Impacts Of Transgenic Cry1Ac/1Ab Cotton A26-5 On Pests And Beneficial Arthropods

The rise of plant genetic engineering has opened up a new way for plant breeding to develop the insect and disease resistance and high-yield.In order to enhance the toxicity to target pests and delay the resistance of pests,many insect-resistant genes have been continuously applied on cotton,and the application of gene pyrimading and fusion has played a key role in controlling cotton bollworm.However,from the beginning of the transgenic crop,the environmental safety of genetically modified crops has been paid much attention,so it is crucial to evaluate the environmental safety before the large-scale planting and commercial application of this kind of crop.The impacts on species diversity and community structure stability in ecosystems,the effect to non-target organism and the risk of resistance to target pests et al are the main concerns of the the environmental safety assessment of transgenic crop.In this paper,the impacts on pests and beneficial arthropods of a new transgenic rice event A26-5 with CrylAc/lAb fusion gene were investigated.The related works focused on the impact to the arthropod community,the resistance to non-target pests and the effect to the development of natural enemies.The study of this paper provides a reliable basis for the safety assessment of CrylAc/lAb cotton.1.Impacts on the arthropod community of CrylAc/1Ab cotton A26-5In order to evaluate the environmental safety of CrylAc/1Ab cotton A26-5,the structure and composition of arthropod community and the dynamic changes of main pests and natural enemies in CrylAc/lAb cotton field were investigated,then the main characteristic parameters of arthropod community were analyzed.The results indicated that there was no significant difference in the total population of arthropods in the transgenic cotton and the parental variety J14 field,but there was significant difference in the peak period of some pests,such as the amount of wingless Aphis gossypii has more 43.75%in the begin of June compared with the parental variety cotton field.In the whole growth period of cotton,there was no significant difference in the number of non-target pests per 100 cottons and the development dynamic.For the major natural enemies Erigonidium graminicolum,Orius sauteri and Propylaea japonica,there was no significant difference among in the dynamic and trend in the whole cotton growth period.There was no significant difference in the diversity,abundance and dominance parameters of arthropod community between transgenic CrylAc/1Ab cotton and parental variety.2.Effects on the target pest,Helicoverpa armigera,and the non-target pests,Spodoptera exigua and Spodoptera litura of Cry1Ac/1Ab cotton A26-5In this study,the resistance to the target pest,Helicoverpa armigera,and the effects on the growth and development of non-target pests,Spodoptera exigua and Spodoptera litura,were assessed.Compared with its parental conventional cotton,A26-5 has a high resistance to H.armigera by the standard leaf feeding bioassay,the corrected mortality of the transgenic Cry1Ac/1Ab cotton was 91.33%.S.exigua and S.litura were continuously fed with cotton leaves,and the growth and development parameters of the two pests were determined,including the survival rate of different instar larva,the nutrition index and the activity of midgut enzyme of third instar larva.The corrected mortality to S.exigua and S.litura was 15.33%and 13.33%,respectively.There is no effect on the development of S.exigua and S.litura larvae fed with transgenic cotton leaves.The activities of acid phosphatase,peroxidase,alkaline phosphatase and reducing glutathione had some change in the larva of S.exigua and S.litura fed on the transgenic cotton leaves.The peroxidase activity of S.exigua fed on the transgenic cotton leaves was 0.0231 U/mg prot,which was significantly lower than 0.0486 U/mg prot.The acid phosphatase activity of S.litura fed on the transgenic cotton leaves was 0.1455 U/mg prot otherwise the acid phosphatase activity was 0.1014 U/mg prot when the larvae were fed on the parental cotton.3.Effect on the development and predation function of Harmonia axyridis of Cry1Ac/1Ab cotton A26-5Based on the tritrophic context of cotton-H.armigera-Harmonia axyridis,the effect on the development and predation function of Harmonia axyridis of A26-5 was investigated.The development duration of H.axyridis were prolonged by 0.77 days from the first instar larva to pupae.There is little decreas on the averge weight of different instar larvae except the weight of the 1st instar larvae which had 0.0773 mg increase.The predatory functional response of H.xyridis in each instar larva was consistent with Holling ? model pattern.The results show that the transgenic Cry1Ac/1Ab cotton had no significant effect on the growth and development of Harmonia axyridis,and there was no significant difference in predation function.