Influence of Roundup Ready Soybean Production Systems and Glyphosate Application on Pest and Beneficial Insects in Narrow-Row Soybean

Abstract

Roundup Ready® soybeans, Glycine max (L.) Merrill, in narrow-row planting systems were investigated in 1998 in Mississippi to evaluate the effects of the transgenic crop and glyphosate herbicide on pest and beneficial insects. Insects found in sufficient numbers for meaningful analysis included adult bean leaf beetle, Cerotoma trifurcata (Forster); adult three-cornered alfalfa hopper, Spissistilus festinus (Say); adult big-eyed bug, Geocoris punctipes (Say), and; larvae of green cloverworm, Plathypena scabra (F.), and velvetbean caterpillar, Anticarsia gemmatalis (Hübner). Populations of C. trifurcata, S. festinus, P. scabra and A. gemmatalis were not reduced in genetically altered Roundup Ready soybean, or by recommended (by label) or delayed applications of glyphosate. Numbers of G. punctipes also were not reduced in Roundup Ready soybean, but were reduced by recommended applications of glyphosate during weeks three and four following the second recommended herbicide application. Geocoris punctipes densities also were reduced at 1 and 2 wks after the first glyphosate application in plots in which the second application of glyphosate was delayed. Numbers of G. punctipes may have been indirectly reduced by glyphosate within sample weeks two and three because of variations in weed densities after treatment with the herbicide.