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 seas onal association between the pitch canker fungus, Fusarium subglutinan s f. sp. pini, and two potential beetle vectors, Conophthorus radiatae Hopkins and Ernobius punctulatus Fall. In samples of reared and disse cted cones, 21.4 +/- 2.5% of C. radiatae and 30.1 +/- 8.0% of E. punct ulatus 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 Febr uary through April. In sticky traps 12.5 +/- 2.3% and 11.8 +/- 3.6% of E. punctulatus and Pityophthorus spp., respectively, were contaminate d with propagules of F. s. pini. Conophthorus radiatae and E. punctula tus co-occurred in 26% of the cones. The percentage of cones containin g contaminated C. radiatae was greater when E. punctulatus progeny wer e also contaminated than when E. punctulatus was not. When contaminati on status of E. punctulatus was not considered, there was no significa nt difference in C. radiatae contamination between cones with and with out E. punctulatus. Because C. radiatae appears to be a vector of the pitch canker fungus, interspecific transmission of inoculum may increa se the incidence of this disease. The parasitoid, Cephalonomia utahens is Brues (Hymenoptera: Bethylidae), was frequently observed parasitizi ng late-instar larvae of E. punctulatus, but was not found on larvae o f C. radiatae, Emergence of large numbers of C. utahensis represents a nother potential source of inoculum for transmission to prey species.