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Experiments were conducted to test the hypothesis that green leaf volatiles (GLVs) abundant in herbaceous plants and angiosperm trees, affect the response by the conifer-infesting ambrosia beetle, Gnathotrichus sulcatus (LeConte), to pheromone-baited multiple-funnel traps. A blend of four green leaf alcohols, 1-hexanol, (E)-2-hexen-1-ol, (Z)-2-hexen-1-ol, and (Z)-3-hexen-1-ol, each released at ca. 4 mg/24 h, combined with a blend of two green leaf aldehydes, hexanal and (E)-2-hexenal, each released at ca. 13 mg/24 h, reduced trap catches to levels no different from those to unbaited control traps for both sexes. Release of the green leaf alcohols, alone or in all possible binary and ternary blends revealed additive rather than synergistic disruptive effects. Only (E)-2-hexen-1-ol was active alone. Binary and ternary blends reduced trap catches 60-88%, and 80-93%, respectively. No blend was superior, demonstrating redundancy in the disruptive effect. Released together, the two green leaf aldehydes enhanced trap catches; (E)-2-hexenal alone caused a weak enhancement. A summary of known responses by 11 scolytids to GLVs revealed variations between and within species in bioactive compounds and their effect. Disruptive GLVs offer promise alone or with other compounds as forest product protectants against ambrosia beetles.

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Trials were conducted to study how spring Bacillus thuringiensis Berliner subsp. kurstaki treatments on apple may be timed to maximize the survival of parasitoids of the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), found in the southern interior of British Columbia, Canada. Orchard collections verified that second through fourth instar obliquebanded leafrollers were found in varying proportions from pink through the petal fall stage of apple development when spring B. thuringiensis treatments are applied vs. lepidopteran pests. Laboratory‐reared second through fourth instar obliquebanded leafrollers, unparasitized and parasitized by one of three native parasitoid species, were fed untreated apple leaves or leaves treated with B. thuringiensis. The highest mortality of unparasitized obliquebanded leafrollers occurred when fourth instars were exposed to B. thuringiensis‐treated leaves; B. thuringiensis‐induced mortality in the unparasitized second and third instars was less than 50%. The consumption of B. thuringiensis‐treated leaves by host larvae significantly increased the percentage of dead host larvae in all parasitized and unparasitized treatments. However, because of the low susceptibility of this leafroller species to B. thuringiensis, relatively high numbers (38–43%) of three obliquebanded leafroller parasitoid species were able to survive the consumption of B. thuringiensis by second and third instar host larvae. Fourth instar obliquebanded leafrollers were found at the full bloom and petal fall stage of apple development in the orchard, at which time B. thuringiensis treatments are recommended for optimal leafroller control. The highest parasitoid mortality due to host mortality was recorded in Apophua simplicipes Cresson (Hymenoptera: Ichneumonidae) and Macrocentrus linearis (Nees) (Hymenoptera: Braconidae), when the hosts were treated as fourth instars. Both of these parasitoids emerge from fifth and sixth instar obliquebanded leafrollers. Bacillus thuringiensis did not have as negative an impact on Apanteles polychrosidis Viereck (Hymenoptera: Braconidae), which emerges when the host is in the fourth instar. When leafroller mortality and parasitism were combined, the B. thuringiensis treatment did not significantly increase host elimination above that of parasitism alone, except for larvae parasitized by A. simplicipes that were in the fourth instar. The consumption of B. thuringiensis by unparasitized larvae was shown to slow larval development.

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