Factors limiting the utility of Homeopronematus anconai (Acari:Tydeidae) in integrated pest management in San Joaquin Valley vineyards [Biological control, California]

A survey showed that the tydeid mite H. (Pronematus) anconai (Baker) occurs in all grape-growing areas of the San Joaquin Valley of California. High temperatures and the pesticides used in vineyards were examined as factors that might explain why H. anconai populations are low in commercial vineyards during the summer. Cyclic high temperatures and long days were not detrimental to egg hatch, development, or reproduction of H. anconai , but sulfur and three acaricides are toxic and may limit vineyard populations. Most insecticides commonly used in California vineyards were also found to be toxic. Suggestions for selective pesticide use are made in the context of the role of H. anconai as an alternate prey of Metaseiulus (Typhlodromus) occidentalis (Nesbitt), an effective predator of the Pacific spider mite, Tetranychus pacificus McGregor.