Conditions Eliciting Aerial Dispersal Behavior Banks Grass Mite, Oligonychus pratensis (Acari: Tetranychidae)

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Abstract
Adult female Banks grass mite (BGM), Oligonychus pratensis (Banks), exhibited a behavior that has been associated with aerial dispersal in other small, wingless arthropods. This behavior consisted of a raised posture with a consistent orientation. When exposed to wind and light, those BGM exhibiting the aerial dispersal posture consistently oriented away from light regardless of position of the wind source in relation to the light. Mites did not exhibit the aerial dispersal behavior in absence of either wind or light. Mites held on inert arenas at 25% RH exhibited the aerial dispersal behavior with increasing frequency over a 6-h period, after which the level of response remained at ca. 12%. Increased relative humidity resulted in lengthened time to reach the maximum response; at 95% RH none of the mites exhibited the behavior within a 12-h test period. In contrast, >47% of the twospotted spider mites (TSM), Tetranychus urticae Koch, collected from corn exhibited the aerial dispersal behavior at 25% RH after 6 h, and the response curve for TSM continued to increase to a level of 62%