RESPONSES TO GREEN LEAF VOLATILES IN 2 BIOGEOCLIMATIC ZONES BY STRIPED AMBROSIA BEETLE, TRYPODENDRON LINEATUM

Experiments in the Coastal Western Hemlock (CWH) biogeoclimatic zone o n the British Columbia (BC) coast and the Interior Douglas-fir (IDF) b iogeoclimatic zone in the BC interior revealed pronounced differences in the effect of six-carbon green leaf volatiles on the response by st riped ambrosia beetles, Trypodendron lineatum to multiple funnel traps baited with the aggregation pheromone lineatin. In the IDF zone, four green leaf alcohols [1-hexanol, (E)-2-hexen-1-ol, (Z)-2-hexen-1-ol, a nd (Z)-3-hexen-1-ol], released alone or in a quaternary blend at ca. 4 mg/24 hr/compound, caused a 63-78% reduction in trap catches. Two ald ehydes, hexanal and (E)-2-hexenal, released together at ca. 13.0 mg/24 hr/compound were weakly disruptive in one of two experiments. Convers ely, in the CWH zone, the two aldehydes together caused a slight, but significant, increase in the response over that to lineatin in one of two experiments, and the blend of all four alcohols caused only weak d isruption of response in one of two experiments. None of the alcohols released alone was bioactive. These results may reflect adaptations th at ensure accurate host location in the two ecological zones. In the C WH zone, T. lineatum attacks conifer logs almost exclusively, and surr enders the cut or broken stump habitat to Gnathotrichus spp. In the ID F zone, T. lineatum readily attacks the base of trees killed by bark b eetles or fire and may utilize green leaf alcohols to detect and avoid the vertical silhouettes represented by nonhost angiosperms such as b lack cottonwood and trembling aspen.