Selection and genetic analysis of behavioral traits of European corn borer (Ostrinia nubilalis), plant abandonment vs. plant establishment

Research on Bt resistance for pest insects has focused primarily on physiological adaptations with few experiments addressing how behavioral adaptations could influence resistance evolution. Through a laboratory selection experiment, we tested whether plant establishment and plant abandonment are heritable traits for the European corn borer, Ostrinia nubilalis. Egg masses were placed on non-Bt corn plants, and plant-abandoning individuals (Rovers) and establishing individuals (Sitters) were collected, reared to adulthood, and mated with a like phenotype. Selection over subsequent generations of the Rover colony showed an increased propensity to abandon the host plant (parental generation 3.12%, 4th generation 19.89%). We used video tracking software (EthoVision) to quantify behavioral differences between the Sitter and Rover colonies. Individual neonates (Rover, Sitter, and wild type) where put in 1 cm diameter cointainers and placed beneath an infrared camera connected to a computer and recorded for 20 minutes. In addition, we are examining both sequence and expression differences in candidate behavioral genes in O. nubilalis (foraging, shaker, and slowmo) to better understand the genetic mechanisms underlying host plant abandonment. We are using quantitative real time (qRT) PCR to determine expression profiles for these genes. Genomic DNA from 100 pupae (Rover, Sitter, and wild type) are being used to determine allelic differences based on variation in open reading frames and single nucleotide polymorphisms. Preliminary results of foraging show potential allelic differences between strains while shaker and slowmo exhibit different expression profiles.