Aerodynamic advantages of upside down take-off for aerial dispersal in Tetranychus spider mites

Abstract

Aerial dispersal may be important for redistribution of spider mites into new habitats. Evidence for behavioral control of aerial take-off has been well documented for Tetranychus urticae Koch. Before aerial dispersal they exhibit the aerial take-off posture that involves lifting the forelegs upright and raising the forebody. However, whether the aerial take-off posture functions to increase drag has remained unclear. The objectives of this study were to clarify: (i) aerodynamic effects of the aerial take-off posture; and (ii) actual aerial take-off behavior in T. urticae. To evaluate the aerodynamic forces experienced by grounded spider mites in different postures, we constructed three-dimensional models of T. urticae, exhibiting the aerial take-off posture and the normal posture, using computer graphics. We found that the aerial take-off posture was effective in receiving greater rearward forces from wind rather than upward forces. As a result, aerial take-off from a horizontal platform is unlikely. Instead, inverted departure surfaces, e.g., lower leaf surfaces, with inclines are likely to be effective sites for take-off. Laboratory experiments and field observations indicated that the mites preferentially adopted such a position for orientation and take-off. Our findings provided a rationale for the take-off behavior of Tetranychus spider mites.

Behavioural responses to potential dispersal cues in two economically important species of cereal-feeding eriophyid mites

“…Although it has been well documented that departure-specific behaviours affect the likelihood of aerial dispersal of spider mites 19, 32 , there has been no empirical evidence that similar behaviours in eriophyoid mites promote the probability of their becoming airborne or being picked up by vector organisms. Melo et al .…”

Lying down with protective setae as an alternative antipredator defence in a non-webbing spider mite

“…However, its long dorsal setae are seemingly not essential for aerial dispersal because spider mites with short dorsal setae, such as Tetranychus urticae Koch and T. kanzawai , also disperse aerially (Smitley and Kennedy 1985; Osakabe et al 2008). Although adult P. citri females with long dorsal setae appeared to be well defended against predatory mites, juvenile P. citri with shorter setae may have less protection against predators.…”

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

“…Wind dispersion is common among mite species, and can be favoured by behaviours and postures that prepare the mite for take‐off and dispersal . The lifting of body parts in spider mites (tetranychids), eriophyids,and phytoseiids, and the production of structures such as silk threads that allow ballooning or roping in spider mites are behaviours commonly associated with (passive) wind dispersal of mites. Exposure to acaricides can affect these behaviours, which may interfere with take‐off.…”