Parasitism levels inOrgyia leucostigmafeeding on two tree species: implications for the slow-growth- high-mortality hypothesis.

The slow-growth-high-mortality hypothesis proposes that increased development time in arthropods feeding on suboptimal food may result in an increased vulnerability to natural enemies. We measured the development time of the forest caterpillarOrgyia leucostigmaJ.E. Smith (Lepidoptera: Lymantriidae: Orgyiini) on two of its host plants and used a 7-year database on parasitism of this species to test the slow-growth-high-mortality hypothesis. We found that femaleO. leucostigmadeveloped faster when fed on willow (Salix nigraMarsh) than when fed on box elder (Acer negundoL.). However, only one of the parasitoids of the parasitoid community that attack these larvae followed the prediction of the slow-growth-high-mortality hypothesis. Overall parasitism ofO. leucostigmaon willow was greater than in box elder, contradicting the slow-growth-high-mortality hypothesis prediction. This is the first test of the hypothesis to consider parasitism by several species in the parasitoid community attacking a free-feeding herbivore on two distantly related plant species. [ABSTRACT FROM AUTHOR]