三种赤眼蜂对不同密度大豆食心虫卵的寄生反应及其自身密度的干扰效应

为评估赤眼蜂对大豆食心虫的生物防治潜能,采用室内接虫法和数学模型拟合法分别研究了黏虫赤眼蜂Trichogramma leucaniae、玉米螟赤眼蜂T.ostriniae和螟黄赤眼蜂T.chilonis对自然寄主大豆食心虫Leguminivora glycinivorella卵的寄生反应及其自身密度对寄主防控效果的影响。结果表明,3种赤眼蜂寄生大豆食心虫卵的数量均表现出随寄主密度的增大而增加的趋势,除寄主密度20粒卵外,3种赤眼蜂在其它寄主密度下的寄生数量均无显著差异。自身密度对3种赤眼蜂寄生作用均存在明显的干扰效应,表现出寻找效应随自身密度增加而降低的趋势,Hassell模型和Beddington模型均能较好地拟合赤眼蜂的寻找效应与其自身密度的关系,黏虫赤眼蜂、玉米螟赤眼蜂和螟黄赤眼蜂的寻找系数Q和攻击率a分别为0.3289、0.3270、0.2906和0.3267、0.3243、0.2853。在自身密度干扰作用下,3种赤眼蜂中,黏虫赤眼蜂对大豆食心虫表现出较好的防控潜能。

Parasitic activity of three indigenous Trichogramma species to different density eggs of Leguminivora glycinivorella and their intraspecific interferences on parasitism

In order to assess biological control potential of Trichogramma species to the soybean pod borer (SPB), Leguminivora glycinivorella, parasitic activity of three indigenous Trichogramma species to SPB eggs at different densities and their intraspecific interferences on parasitism were studied in the laboratory. The results showed that the number of eggs parasitized by three Trichogramma species increased with increasing host density when 5-80 SPB eggs were offered. There was no significant difference in the number of SPB eggs parasitized by three Trichogramma species at all host densities offered with an exception of 20 eggs. A clear intraspecific interference on parasitism for each Trichogramma species was exhibited, i.e., the number of parasitized SPB eggs decreased with their own increasing densities. The relationships between each Trichogramma species density and their searching efficiencies were well simulated by Hassell model and Beddington model. Based on the two models, the values of searching parameter and attacking rate for T. leucaniae, T. ostriniae and T. chilonis were 0.3289, 0.3270, 0.2906, and 0.3267, 0.3243, and 0.2853, respectively. Under the interference of itself density, T. leucaniae exhibited the best biological control potential to L. glycinivorella among three Trichogramma species.