Effectiveness of conservation biological control of indigenous predatory natural enemy, Scolothrips takahashii Priesner against Tetranychus urticae Koch on strawberry during nursery period.

Abstract

To evaluate conservation biological control utilizing indigenous natural enemies Scolothrips takahashii Priesner against Tetranychus urticae Koch on strawberry during the nursery period, we investigated the seasonal occurrence of the spider mite and their natural enemies on strawberry potted plants in agricultural fields to which selective insecticides had been sprayed during 2012-2014. Then we also examined the spider mite control effect of the conservation of S. takahashii by using selective pesticide （treatment） in comparison with the non-selective pesticide control method which excludes the predator （control） in an experimental field. In the agricultural field studies, S. takahashii was the only natural enemy observed on strawberry potted plants while the spider mite density was low in all fields in each year. Meanwhile in the experimental field, the number of spider mites in the S. takahashii conservation treatment was significantly lower than that in the control （repeated measures ANOVA, P＜0.001） by the conservation of S. takahashii. These results suggest that S. takahashii was an effective control agent against the spider mite, and could contribute to the development of IPM for strawberry during the nursery period.