Testing the adaptive plasticity of gypsy moth digestive enzymes in response to tannic acid using phenotypic selection analysis

Abstract

The adaptive significance of plasticity of digestive enzyme responses to allelochemical stress was tested on 32 full-sib gypsy moth families from an oak forest (the Quercus population) and 26 families from a locust-tree forest (the Robinia population), reared on control or tannic acid-supplemented diets. By using the relative growth rate as a fitness measure in phenotypic selection analyses, we revealed that higher specific activity of leucine aminopeptidase in Quercus larvae and lower specific activity of trypsin in Robinia larvae were adaptive in the control environment. In Quercus larvae, elevated specific activities of leucine aminopeptidase and lipase were adaptive in the stressful environment. There were no plasticity costs for the enzyme activities in either experimental group. The obtained results suggest that adaptive plasticity of digestive enzyme activity in gypsy moth larvae contributes to optimal growth rate under various environmental conditions.