Behavioral characteristics of neonate European corn borer, Ostrinia nubilalis, on Bt corn
University of Delaware
European corn borer (ECB), Ostrinia nubilalis (Hübner), is an economically important insect pest of corn in the US and Canada. The development of genetically modified corn expressing genes derived from Bacillus thuringiensis (Bt) that encodes insecticidal crystalline (Cry) proteins has proven to be effective in controlling this insect. The purpose of this study was to assess dispersal and feeding behavior of neonate ECB on Bt corn. I examined differences in neonate ECB dispersal behavior for the first four hours following eclosion in the field among stacked pyramid (DAS 59122-7 × TC1507 × MON810) Bt corn, non-Bt near isoline, and non-Bt sweet corn; and in the laboratory among Bt corn hybrids TC1507, MON810, a pyramid combining TC1507 and MON810, and non-Bt near isoline corn. I also examined differences in feeding behavior between MON810 Bt corn and non-Bt near isoline corn for four intervals over a 48-hour period. In field experiments, I found that dispersal was significantly higher on non-Bt near isoline and Bt corn when compared to sweet corn. In laboratory experiments, dispersal was significantly higher on MON810 and stacked pyramid Bt corn than on non-Bt near isoline corn. Finally, feeding experiments suggested that there was a significant difference in feeding behavior between MON810 Bt corn and non-Bt near isoline corn. The findings from the feeding experiment also suggested that more than 50% of the larvae abandoned the plant before there was evidence of feeding for both Bt and non-Bt corn. Results indicated that a mixed refuge method could prove to be an effective solution for managing ECB resistance on Bt corn. However, additional research needs to be conducted on ECB larval movement between Bt and non-Bt corn to fully assess the efficacy of the mixed refuge strategy.