Impact of Predatory Mite Releases on the Abundance of Pecan Leaf Scorch Mite (Acari: Tetranychidae)

Abstract

Release of the predatory mites, Galendromus occidentalis (Nesbitt) and Phytoseuilis persimilis Athias-Henriot, suppressed or controlled populations of pecan leaf scorch mite (Eotetranychus hicoriae McGregor [Acari:Tetranychidae]) in an 18-yr-old ‘Desirable’ pecan orchard. Predators controlled a low population (4.4 pecan leaf scorch mites and eggs per leaf in untreated trees) of pecan leaf scorch mites in the 2002 season at 28 days after the release date. In 2003, both species of predatory mites were released at 500 and 1000 mites per tree in the center tree of a 25-tree, square plot (0.41 ha). Untreated trees had 63, 240, and 38 pecan leaf scorch mites and eggs per leaf at 6, 10, and 24 d postrelease, respectively. Pecan leaf scorch mites were controlled at this high population density in the release area 24 d after the release. Release of the mites at 500 and 1000 G. occidentalis mites per tree reduced the pecan leaf scorch mite infestation by 67 and 91%, respectively. Release of 500 and 1000 P. persimilis mites per tree reduced the pecan leaf scorch mite infestation by 90 and 98%, respectively. Predatory mite releases appear to provide an effective management tactic for pecan leaf scorch mite for pecan producers in Georgia.