Moisture and temperature effects on survival and infectivity of first-stage larvae of Parelaphostrongylus odocoilei and P. tenuis (Nematoda: Metastrongyloidea).

The survival of first-stage larvae (L1) of Parelaphostrongylus odocoilei and P. tenuis (Nematoda: Metastrongyloidea) and their infectivity to the snail Triodopsis multilineata were determined experimentally in a variety of temperature and moisture conditions. Survival of larvae of P. odocoilei increased with decreasing temperature. Survival of larvae in water was similar to survival in air at 17 and 45% RH; survival of larvae in air at 75, 85, and 95% RH was considerably lower at corresponding temperatures. The infectivity of larvae of P. odocoilei that survived desiccation was greatly reduced. Repeated freezing or repeated desiccation resulted in reduced survival of P. odocoilei and P. tenuis. Larvae of Parelaphostrongylus odocoilei from mule deer of Jasper National Park, Canada, were better able to resist the effects of freezing, but less able to resist the effects of desiccation, than were larvae of P. tenuis from white-tailed deer of Pennsylvania, USA.