwin Ave, Urbana, IL and Joris J. Glas, joris.glas@wur.nl, Wageningen University, Entomology, PO Box 8031, Wageningen, Netherlands.

The western corn rootworm has developed resistance to crop rotation as a control method in Illinois and Indiana. In regions where resistance is present, females oviposit in non-corn fields that are planted with corn the following spring. The mechanism for this behavioral adaptation is likely to be related to heightened levels of flight and locomotory activity in resistant females. Oviposition by resistant females is thought to be indiscriminate with respect to crop; soybean fields receive most non-corn oviposition because they are most prevalent. Oviposition choice and tendency to feed on soybean were examined in two arenas. Females were placed in Petri dishes containing two moistened filter papers, on which one was placed corn tissues and one was placed soybean leaf discs. Another apparatus was devised to examine the combined behaviors of dispersal and oviposition. These arenas were composed of two chambers for oviposition and feeding: one with corn tissues and one with soybean leaf discs. Chambers were connected with a short piece of tubing; increased movement between chambers simulates heightened activity levels. Oviposition choice will be compared to results of a documented behavioral assay in the field. Implications of soybean herbivory will be discussed.

Species 1: Coleoptera Chrysomelidae Diabrotica virgifera virgifera (western corn rootworm)