2种瓢虫捕食烟粉虱行为的时间分配策略

【背景】沙巴拟刀角瓢虫和越南斧瓢虫是自东南亚地区引进的粉虱类害虫的优势捕食性天敌,然而其控制烟粉虱的有效性尚未明确。【方法】在室内研究了2种瓢虫幼虫捕食烟粉虱若虫时取食、爬行与休息等行为的时间分配,以及2种瓢虫幼虫和成虫在既定时间内对烟粉虱的取食时间和取食量。【结果】随着瓢虫幼虫龄期的增大,其取食烟粉虱低龄和高龄若虫的时间和休息时间均逐渐减少,而爬行寻找猎物的时间逐渐增多。沙巴拟刀角瓢虫幼虫取食烟粉虱各虫态的时间显著长于越南斧瓢虫幼虫,取食量也显著大于后者;而沙巴拟刀角瓢虫成虫取食烟粉虱的时间长于越南斧瓢虫成虫,但取食量明显低于后者。【结论与意义】2种瓢虫对烟粉虱都有较好的捕食作用,但其时间分配策略有所不同。因此,应根据田间烟粉虱的发生时期,选择合适的瓢虫进行释放。

Time allocation in two ladybird beetles Serangiella sababensis and Axinoscymnus apioides preying on Bemisia tabaci nymphs under laboratory conditions

Background] Serangiella sababensis Sasaji and Axinoscymnus apioides Kuznetsov and Ren are two dominant predatory la- dybird beetles of whitefly pests, which were introduced from Southeast Asian years ago. Their effectiveness against the target pest, however, is not known in detail. Method] The time allocation and predation level when hunting for younger and older instar Bemisia tabaci nymphs were investigated in the laboratory. Result] With the increasing larval instars, the time spent on prey handling and rest decreased while that on searching increased in both predators. The prey handling times of S. sababensis larvae were significantly longer than that of A. apioides, and the level of predation was also higher than in A. apioides, regardless of B. tabaci instar. When comparing adults, the prey handling time by S. sababensis was higher than that in A. apioides, whereas the level of predation on B. tabaci was significantly lower than that of A. apioides. Conclusion and significance ] The both predatory ladybirds have large poten- tial in whitefly control, but their time allocation are different. Therefore, different species of ladybird beetles should be released in the field according to the occurrence period of whitefly.