title: 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.
authors.affiliation: Laboratory of Ecological Information, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. mhosaka@kais.kyoto-u.ac.jp
authors.forename: Mh
authors.initials: M
authors.lastname: Osakabe
authors.forename: H
authors.initials: H
authors.lastname: Isobe
authors.forename: A
authors.initials: A
authors.lastname: Kasai
authors.forename: R
authors.initials: R
authors.lastname: Masuda
authors.forename: S
authors.initials: S
authors.lastname: Kubota
authors.forename: M
authors.initials: M
authors.lastname: Umeda
mesh_terms: D000818:Animals; D005260:Female; D005426:Flight, Animal / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D011187:Posture; D011235:Predatory Behavior; D013662:Tea / Q000469:parasitology; D040102:Tetranychidae / Q000033:anatomy & histology* / Q000472:pathogenicity / Q000502:physiology*; D014919:Wind
chemical_list: D013662:Tea