转Bt基因棉对土壤无脊椎动物群落结构的影响

采用干、湿漏斗分离法,运用群落生态学方法,研究了转Bt基因棉"GK12"和"新棉33B"对棉田0～15 cm土层土壤无脊椎动物群落结构的影响.结果表明,线虫和螨类为棉田土壤无脊椎动物优势类群,其频度分别为54%以上和18%以上,与亲本常规棉"泗棉3号"相比,"GK12"提高了土壤线蚓数量,但降低了某些土壤无脊椎动物类群(如同翅目、目和双翅目)的数量;两种Bt棉田中,"新棉33B"棉田的同翅目昆虫数量显著高于"GK12",蜘蛛目数量显著低于"GK12"棉田,其他土壤无脊椎动物类群的数量则基本上无显著差异."GK12"显著降低了土壤无脊椎动物类群的丰富度、多样性和均匀度;两种Bt棉中,"新棉33B"棉田土壤无脊椎动物类群的丰富度、多样性和均匀度较高.Renyi多样性指数曲线也表明,"GK12"棉田各土层土壤无脊椎动物群落的多样性均显著低于"泗棉3号"棉田;"新棉33B"棉田各土层土壤无脊椎动物群落的多样性高于"GK12",但10～15 cm土层常见类群和优势类群的多样性较低.在各土层中,土壤无脊椎动物数量、多样性指数和均匀度指数动态在不同类型棉田趋势基本相同.7～11月期间,10月是土壤无脊椎动物数量的高峰期,此时在"泗棉3号"棉田土壤无脊椎动物在0～5 cm的表层和10～15 cm的深层土壤均较多,在"GK12"和"新棉33B"棉田则集中于10～15 cm的深层土壤.11月, "泗棉3号"土壤无脊椎动物类群的多样性和均匀度呈下降趋势,"GK12"则呈上升趋势.可见,种植Bt棉"GK12"可改变某些土壤无脊椎动物类群的数量,降低类群的丰富度、多样性和均匀度;两种Bt棉田的土壤无脊椎动物群落结构也有一定的差异,"新棉33B"棉田土壤无脊椎动物群落的多样性高于"GK12".

Effect of transgenic Bt cotton on soil invertebrate community structure

Soil invertebrates were collected by Tullgren and Baermann funnels and analyzed using community ecology method. Then soil invertebrate community structures in the 0～15 cm soil layer in transgenic Bt cotton (cvs. "GK12" and "NuCOTN 33B") fields were compared with those in non-Bt cotton (cv. "SM3") fields. Nematodes and acarids are dominant soil invertebrate groups with frequencies above 54% and over 18% respectively in each cotton cultivar field. Compared with parental non-Bt cv. "SM3"field, "GK12" field has more enchytraelidae and less homopetera, psocoptera and diptera. Cumulative numbers of most soil invertebrate groups do not significantly differ in "GK12" and "NuCOTN33B" fields, except that there are less homoptera and more araneae in "GK12" field. Soil invertebrate group richness, Shannon diversity and Pielou evenness are significantly lower in "GK12" field than in "SM3" field. Those in "NuCOTN 33B" field are also higher than in "GK12" field. Scalable one-parametric Renyi-diversity profiles also indicate significantly lower diversity in "GK12" than in "SM3" field, and generally lower diversity in "GK12" than in "NuCOTN 33B" field, except for dominant and common invertebrate groups in the 10～15 cm soil layer. The dynamics of soil invertebrate abundance, diversity and evenness have a similar fluctuation trend for the three cotton cultivar fields. Abundance of soil invertebrate reaches its peak in October during the period from July to November. At the peak, soil invertebrates are concentrated in the 0～5 cm and 10～15 cm soil layers in "SM3" field, but in the 10～15 cm soil layer in "GK12" and "NuCOTN 33B" fields. While invertebrate diversity and evenness decrease in November in "SM3" field, they increase in "GK12" field. The above findings imply that planting "GK12" changes the abundance, and decreases the richness, diversity and evenness of soil invertebrate groups. Soil invertebrate community structures also differ between the two Bt cotton cultivars, with higher diversity in "NuCOTN 33B" than in "GK12" field.