Influence of host pine species on the adult body mass and emergence date of Monochamus carolinensis, M. notatus, M. scutellatus and M. titillator (Coleoptera: Cerambycidae)

To determine the influence of pine species on the adult body mass and emergence date of Monochamus (Coleoptera: Cerambycidae) species, bolts of red, Scotch and eastern white pines infested with larvae were collected from Sinnissippi, Champaign, and Dixon Springs, Illinois, U.S.A and adults were daily captured. Monochamus carolinensis occurred in the three localities whereas M. titillator only in Dixon Springs, and M. notatus and M. scutellatus only in Sinnissippi. Eastern white pine produced heavier adults than Scotch pine introduced into North America for each Monochamus species except M. titillator. The three pine species produced M. carolinensis adults that were significantly lighter than those of the three other beetle species in 19 of the 34 pairwise comparisons. The magnitude relationship of adult body size among Monochamus species was modified by pine species; M. notatus was heavier than M. scutellatus when produced by Scotch or eastern white pine whereas M. scutellatus produced by eastern white pine was heavier than M. notatus by red pine. There was no difference in the mean body mass between M. carolinensis produced by red and eastern white pines and M. scutellatus by Scotch pine. The date of adult emergence was affected by pine species for M. carolinensis and M. notatus. However, the temporal order of the mean adult emergence date among three Monochamus species was not affected by pine species; Monochamus scutellatus emerged earliest and M. notatus latest. Thus, mixed forests might make the interspecific competition of Monochamus species for oviposition resources severer than pure forests.