Predation of Aphis craccivora (Hemiptera: Aphididae) by Orius sauteri (Hemiptera: Anthocoridae) Under Different...

Aphids are important agricultural pests because of their feeding and, for many species, their ability to transmit plant pathogenic viruses. Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is an important predator in northern China of many aphid species, including Aphis craccivora (Koch) (Hemiptera: Aphididae). We measured the functional response and intraspecific competition of O. sauteri under different densities of A. craccivora at several constant temperatures. Predation of O. sauteri on A. craccivora conformed to Holling's type II functional response at all temperatures tested. The predation capability of O. sauteri showed a significant correlation with temperature. The predation capacity of O. sauteri was highest at 25°C, at which temperature we found the highest instantaneous attack rate (a = 0.8711), the theoretical maximum number of aphids captured (181.36), and the shortest handling time (Th = 0.0055). Predation by O. sauteri increased progressively with temperature from 15 to 25°C, but then decreased at 30°C. Intraspecific competition of O. sauteri increased positively with predator density under all temperatures examined. Our results indicate O. sauteri has significant potential for use as a biocontrol agent, under a wide range of temperatures. The inverse density-dependent predation and intraspecific competition of O. sauteri suggests that to obtain the greatest degree of pest suppression, releases of O. sauteri should begin early in the cropping season and numbers released should take prey density into consideration.