The Impact Of Non-Bt Genetically Modified Cotton Varieties On The Biodiversity In The Fields

With the continuous decrease of cultivated land area for crop production in China,we have to enhance the land economical utilization through increasing crop resistance and yields.Therefore,it becomes extremely urgent to develop high yield crop varieties with disease-resistance,drought-tolerance,salinity-tolerance,or insect-resistance with biotechnology.However,large scale plantation of genetic modified crops may result in unintended effects including potential adverse effects on the agricultural ecosystem.In order to promote the development and utilization of transgenic cotton with disease-resistance,drought-tolerance,salt-resistance or other types,we have to insure their environmental safety,especially on agricultural biodiversity.In this study,2 year field investigations were couducted during 2014-2015,in order to assess the impact of non-Bt genetically modified cotton varieties,including genetically modified disease-resistanct cotton,salt-tolerant cotton,and drought-resistant cotton,on agricultural biodiversity,with their corresponding non-transgenic1.The impact of non-Bt genetically modified cottons on the agricultural arthropod biodiversityIn 2014-2015,we found that there were no obvious difference on the arthropod diversity between three new genetically modified cotton varieties and their control cotton varieties,and the arthropod community in each type of transgenic cotton and its control cotton was similar.But by comparing the arthropod community similarity index between the two years,we found that the arthropod community similarity index in the three kinds of transgenic cotton and its control of cotton had changed significantly between 2014 and 2015(P < 0.05).The arthropod community similarity in genetically modified disease-resistance cotton and its non-transgenic counterpart was signi?cantly reducted in 2015(49.86%�0.19)compared to 2014(76.53%�0.07).Same results were observed in genetically modified drought-resistant cotton and its non-transgenic counterpart in 2015(32.99%�0.30)and 2014(73.18%�0.06),and in genetically modified salt-tolerant cotton and its non-transgenic counterpart in2015(62.34% �0.11)and 2014(77.65%�0.33).This means that the effect of non-Bt genetically modified cottons on the agricultural arthropod biodiversity may be yearly cumulative,but it still needs further research to comfirm the hypothesis.2.The impact of non-Bt genetically modified cottons on the soil nematode biodiversityIn 2014-2015,the abundances of fungi nematodes was significantly increased,especially Aphelenchus,while the abundances of predatory nematodes reduced significantly in genetically modified disease-resistance cotton compared to its non-transgenic counterpart(P<0.05).the abundances of bacterial-feeding nematodes was significantly increased,especially Rhabditis,in genetically modified drought-resistant cotton in comparison wtih its non-transgenic counterpart(P<0.05),same as abundances of Thorneella in genetically modified drought-resistance cotton compared to its non-transgenic counterpart(P<0.01).Meanwhile,higher values of the Shannon evenness index in genetically modified disease-resistance cotton were observed in 2014,while it did not happened in 2015.Lower values of the NCR and higher values of the fungivores to bacterivores ratio(F/B)in genetically modified disease-resistance cotton were observed in 2014-2015.And the lower values of the richness index in genetically modified drought-resistant cotton were observed in 2014-2015.However,there were no obvious difference between genetically modified salt-tolerant cotton and its non-transgenic counterpart in2014-2015.3.The impact of non-Bt genetically modified cottons on the soil springtail biodiversityIn 2014-2015,we found that there were no obvious differences in the soil springtail biodiversity between three new genetically modified cottons and its control cotton.However,we found that the soil springtail biodiversity(S,H,TD)in genetically modified salt-tolerant cotton and its non-transgenic counterpar had changed significantly between 2014 and 2015(P < 0.05).