A Meta-analysis Of The Effects Of Bt Rice On Rice Planthoppers And Its Effects On The Interspecific Interaction Between Two Rice Planthoppers

The genetically modified crops expressing cry genes derived from Bacillus thuringiensis(Bt)have been grown commercially since 1996,substantial economic and environmental benefits have been taken worldwide.Rice,Oryza sativa L.,is one of the world's most important food crops,although a series of insect-resistance transgenic rice lines had been generated,they were still not allowed to be planted commercially up to now.It is necessary to make some sufficient risk assessments for Bt rice before they were planted in a large scale.In present study,we conducted a meta-analysis of the accessible literature on the influence of Bt rice on planthoppers.Meanwhile,the effects of transgenic cry2A rice on the interspecific interaction between brown planthopper(BPH),Nilaparvata lugens,and white-backed planthopper(WBPH),Sogatella furcifera,were assessed to get a more reliable assessment in field where many species coexisted.The results were described as follows:1.Meta-analysis of Bt rice on planthoppersThe meta-analysis showed that rice planthoopers,especially BPH,laid few eggs on Bt rice when compared to non-Bt rice.While the field abundance of planthoppers was not significantly affectd by Bt rice.As for the transgenic cry2A rice(T2A-1),there was no significant difference of survival rate,development time and fecundity for planthoppers in the laboratory between T2A-1 and its non-Bt control(MH63),but a slight lower abundance was detected in field studies.2.Effects of transgenic cry1A rice on the interspecific interaction between BPH and WBPHIn laboratory studies,we assessed the effects by the parameters of development,growth and fecundity for BPH and WBPH.Two-way anova analysis showed that the interspecific interaction between BPH and WBPH on T2A-1 did not significantly affected the parameters of the two planthoppers,except their nymphal development time and BPH's adult longevity.Compared to non-Bt control(MH63),WBPH solely on T2A-1 moved to middle and bottom part of rice plant,while the vertical distribution of BPH between MH63 and T2A-1 was similar.However,as the time for coexistence of two planthoppers goes on,BPH on T2A-1 began to move to middle and upside of rice plant,while WBPH kept almost consistent between the two rice lines.We also studied on the spawning location of the two planthoppers on different rice lines.The egg mass number and egg number of BPH and WBPH in different location were similar between T2A-1 and MH63.They were also not affected when combined rice lines and planthoppers interaction in two-way anova analysis.The results of field investigation varied in different year.In 2014,the abundance of BPH in T2A-1 paddy was significant lower than its in MH63,and the abundance of BPH was not related to WBPH in the two rice fields.However,there was a larger abundance of BPH in T2A-1 compared to MH63 in 2015.And the correlations between BPH and WBPH both in T2A-1 and MH63 were significant.In total,the correlation between BPH and WBPH in one year was consistent,which indicated that transgenic cry2A rice did not change the relationship between BPH and WBPH.In general,transgnic cry2A rice had no significant impacts on the interaction between BPH and WBPH.