Suppressive effect of phytoseiid mites in intercropped barley on population density of onion thrips on Welsh onion

Abstract

We investigated the ability of phytoseiid mites in intercropped barley to suppress onion thrips (Thrips tabaci Lindeman) on Welsh onion in the laboratory. Ten adult females of T. tabaci were released into a cage containing Welsh onion seedlings planted in a pot and intercropped with barley transplanted from a Welsh onion field. For comparison, insecticide-treated barley and soil from the Welsh onion field were tested. At 20 days after release, the number of T. tabaci was lowest (significantly) in the untreated barley, but there was no change in the treated barley. Phytoseiid mites (mainly Gynaeseius liturivorus (Ehara)) were observed only in untreated barley.