Heritability of Host Acceptance and Gallery Construction Behaviors of the Bark BeetleIps pini(Coleoptera: Scolytidae)

Abstract

We examined genetic variation in host selection behavior of a phloeophagous insect herbivore. Data from paternal families of the bark beetle Ips pini (Say) were used to estimate the heritability of host acceptance and gallery construction behaviors. Males are the host-selecting gender in this genus. Male beetles were assayed over three generations to determine whether they rejected or accepted host media amended with concentrations of alpha-pinene that simulated host tissue, and 10% from each group were selected for breeding lines. In a separate experiment, 10% of individuals constructing the shortest and 10% of individuals constructing the longest galleries in this medium were established in separate breeding lines. The results indicate high additive genetic variation with respect to both traits. On the basis of the results with full-sib breeding lines, we estimated heritability of host acceptance behavior (i.e., entry into simulated hosts) at 0.78 and heritability of gallery construction behavior at 0.64. The divergence between lines in host acceptance and gallery construction behaviors was associated with paternal performance and was symmetrical. This study demonstrates that the use of phytochemical cues to accept potential hosts has a heritable component in bark beetles. I. pini is a useful and convenient model for such studies.