Effects of Bt transgenic rice on population dynamics of main non-target insect pests and dominant spider species in rice paddies.
The impacts of two Bt transgenic rice lines (TT9-3 and TT9-4) containing the heterozygous gene, cry1Ab+cry1Ac, from Bacillus thuringiensis, on the field population dynamics of Sogatella furcifera and Nephotettix cincticeps, as well as the dominant spider species were evaluated. The results showed that there were no significant differences between the densities of adult S. furcifera and N. cincticeps in the plots of the two Bt rice lines and their parental control (IR72) during the whole growing season of rice. In TT9-3 plots, both the nymph densities of S. furcifera in early- to mid-season and N. cincticeps in middle- to late-season were significantly higher than those of the control. In contrast, there were no significant differences between the nymph densities of the two pests on TT9-4 and its control variety. In TT9-3 and TT9-4 plots, the population dynamics of five dominant spider species, namely, Tetragnatha maxillosa, Dyschiriognatha quadrimaculata, Ummeliata insecticeps, Pardosa pseudoannulata and Pirata subpiraticus were similar to those in control field, where the population of most of spiders showed no significant. The result indicate that the two Bt rice lines have no adverse effects on the dominant spider species in rice paddies.