Effect of spiders on inoculated populations of the migrant skipper Parnara guttata guttata Bremer et Grey (Lepidoptera: Hesperiidae) in untilled and tilled paddy fields

抄録

To examine the effects of spider predation on pest populations in untilled paddy fields, we constructed life tables for immature stages of the migrant skipper Parnara guttata guttata Bremer et Grey artificially inoculated into untilled and tilled paddies in 2000 and 2001, and conducted a spider removal experiment in 2001. The life tables showed that the migrant skipper larval mortality rate was significantly higher in untilled than in tilled paddies. Unknown factors mainly contributed to this high mortality rate in untilled paddies. The spider removal experiment suggested that the presence of spiders was related to the high mortality rate of migrant skippers in untilled paddies.