scholarly journals Diazinon resistance, fluctuating asymmetry and fitness in the Australian sheep blowfly, lucilia cuprina.

Genetics ◽  
1988 ◽  
Vol 120 (1) ◽  
pp. 213-220 ◽  
Author(s):  
J A McKenzie ◽  
G M Clarke
Keyword(s):  
Fluctuating Asymmetry ◽  
Natural Populations ◽  
Lucilia Cuprina ◽  
Resistance Locus ◽  
Gene Complex ◽  
Subsequent Evolution ◽  
Genetic Analyses ◽  
Evolution Of Resistance ◽  
Australian Sheep ◽  
Chromosome Iii

Abstract Genetic evidence suggests that the evolution of resistance to the insecticide diazinon in Lucilia cuprina initially produced an increase in asymmetry. At that time resistant flies were presumed to be at a selective disadvantage in the absence of diazinon. Subsequent evolution in natural populations selected modifiers to ameliorate these effects. The fitness and fluctuating asymmetry levels of resistant flies are currently similar to those of susceptibles. Previous genetic analyses have shown the fitness modifier to co-segregate with the region of chromosome III marked by the white eyes, w, locus, unlinked to the diazinon resistance locus, Rop-1, on chromosome IV. This study maps the asymmetry modifier to the same region, shows, as in the case of the fitness modifier, its effect to be dominant and presents data consistent with the fitness/asymmetry modifier being the same gene (gene complex). These results suggest changes in fluctuating asymmetry reflect changes in fitness.

Predicting resistance and managing susceptibility to cyromazine in the Australian sheep blowfly Lucilia cuprina

1996 ◽  
Vol 36 (4) ◽  
pp. 413 ◽  
Author(s):  
YL Yen ◽  
P Batterham ◽  
B Gelder ◽  
JA McKenzie
Keyword(s):  
Single Gene ◽  
Limited Range ◽  
Resistance Mechanisms ◽  
Lucilia Cuprina ◽  
Relative Fitness ◽  
Laboratory Studies ◽  
Effective Strategies ◽  
Evolution Of Resistance ◽  
Australian Sheep ◽  
Line Analysis

Four cyromazine-resistant variants of Lucilia cuprina were selected after ethyl methanesulfonate mutagenesis and screening above the concentration of cyromazine lethal to susceptibles. Resistance is controlled by a single gene in each variant. Two resistance loci have been identified, one (Cyr 4) closely linked to the marker 'reduced eyes' on chromosome IV, the other (Cyr 5) closely linked to the 'stubby bristles' marker on chromosome V. Concentration-mortality line analysis shows resistance ratios are low (1.5-3x). One variant [Cyr 4(2)] is viable as a homozygote, the others are lethal [Cyr 4(1)] or, at best subvital [Cyr 5(1) and Cyr 5(2)]. Competition experiments between resistant heterozygotes and susceptibles show that resistance to cyromazine is selected for over a limited range of concentrations. The capacity of laboratory studies to predict likely resistance mechanisms before they evolve in the field is discussed. The use of genetic, toxicological and relative fitness data arising from these studies to devise the most effective strategies of insecticide usage while minimising the evolution of resistance is emphasised.

scholarly journals Predicting insecticide resistance: mutagenesis, selection and response

1998 ◽  
Vol 353 (1376) ◽  
pp. 1729-1734 ◽  
Author(s):  
J. A. McKenzie ◽  
P. Batterham
Keyword(s):  
Single Gene ◽  
Natural Populations ◽  
Selective Advantage ◽  
Resistance Mechanisms ◽  
Predictive Capacity ◽  
Evolution Of Resistance ◽  
Australian Sheep ◽  
Delivery Strategies ◽  
Low Levels ◽  
Molecular Bases

Strategies to manage resistance to a particular insecticide have usually been devised after resistance has evolved. If it were possible to predict likely resistance mechanisms to novel insecticides before they evolved in the field, it might be feasible to have programmes that manage susceptibility. With this approach in mind, single–gene variants of the Australian sheep blowfly, Lucilia cuprina , resistant to dieldrin, diazinon and malathion, were selected in the laboratory after mutagenesis of susceptible strains. The genetic and molecular bases of resistance in these variants were identical to those that had previously evolved in natural populations. Given this predictive capacity for known resistances, the approach was extended to anticipate possible mechanisms of resistance to cyromazine, an insecticide to which L. cuprina populations remain susceptible after almost 20 years of exposure. Analysis of the laboratory–generated resistant variants provides an explanation for this observation. The variants show low levels of resistance and a selective advantage over susceptibles for only a limited concentration range. These results are discussed in the context of the choice of insecticides for control purposes and of delivery strategies to minimize the evolution of resistance.

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