Aerial dispersal of European red mites (Acari: Tetranychidae) in commercial apple orchards

Abstract

Aerial dispersal of European red mite, Panonychus ulmi (Koch), in commercial apple orchards was estimated by trapping windborne mites. Studies were conducted at four orchards in eastern New York during 1989 and 1990 and at three orchards in western New York during 1989. In each orchard mites were trapped in three locations; the interior of the orchard, at the border of the orchard and in a field or woodlot beyond the orchard. Large numbers of mites were captured, even when the numbers of mites on apple foliage were well below levels where mite injury to leaves was visible (less than five per leaf). The log numbers of mites trapped were linearly related to the log density of mites on leaves and this relationship was consistent for each year and region the study was conducted. The trap captures among the three locations in and outside an orchard were highly correlated. The implications these findings may have on metapopulation dynamics and resistance to acaricide dynamics are discussed.