SURVEY OF PREDATORS ASSOCIATED WITH EUROPEAN RED MITE (PANONYCHUS-ULMI, ACARI, TETRANYCHIDAE) IN OHIO APPLE ORCHARDS

A survey was conducted to identify the types and relative abundance of predatory arthropods associated with Panonychus ulmi in 21 Ohio apple orchards. Mite populations were sampled by leaf blushing, and insects and spiders were sampled by limb jarring. A state-wide survey was con ducted in early July and in late August 1992, and five blocks were eva luated periodically from May until August 1992 at one farm in central Ohio. Predatory mites were detected in only 27% of the blocks surveyed in early July, but in 74% of the blocks surveyed in late August. The ratio of predatory mites to motile P. ulmi was greater than or equal t o 10.1 in 20% of blocks in July and in 26% of blocks in August. In com mercial orchards, the predominant species was Neoseiulus (Amblyseius) fallacis (Acari: Phytoseiidae), but Agistemus fleschneri (Acari: STigm aeidae) and Zetzellia mall (Acari: Stigmaeidae) were found in several blocks. In orchards monitored throughout the season, N. fallacis was r arely detected until July, and reached the highest density in August w hen P. ulmi was at a seasonal peak. Important predators of P. ulmi tha t were detected in limb-jarring samples were Stethorus punctum punctum (Coleoptera: Coccinellidae), green lacewings (Neuroptera: Chrysopidae ), the black hunter thrips (Leptothrips mall; Thysanoptera: Phlaeothri pidae), and the insidious flower bug (Orius insidiosus; Heteroptera: A nthocoridae). No regional differences were observed in types of predat ory mites or insects; the same types were found in all parts of Ohio.