Articles with the keyword: 
Two Resistance Genes for the Price of One--Ideal?
Sue Wu submitted, created time 8 months 4 weeks (sciencenow.sciencemag.org)
It seems like a no-brainer, even for mosquitoes: Why be resistant to one pesticide when you can be resistant to two? In practice, however, such adaptations weaken insects in other ways, so more might not be a good thing. 
\ 1
\