QUANTITATIVE AND SEASONAL ASSOCIATION OF THE PITCH CANKER FUNGUS, FUSARIUM SUBGLUTINANS F. SP. PINI WITH CONOPHTHORUS RADIATAE (COLEOPTERA: SCOLYTIDAE) AND ERNOBIUS PUNCTULATUS (COLEOPTERA: ANOBIIDAE) WHICH INFEST PINUS RADIATA

The objective of this study was to determine the quantitative and seasonal association between the pitch canker fungus, Fusarium subglutinans f. sp. pini, and two potential beetle vectors, Conophthorus radiatae Hopkins and Ernobius punctulatus Fall. In samples of reared and dissected cones, 21.4 ± 2.5% of C. radiatae and 30.1 ± 8.0% of E. punctulatus adults carried propagules of F. s. pini. Seasonal variation in mean percentage of contaminated C. radiatae and E. punctulatus emerged from cones ranged from 0 to 67% and was highest for both species February through April. In sticky traps 12.5 ± 2.3% and 11.8 ± 3.6% of E. punctulatus and Pityophthorus spp., respectively, were contaminated with propagules of F. s. pini.Conophthorus radiatae and E. punctulatus co-occurred in 26% of the cones. The percentage of cones containing contaminated C. radiatae was greater when E. punctulatus progeny were also contaminated than when E. punctulatus was not. When contamination status of E. punctulatus was not considered, there was no significant difference in C. radiatae contamination between cones with and without E. punctulatus. Because C. radiatae appears to be a vector of the pitch canker fungus, interspecific transmission of inoculum may increase the incidence of this disease.The parasitoid, Cephalonomia utahensis Brues (Hymenoptera: Bethylidae), was frequently observed parasitizing late-instar larvae of E. punctulatus, but was not found on larvae of C. radiatae. Emergence of large numbers of C. utahensis represents another potential source of inoculum for transmission to prey species.