OXIDATIVE RESPONSES IN SOYBEAN FOLIAGE TO HERBIVORY BY BEAN LEAF BEETLE AND 3-CORNERED ALFALFA HOPPER

Variation in induced responses in soybean is shown to be dependent, in part, upon herbivore species. Herbivory by the phloem-feeding three-c ornered alfalfa hopper caused increases in the activities of several o xidative enzymes including lipoxygenases, peroxidases, ascorbate oxida se, and poly phenol oxidase. Bean leaf beetle defoliation caused incre ased lipoxygenase activity, but had little effect upon peroxidase, pol yphenol oxidase, ascorbate oxidase, or trypsin inhibitor levels in eit her field or greenhouse studies. In one field experiment, prior herbiv ory by the bean leaf beetle subsequently reduced the suitability of fo liage to the corn earworm Helicoverpa tea. The contribution of these f indings to emerging theories of insect-plant interactions is discussed .