Bt Rice Does Not Stimulate an Outbreak of its Non-target Herbivore

Brown planthopper (Nilaparvata lugens), is one of the major insect pests of rice in temperate and tropical Asia. It feeds mainly on stem, sucking nutrients from the living tissues, which leads to leaf drying and tiller wilting called "hopperburn". In a previous study, it was observed that the symptoms of BPH were most serious in the non-Bt rice field than the Bt rice field. This led Yang Chen of Zhejiang University and other scientists to investigate if Bt rice KMD2 could stimulate an outbreak of BPH over four generations in the laboratory and the field.

Laboratory findings showed that the survival of BPH nymphs fed with Bt and non-Bt rice were similar. The development of BPH nymph was significantly delayed by the Bt rice in the 1st and 2nd generation, but not in the 4th generation. The pest's ability to reproduce on Bt rice was significantly lower in all generations compared with non-Bt rice. In the field, the population density of BPH nymphs was significantly lower in the Bt rice field, but the temporal pattern of population dynamics of BPH adults was similar in Bt and non-Bt rice fields. This could be due to migratory interference of the adults. Further morphological analysis indicated that Cry1Ab protein was absent in the guts of BPH adults. Hence, Bt rice "KMD2" could not cause an outbreak of BPH.

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This article is part of the Crop Biotech Update, a weekly summary of world developments in agri-biotech for developing countries, produced by the Global Knowledge Center on Crop Biotechnology, International Service for the Aquisition of Agri-Biotech Applications SEAsiaCenter (ISAAA)

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