Plant proteinase inhibitors are potential anticereal aphid compounds

Trials were conducted to identify new compounds that may be useful in the control of cereal aphids on wheat, Triticum aestivum (L.). Five plant proteinase inhibitors were tested for their ability to control 3 species of cereal aphids in feeding trials. The proteinase inhibitors were tested against the Russian wheat aphid, Diuraphis noxia (Mordvilko), the greenbug, Schizaphis graminum (Rondani), and the bird cherry-oat aphid, Rhoalosiphum padi (L.). Two of these compounds, potato proteinase inhibitors I and Il, increased mortality among late instar aphids and reduced production of nymphs in feeding trials. Potato carboxypeptidase inhibitor and soybean trypsin inhibitor showed variable effects ranging from significant to nonsignificant abiosis, depending on the species of aphid examined. The lima bean proteinase inhibitor showed little effect on any of the 3 species. Though the effectiveness of the inhibitors varied, it appears that the proteinase inhibitors from potato are potentially effective proteins for the control of these species.