Ipsdienol Ipsenol

Figure 6.13 Examples of the application of normal-phase, radio-HPLC to the analysis of de novo biosynthetic pathways in bark beetles (Scolytidae). Demonstration of sex-specific de novo biosynthesis of ipsenol, ipsdienol, and amitinol through radio-HPLC analysis of pentane extracts of Porapak-trapped volatiles from (A) male and (B) female Ips paraconfusus Lanier feeding for 168 h in Pinus ponderosa and (C) male and (D) female Ips pini (Say) feeding for 168 h in Pinus jeffreyi (Seybold et al., 1995b). Demonstration of sex-specific de novo biosynthesis of frontalin through radio-HPLC analysis of pentane extracts of Porapak-trapped volatiles from (E) male and (F) female...

In some insects, fatty acid elongation followed by decarboxylation produces the hydrocarbon pheromones, and these include examples of lepidopterans (Jurenka), dipterans [71], the German cockroach [72a] (see Fig. 6) and the social insects [73]. More recent work in bark beetles has shown that Ips and Dendroctonus spp. produce their monoterpenoid-derived pheromones ipsenol, ipsdienol and frontalin by modifications of... 

D. 4-Oxygenated 2,6-Dimethyloctanes Ipsenol, Ipsdienol, Tagetones, and Ocimenones... 

A number of new and asymmetric syntheses of (S)-(-)-ipsenol (34) and (S)-(+)-ipsdienol (35), the pheromone of Ips bark beetles, were reported. Scheme 49 summarizes the synthesis of ipsenol by Riedeker and Steiner [75], which enabled them to prepare 56 g of (S)-34. They employed chiral auxiliary B derived from D-glucose. 

Attempts to investigate boll weevil (Anthonomus grandis) pheromone biosynthesis have identified isomerization, dehydration, and oxidation of the pheromone alcohols, and anticipated allylic oxidation of myrcene and limonene, but no evidence for the cyclization of acyclic precursors. The aggregation pheromones of bark beetles have been reviewed. Ips calligraphus responds to ipsdienol only in the presence of the c/5-verbenol (32) large additional concentrations of the enantiomer (l/ ,4i ,5/ )-(32) reduce beetle response. 5-(-)-Ipsenol, the pheromone of Ips grandicollis, increases the response of /. avulsus to its own pheromone ipsdienol. ... 

Seybold S. J., Quilici D. R., Tillman J. A., Vanderwel D., Wood D. L. and Blomquist G. J. (1995) De novo biosynthesis of the aggregation pheromone components ipsenol and ipsdienol by the pine bark beetles Ips paraconfusus Lanier and Ipspini (Say) (Coleoptera Scolytidae). Proc. Natl. Acad. Sci. USA 92, 8393-8397. 

Figure 6.9 Examples of pheromone components of bark beetles (Scolytidae) and ambrosia beetles (Scolytidae and Platypodidae) classified by likely biosynthetic origin (based on Francke and Schulz, 1999). (A) References for identification and/or behavioral activity of isoprenoid pheromone compounds are as follows-. 2-methyl-3-buten-2-ol (Bakke efa/., 1977 Giesen etal., 1984 Klimetzek etal., 1989a Lanne etal., 1989), 3-methyl-3-buten-1-ol (Stoakley etal., 1978 Bowers and Borden, 1990 Bowers etal, 1991 Zhang efa/., 2000), 3-methyl-1-butanol (Renw ick etal, 1977), 3-hydroxy-3-methylbutan-2-one (Francke and Heeman, 1974 Francke etal 1974), ipsenol and ipsdienol...

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...

In other late-stage reactions, studies of the conversion of myrcene and ketone analogues of ipsenol and ipsdienol to the alcohols have been investigated in I. paraconfusus (Fish etal., 1979,1984 Vanderwel, 1991 Ivarsson and Birgersson,... 

Figure 6.15 Hypothetical alternative late stages of enantiospecific de novo biosynthesis of ipsenol and ipsdienol in male Ips paraconfusus and Ips pini. Biosynthesis may proceed from geranyl diphosphate to myrcene as catalyzed by a sex-specific monoterpene synthase. Terpene synthases (including a myrcene synthase) have been characterized from conifers (Bohlmann et al. 1997, 1998). Alternatively, biosynthesis may proceed from geranyl diphosphate to 5-hydroxygeranyl diphosphate (W. Francke, personal communication).

Either or both myrcene and 5-hydroxygeranyl diphosphate are then converted to ipsdienol, or 5-hydroxygeranyl diphosphate is converted to ipsdienone via a ketone (5-keto-geranyl diphosphate) intermediate. As outlined in Vanderwel (1991), ipsdienol can be converted directly or via other ketone intermediates to ipsenol. Note that the ultimate enantiomeric composition of ipsdienol may result from the enantioselective insertion of a hydroxyl group at C5 of geranyl diphosphate or from an enantioselective interconversion of ipsdienol and ipsdienone (modified from Fish etal., 1984 Vanderwel, 1991). For intermediates in this pathway, OPP denotes a diphosphate moiety. Figure adapted from Seybold et al. (2000). 

Some early and obvious questions about bark beetle pheromone components concerned their origins are they synthesized de novo from acetate or derived from plant precursor molecules And are the biochemical reactions performed by insect tissues or symbiotic bacteria Ipsdienol and ipsenol are clearly monoterpenoid alcohols. Since de novo monoterpenoid biosynthesis was unprecedented in the Metazoa before 1995, and monoterpenes are produced by host trees, it seemed logical that monoterpenoid pheromone components were derived from ingested plant precursor molecules (reviewed in Vanderwel and... 

Addition of an allylsilane to acid chlorides has been used to synthesize ipsenol and ipsdienol, principal components of the aggregation pheromone of the bark beetle Ips paraconfusus (Figure Si6.3). It is of note that the allylsilane used in these syntheses is a versatile source of the isoprene unit. 

Scolytidae. The worldwide ranges of bark beetles have made them ideal candidates for research directed toward the isolation and identification of pheromones that can be used for population monitoring and regulation. A decade ago, the aggregative pheromone liberated by males of Ips paraconfusus (=confusus) was identified as a mixture of (-)-2-methyl-6-methylene-7-octen-4-ol (ipsenol) (XVI), (+)-cis-verbenol (XVII), and (+)-2-methyl-6-methylene-2,7-octadien-4-ol (ipsdienol) (XVIII)... 

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