转基因抗草甘膦抗虫棉田天敌群落多样性的季节动态变化

为明确转基因抗草甘膦抗虫棉对棉田天敌群落多样性的影响,于2010—2012年在田间隔离条件下,采用节肢动物群落调查方法,对转基因抗草甘膦抗虫棉田、Bt棉田和常规棉田的天敌种类及数量进行系统调查,统计3种棉田天敌的群落特征参数并分析比较其在年份间和年度内的变化。结果表明,转基因抗草甘膦抗虫棉田天敌群落的特征参数与另2种棉田均无显著差异。3种棉田天敌群落多样性指数、均匀性指数和优势集中性指数的时间动态规律在同年份基本一致,且随棉花生育期而呈现阶段性变化,前二者表现为5月底或6月初开始上升,6月中下旬至8月中旬达到并保持同等的较高水平,8月下旬呈下降趋势;而后者则在棉花生长前期和后期处于较高水平,7—8月中间生长期处于较平稳的低水平。转基因抗草甘膦抗虫棉田的优势天敌种类比较稳定,与其它2类棉田相比,天敌群落的优势种基本一致,仅有个别种群的优势度有所差异。表明种植转基因抗草甘膦抗虫棉对棉田天敌群落结构的影响较小,不会扰乱天敌群落的稳定性,其合理种植更有利于优势天敌的生存和繁殖。

Seasonal dynamics of the diversity of natural enemy communities in the transgenic glyphosate-insect resistant cotton

In order to study the effects of transgenic glyphosate-insect resistant cotton on natural enemy community diversity, the species and abundance of natural enemy were investigated by using direct observation method in glyphosate-insect resistant cotton, Bt cotton and non-transgenic cotton fields from 2010 to 2012. The community characteristic parameters of natural enemies in three types of cotton fields were analyzed by using statistical calculation, and compared within the year and among the years. The natural enemy community parameters had no significant differences among the three types of cotton fields. The dynamic regularity of Shannon-Winner diversity index, evenness index, Simpson index of natural enemies were consistent in the same year, but presented periodical change with the growth of cotton:the former two showed a rising trend in late May or early June, with a high level from mid-to-late June to mid-August, but falling in the late August. The dynamic regularity of natural enemy Simpson index showed high levels in both early and later cotton growth stages, and kept at low levels in the metaphase of cotton growth between July and August. Compared to other two types of cotton fields, the natural enemy community dynamics was more stable and less changeable in glyphosate-insect resistant cotton fields in the years, and the dominant species of natural enemies were the same among three types of cotton fields, but the dominance of natural enemy was somewhat different. In conclusion, planting transgenic glyphosate-insect resistant cotton has no significant effects on the natural enemy communities, and did not disrupt the stability of natural enemy communities.