Brevicomin: Principal Sex Attractant in the Frass of the Female Western Pine Beetle

Abstract

The principal component of the sex attractant produced by the female western pine beetle (Dendrotonus brevicomis) is exo-7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1]octane; the trivial name brevicomin is suggested.

A Stereoselective Synthesis of (±)-endo-Brevicomin, a Pheromone Inhibitor Produced byDendroctonusBark Beetles

“…The mixture was stirred for 2 hr at o~ 5°C, washed with sodium carbonate solution, dried over potassium carbonate and concentrated ill vacuo. The residue was distilled to give 1.2 g (70%) of 7, bp 85-87°C (0.9 mmHg); n~4 1.4428; IR lJ max cm- (± )-endo-Brevicomin (7-ethyl-5-methyl-6.8-dioxabicyclo [3.2.1] octane (1) The epoxide (7, 1.1 g) was mixed with 0.1 M-perchloric acid (6 ml) and the mixture was vigorously stirred for 3 hr at room temperature (30-32°C). Then it was extracted with a small amount of ether.…”

“…Oxidation of 6 with m-chloroperbenzoic acid gave an epoxide (7). This was hydrolyzed and cyclized with dilute perchloric acid to give (±)-endo-brevicomin (1). The product was gas chromatographically pure (>99%) and exhibited IR and NMR spectra completely identical with the published charts.")…”

“…as a biologically inactive component of the frass of western pine beetle, Dendroctonlls brevicomis, from which exo-brevicomin (1, Et= exo, instead of endo) was also isolated as the aggregation pheromone. l ) Later Vite and Renwick found that the olfactory response of flying male and female southern pine beetles, D. frontalis, to the female-produced pheromone, frontalin (2), was inhibited under field conditions by endo-brevicomin (1). 3) This suggested its use in pest control as a pheromone inhibitor.…”

Optimal fractionation and bioassay plans for isolation of synergistic chemicals: The subtractive-combination method

“…The exact methodology is unclear, but it can be assumed that all fractions would be tested individually first, then in two-way combinations, then three-way, and so forth in an additive-combination procedure. This method has been used on other important beetle species for isolation of their pheromone components: western pine beetle, Dendroctonus brevicomis (Silverstein et al, 1968), smaller elm bark beetle, Scolytus multistriatus (Pearce et al, 1975), and fiat grain beetle, Cryptolestes pusillus, (Millar et al, 1985). However, because of the large number of combinations possible, relatively few other studies have attempted isolation of components using the additive-combination method due to the work involved.…”

“…This method will be discussed subsequently. Another scheme, developed in the 1960s during the pioneering isolation of bark beetle pheromones, is here called the additive-combination method (Silverstein et al, 1966(Silverstein et al, , 1967(Silverstein et al, , 1968. In principle, the method uses chromatography, for example, gas chromatography (GC), to separate chemicals as they elute sequentially into fractions.…”