Movement of (Smith) (Lepidoptera: Noctuidae) Larvae on Transgenic and Non- Maize.

Exposure of lepidopteran pests to () proteins has been shown to affect the behavior of larvae, including increased movement and avoidance of -expressing plants or diet. Therefore, we hypothesized that the behavior of western bean cutworm, (Smith) (Lepidoptera: Noctuidae), an important pest of maize, could be affected when exposed to plants. To test this hypothesis, we conducted a series of artificial arena and on-plant experiments to determine neonate behavior when exposed to and non- plant tissue. Video tracking experiments presented neonate larvae with the choice of or non- pollen in a Petri dish for 15 min while being video recorded for analysis with EthoVision software. This study showed an increase in mean velocity and total time spent moving for larvae in the presence of Cry1F vs. non- when compared with Vip3A vs. non- or Cry1F vs. Vip3A. However, there was no difference in total distance moved or time spent in the food zone for all scenarios. Maize tissue choice experiments allowed neonatal larvae the choice of feeding on or non- tassel or leaves for 9 h in Petri dish arenas. This experiment showed that larvae preferred tassel tissue over leaves but did not indicate that larvae could distinguish between and non- tissue. In contrast, on-plant experiments (including a whole plant neonate dispersal study under controlled conditions and an in-field silking behavior experiment) indicated that the presence of Cry1F and Vip3A toxins increased plant abandonment, suggesting that larvae are able to detect and avoid toxins. The discrepancy of these results is likely due to the on-plant studies providing more field-realistic environmental conditions and a longer duration of exposure to Bt toxins for the behavioral experiments. Our results represent the first steps in understanding the complex behavior of when exposed to plants. A better understanding of the response of larvae when exposed to traits can aid in the management of this pest, particularly for the design of resistance management strategies and refuge design.