Abstract
The effect of releasing of natural enemy mites, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot on a population of two-spotted spider mite, Tetranychus urticae Koch was investigated in greenhouse strawberries in Osaka Prefecture. In the mite-release plot, N. californicus twice in October, and P. persimilis four times from January to March, were released in 2007-2008, and N. californicus once in November, and P. persimilis twice in February and March, were released in 2008-2009. The population density of the spider mite became lower in the mite-release plot than in the conventional chemical control plot in both years, and the number of applications of acaricides was reduced three or four times more in the mite-release plot than in the conventional chemical control plot. These results suggest that releasing natural enemy mites, N. californicus from October to November and P. persimilis from January to March, can effectively control the population density of the spider mite.
