How do primary nutrients affect the performance and preference of forest tent caterpillars on trembling aspen?

Abstract

AbstractVariation in leaf quality includes differences in both primary nutrients and secondary metabolites. Both of these factors can influence the feeding preference and resulting performance of herbivores in ways that are difficult to disentangle when comparing foliage from different sources. Our study was designed to assess the effects of the ratio of the primary nutrients in host-tree foliage, protein and sugar, on the performance and feeding behaviour of the forest tent caterpillar (Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae)). Fourth-stadium larvae were fed trembling aspen leaves (Populus tremuloides Michx (Salicaceae)) supplemented with casein, sucrose, or buffer only (control). No differences in taste responses to the three leaf types were detected. In a cafeteria situation, feeding behaviour over the short term was largely determined by the use of pheromone trails and hence depended on which leaf was contacted first. Over the longer term, caterpillars fed most on the control leaf and the sugar-supplemented leaf and discriminated against the protein-supplemented leaf. Sugar supplementation increased survivorship relative to the control treatment but slowed development and did not affect growth; protein supplementation decreased growth. These findings are consistent with past research comparing forest tent caterpillar performance and feeding preference on different host plants.