Field studies were carried out to evaluate the effect of two transgenic cotton varieties （SGK321 carrying CryIA ＋ CpTI and DP99B carrying CryIAc） and the conventional variety （shiyuan321-parental line of SGK321） ...Field studies were carried out to evaluate the effect of two transgenic cotton varieties （SGK321 carrying CryIA ＋ CpTI and DP99B carrying CryIAc） and the conventional variety （shiyuan321-parental line of SGK321） on spider mites, Tetranychus spp. from 2002 to 2004. In 2002, this experiment included three treatments： Bt cotton field （SGK321） treated with acaricides against spider mites, untreated non-Bt cotton field （Shiyuan321）, and untreated Bt cotton field （SGK321）. In 2003-2004, there are four types of treatments after a new transgenic Bt cotton variety, DP99B （non-chemical control）, was added into the experiments. The results showed that there were no significant difference in densities of spider mites among Bt without acaricides and non-Bt without acaricides cotton fields, nor was there a significant difference in damage of spider mites to cotton among these treatments （P 〉 0.1）. However, there are significant differences （P 〈 0.05） in densities of spider mites and damage caused by spider mites between cotton fields with and without acaricides. Acaricide significantly reduced the densities of spider mites in Bt cotton （P 〈 0.05）. These results suggest that Bt cotton has no effect on spider mites populations. However, spider mites have the potential for severe damage in Bt cotton fields. Acaricides are essential tools in controlling cotton spider mites in northern China.展开更多
文摘Field studies were carried out to evaluate the effect of two transgenic cotton varieties （SGK321 carrying CryIA ＋ CpTI and DP99B carrying CryIAc） and the conventional variety （shiyuan321-parental line of SGK321） on spider mites, Tetranychus spp. from 2002 to 2004. In 2002, this experiment included three treatments： Bt cotton field （SGK321） treated with acaricides against spider mites, untreated non-Bt cotton field （Shiyuan321）, and untreated Bt cotton field （SGK321）. In 2003-2004, there are four types of treatments after a new transgenic Bt cotton variety, DP99B （non-chemical control）, was added into the experiments. The results showed that there were no significant difference in densities of spider mites among Bt without acaricides and non-Bt without acaricides cotton fields, nor was there a significant difference in damage of spider mites to cotton among these treatments （P 〉 0.1）. However, there are significant differences （P 〈 0.05） in densities of spider mites and damage caused by spider mites between cotton fields with and without acaricides. Acaricide significantly reduced the densities of spider mites in Bt cotton （P 〈 0.05）. These results suggest that Bt cotton has no effect on spider mites populations. However, spider mites have the potential for severe damage in Bt cotton fields. Acaricides are essential tools in controlling cotton spider mites in northern China.
