Ecological Safety Of Transgenic Cry1Ab/2Aj And Cry1Ac Maize Lines For Propylea Japonica Thunberg And Chrysoperla Sinica Tjedar

Transgenic Bacillus thuringiensis (Bt) crops can effectively control insect pests, led to a significant reduction in insecticide use, protect agricultural ecosystem. However, the potential effects of Bt crops on non-target organisms, especially the effect on beneficial arthropods have drawn much attention.The Ladybird Propylea japonica Thunberg and lacewing Chrysoperla sinica Tjedar are prevalent and common predators in many crop systems. Both of them are predaceous, feeding predominantly on phytophagous insects and on plant pollen during plant anthesis. Especially the lacewing adult mainly feed on pollen. Thus, they can exposed to Cry protein by feeding on Bt crops pollen. Therefore, they have been widely used as indicator species in the assessment of non-target effecs of Bt crops. In the present study, we investigated the potential effects of consumption of Bt maize pollen containing Cry1Ab/2Aj or Cry1Ac protein on P. japonica larvae and C. sinica adult in the laboratory. The results were summarized as follows:(1) A bioassay system was developed for assessing the potential effects of transgenic Bt corn pollen on P. japonica larvae based on our previous work and experience. Pollen from the non-Bt maize cultivar Z58 was fed to P. japonica using the developed diet. The results indicated that the larvae of P. japonica readily consumed maize (Z58) pollen. Pollen consumption increased significantly with the growth and development of P. japonica larvae. The result demonstrate the larvae of P. japonica can consumed a large amount of maize pollen. An experiment was conducted in which P. japonica was fed Bt or non-Bt (control) maize pollen using the feeding system. The results show that the larval developmental time was significantly shorter when P. japonica larvae were fed pollen from Bt maize cultivars rather than control pollen but that survival, pupation rate, eclosion rate, and adult fresh weight were not significantly affected. To clear the fate of Cry protein when Bt corn pollen passed through the gut, the mean Cry1Ab/2Aj contents in pollen grains before ingestion and after ingestion were compared. The results showed that almost 77% Cry protein were eliminated from the ladybird larvae. However, the CrylAb/2Aj and CrylAc protein have no toxicity to the ladybird larvae, the growing of CrylAb/2Aj-or CrylAc-containing transgenic maize will not pose a risk on larvae of P. japonica.(2) A bioassay system was developed for assessing the toxicity of transgenic Bt maize pollen on adult C. Sinica. The potential effect of Cry1Ab/2Aj-or Cry1Ac-containing transgenic maize pollen on the fitness of adult C. sinica was assessed using the bioassay system. Life table parameters of C. sinica adult did not differ when the adult were fed with Bt or non-Bt maize pollen together with a 2-M sucrose solution for 25 days. The stability of the Cry protein in the pollen were confirmed by ELISA. The adults of C. sinica in our bioassays were likely exposed to higher Cry protein concentrations by ingestion of Bt maize pollen. These results demonstrate that the Cryl Ab/2Aj and CrylAc protein have no toxicity to the adult of C. Sinica. Overall, the data indicate the growing of CrylAb/2Aj-or CrylAc-containing transgenic maize should pose a negligible risk to adult of C. sinica.