Byers, J.A., Wood, D.L., Craig, J. & Hendry, L.B. 1984. Attractive and inhibitory pheromones produced in the bark beetle, Dendroctonus brevicomis, during host colonization: Regulation of inter- and intraspecific competition. Journal of Chemical Ecology 10:861-877.

Abstract-- Quantities of attractive (exo-brevicomin and frontalin) and inhibitory (trans-verbenol, verbenone and ipsdienol) pheromones were monitored in both sexes of D. brevicomis (Coleoptera: Scolytidae) during their colonization of a ponderosa pine (Pinus ponderosa). Verbenone was found in males in the greatest amounts at the time of landing, and it declined more rapidly than the other pheromones in either sex. The amounts of frontalin and exo-brevicomin in males and females, respectively, increased after initial boring within the host but began to decline after mating. The quantity of trans-verbenol in both sexes (females had significantly more) declined more gradually than exo-brevicomin, frontalin and verbenone. Ipsdienol was found only in males during the initial stages of attack when encountering the resin. Along with a general decline in all pheromonal components, a sufficient change in the ratio of the attractive pheromones to an inhibitory pheromone, trans-verbenol, may play a role in termination of aggregation. trans-Verbenol may also function along with verbenone and ipsdienol in limiting the density of attack and thus intraspecific competition. These inhibitory pheromones also appear to cause several competing species of bark beetle to avoid landing in areas infested with D. brevicomis, even when their own pheromone is present.
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Chemical Ecology