Host plant effects on the genetic variation and correlations in the individual performance of the gypsy moth

Abstract

1. Quantitative genetic analysis of variation in host-use ability was performed in an extremely polyphagous species – the Gypsy Moth. Various life-history traits were investigated by applying a split-family two-environment experimental design, where 30 full-sibling families were reared on oak and Locust Tree leaves. 2. Feeding on Locust Tree leaves decreased preadult viability, prolonged development time, decreased pupal mass both in males and females, and decreased reproductive effort in females. 3. The majority of broad-sense heritabilities did not change across host plants. 4. Significant expression of genetic variation in diet breadth was observed for development time and pupal mass both in males and females, but not for female reproductive effort traits. The heritabilities of plasticities were, on average, lower than heritabilities of the traits themselves. 5. The majority of genetic correlations between the host plants were significantly positive. The only trade-off was found between reciprocal value of reproductive index and the average mass of a fertilized egg within oak. This means that selection for the decrease in relative reproductive investment (under starvation during gradation) will be followed by laying larger eggs. Given that the Gypsy Moth has a cyclic population dynamics, this negative genetic correlation could have a role in maintaining genetic variability in this species.