Evaluation of predation on Panonychus citri (McGregor) (Acari: Tetranychidae) from feeding traces on eggs

Abstract

To evaluate the effect of predation on spider mite populations in the field, we identified the predator species that caused the death of the eggs of Panonychus species using scanning electron micrographs of their feeding traces. The predator species could be distinguished from the shape of the feeding traces, which showed clear differences among the species studied. We evaluated the predation of individual predator species on Panonychus citri eggs from their feeding traces in comparison with their abundance on pear in Tsukuba, eastern Japan. The proportion of feeding traces by Oligota spp. was dominant, although both Oligota spp. and Scolothrips takahashii Priesner showed high population densities. Stethorus japonicus H. Kamiya with a low population density, showed a similar proportion of feeding traces to that of S. takahashii. These differences seemed to be due to differences in predation capacity among the species. Therefore, this study revealed the impact of individual predator species on Panonychus species more directly than simple population dynamics analyses in the field.