Dendroctonus brevicomis

The western pine beetle Dendroctonus brevicomis is perhaps the most destmctive insect enemy of western pine forests. The aggregation pheromone is a mixture of the terpenoid myrcene [123-35-3J (163) from the tree and the frass pheromones exo-hsevicomki [20290-99-7] (164) and frontalin [28401-39-0] (165). The Norway spmce beede Ips tppopraphus converts the tree terpenoid myrcene into the frass pheromone ipsdienol [33628-00-3] (166) and the beedes also produce 2-methyl-3-buten-2-ol [115-18-4] and rir-verbenol [473-67-6] (167), all of which are components of the aggregation pheromone. 

Recently, M. Asami and T. Mukaiyama 124) synthesized ot-benzyloxyaldehydes (109) having a chiral tertiary center at the ot-carbon atom in high enantiomeric excess by successive treatment of the aminal (102) with diisobutylaluminium hydride (DIBAL-H) and Grignard reagents. The asymmetric reaction is applied to the total synthesis of exo-(+)-brevicomin (110), the principal aggregation pheromone in the frass of the female western pine beetle (Dendroctonus brevicomis). 

Hughes P. R. and Renwick J. A. A. (1977a) Hormonal and host factors stimulating pheromone synthesis in female western pine beetles, Dendroctonus brevicomis. Physiol. Entomol. 2, 289-292. 

Figure 6.11 Biosyntheses of isoprenoid pheromone components by bark and ambrosia beetles from host conifer monoterpenes. (A) Conversion by the male California fivespined ips, Ips paraconfusus Lanier (Coleoptera Scolytidae), of myrcene from the xylem and phloem oleoresin of ponderosa pine, Pinus ponderosa Laws., to (4S)-(+)-ipsdienol and (4S)-(-)-ipsenol, components of the aggregation pheromone (Hendry et al., 1980). (B) Conversion by male and female I. paraconfusus of (1 S,5S)-(-)-a-pinene (2,6,6-trimethyl-bicyclo[3.1,1]hept-2-ene) from the xylem and phloem oleoresin of P. ponderosa to (1 S,2S,5S)-(+)-c/s-verbenol (c/s-4,6,6-trimethyl-bicyclo[3.1,1]hept-3-en-2-ol), an aggregation pheromone synergist and of (1 R,5R)-(+)-a-pinene to (1 fl,2S,5fl)-(+)-frans-verbenol (frans-4,6,6-trimethyl-bicyclo[3.1,1]hept-3-en-2-ol), a compound of unknown behavioral activity for /. paraconfusus. Male and female western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera Scolytidae), convert (1 S,5S)-(-)-a-pinene to (1S,2ft,5S)-(-)-frans-verbenol, an aggregation pheromone interruptant and (1R,5R)-(+)-a-pinene to (1 R,2S,5R)-(+)-frans-verbenol, a compound of...

Byers J. A. (1982) Male specific conversion of the host plant compound, myrcene, to the pheromone, (+) ipsdienol, in the bark beetle, Dendroctonus brevicomis. J. Chem. Ecol. 8, 363-371. 

Byers J. A. (1983b) Influence of sex, maturity and host substances on pheromones in the guts of the bark beetles, Ips paraconfusus and Dendroctonus brevicomis. J. Insect Physiol. 29, 5-13. 

Renwick J. A. A. (1967) Identification of two oxygenated terpenes from the bark beetles Dendroctonus frontalis and Dendroctonus brevicomis. Contrib. Boyce Thompson Inst, of Plant Res. 23, 355-360. 

If the reaction depicted in Figure Si3.8 is performed with a slightly modified diene, a dihydropyran is formed which provides the framework for exo-brevicomin, a pheromone of the western pine beetle Dendroctonus brevicomis, and dehydrobrevicomin, a compound which promotes agression in male mice (Figure Si3.9). 

The frass of females of the western pine beetle Dendroctonus brevicomis is enriched with endo- (XIX) and exo-7-ethyl-5-methyl-6,8-dfoxabicyclot3.2.1]octane (XX), which are assigned the trivial epithets endo- and exo-brevicomin (61). Males of 2 brevicomis synthesize 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (frontalin) (XXI) in their hind guts (62), and this compound, in combination with the brevicomins and host-derived myrcene, constitutes a potent attractant for both sexes of J). brevicomis (63). Frontal in, also produced by females of . frontalis (62T7 is reported to function as a powerful aggregative pheromone when combined with host monoterpenes such as a-pinene (64). J). pseudotsugae... 

Some of the aggregation pheromones of scolytid beetles also appear to be synthesized with great chiral specificity. The flight response of both sexes of the western pine beetle Dendroctonus brevicomis to (lR,5S,7R)-(+)-exo-brevicomin (XX), host terpenes, and racemic frontal in (XXI) was much greater than the response when the antipode of brevicomin was substituted (160). Similarly, (lS,5R)-(-)-frontalin was a much more powerful attractant than its antipode when tested in admixture with... 

