Prevalence of Strongyloides robustus in tree squirrels (Sciuridae) in South-Central Pennsylvania and potential impacts for the endangered northern flying squirrel, Glaucomys sabrinus.

Abstract

Strongyloides robustus is a unique parasite that has conservation impacts for sciurid populations in North America. In some squirrel species, like the southern flying squirrel (Glaucomys volans), the eastern gray squirrel (Sciurus carolinensis) and the red squirrel (Tamiasciurus hudsonicus), pathology is relatively benign. However in the northern flying squirrel (Glaucomys sabrinus), S. robustus infestation can result in high mortality. The objective of this project was to survey the prevalence of S. robustus within the squirrel species currently found in south- central Pennsylvania so that the risk to the northern flying squirrel could be evaluated in light of the parasite mediated competition hypothesis. Fecal samples from eastern gray, red, and southern flying squirrels were obtained through nest boxes, road kills and hunting. A modified Sheather’s sugar floatation was prepared with a specific gravity of 1.27 to evaluate parasite prevalence. Ten of the 40 nest boxes examined had flying squirrel evidence in the form of feces deposited within the nest. Strongyloides robustus was present in 30% of the 10 samples. The prevalence of S. robustus was 77.3% in the 22 road-killed and hunter-killed eastern gray squirrels. The single hunter-killed red squirrel examined in this study demonstrated S. robustus infestation. This study evaluated infection in possible reservoirs that are understudied in Pennsylvania and supported the idea of parasite mediated competition.