The heritability of size and its effect on fecundity in two bark beetle species, Dendroctonus brevicomis and Ips pini (Coleoptera: Curculionidae)

Phloephagous herbivores in the insect family Curculionidae are both ecologically and economically influential to many coniferous forests in the western United States. There has been considerable research focus on the population dynamics of bark beetles because of widespread host mortality and their importance in natural resource management. Beetle fitness is a key factor in achieving stand-replacing population levels. Beetle size is often used as a proxy for fitness because it is known to have a significant effect on the quality and quantity of breeding opportunities. Our study investigated parental influences on offspring phenotype in a primary bark beetle, Dendroctonus brevicomis and a secondary bark beetle, Ips pini. We tested the narrow-sense heritability of beetle size and its significance in fecundity through a controlled laboratory experiment using live beetles and individual bolts of Pinus ponderosa. We examined the influences of parental beetle size and sex on progeny size, number of progeny, and oviposition gallery length. We discuss results with an emphasis on beetle size’s influence on behavior and evolution.