title: Amplification of DNA from preserved specimens shows blowflies were preadapted for the rapid evolution of insecticide resistance.
abstract: Mutations of esterase 3 confer two forms of organophosphate resistance on contemporary Australasian Lucilia cuprina. One form, called diazinon resistance, is slightly more effective against commonly used insecticides and is now more prevalent than the other form, called malathion resistance. We report here that the single amino acid replacement associated with diazinon resistance and two replacements associated with malathion resistance also occur in esterase 3 in the sibling species Lucilia sericata, suggesting convergent evolution around a finite set of resistance options. We also find parallels between the species in the geographic distributions of the polymorphisms: In both cases, the diazinon-resistance change is absent or rare outside Australasia where insecticide pressure is lower, whereas the changes associated with malathion resistance are widespread. Furthermore, PCR analysis of pinned specimens of Australasian L. cuprina collected before the release of organophosphate insecticides reveals no cases of the diazinon-resistance change but several cases of those associated with malathion resistance. Thus, the early outbreak of resistance in this species can be explained by the preexistence of mutant alleles encoding malathion resistance. The pinned specimen analysis also shows much higher genetic diversity at the locus before organophosphate use, suggesting that the subsequent sweep of diazinon resistance in Australasia has compromised the scope for the locus to respond further to the ongoing challenge of the insecticides.
authors.affiliation: Division of Entomology, Commonwealth Scientific and Industrial Research Organization (CSIRO), P.O. Box 1700, Canberra, ACT 2601, Australia. carol.hartley@csiro.au
authors.forename: C J
authors.initials: CJ
authors.lastname: Hartley
authors.forename: R D
authors.initials: RD
authors.lastname: Newcomb
authors.forename: R J
authors.initials: RJ
authors.lastname: Russell
authors.forename: C G
authors.initials: CG
authors.lastname: Yong
authors.forename: J R
authors.initials: JR
authors.lastname: Stevens
authors.forename: D K
authors.initials: DK
authors.lastname: Yeates
authors.forename: J
authors.initials: J
authors.lastname: La Salle
authors.forename: J G
authors.initials: JG
authors.lastname: Oakeshott
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D044362:Australasia; D004175:Diptera / Q000235:genetics*; D019143:Evolution, Molecular; D017344:Genes, Insect / Q000235:genetics; D006239:Haplotypes; D007305:Insecticide Resistance / Q000235:genetics*; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics; D014021:Tissue Preservation
chemical_list: D009943:Organophosphorus Compounds