种间竞争对烟粉虱天敌日本刀角瓢虫和丽蚜小蜂捕食功能反应的影响
Influences of interspecific competition between ladybeetle Serangium japonicum and parasitoid Encarsia formosa on predation of tobacco whitefly Bemisia tabaci

为明确烟粉虱Bemisia tabaci的2种天敌——日本刀角瓢虫Serangium japonicum和丽蚜小蜂Encarsia formosa共存时的种间竞争对其捕食/寄生作用的影响，采用小叶蝶法在室内测定了2种天敌单独和共存条件下对Q型烟粉虱3~4龄若虫的捕食/寄生功能反应。结果表明：日本刀角瓢虫和丽蚜小蜂的捕食/寄生功能反应均符合Holling Ⅱ型方程。2种天敌共存时，日本刀角瓢虫成虫对烟粉虱3~4龄若虫的最大捕食量为222.2头，显著高于其单独捕食时的91.7头，平均处理时间为0.005，显著低于其单独捕食时的0.011，瞬间攻击率为0.955，与其单独捕食时的1.055差异不显著；丽蚜小蜂对烟粉虱3~4龄若虫的最大寄生量为24.4头，显著高于其单独寄生时的18.5头，寄生烟粉虱3~4龄若虫时的瞬间攻击率和平均处理时间分别为0.066和0.041，均显著低于其单独寄生时的0.522和0.054；丽蚜小蜂对烟粉虱3~4龄若虫的最大取食量为7.2头，显著高于其单独取食时的4.3头，取食烟粉虱3~4龄若虫时的瞬间攻击率和平均处理时间分别为0.101和0.139，均显著低于其单独取食时的0.986和0.231。表明2种天敌联合释放能够提高其对烟粉虱的控制效果，天敌间可能存在增效作用。
In order to study the effects of interspecific competition between the ladybeetle Serangium japonicum and the parasitoid Encarsia formosa on the predation/parasitization of tobacco whitefly Bemisia tabaci Q biotype 3rd-4th instar nymphs, the predation functional responses of S. japonicum and E. formosa were investigated respectively and simultaneously in the laboratory. The results showed that the predation/parasitization functional responses of S. japonicum and E. formosa could be fitted by Holling Ⅱ model. When the two natural enemies coexisted, the daily maximum predation number of S. japonicum was 222.2, which was significantly higher than that of 91.7 of the ladybird alone; the average handling time was 0.005, which was significantly lower than that of 0.011 of the ladybird alone; the instantaneous attack rate was 0.955, which was not significantly different from the 1.055 of the ladybird alone. The daily maximum parasitization number of E. formosa was 24.4, which was significantly higher than that of 18.5 of the parasitoid alone; the instantaneous attack rate and the average handling time were 0.066 and 0.041, which were significantly lower than those of 0.522 and 0.054 of the parasitoid alone respectively; the daily maximum host-feeding number of E. formosa was 7.2, which was significantly higher than that of 4.3 of the parasitoid alone; the instantaneous attack rate and the average handling time were 0.101 and 0.139, respectively, which were significantly lower than those of 0.986 and 0.231 of the parasitoid alone. The results indicated that the combined release of S. japonicum and E. formosa may give rise to a synergistic effect, and improve control efficiency against B. tabaci.