黄带犀猎蝽对斜纹夜蛾3、4龄幼虫的捕食功能反应

Predatory functional responses of assassin bug Sycanus croceovittatus to the 3rd-and 4th-instar larvae of taro caterpillar Spodoptera litura

为明确黄带犀猎蝽Sycanus croceovittatus对斜纹夜蛾Spodoptera litura的控害潜能,在实验室条件下对黄带犀猎蝽3~5龄若虫和雌雄成虫对斜纹夜蛾3、4龄幼虫的捕食功能反应、搜寻效应和自身密度干扰反应进行研究。结果表明,黄带犀猎蝽对斜纹夜蛾幼虫的捕食功能反应均符合Holling Ⅱ型和Holling Ⅲ型2种模型;在拟合Holling Ⅱ模型中,黄带犀猎蝽3~5龄若虫和雌雄成虫对斜纹夜蛾3龄幼虫的日均最大捕食量分别为2.78、4.17、4.35、12.50和8.33头,控害效能分别为5.53、6.54、8.78、14.75和10.42;对斜纹夜蛾4龄幼虫的日均最大捕食量分别为2.56、2.86、3.85、3.57和4.35头,控害效能分别为2.23、3.94、4.54、11.32和5.70,其中雌成虫的控害效能最大。在拟合Holling Ⅲ模型中,对斜纹夜蛾3龄幼虫的日均最大捕食量分别为2.75、4.10、4.32、10.76和7.41头,最佳寻找密度分别为1.19、2.03、1.73、5.28和3.88头/盒;对斜纹夜蛾4龄幼虫的日均最大捕食量分别为2.38、2.78、3.55、3.58和4.00头,最佳寻找密度分别为1.83、1.50、2.06、0.95和2.10头/盒。搜寻效应与害虫密度呈负相关;种内干扰效应与天敌密度呈正相关。表明黄带犀猎蝽成虫对斜纹夜蛾3、4龄幼虫的捕食能力优于黄带犀猎蝽若虫。

To clarify the predation ability of the assassin bug Sycanus croceovittatus against Spodoptera litura,the 3rd-to 5th-instar nymphs,and female and male adults of Sy.croceovittatus were tested for their predatory functional responses to and searching effects on the 3rd-and 4th-instar larvae of Sp.litura as well as the effect of conspecific density on their predation success under laboratory conditions.The results showed that the functional responses of Sy.croceovittatus at all developmental stages fitted the Holling Ⅱ and Holling Ⅲ disc equations.In the Holling Ⅱ model,the 3rd-to 5th-instar nymphs,and female and male adults of Sy.croceovittatus had a daily maximum consumption of 2.78,4.17,4.35,12.50 and 8.33,and a predatory capacity of 5.53,6.54,8.78,14.75 and 10.42,respectively,against Sp.litura 3rd-instar larvae;a daily maximum consumption of 2.56,2.86,3.85,3.57 and 4.35,and a predatory capacity of 2.23,3.94,4.54,11.32 and 5.70 were observed against Sp.litura 4th-instar larvae,respectively,with the female adult showing the best pest control efficiency.According to the Holling Ⅲ model,the 3rd-to 5th-instar nymphs,and female and male adults of Sy.croceovittatus had a daily maximum consumption of 2.75,4.10,4.32,10.76 and 7.41,and an optimal searching density of 1.19,2.03,1.73,5.28 and 3.88 per box,respectively,against Sp.litura 3rd-instar larvae;there was a daily maximum consumption of 2.38,2.78,3.55,3.58 and 4.00,and an optimal searching density of 1.83,1.50,2.06,0.95 and 2.10 per box,respectively,against Sp.litura 4th-instar larvae.The searching effect was negatively correlated with the pest density.The intraspecific interference effect was positively correlated with the density of predator.The results indicated that the predation ability of Sy.croceovittatus adults was stronger than nymphs.