Dieldrin resistance in Lucilia cuprina (the australian sheep blowfly): chance, selection and response.
Discrete-generation population cages of Lucilia cuprina were initiated with dieldrin-resistant allele (Rdl ) frequencies of 1 or 5% and maintained for 17 generations on media with concentrations of dieldrin in the range 0-0.006% (w/v). The probability of the initial establishment of the Rdl allele in a population was consistently greater at the 5% frequency and dependent on the concentration of dieldrin in the medium for both starting frequencies. Once the resistant allele was established responses to selection were concentration-dependent. It was concluded that in the absence of dieldrin the susceptible allele was selectively favoured, at 0. 00005% (w/v) concentration selection and random genetic drift influenced changes in allele frequency and at concentrations above this the Rdl allele was at a selective advantage. Fixation of Rdl occurred at the higher concentrations. The influence of random genetic drift and selection on the genetic response during the evolution of insecticide resistance is discussed.
Scott
M
M
Department of Genetics, The University of Melbourne, Victoria, Australia.
Diwell
K
K
McKenzie
J A
JA
D000483:Alleles; D000818:Animals; D001315:Australia; D001947:Breeding; D004026:Dieldrin / Q000494:pharmacology*; D004175:Diptera / Q000187:drug effects / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D005787:Gene Frequency; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides / Q000494:pharmacology*; D012641:Selection, Genetic; D012756:Sheep
D007306:Insecticides; D004026:Dieldrin