Plant substances are said to enhance some insect hormones, to the advantage of the insect. Bedard et al. (44) have described how the western pine beetle (Dendroctonus brevicomis) uses its host pine trees (Firms ponderosa and P. coulteri) to enhance the drawing power of its sex attractant, exobrevicomin. When ready to mate, both sexes emit the attractant. Bedard found the attractant s power (in terms of numbers of insects attracted) was doubled when mixed with myrcene, a normal constituent of pine wood. Myrcene alone was not attractive. Myrcene, however, is not restricted to pine we have seen earlier (10) that it is consistently found in spruce needles, and in general it is not characteristic of any single group of plants. Since the western pine beetle feeds only on pine, of what real ecological significance is Bedard s report of the enhancement of its hormone by myrcene Why isn t a more specific constituent of pine wood involved Perhaps one is, but research has not yet revealed it. Apart from Brower s work with the monarchs, we have not examined the rich area of herbivore—predator interactions. 

Frontalin (98, Figure 4.49) is the active component of the aggregation pheromone of the southern pine beetle (Dendroctonus frontalis), the western pine beetle (Dendroctonus brevicomis) and the Douglas-fir beetle (Dendroctonuspseudotsugae). Mori s 1975 synthesis of the enantiomers of frontalin via enantiomer separation (optical resolution) of an intermediate87 enabled their bioassay, and only (lS,5/ )-98 was bioactive as the pheromone component of D. brevicomis.32 A recent study on female D. frontalis revealed its (15, 5/C)-98 to be of about 91% ee.88... 

Brevicomins, first identified by Silverstein [37] have been recognized as aggregation pheromones for the western pine bark beetles, Dendroctonus brevicomis Le Conte. (15, 75)-(— )-exo-Brevicomin (87) is prepared in high optical purity starting from 79 by selectively... 

A second type of analysis is undertaken to ascertain the effect of some extraneous factor on a plant. Examples are the studies made on the effect of various metabolites or inhibitors that might change the monoterpenoid production of a commercial crop such as roses. Effect of seasonal change on the composition of monoterpenoids from Rosmarinus officinalis, particularly in the spring, has been examined.The fact that the bark beetles Dendroctonus brevicomis and D. ponderosae preferentially attack Pinus ponderosa trees that have been injured by photochemical air pollution suggested study of the monoterpenoid composition... 

KELLEY, S.T., MITTON, J.B., PAINE, T.D., Strong differentiation in mitochondrial dna of Dendroctonus brevicomis (Coleoptera Scolytidae) on different subspecies of ponderosa pine, Ann. Entomol Soc. Am, 1999, 92, 193-197. 

Acetylenic ketones are useful intermediates in terpenoid synthesis. Coke and co-workers have described a novel synthesis of acetylenic ketones, inspired by, but different from, the Eschenmoser fragmentation. The procedure is illustrated in Scheme 34 by its application to the synthesis of exo-brevicomin (134) the pheromone from Dendroctonus brevicomis. Hydroboration of the double bond of oct-l-en-4-yne with 9-BBN, followed by the acetylene zipper procedure, and base-induced alkyl transfer to t-butyl bromo-methyl ketone offers an efficient route to acetylenic ketones in greater than 70% yield [(135)->(136)]. °... 

Sex pheromone of Dendroctonus brevicomis sequestered from pine oleoresin together with two bicyclic ketals synthesized by the beetle... 

Byers, J. A. and Wood, D. L. (1981) Interspecific effects of pheromones on the attraction of bark beetles, Dendroctonus brevicomis and Ips paraconfusus in the laboratory. J. Chem. Ecol., 7, 9-17. 

In none of his experiments could Moeck demonstrate that primary attraction is used in host selection by the three principal species in the area Dendroctonus brevicomis (the western pine beetle), D. ponderosae (the mountain pine beetle) and Ips paraconfusus (the California five-spined engraver beetle). What Moeck s results did show, however, was that beetles landed indiscriminantly on healthy and stressed trees at about one beetle a day on each tree. Theoretically only one beetle is needed to initiate mass attack, since as soon as it releases pheromone, landing rates would increase markedly on that tree. In Moeck s study, landing rates on trees that became attacked by D. brevicomis increased to up to 800 beetles a day. 

Bedard, W. D., Tilden, P. E., Lindahl, Jr., K. Q., Wood, D. L. and Rauch, P. A. (1980a) Effects of verbenone and trans-werbenol on the response of Dendroctonus brevicomis to natural and synthetic attractant in the field. /. Chem. EcoL, 6, 997-1013. 

Berryman, A. A. (1970) Evaluation of insect predators of the western pine beetle. In Studies on the Population Dynamics of the Western Pine Beetle, Dendroctonus brevicomis LeConte (Coleoptera Scolytidae) (Stark, R. W. and Dahlsten, D. L., eds). University of California Press, Berkeley. 

Paine, T. D. (1981) Aspects of the Physiological and Ecological Relationships between the Western Pine Beetle, Dendroctonus brevicomis, and associated Fungi. PhD Thesis University of California, Davis. 

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