Genetical Research

Insecticide resistance genes confer a predation cost on mosquitoes, Culex pipiens

C. BERTICAT a1, O. DURON a1, D. HEYSE a1 and M. RAYMOND a1c1
a1 Institut des Sciences de l'Evolution (UMR CNRS 5554), C.C. 065, Université de Montpellier II, 34095 Montpellier cedex 05, France

Article author query
berticat c   [PubMed][Google Scholar] 
duron o   [PubMed][Google Scholar] 
heyse d   [PubMed][Google Scholar] 
raymond m   [PubMed][Google Scholar] 


Newly occurring adaptive genes, such as those providing insecticide resistance, display a fitness cost which is poorly understood. In order to detect subtle behavioural changes induced by the presence of resistance genes, we used natural predators and compared their differential predation on susceptible and resistant Culex pipiens mosquitoes, using strains with a similar genetic background. Resistance genes were either coding an overproduced detoxifying esterase (locus Ester), or an insensitive target (locus ace-1). Differential predation was measured between susceptible and resistant individuals, as well as among resistant mosquitoes. A backswimmer, a water measurer, a water boatman and a predaceous diving beetle were used as larval predators, and a pholcid spider as adult predator. Overall, the presence of a resistance gene increased the probability of predation: all resistance genes displayed predation costs relative to susceptible ones, at either the larval or adult stage, or both. Interestingly, predation preferences among the susceptible and the resistance genes were not ranked uniformly. Possible explanations for these results are given, and we suggest that predators, which are designed by natural selection to detect specific behavioural phenotypes, are useful tools to explore non-obvious differences between two classes of individuals, for example when they differ by the presence or absence of one recent gene, such as insecticide resistance genes.

(Received January 5 2004)
(Revised February 19 2004)

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