Facultative intraguild predation by larval Cerambycidae (Coleoptera) on bark beetle larvae (Coleoptera : Scolytidae)

Larvae of the Carolina saw)er Monochamus carolinensis (Olivier) (Cerambycid ae) and bark beetle larvae (Scolytidae) often simultaneously feed in phloem of recently killed pine trees. Our investigations reveal that hi. caroline nsis lan ae may act as facultative intraguild predators of bark beetle larv ae. Phloem sandwiches were used in four experiments to examine inter- and i ntraspecific interactions. We discovered that all sizes of M. carolinensis larvae killed bark beetle larvae. Seventy six percent of the killed bark be etle larvae were consumed by M, carolinensis, including 58% that were entir ely ingested. Cannibalism in M. carolinensis occurred in every experimental trial. Based on this evidence, hi. carolinensis, and possibly related cera mbycid species associated with bark beetles, are facultative intraguild pre dators of larvae of other phloem inhabiting species. The consequences of th is behavior may have important implications for bark beetle population dyna mics.