The eastern tent caterpillar (ETC), Malacosoma americanum Fabricius, has been implicated as a factor causing foal losses associated with equine Mare Reproductive Loss Syndrome. My goal was to assess age specific mortality rates of ETC in the Bluegrass region of Kentucky, while observing daily behavioral patterns. ETC egg masses (N=40) at three pasture fencerow sites were observed daily beginning one week before hatch and concluding when caterpillars had matured. Randomly chosen tents were sequentially sampled at 3-5 d intervals throughout development. Egg masses contained 130-457 eggs with a mean of 287, and a standard error of 7.6; greater than 81% were viable. Of the 18.5% that were non-viable, parasitization accounted for 14%, others failed to properly develop. Braconid and ichneumonid parasitoids hatched from early and late instar caterpillars. Other commonly observed mortality factors include predation by Salticidae, Formicidae and Pentatomidae among early instar ETC; and nuclear polyhedrosis virus among late instar caterpillars.
Tent characteristics such as distance from the egg mass to the initial tent, and the time between initial tent formation and coalescing of adjacent tents was determined. Caterpillar foraging bouts and development rates were assessed with consideration to temperature and degree day accumulation. Processing of sequentially sampled tents to discern developmental rates and mortality agents continues.
My research will provide data that will enable farm managers to minimize pregnant mare exposure to ETC, enhancing our abilities to effectively manage caterpillar populations, thereby reducing the incidence of foal loss.
Species 1: Lepidoptera Lasiocampidae Malacosoma americanum (eastern tent caterpillar)
Keywords: mare reproductive loss syndrome, life table analysis
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