Thermoregulatory Capability and Temperature Effects on Foraging Success in Two Species of Crab Spider, Misumenoides formosipes and Misumenops asperatus

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9311203 Casey Temperature affects organisms at many levels and influences such fundamental processes as metabolic rate, growth rate, and movement capability. Although a great deal of research has been devoted to determining how temperature affects various processes within a single organism, little work has been done to investigate the influence of temperature on between-organism interactions. Using spiders as model terrestrial predators, our research will focus on the affect of temperature on predator-prey interactions by asking the following questions: does spider foraging success change as environmental temperature changes over the course of a day, and if so, can spiders extend the period of maximal prey capture by regulating body temperature? We will use two species of crab spider, Misumenops asperatus and Misumenoides formosipes, which mature in late spring and late summer, respectively. These spiders are ambush predators that hunt on flowers and physically over-power prey rather than ensnaring it in silk. Employing a combination of laboratory and field experiments, we will determine (for each species) preferred temperature, the temperature range over which spiders are capable of activity, the effect of temperature on spider foraging success within that temperature range, the timing of greatest prey capture in the field, and the timing of greatest prey visitation to flowers used by the spiders. Using spider species which mature at different times during the season, and thus experience different temperature regimes, will allow us to make a better determination of how temperature may affect spiders directly by limiting the amount of time a spider can remain active. Alternatively, spiders may be tolerant to a broad temperature range, yet may still be indirectly temperature limited by direct temperature limitations on prey activity time. *** v s t $ $ $ ( F / C Dutch (scalable) Symbol " Swiss (scalable) 5 Courier New " h G H W G R:\WW20USER\ABSTRACT.DOT Rochelle D Ray Rochelle D Ray