DIAGNOSIS AND CHARACTERIZATION OF INSECTICIDE-INSENSITIVE ACETYLCHOLINESTERASE IN 3 POPULATIONS OF THE SWEET-POTATO WHITEFLY BEMISIA-TABACI

A biochemical approach was used to characterize acetylcholinesterase ( AChE) insecticide insensitivity in several sweetpotato whitefly (Bemis ia tabaci; SPW) populations. Discriminating doses of insecticide were established to differentiate between sensitive and insensitive SPW str ains and to genotype individual whitefly. This technique was then used to examine the frequency of insensitive AChE alleles in several SPW p opulations and to isolate a line homozygous for insensitive AChE from a heterogenous B-type population. Inheritance of putative altered AChE genotypes was consistent with the proposed haplo-diploid status of B. tabaci. This biochemical diagnostic was also employed to determine th e role of insensitive AChE in the observed resistance profiles of seve ral laboratory populations subjected to different selection regimes. I n keeping with previous studies on insecticide resistance in SPW, resi stance does not appear to be uniquely associated with the B-type but r ather with SPW populations found in crop systems. (C) 1998 SCI.