Insect Populations on Forage Grasses: Effect of Nitrogen Fertilizer and Insecticides 12

Abstract

Significantly more leafhoppers, especially Ambylsellus curtisii (Fitch), Doratura stylata (Boheman), Draeculacephala antica (Walker), Graminella nigrifrons (Forbes), Endria inimica (Say), and Macrosteles fascifrons (Stål), were collected from nitrogen fertilized (480 kg N/ha) than from unfertilized plots of 3 grass cultivars out of 39 in 1971 and 9 out of 23 N-fertilized (240kg N/ha) cultivars in 1972. Also, more grasshoppers, Dicromorpha viridis Scudder, Melanoplus bivittatus (Say), and another Melanoplus species; the flea beetles, Chaetocnema pulicaria Melsheimer and Systena frontalis (F.); and the frit fly, Oscinella frit (L.), were collected in significantly higher numbers on some N-fertilized cultivars. Peak numbers of most insect species occurred in late summer. Carbofuran (10% granules, 2.24 kg AI/ha in 1972) and (flowable, 1.12 kg AI/ha in 1973) reduced mean numbers of most species of insects and resulted in increased dry matter yield of a few cultivars both years.