Predatory ability of two species of spiders [Araneae], Trachelas japonica and Oxyopes sertatus on the tea green leafhopper, Empoasca onukii
1999
Kosugi, Y. (Shizuoka-ken. Tea Experiment Station, Kikugawa (Japan))
The predatory ability of two species of spiders, Trachelas japonica and Oxyopes sertatus on the Tea green leafhopper, Empoasca onukii was evaluated in the laboratory. 1. In the tasting condition, T. japonica captured more leafhoppers than in the well-fed condition. But the number of captured leafhoppers and the amount of food ingested by the spider were almost equal under the different tasting periods. In O. sertatus, the number of captured leafhoppers and the amount of food ingested by the spider increased in proportion to the length of the tasting period, to a maximum of 6 days. 2. In the same tasting period, O. sertatus captured more leafhoppers than T. japonica. 3. In both T. japonica and O. sertatus, the number of leafhoppers captured increased in proportion to the density of leafhoppers in the cage, until a maximum was reached. 4. In both T. japonica and O. sertatus, the number of leafhoppers captured on the tea plant was around one-tenth the number captured it in the cage. It seems that the influence of opportunity on predatory ability is greater than the fasting period
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