Study On the Community Structure and Abundance of Soil Collembolan Flora In Paddyfields of Transgenic Bt Rice with Different Breading and Genotypes.

Collembolan, as being one of the key functional groups of soil animals, has been widely used as biomarker to monitoring soil environmental quality and ecological safety, owing to its large quantity of species and abundances, and the sensitive response to environmental disturbance. In this study, different breeding (restorer vs. hybrid) and genotypes (pure vs. dual) of transgenic Bt rice, including the restorer lines of Cry1Ab cv. KMD and Cry1Ab+Cry1Ac cv. HH1 and the Hybrid Cry1Ab+Cry1Ac cv. Bt-SY63, and their respective parent control lines of cv XSD, MH63 and SY63, were used to study the effects of breeding and genotypes of Bt rice on community composition and structure, and abundance dynamics of soil collembolan in paddyfields. The results were indicated that Bt rice only significantly affected some special groups of soil collembolan, and had no effects on the community structure; while most significant effects of different breeding and genotypes of Bt rice were showed on the community composition and quantity. Six families and 12 genuses of soil collembolan were found, including seven common genuses of Entomobry, Onychiurus, Probolaphorura, Hypogastrura, Folsomides, Proisotoma and Isotomodes. And transgenic Bt rice planting was also resulted in the lost of some rare or common genuses, that is, Arrhopalites, Cribrochiurus and Isotoma for the restorer of pure-transgene Bt rice, Arrhopalites for the restorer of dual-transgene Bt rice, and Isotoma for the hybrid of dual-transgene Bt rice. Compared with nontransgenic rice, the hybrid of dual-transgene Bt rice significantly increased the percent of Hypogastrura and the abundances of the fungal/bacterial feeders. For the restorers of Bt rice, significant decrease was also found in the abundance of saprophagous-feeders for the dual-transgene Bt rice in contrast to the pure-transgene Bt rice. Moreover, for the dual-transgene Bt rice, the hybrid significantly enhanced the abundances of the saprophagous-feeders and total soil collembolan, simultaneously increased the genus richness and community diversity of soil collembolans. It is presumed that the utilization of transgenic Bt rice hybrid is much more helpful to improve the community stability of soil collembolan flora in paddyfield production.