Suitability of Legume Cover Crops for Grasshopper (Orthoptera: Acrididae) Development and Reproduction

Abstract

The use of legume cover crops is a potentially valuable practice in mitigating problems associated with annual crop-fallow rotations in the Northern Plains. Because grasshoppers may become a pest in a cover crop system, we determined the suitability of 4 annual legumes for grasshopper development and reproduction. No-choice diets of grass pea (Lathyros sativus L.), lentil ( Lens culinaris Medikus), field pea ( Pisum sativum L.), and hairy vetch (Vicia villosa Roth) were fed to 5 species of grasshoppers: Melanoplus bivittatus (Say), Melanoplus differentialis (Thomas), Melanopltls femtlrrubrum (De Geer), Melanoplus packardii Scudder, and Melanoplus sangllinipes (F.). Field pea and lentil were the least suitable legumes when considering the combination of grasshopper survival, development, and reproduction. The effect was most pronounced for M.sanguinipes and M. femurrubrum. These grasshoppers displayed poor survival and delayed development when fed field pea or lentil compared with other legumes or a control. Adult fecundity and fertility of eggs also were adversely affected when no-choice diets of field 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 experienced limited mortality when fed field pea or lentil. Nevertheless, development was substantially delayed and reproduction inhibited to varying degrees. Field pea and lentil appear to have good potential in providing the benefits of cover crops, while decreasing the economic impact of common grasshopper species.