Effects of mite age, mite density, and host quality on aerial dispersal behavior in the twospotted spider mite

Abstract

AbstractMite age, population density, and host leaf quality affect various life history traits in spider mites. We investigated the effects of these factors on the aerial dispersal behavior of adult female twospotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae). The proportion of adult females exhibiting the dispersal behavior dropped significantly with age following adult emergence, particularly in the first 3 days. Sixty to eighty percent of female mites 2‐days old or younger displayed the behavior under test conditions, whereas less than 20% of female mites older than 3‐days‐old showed the behavior. Younger adult females also exhibited shorter latency for the behavior, although this trend was not as clear. Leaf quality experienced during deutonymph development had no effect on the behavior adults subsequently displayed. On the other hand, adult females that fed on poor quality leaves after emergence were twice as likely to display the behavior (90% vs. 45%), and with shorter latency (37 vs. 77 min), than those that fed on high quality leaves. When newly emerged adult females encountered high mite density and dry leaves, the incidence of the behavior increased (69% vs. 47%) and latency decreased (69 vs. 93 min) compared to mites that encountered low density on well watered leaves. Our results suggest that both starvation and desiccation of adult females may enhance their dispersal behavior.