SUITABILITY OF LEGUME COVER CROPS FOR GRASSHOPPER (ORTHOPTERA, ACRIDIDAE) DEVELOPMENT AND REPRODUCTION

The use of legume cover crops is a potentially valuable practice in mi tigating problems associated with annual crop-fellow rotations in the Northern Plains. Because grasshoppers may become a pest in a cover cro p system, we determined the suitability of 3 annual legumes for grassh opper development and reproduction. No-choice diets of grass pea. (Lat hyrus sativus L.), lentil (Lens culinaris Medikus), field pea (Pisum s ativum L.), and hairy vetch (Vicia villosa Roth) were fed to 5 species of grasshoppers: Melanoplus bivittatus (Say), Melanoplus differential is (Thomas), Melanoplus femurrubrum (De Geer), Melanoplus packardii Sc udder, and Melanoplus sanguinipes (F.). Field pea and lentil were the least suitable legumes when considering the combination of grasshopper survival, development, and reproduction. The effect was most pronounc ed for M. sanguinipes and M. femurrubrum. These grasshoppers displayed poor survival and delayed development when fed field pea or lentil co mpared with other legumes or a control. Adult fecundity and fertility of eggs also were adversely affected when no-choice diets of Beld pea or lentil were offered. For M. packardii, a nymphal diet of field pea resulted in the poorest development; grasshoppers fed an adult diet of field pea did not reproduce. M. bivittatus and M. differentialis expe rienced limited mortality when fed field pea or lentil. Nevertheless, development was substantially delayed and reproduction inhibited to va rying degrees. Field pea and lentil appear to have good potential in p roviding the benefits of cover crops, while decreasing the economic im pact of common grasshopper species.