转Bt基因棉田昆虫群落多样性及其影响因素研究

Studies on the components of diversity of the community in transgenic Bt cotton

运用群落生态学的方法 ,研究了转 Bt( Bacillusthuringiensis)基因棉田昆虫群落及害虫和天敌亚群落多样性 ,对多样性及其主要组成成分——物种数、个体数、均匀度、优势集中性进行了通径分析。试验设 3个处理 :转基因棉自然控制(全生育期不施用任何农药 ,简称自控田 )、转基因棉综合防治 (采取综合防治措施 ,简称综防田 )和常规棉自然控制 (常规品种 ,全生育期不施用任何农药 ,简称对照田 )。结果表明 :转基因棉田昆虫群落、害虫和天敌亚群落的多样性指数均低于常规棉 ;决定 3种棉田昆虫群落多样性指数的主要因素均为均匀度和优势集中性 ,即均匀度值越高 ,优势集中性值越低 ,则多样性越高 ;决定害虫亚群落的主要因素各不相同 ,对照田和自控田为优势集中性和均匀度 ,综防田为优势集中性和物种数 ,即优势集中性值越低或物种数越高 ,则多样性越高 ;决定天敌亚群落的主要因素亦不同 ,对照田和自控田为物种数和优势集中性 ,综防田为均匀度和优势集中性。害虫亚群落的多样性对总群落的多样性影响最大。

During 1996～1997,the components of diversity of the community in transgenic Bt cotton were studied in three plots i.e.,integrated pest management(IPM),natural enemies control(NEC)in transgenic Bt cotton and natural enemies control in traditional cotton(Control).Path analysis of composition of species diversity showed that it was dominant concentration and evenness that mainly decided the change of diversity index for pest natural enemy communities.Diversity index( H ')would be reduced with increasing of dominant concentration of decreasing of evenness.The diversity index of pest natural enemy community directly depended on that of pest sub community.The diversity index showed that Control(2.5114)>IPM(2.4846)>NEC(1 8181),IPM(1.9859)>Control(1.9240)>NEC(1.3371),Control(2 0786)>NEC(1 8313)>IPM(1 7808) in the pest natural community,pest sub community,and natural enemy sub community,respectively.