Effects of transgenic Bt rice lines with single Cry1Ab and fused Cry1Ab/Cry1Ac on the abundance dynamics and community diversity of soil mites

Risk assessment and ecological effects are a concern of transgenic rice. In this study, the effects of three lines of Bt rice expressing single Cry1Ab protein (Kemingdao: cv. KMD) and fused Cry1Ab/Cry1Ac proteins (Huahui 1: cv. HH1; Bt Shanyou 63: cv. Bt-SY63) on soil mite community were investigated under field conditions. Transgenic treatment (cv. Bt-rice vs. non-Bt rice) significantly decreased the community index of Margalef’s richness (SR) of soil mite in KMD, and significantly increased the abundance and the community indexes of Shannon diversity (H’), Pielou’s evenness (J) and SR of soil mite in Bt-SY63 (p < 0.05). Transgene type (cv. KMD vs. HH1) did not significantly affect the composition, abundance and the community index (p > 0.05). Breeding type (cv. HH1 vs. Bt-SY63) significantly changed the composition and markedly improved the abundance and the J value in Bt-SY63 (p < 0.05). However, seasonal and inter-annual changes were apparent, and the Bt effects were not consistent at all for the different plant backgrounds over a 2-year period. These results suggested that the cultivation of Bt rice has a significant but transient effect on soil mite community.