Subacute Effects of Cry1Ab Bt Corn Litter on the Earthworm Eisenia fetida and the Springtail Folsomia candida

Abstract

<p>Laboratory toxicity studies were conducted to determine the subacute effects of <em>Bt</em> Cry1Ab corn leaf material on nontarget soil organisms. Survival and growth were measured for an earthworm, <em>Eisenia fetida</em> Savigny, and survival and reproduction were measured for a springtail, <em>Folsomia candida</em> Willem. The organisms were provided leaf material of two Bt11 corn varieties, two Mon810 corn varieties, and the isolines of each, in a soil system and monitored for 28 d. An assay control treatment of an optimal food and a reference control treatment, using the herbicide pendimethalin, were used to provide a context for the observed results. Basic nutritional data of protein, fat, and sugar content were analyzed for each food type. Greater growth was observed for <em>E. fetida</em> in two <em>Bt</em> varieties, Bt11 90-d and Mon810 108-d, compared with their isolines. <em>F. candida</em> receiving Bt11 90-d isoline material had more offspring compared with those in the corresponding Bt line, but no other pairs were different. Time to reproduction of <em>F. candida</em> was only affected by the reference control treatment. Both protein and sugar content were found to correlate significantly with growth for <em>E. fetida</em>, but the nutritional parameters were not found to correlate with the effects observed for <em>F. candida</em>. These results indicate that there is little direct hazard from <em>Bt</em> corn leaf material to <em>E. fetida</em> and <em>F. candida</em> but that differences in nutritional parameters of the<em>Bt</em> lines and the isolines may lead to differences in the effects on nontarget organisms.</p>