Activities of enzymes associated with inheritance of bifenthrin resistancein the silverleaf whitefly, Bemisia argentifolii

Activities of certain enzymes thought to be associated with inheritance of bifenthrin-resistance in silverleaf whitefly, Bemisia argentifolii (Bellows & Perring) were analyzed in both the crude homogenates and supernatants. E sterase activity was determined for bifenthrin-resistant, susceptible, and crossed strains of whitefly. The results indicated that an alpha -naphthyle sterase is a significant hydrolyzing enzyme associated with bifenthrin resi stance in the silverleaf whitefly, with glutathione-S-transferase and other esterase systems involved to lesser degrees. Also, an oxidative enzyme sys tem was involved with bifenthrin resistance based on an observed five-fold inhibition by piperonyl butoxide. These enzymes activities appeared to be i mportant to bifenthrin resistance in the silverleaf whitefly, but target si te insensitivity nees to be explored as another mechanism because the resis tance ratios reported here were relatively low.