Differential effects of wavelength on prey recognition by praying mantises

Our laboratory investigates the algorithms by which praying mantises (Insecta: Mantodea) identify potential prey objects amid the heterogeneous environments in which they live. We have identified ten stimulus parameters that several species of Mantises use to identify prey objects. However, nothing is known about whether mantids use different wavelengths of light in prey recognition. Currently, our laboratory is using behavioral, anatomical, and immuno-histochemical analyses to investigate (1) the degree to which wavelength affects mantid prey recognition, (2) the possible presence of wavelength specific opsins in the mantis’ compound eye, (3) and whether wavelength-specific neural pathways are coupled to, or independent of other object recognition neural pathways. We are currently conducting these studies on five species: Deroplatys dessicata, Euchomenella macrops, Hierodula membranacea, Parasphendale affinis, and Rhombodera basalis. In the behavioral experiments, the animals were presented with three series of computer generated circular stimuli (disks) moving in an erratic path around visual field center. Each series included a black disk (0.1 lux) and a series of blue, green or red disks that became increasingly brighter (from 0.2 to 13.2 lux) until they appeared white. All stimuli moved against the same grey background (0.9lux). Two appetitive behaviors were scored, visual tracking and predatory striking. E. macrops tracked all disks with Mickelson ratios <0.50 ([stim lux-background lux]/[stim lux+background lux]), but struck preferentially at red disks. In contrast, R. basalis preferentially tracked and struck only at the red disks. Tracking behavior of P. affinis was similar to E. macrops but they struck at disks in all three color series. In a separate experiment, H. membranacea showed a strong preference for red disks in both tracking and striking.