[Occurrence dynamics of migratory pest insects Cnaphalocrocis medinalis and Sogatella furcifera in transgenic Bt rice field in Xing'an County of Guangxi Province].

An investigation was conducted in Xing' an County of Guangxi Province in 2010 to study the occurrence and damage characteristics of two unique migratory pest insects, rice leaffolder (Cnaphalocrocis medinalis) and white-backed planthopper (Sogatella furcifera), in a transgenic Bt rice (cv. HH1 with dual Cry1Ab+Cry1Ac genes) field, taking the corresponding non-transgenic parent (cv. MH63) field as the control. No significant differences were observed in the abundance of C. medinalis eggs and larvae in the two fields, but the percentage of fold-leaf plants and the fold-leaf rate per plant were significantly lower in transgenic Bt rice field than in the control, suggesting that transgenic Bt rice had higher resistance against the target pest insect C. medinalis. As for S. furcifera, its occurrence dynamics of nymphs, adults (including macro- and brachypterous forms), and whole population had no significant differences between the two fields, but the abundance of the nymphs and brachypterous adults at the peak stage of S. furcifera occurrence was obviously higher in transgenic Bt rice field than in the control, while the macropterous abundance was in adverse. The sex ratio of female of the macropterous adults at the late growth stage of rice was generally lower in transgenic Bt rice field than in the control. These results suggested that under the background of large area commercial production of transgenic Bt rice, the occurrence and harm of the non-target pest insect S. furcifera could become more complicated.