Biochemical characterization of chlorantraniliprole and spinetoram resistance in laboratory-selected obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae)

Neonate larvae of obliquebanded leafroller, Choristoneura rosaceana, from a laboratory colony were exposed to two reduced-risk insecticides, chlorantraniliprole and spinetoram. After nine generations of selection, significant levels of resistance to each insecticide were observed. Biochemical assays were performed on third instars to determine potential resistance mechanisms. Enzyme assays indicated that esterase activity was significantly increased in the chlorantraniliprole-selected colony, whereas mixed-function oxidase levels were elevated in the spinetoram-selected colony as compared to the unselected colony. No difference in glutathione-S-transferase activity was seen in either of the insecticide-selected colonies. These results indicate the potential involvement of esterases and mixed-function oxidases as detoxification mechanisms responsible for resistance to chlorantraniliprole and spinetoram, respectively. Furthermore, the results of this study suggest that chlorantraniliprole and spinetoram are not detoxified by similar mechanisms and could therefore be incorporated into resistance management programs in tree fruit leading to sustainable management of C. rosaceana.