Ecological Safety Evaluation Of Transgenic Cry1c Rice For Daphnia Magna

Cladocera species are common aquatic arthropods that maybe exposed to insecticidal proteins which produced by transgenic Bacillus thuringiensis?Bt?plants by ingestion of pollen or crop residues.As the cladoceran Daphnia magna plays a special role in the aquatic food chain,it is very important to know the ecological risk of Bt crops to D.magna.In the current study,we have evaluated the potential effects of Cry1C pure protein on the development and reproduction of D.Magna,and effects of transgenic cry1c and transgenic cry2a rice on the species diversity of zooplankton community in paddy fields.The results were summarized as follow:?1?A bioassy system was developed for assessing the potential effects of Cry1C protein on D.magna based on our previous work and experience,and then a two-generation reproduction test was executed.Exposed D.magna to different concentrations of purified Cry1C protein in M4 medium for21 days,meanwhile,potassium dichromate?K₂Cr₂O₇?which is toxin to D.magna and blank M4medium were used as the positive and negative control respectively.Our results showed the developmental,reproductive,and biochemical parameters of D.magna in F0 and F1 generation were not significantly affected in Cry1C protein treatment and negative control,but were significantly inhibited in positive control.We thus conclude that Cry1C protein does not substantively impact D.magna.?2?In the current study,we studyed the potential effects that transgenic Bt rice might have on zooplankton community in rice paddy fields.We used transgenic cry1c,cry2a rice?T1C-19,T2A-1?,and their non-transgenic parental rice Minghui63?MH63?,and then evaluated the zooplankton species and community diversity at different growing stages.We found that the numbers of zooplankton fluctuated significantly in rice paddy fields at different growing stages,with the Shannon-Wiener diversity and evenness indexes reaching the highest levels at the jointing stage.During the booting stage,pesticides had to be used to control locust infestation.Subsequently,the numbers of zooplankton,Shannon-Wiener diversity and evenness indexes started to decline.The decline in diversity and evenness indexes continued throughout the rest of the growing stages.However,almost no significant differences in the diversity and quantity of zooplankton species were found between fields planted with transgenic Bt rice and non-transgenic Bt rice at all growing stages.Our results showed it is the use of pesticides not the transgenic Bt rice,had negative effects on the zooplankton community in rice paddy fields.