Morphological variation associated with dispersal capacity in a tree‐killing bark beetleDendroctonus ponderosaeHopkins

Abstract

AbstractIntrinsic factors influencing the dispersal of insect pests during outbreaks are poorly understood, yet these factors need to be quantified to parameterize dispersal in models that predict population spread. The present study related wing and body morphology of female mountain pine beetles (Dendroctonus ponderosae) to flight distance, as measured by flight mill bioassays.Beetles that flew long distances (> 11 km) had a greater body weight and larger wings than beetles that flew short distances (< 1 km). These heavier female beetles should also be more capable pioneers because other studies have shown that body weight is positively correlated with lipid content.Wing and body morphology of females are significant predictors of flight distance; heavy beetles with large wings generally flew further than smaller beetles, although this relationship is heteroscedastic. Dispersion of flight distance values increases with wing loading (weight/wing area) as a result of a cohort of ‘lazy’ individuals that fly short distances (< 1 km) regardless of flight phenotype.The observed morphology explained less than 20% of the variation in flight capacity, indicating a substantial contribution from other intrinsic factors that remain to be investigated. The present study may have implications for dispersal modelling, providing estimates of flight capacity using morphological measurements.