Effects of host plant quality and microsporidia infection on forest tent caterpillar, Malacosoma disstria (Lepidoptera: Lasiocampidae) performance and disease susceptibility

Abstract

The cyclic population dynamics of forest tent caterpillar (FTC) (Malacosoma disstria Hbn.) (Lepidoptera: Lasiocampidae) are driven by a variety of factors including delayed-density dependent mechanisms such as disease. We measured the performance and microsporidia infection load of FTC when reared on four different diets, including trembling aspen foliage (Populus tremuloides Michx.), sugar maple foliage (Acer saccharum Marshall), a standard artificial diet, and an artificial diet fortified with lyophilized trembling aspen foliage to determine if diet interacts with microsporidia infection to alter FTC performance and their susceptibility to infection. There were no interactive effects between diet and microsporidia infection on adult performance of FTC, but diet affected FTC susceptibility to infection. Adult FTC had lower rates of infection when reared on fresh aspen foliage or an aspen-fortified artificial diet, compared to the other diet types. While diet and microsporidia infection do not interact to effect adult FTC performance, they may interact to effect larval performance as susceptibility to microsporidia infection varies by diet. The findings of this study help to increase our understanding of how disease and plant quality effect FTC and ultimately their population dynamics. Additionally, this study provides more information on tri-tropic interactions involving disease.

Department: Biological Sciences

Faculty Mentor: Dr. Leah Flaherty