Pesticides and passive dispersal: acaricide- and starvation-induced take-off of the predatory mite Neoseiulus baraki.

Background: An understanding of the causes and consequences of dispersal is vital for managing populations. Environmental contaminants, such as pesticides, provide potential environmental context-dependent stimuli for dispersal of targeted and non-targeted species, which may occur not only for active but also for passive dispersal, although such a possibility is frequently neglected. Here, we assessed the potential of food deprivation and acaricides to interfere with the take-off for passive (wind) dispersal of the predatory mite Neoseiulus baraki.

Results: Wind tunnel bioassays indicated that starvation favoured the take-off for wind dispersal by the mite predator, which also varied with wind velocity, and dispersal increased at higher velocities within the 1-7 (m s ) range tested. For the acaricides tested, particularly the biopesticide azadirachtin but also abamectin and fenpyroximate, the rate of predator take-off for dispersal increased, and further increased with wind velocity up to 7 m/s. Such responses were associated with changes in the predator behavioural preparation for wind-mediated passive dispersal, with a greater incidence of the standing posture that permitted take-off.

Conclusion: The rate of take-off for passive dispersal by N. baraki increased with food deprivation and exposure to the residues of agricultural acaricides. Azadirachtin exposure resulted in a particularly strong response, although abamectin and fenpyroximate also stimulated dispersal. © 2018 Society of Chemical Industry.