Do the Stripes on Three-Dimensional Models Overcome the Odor Signals in Tabanids Landing Choice?

Abstract

Information about the important factors in tabanid flies visual orientation to hosts has been largely derived from experimental modifications of visual traps and decoys. In the present study performed in wood pasture (Hästhult), southern Sweden, three-dimensional striped models resembling the shape of Zebra, Bongo, Kudu and four control models of different homogenous colors (black, white, reddish-brown and brown) were baited with acetone and aged cow urine in order to test the behavioral preferences in terms of visual and olfactory stimuli in host-seeking tabanids. Attraction of tabanid flies to these models (3D) was high, possibly due to the greater visibility from several directions and also from a greater distance. Vision is important in activating, orienting tabanid flies to the host, as well as for their decision whether and where to land. This research revealed that the visual cues such as stripes on striped models became increasingly important in directing tabanids landing and searching behavior at close range. Likewise, the tabanids approach to attractants sources was overridden by visual cues (stripes) at greater extent compared with the more attractiveness to homogenous colors on control models. Moreover, the visual stimuli (stripes) played also a supplementary role, modifying the selection of landing area on striped model (land on homogenous color part in Bongo and Kudu) once alighting responses were initiated by odor. Tabanid species, especially Haematopota pluvialis and Tabanus bromius exhibited a preference for landing mostly on reddish-brown control model when given the choice of other colors. However, the complex interaction of attractants and visual cues (stripes, color, shape) in the later stages of resource location, remains relatively little studied in all species of tabanids.