Testing for trade-offs between flight and reproduction in the mountain pine beetle (Coleoptera: Curculionidae) on two pine (Pinaceae) hosts

Mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), adults fly to disperse before host colonisation. The effect of flight on reproduction was tested by comparing the number and quality of offspring from beetles flown on flight mills to that of unflown control beetles. Beetles reproduced in bolts of their native host, lodgepole pine (Pinus contorta var. latifolia Engelmann (Pinaceae)), or a novel host, jack pine (Pinus banksiana Lambert (Pinaceae)). Bolts infested by control beetles produced more offspring overall than bolts with flown beetles. The effect of pine species on the number of offspring produced per bolt varied by individual tree. Flown adults produced fewer offspring compared to control parents in all bolts in jack pine regardless of the tree, but tree-level variation was visible in lodgepole pine. An interaction between flight treatment and tree host affected beetle body condition. More offspring emerged from jack pine, but higher quality offspring emerged from lodgepole pine. The offspring sex ratio was female-biased regardless of parental flight treatment. This study reveals trade-offs between flight and reproduction in mountain pine beetle as measured at the level of the bolt.