Collection and selection of natural enemies of twos potted spider mites for biological control

Natural enemies of the twospotted spider mite, Tetranychus urticae (Koch) were surveyed (at three locations) in the lower Fraser Valley, British Columbia. Our objective was to identify predators that might be used for the biological control of spider mites in greenhouse tomato crops. Three to four pots of bean plants infested with spider mites were exposed each week at each of three locations from early April through to October, in both 1992 and 1993. Predators were collected from these trap plants, identified and tested as potential of spider mites. Twenty-two species were collected, more than half of them predatory Hemiptera. Two species, Feltiella acarisuga (Vallot) (Diptera: Cecidomyiidae), Stethorus punctum picipes (Casey) (Coleoptem: Coccinellidae) were specialist predators of spider mites. Feltiella acarisuga was the most promising candidate for use in and biological control of spider mites (on tomatoes) based on the frequency with which it occurred on trap plants, its cosmopolitan distribution, and its monophagous feeding habits. Key words: biological control; British Columbia; greenhouse; tomato; Tetranychus urticae ; Feltiella acarisuga ; Therodiplosis persicae ; predators