Dispersal of boll weevil toward and within the cotton plant and implications for insecticide exposure.

Background: Immature stages of boll weevil complete development endophytically leaving only the adult stage accessible for chemical control. We tested the hypothesis that boll weevil colonization of the cotton plants significantly affects their exposure to sprayed insecticides. We determined the adult dispersal toward and within cotton plants, lethal time (LT), and residual control by recommended insecticides (malathion, carbosulfan, thiamethoxam, fipronil, beta-cyfluthrin, lambda-cyhalothrin, and thiamethoxam + lambda-cyhalothrin) through dried residue exposure and residual control regarding the leaf position in the upper and the lower thirds of the treated plant canopy.