Effects of transgenic rice expressing Bacillus thuringiensis Cry1Ab protein on ground-dwelling collembolan community in postharvest seasons.

During 2005-2008, field studies were conducted at two locations in Chongqing, China, to assess the potential effects of transgenic rice expressing Bacillus thuringiensis (Bt) Cry1Ab protein on the nontarget ground-dwelling collembolan community in three postharvest seasons. Collembolans in non-Bt and Bt rice fields were sampled with pitfall traps during each of two postharvest seasons of 2005/2006 and 2006/2007 and litterbag traps during each of three postharvest seasons of 2005/2006, 2006/2007, and 2007/2008. Ground-dwelling collembolans in rice fields during the postharvest seasons were abundant, whereas community densities varied considerably between the two locations and among the three seasons. A total of 67,310 collembolans, representing three species, Entomobrya griseoolivata, Hypogastrura matura, and Bourletiella christianseni, were captured during the three postharvest seasons. E. griseoolivata was the predominant species, accounting for 87.7% of the total captures, followed by H. matura (10.7%) and B. christianseni (1.6%). In general, there were no significant differences in species compositions and abundances of each species between Bt and non-Bt paddy fields, suggesting no significantly impact of plant residues of Cry1Ab rice on collembolan communities during postharvest seasons.