Movement behavior of red flour beetle: response to habitat cues and patch boundaries.

ABSTRACT

Movement behavior determines the success or failure of insects in finding important resources such as food, mates, reproductive sites, and shelter. We examined the response of female red flour beetles (Tribolium castaneum Herbst Coleoptera Tenebrionidae) to habitat cues by quantifying the number of individuals that located a patch (either with or without flour) in response to the distance released from the patch, air movement over the arena, and food-deprivation status. We also investigated how patch characteristics, such as resource amount and presence of cover, influenced time taken to find a flour patch, the frequency of entering or leaving, and residence time within the patch. Although the proportion of beetles successfully locating the patch decreased as a function of release distance, the probability that beetles reached the patch was ultimately unaffected by whether flour was present or not, suggesting that search behavior in red flour beetles may exhibit a simple distance-decay function. Significantly more beetles reached the patch when they had not been food deprived and air was flowing over the arena, which indicates that walking beetles may orient to airflow, exhibiting anemotaxis. Results of the second experiment showed that, on first encounter, fewer beetles entered patches with a greater amount of flour; but once they had entered, they left them less frequently than patches with less resource. Beetles entered covered patches more quickly than uncovered patches irrespective of resource amount, which indicates that shelter is perhaps more important to red flour beetles than resource levels in determining whether to enter patches.