Behavioral Response of Plutella xylostella (Lepidoptera: Plutellidae) Populations to Permethrin Deposits

Abstract

An experiment was designed to measure behavioral response of diamondback moth, Plutella xylostella L., populations collected as part of a nationwide survey to insecticide deposits. Cabbage leaf disks were treated with droplets of permethrin and arranged to form a graded series of droplet densities. Larvae were exposed to the gradient for 24 h, after which their positions along the gradient and amount of feeding on each disk were recorded. As measured by average position, populations showed varied behavioral response to the gradient. Results from feeding experiments were correlated with average position. When our measure of behavioral response was compared with a measure of physiological response, a negative correlation between the two was evident for most populations. These data suggest that irritation and intoxication are responsible for behavioral and physiological responses, respectively, and these effects are caused by the same physiological process. Some populations did not fit this pattern, however, indicating that behavioral and physiological responses could also arise from different physiological mechanisms.