ETHANOL SYNTHESIS IN DOUGLAS-FIR LOGS FELLED IN NOVEMBER, JANUARY, AND MARCH AND ITS RELATIONSHIP TO AMBROSIA BEETLE ATTACK

Phloem and sapwood from Douglas-fir, Pseudotsuga menziesii (Mirb.) Fra nce, logs felled in November, January, and March were sampled within 2 4 h of harvest and resampled on each subsequent felling date. In fresh logs, constitutive ethanol concentrations were similar among dates, b ut concentrations in the phloem were always greater than in the sapwoo d. In March, after 4 months on the ground, ethanol in November-felled logs had increased 4 times in the phloem and 83 times in the sapwood, which resulted in equal tissue concentrations. For January-felled logs , ethanol concentrations remained unchanged in log tops, but decreased in the bottoms and sides between January and March. alpha-Pinene conc entrations did not differ among harvest dates or tissue types, but the y did decrease when tissues respired anaerobically. When ambrosia beet les began attacking logs in March, tissues of November-felled logs con tained the most ethanol. Attack densities of Trypodendron lineatum (Ol iv.) and Gnathotrichus retusus (LeConte), counted in August, were high est in November-felled logs and lowest in March-felled logs and correl ated with tissue ethanol concentrations from logs sampled in March. Th is beetle behavior is consistent with the expected response to a compo und that functions as a beetle arrestant and attack stimulant. Absorpt ion of rain, which could interfere with gas exchange between the atmos phere and log tissues, probably contributed to the establishment of an aerobic conditions in the logs.