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AbstractThe mountain pine beetle Dendroctonus ponderosaeHopkins (Coleoptera: Curculionidae) kills its hosts by attacking en masseand overwhelming tree defences. Young adult beetles completing development under the bark may have the opportunity to mate with siblings or with brood from adjacent galleries prior to emerging from the natal host tree. We investigated the incidence of preemergence mating among female beetles at two locations in the recently expanded range of the insect in northern Alberta, Canada. Female beetles emerging from under the bark late in the emergence period were more likely to be mated upon emergence than beetles that emerged earlier. Delaying emergence of brood adults once they were at the teneral adult stage had little effect on the incidence of preemergence mating. The frequency of preemergence mating varied from 3–12% among female beetles. This is higher than the 1–2% reported in other studies within the historic range of the mountain pine beetle. Reasons for these differences are discussed.

AbstractPseudips mexicanus(Hopkins) is a secondary bark beetle native to western North and Central America that attacks most species of pine (PinusL. (Pinaceae)) within its range. A pair of life-history studies examined P. mexicanusin other host species, but until now, no work has been conducted on lodgepole pine (Pinus contortaDouglas exLouden var. latifoliaEngelm. exS. Watson). Pseudips mexicanusin lodgepole pine was found to be polygynous. Galleries were shorter, offspring smaller, and the eggs laid per niche and the potential progeny fewer than in populations from California and Guatemala. Development from the time of female attack to emergence of adult offspring took less than 50 days at 26.5 ?C, and the accumulated heat required to complete the life cycle was determined to be 889.2 degree days above 8.5 ?C, indicating that in the northern portion of its range P. mexicanusis univoltine. Determination of these life-history traits will facilitate study of interactions between P. mexicanusand other bark beetle associates in lodgepole pine.