Determining the instar of mountain pine beetle (Coleoptera: Curculionidae) larvae by the width of their head capsules

Abstract

AbstractCut-points to distinguish larval instars of the mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), from the measurement of head-capsule width were determined using a maximum likelihood approach. The cut-points that distinguish the four instars are suitable to classify individual larvae from field populations collected from lodgepole pine Pinus contorta var. latifolia Engelmann (Pinaceae) or jack pine (P. banksiana Lambert)×lodgepole pine hybrids throughout most of the beetle’s current range in British Columbia and Alberta, Canada. The ability to designate the instar of field-collected larvae will facilitate the calibration of phenology and populations models that assess the climatic suitability of habitats and the potential for MPB to continue expanding its range.