Ecology of root-feeding beetles and their associated fungi on longleaf pine in Georgia

Root-feeding beetles, particularly of the curculionid subfamilies Scolytinae and Molytinae, are known to be effective vectors of Ophiostomatoid fungi. Infestation by these insects and subsequent infection by the Ophiostomatoid fungi may play an important role in accelerating symptom progression in pine declines. To examine the relationship between beetles and fungi in longleaf pine stands, root-feeding curculionids were collected in pitfall traps baited with ethanol and turpentine for 62 wk, and Ophiostomatoid fungi were isolated from their body surfaces. The most abundant root-feeding beetles captured were Hylastes tenuis, H. salebrosus, Pachylobius picivorus, Hylobius pales, and Dendroctonus terebrans. The number of insects captured peaked in spring and fall, although peaks for different insect taxa did not coincide. The most frequently isolated fungi were Grosmannia huntii, Leptographium procerum, L. terebrantis, and L. serpens. Other Ophiostomatoid fungi recovered included Ophiostoma spp. and Pesotum spp. Insect infestation data suggest that Hylastes spp. share an ecological niche, as do Hb. pales and P. picivorus, because the ratios of their fungal symbionts were similar. The fungi associated with D. terebrans suggest that it did not share habitat with the other principle vectors.