BLUE-STAIN FUNGI AND THEIR TRANSPORT STRUCTURES ON THE DOUGLAS-FIR BEETLE

Parent and preflight-adult Douglas-fir beetles (Dendroctonus pseudotsu gae Hopk., Coleoptera: Scolytidae) were collected from felled Douglas- fir (Pseudotsuga menziesii (Mirb.) France) trees. Fungi isolated from the beetles included blue-stain fungi, such as Ophiostoma pseudotsugae (Rumbold) von Arx, Leptographium terebrantis Barras and Ferry, and Le ptographium abietinum (Peck) Wingfield; other ascomycetes, such as Gra phium spp. and Leptogmphium spp.; yeasts; and unidentified basidiomyce tes. All fungal cultures derived from parent beetles, preflight adults , beetle eggs, larvae, frass, and bark from galleries had yeasts prese nt. Ophiostoma pseudotsugae was isolated from 67% of the parent female s, 19% of the parent males, and 100% of the preflight adults of both s exes collected from their pupal cells. Rinsing the beetles with 70% et hanol prior to fungus isolations reduced the frequency of all fungi, e xcept yeasts. Parent and preflight adult beetles (of both sexes) were examined with a scanning electron microscope, where spores of O. pseud otsugae were visible in shallow pits on the elytra of both male and fe male beetles. Spores of other fungi were observed in shallow pits on e lytra and in much smaller but deeper pits on the scutellum of both sex es. The results indicate a close association between Douglas-fir beetl es and fungi, accompanied by anatomical differentiation on the beetles that allows the dissemination of blue-stain fungi to new Douglas-fir hosts and substrates.