Aerial dispersal of Raoiella indica Hirst (Acari: Tenuipalpidae): Influence of biotic and abiotic factors, dispersal potential and colonization rate

Abstract

Aerial dispersal can occur in response to both internal state of individuals and environmental conditions and probably contributed to the expansion of red palm mite Raoiella indica throughout the American continent within a decade. We report here experiments using wind tunnel in the laboratory and adhesive traps in the field to identify general aspects and precursors of R. indica’s aerial dispersal. Wind tunnel analyses indicated that dispersal rates increased with increasing wind speed up to 15 m/s and decreased with increasing population density. Although adult male and immature were dispersed by wind, adult females showed the highest frequency of dispersal. Mating status and 24 h food deprivation had no significant influence on the aerial dispersal of this species. In the field, the dispersal was also mainly observed among adult females. The number of captured mites increased progressively with height, up to the highest assessed state (4.8 m), and up to a distance of 48 m from infested coconut palms, at which colonization rates were equivalent to 1.4 × 105 mites/plant, although it was lower at the distance of 64 m (farthest assessed distance) from the source. The results identify conditions that elicit R. indica’s dispersal, and characterize its dispersal potential and colonization rates, allowing an ecological understanding of this invasive mite species.