环斑猛猎蝽对猎物的选择捕食作用

研究了环斑猛猎蝽雌成虫对玉米螟和蚜虫混合种群的选择捕食作用。结果表明:当玉米螟2龄幼虫和3龄幼虫共存时,环斑猛猎蝽雌成虫对玉米螟在各猎物密度下均表现正喜好性,而对蚜虫在各猎物密度下均不表现喜好性。对玉米螟的转换效应因总猎物密度的不同而不同,即在低密度(60头·瓶-1)和中密度(90头·瓶-1)时无转换行为,在高密度(120头·瓶-1)时有负转换行为;对蚜虫在低密度(60头·瓶-1)和中密度(90头·瓶-1)时有负转换行为,在高密度(120头·瓶-1)时无转换行为。当2龄、3龄玉米螟幼虫和蚜虫3种猎物共存、总猎物密度为90头·瓶-1时,环斑猛猎蝽雌成虫对玉米螟3龄幼虫表现正喜好性并有正转换行为,对蚜虫则表现负喜好性和负转换行为。

Selective predation of Sphedanolestes impressicollis on preys

A laboratory study was made on the selective predation of female Sphedanolestes impressicollis adults on Ostrinia furnacalis and Chaitophorus populialbae. The results showed that when the second and third instar larvae of O. furnacalis coexisted, the female S. impressicollis adults had positive preference to O. furnacalis but no preference to C. populialbae in all degrees of total prey densities. The female S. impressicollis adults also showed different switching to O. furnacalis in different degrees of total prey densities, i.e., no switching in the density of 60 and 90 individuals per canned food bottle, and negative switching in the density of 120. However, the female adults had negative switching to C. populialbae in the density of 60 and 90, and no switching to C. populialbae in the density of 120. When the second and third instar larvae of O. furnacalis and C. populialbae coexisted, the female S. impressicollis adults had positive preference and positive switching to the third instar of O. furnacalis, but negative preference and negative switching to C. populialbae in the total density of 90.