A mutation Leu1029 to His in Heliothis virescens F-hscp sodium channel gene associated with a nerve-insensitivity mechanism of resistance to pyrethroid insecticides

Two mutations in the Heliothis virescens F. sodium channel gene hscp are as sociated with pyrethroid resistance in field populations. These are valine4 21 to methionine (V421M) in domain I transmembrane segment S6 (IS6) and leu cine 1029 to histidine (L1029H) in IIS6. L1029H was found to be common in 1 995 Louisiana field collections. In order to test whether the L1029H mutati on is associated with a nerve-insensitivity resistance mechanism, we design ed a simplified genetic crossing and tested progenies with bioassay and ele ctrophysiology. Individuals with the L1029H mutation displayed greater resi stance to the knockdown effect of permethrin in subsequent mass-selection a nd family-selection experiments. Reduced sensitivity to pyrethroid was foun d in extracellular recordings of neuromuscular junctions and in whole-cell patch-clamp assays of dissociated single cells from the central nerverous s ystem of the individuals carrying the L1029H mutation. (C) Academic Press.