蚜虱净对苜蓿田节肢动物群落结构及动态的影响

以物种丰富度(S)、个体数量(N)、香农指数(Shannon’sindex,H′)和均匀度指数(E)作为多样性指标,研究了蚜虱净对苜蓿田节肢动物群落结构和季节动态的影响.结果表明:蚜虱净对天敌亚群落物种数的影响大于害虫亚群落,使总群落和害虫亚群落的优势集中性显著增加,但5月底施药对传粉蜜蜂类亚群落的优势集中性无显著影响.喷药初期,蚜虱净显著降低了蚜虫、蓟马等害虫数量,7d后蚜虫、蓟马等种群数量迅速回升,40d后超过对照;施药初期天敌亚群落的物种数大幅减少,多样性和均匀度指数较低,7d后天敌的物种数逐渐回升,到后期与对照田基本一致,但个体数量一直未恢复至对照水平.

Effects of imidacloprid on arthropod community structure and its dynamics in alfalfa field

With species richness(S),individual number(N),Shannon's index(H')and evenness(E)as the indices of biodiversity,this paper studied the arthropod community structure and its seasonal dynamics in alfalfa field under effects of imidacloprid.The results showed that imidacloprid more affected the species number of natural enemies rather than that of insect pests,resulting in a significant increase of the dominance concentration of both total arthropod community and pest sub-community,but spraying the insecticide by the end of May had little effects on the dominance concentration of pollination bee sub-community.The numbers of dominant pests such as aphid and thrip reduced significantly at the initial stage of spraying imidacloprid,increased rapidly after 7 days,and exceeded the control after 40 days.As for the natural enemy sub-community,its species number decreased greatly and its species diversity and evenness were lower at the initial stage of spraying imidacloprid,its species number increased gradually after 7 days and approached to the level of the control thereafter,while its individual number was lower than the control all the time.