Subterranean termite feeding preference for wood containing various sap-stain fungi

Bark beetles and their associated ophiostomatiod fungi are major pests of pine forests in the southeastern USA, and termites are major insect decomposers of dead trees and wood products in the southeastern USA. Recent literature indicates that native subterranean termites (Reticulitermes species) feed preferentially on sapwood containing blue-stain fungi over unstained sapwood in laboratory choice assays. In addition, certain brown-rot decay fungi are known to produce chemicals that mimic the trail following pheromones of native subterranean termites. Southern yellow pine sapwood stakes were inoculated with various ophiostomatoid fungi, then installed at four different locations throughout MS, and visually rated monthly for subterranean termite feeding damage for eight months. Stake inoculation treatments were as follows: 1) Ophiostoma minus (Hedgc.) H. and P. Sydow, 2) O. ips (Rumb.) Nannf., 3) Leptographium terebrantis Barras and Perry, 4) L. procerum (W.B. Kendr.) M.J. Wingf., 5) Gloeophyllum trabeum (Pers.) Murrill, and 6) untreated controls. Covariate analyses were performed using the SAS program PROC GLMMIX for increasing subterranean termite feeding preference of sapwood stakes over time for each treatment. The treatments were reduced to three significantly different regressions. Subterranean termites consistently fed preferentially on stakes inoculated with O. minus over any other treatment or the controls (F = 64.17; df = 1, 22; P < 0.0001). Stakes treated with the two Leptographium spp. and the untreated controls yielded the lowest feeding preference compared to all other treatments throughout the study (F = 38.16; df = 1, 94; P < 0.0001). Although subterranean termite feeding preference did not differ between stakes inoculated with O. ips and G. trabeum, these treatments were preferred over stakes inoculated with either of the two Leptographium spp. or the untreated controls (F = 101.96; df = 1, 62; P < 0.0001). The results indicate that native subterranean termites feed preferentially on sapwood containing the blue-stain fungus O. minus over sapwood containing other ophiostomatoid fungi or the brown-rot decay fungus G. trabeum, which is known to elicit feeding preferences and trail following behaviors from native subterranean termites.