PROTEIN TOXICITY TO APHIDS - AN INVITRO TEST ON ACYRTHOSIPHON-PISUM

Recent progress in plant transformation for insect resistance has incr eased the interest in the potential toxicity of proteins towards insec t pests. While studies have been targeted to a large array of insect s pecies, phloem-feeding Homoptera have not been investigated yet. The p aper describes a routine test for screening toxicity and growth inhibi tion of purified proteins in artificial diets on Acyrthosiphon pisum ( Harris). Twenty-five commercially available proteins of different clas ses were tested and compared to some non-protein chemicals (an insecti cide, an antibiotic ... ). A. pisum proved to be very sensitive to all proteases tested and to some venoms with general cytolytic properties . A plant lectin, concanavalin A, displayed significant toxicity and g rowth inhibition, while various proteins such as a soybean proteinase inhibitor, a chitinase, and bovine serum albumin showed measurable imp airments of growth only at higher dose (greater-than-or-equal-to 250 m ug.ml-1). Some proteins were without short-term effect on A. pisum phy siology. The influence of these results on aphid-plant interactions ar e discussed.