Diagnosis and characterization of insecticide-insensitive acetylcholinesterase in three populations of the sweetpotato whiteflyBemisia tabaci

Abstract

A biochemical approach was used to characterize acetylcholinesterase (AChE) insecticide insensitivity in several sweetpotato whitefly (Bemisia tabaci; SPW) populations. Discriminating doses of insecticide were established to differentiate between sensitive and insensitive SPW strains and to genotype individual whitefly. This technique was then used to examine the frequency of insensitive AChE alleles in several SPW populations 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 the role of insensitive AChE in the observed resistance profiles of several laboratory populations subjected to different selection regimes. In keeping with previous studies on insecticide resistance in SPW, resistance does not appear to be uniquely associated with the B‐type but rather with SPW populations found in crop systems. © 1998 SCI.

Optimization of A Bioassay Method for Specific Activity of Acetylcholinesterase of B BiotypeBemisia tabaci(Hemiptera: Aleyrodidae)

“…The AChE of insecticide-susceptible insects is inhibited by OPs and CBs, whereas that of resistant insects is insensitive to insecticide inhibition. The mechanism of OP -and CB -resistance in B. tabaci from different regions of the world has been found to be insensitive AChE (Dittrich et al 1985(Dittrich et al , 1990Byrne & Devonshire 1993, 1997Byrne et al 1994;Anthony et al 1998;Byrne & Toscano 2002;Byrne et al 2003;Erdogan et al 2008). We have provided a quick and accurate method of determination of specific activity of the AChE of B. tabaci, which is a direct indication of the level of resistance to OPs and CBs.…”