Effects of Mycangial Fungi and Host Tree Species on Progeny Survival and Emergence of Dendroctonus ponderosae (Coleoptera: Scolytidae)

Abstract

Dendroctonus jeffreyi Hopkins and its sibling species, D. ponderosae Hopkins, are bark beetles associated with symbiotic fungi disseminated in maxillary mycangia. Although both D. jeffreyi and D. ponderosae are associated with the fungus Ophiostoma clavigerum (Robinson-Jeffrey & Davidson), D. ponderosae is also associated with a 2nd fungus, Ophiostoma montium (Rumbold von Arx). Adult D. jeffreyi and D. ponderosae that carried O. clavigerum (isolated from D. jeffreyi ), O. clavigerum (isolated from D. ponderosae ), O. montium , or were fungus-free, were reared in the laboratory and introduced into bolts of Pinus contorta Douglas ex Louden and Pinus jeffreyi Greville & Balfour, hosts of D. ponderosae and D. jeffreyi , respectively, to test for effects of the fungi on progeny survival and ability to use different host tree species. Dendroctonus ponderosae associated with O. clavigerum (isolated from D. jeffreyi ) and D. ponderosae associated with O. montium produced brood in both P. contorta and P. jeffreyi . The average weight of female progeny was not significantly affected by fungal or tree species. However, the production of progeny adults was significantly higher, and emergence significantly earlier, for D. ponderosae associated with O. clavigerum (isolated from D. jeffreyi ) and developing in P. contorta than for D. ponderosae developing with O. montium in P. contorta . No brood was produced by D. jeffreyi or by fungus-free D. ponderosae . Larval galleries were shortest in the O. clavigerum / P. contorta treatment, whereas the longest larval galleries were produced in the O. montium / P. jeffreyi treatment. Both host tree species and fungus have an effect on the ability of progeny to successfully develop.