Visual stimulus characteristics that elicit tracking and striking in the praying mantises Parasphendale affinis, Popa...

We tested three species of praying mantis, Parasphendale affinis, Popa spurca and Sphodromantis lineola, with computer-generated stimuli that differed in size, contrast, configuration and movement pattern to determine the effects of these parameters on visual tracking and striking behavior. Overall, black disks moving erratically against a white background were strong releasers of both behaviors. When stimulus presentation order was randomized by size, P. affinis and P. spurca struck at progressively higher rates as the stimuli enlarged up to 44 deg; S. lineola struck most at intermediate sized (10-20 deg) disks. When disks were size-ordered from small to large, P. affinis and S. lineola struck at the smaller disks at higher rates; however, when the order was reversed, the early appearance of large disks suppressed subsequent responses to the smaller disks. Stimulus order did not differentially affect the responses of P. spurca. All species responded at higher rates to black disks moving against a white background versus the reverse. However, only P. spurca and S. lineola responded at higher rates to relatively darker grey disks, only P. affinis responded to mottled grey disks moving against an identically patterned background, and only P. spurca struck more frequently in response to rectangular stimuli oriented parallel (versus orthogonal) to their direction of movement. In conjunction with data on other species, these results support the hypothesis that praying mantises recognize prey based on assessment of several category-specific, spatiotemporal features, e.g. size, contrast, speed, movement pattern and leading edge length.