Target site mediated insecticide resistance: what questions remain?

Recent advances in the molecular genetics of insecticide resistance have id entified the point mutations associated with target site insensitivity in t he genes encoding the three major insecticide targets: the Rdl GABA recepto r, the para voltage gated sodium channel and insect acetylcholinesterase. H owever central questions relating to the origin, selection and fitness of t hese mutations in natural populations remain. This review examines the exte nt to which we understand how a specific subset of potential resistance ass ociated mutations are selected, how often they may arise and/or recombine, and whether we can explain any potential fitness disadvantages based on our knowledge of the molecular mechanisms of resistance involved. (C) 1999 Els evier Science Ltd. All rights reserved.