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METHODS
In the spring and summer of 1993, we tested the response of five species of bark beetles to methyl chavicol in
California and Idaho. In April and May, we tested western pine beetle, red turpentine beetle, and two species of Ips, L
paraconfusus and I. pini, at the University of California's Blodgett Forest Research Station in the central Sierra Nevada.
Tests were conducted as described previously (Hobson 1992, Hobson et al. 1993). For each beetle species, attractive lures
were placed on lindgren traps. In each test there were four treatments" (1) attractant, (2) attractant and methyl chavicol, (3)
methyl chavicol alone, and (4) control blank.
Beetles were collected daily and treatments were randomized after each collection. All four treatments were replicated
in 4-10 blocks. Methyl chavicol was released from four open 1.5-ml ependorf tubes at a rate of 0.5 ml/day. The
attractant for D. valens was a set with four 1.5-ml ependorf tubes of S(-)[3-pinene. For the western pine beetle, I. pini and I.
paraconfusus commercial lures provided by Phero Tech (Delta, BC) were used. Western pine beetle lures contained exobrevicomin,
frontalin and myrcene. I. pini lures contained ipsdienol (3%+/97%-). I. paraconfusus lures were ipsenol (50%+/
50%-), ipsdienol (97%+/3%-), and cis-verbenol.
In July and August of 1993, we tested mountain pine beetle and I. pini in the Sawtooth National Recreation Area in
south central Idaho. The experimental design was as above. Attractant lures for mountain pine beetle (trans-verbenol, exobrevicomin
and myrcene) were obtained from Phero Tech. Attractant lures for I. pini were as above.
RESULTS
Methyl chavicol significantly reduced attraction of western pine beetle and mountain pine beetle to their respective
aggregation pheromones (Table 1). Attraction of D. valens to [3-pinene was not significantly interrupted by methyl chavicol.
L pini catch was reduced by 29%, but this was not significant. I. paraconfusus flew too late in California for us to collect
adequate data for statistical analysis; however, in five of six blocks where I. paraconfusus was collected, traps baited with
methyl chavicol and the bait had fewer beetles than traps with bait alone.
Table 1.--Bark beetle response to Methyl chavicol
Pheromone Pheromone & Percent
baifi SD methyl chavicol _ SD reduction
Western pine beetle 53.5 a2 69.7 21.6b 28.0 60
Mountain pine beetle 27.4c 47.5 7.9d 12.4 71
Red turpenti ne beetle 10.6 6.28 9.06 6.8 14
Ips pini 20.5 19.7 14.5 12.2 29
_Meancatch.
2Numbersin a row followed by different letters are significantly different o_= 0.05 ANOVA followed by Wilcoxon test.
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