Pre-emergence feeding in bark beetles (Coleoptera: Scolytidae)

Abstract

Dissection of digestive tracts showed that five bark beetle species, Ips paraconfusus Lanier, Dendroctonus jeffreyi Hopkins, Tomicus piniperda (L.), Scolytus multistriatus (Marsham), and Phloeosinus sequoiae Hopkins, feed beneath the bark as callow adults before emergence from their brood trees. T. piniperda, S. multistriatus, and P. sequoiae also feed in host shoots before colonizing trees in which reproduction occurs. Callow I. paraconfusus and D. jeffreyi were found to ingest food material once the cuticle became yellow, whereas callow T. piniperda and S. multistriatus did not feed until their cuticles were light brown and black, respectively. Feeding behavior differed between the sexes only in D. jeffreyi, in which yellow males contained less food material than yellow females. Yellow I. paraconfusus removed from beneath the bark of Monterey pine, Pinus radiata D. Don, did not blacken without additional feeding, and some starved, brown adults became black. Callow adults that were allowed to feed survived longer and became darker-colored individuals more frequently than starved beetles. The potential benefits of pre-emergence feeding are discussed.