Hedley_1998_Pest.Sci_53_201

A range of potential proinsecticides was synthesised and tested against insecticide-susceptible and -resistant clones of Myzus persicae (Sulzer). They were all esters of compounds known to be toxic or pharmacologically active, and were designed to have increased lipophilicity and to be subject to more rapid activation by hydrolysis in resistant than in susceptible aphids due to the increased amount of esterase present in the resistant clones. The most potent toxins were esters of monofluoroacetic acid. When applied topically, the toxicity of these esters to M. persicae was directly proportional to the esterase content of the aphids. Such compounds would not be suitable as commercial insecticides, but the results serve to illustrate the potential benefits of exploiting a resistance mechanism against one class of compounds to render another class more toxic, i.e. to design compounds that show negative cross-resistance.