Lepidopteran pheromones

Pheromone identification is still difficult because the structure of unique compounds present in small amounts in mixtures of similar molecules has to be elucidated. This topic will be discussed in detail by Ando as well as by others, showing nicely the recent progress in analytical techniques. The following chapter by R. Jurenka deals with insect pheromone biosynthesis with special emphasis on lepidopteran pheromones and also covers genetic aspects. The subsequent chapter by C. Keeling et al. describes the hymenopteran semio-chemicals (bees and ants), describing pheromones and allelochemicals. The hymenoptera add a certain flavor to the scene, because now the complexity of social insects with their many interactions comes into play, as well as the multi-level (multi-trophic) signals used by parasitoids. 

Organocatalytic transfer hydrogenation of enals has been discussed as a route for synthesis of some lepidopteran pheromones. 

Krasnoff, S. B. (1996). Evolution of male lepidopteran pheromones a phylogenetic perspective. In Insect Pheromone Research New Directions, eds. R. T. Cardd and... 

Figure 12.5 Examples of straight-chain lepidopteran pheromones (SCLPs).

Lepidopteran Pheromones Exemption from the Requirement of a Tolerance. Code of Federal Regulations 40 Parts 150 to 189. Revised as of 1 July 2009. 

Although E double bonds are uncommon in unsaturated fatty acids of animals, many have been found among the unsaturated components of lepidopteran pheromones. Early investigations of pheromone biosynthetic pathways showed that E isomers are not produced by isomerization of the Z double bonds, but rather are produced directly by the catalytic activity of desaturases possessing... 

Polyene hydrocarbons, epoxides, and related compounds as components of lepidopteran pheromone blends... 

Thus, the majority of known lepidopteran pheromones are comprised of compounds that are between 10 and 23 carbons in length, with one or no polar functional groups. Within these broad limits, there are two major structural classes, each of which arises from different biosynthetic pathways. The first class, designated as Type I pheromones (Ando et al., 2004) consists primarily of alcohols, aldehydes, and acetates with unbranched carbon chains of 10-18 carbons, and with 0-3 double bonds. Unusual structures or functional groups, such as triple bonds, nitro groups, or esters other than acetates, are occasionally... 

The goal of this chapter is to provide an overview of the occurrence of Type II polyene pheromones and their derivatives, and their chemistry, including their biosynthesis and synthesis. The older literature in this subject area was reviewed in Millar (2000), and summarized more recently in Ando et al. (2004). Thus, this chapter will provide a comprehensive summary of all known Type II pheromone structures and their occurrence in Tables 1 1, whereas the text will focus more on work over the past ten years. The interested reader is further directed to three useful online databases, two of which focus on lepidopteran pheromones (www.tuat.ac.jp/ antetsu/review/e-List.pdf Ando, 2003 www-pherolist.slu. se/pherolist.php Witzgall et al., 2004) and the third of which covers insect pheromones in general (www.pherobase.com El-Sayed, 2008). 

Scheme 1. Examples of Type II lepidopteran pheromone structures...

The taxonomic distribution of Type II pheromones has been previously reviewed in some detail (Millar, 2000 Ando et al., 2004), and so I will focus only on the main patterns and trends, along with a discussion of more recent findings. The reader is also cautioned that these patterns and trends are heavily biased by the fact that the identification of lepidopteran pheromones has not been conducted methodically. Rather, species that are of economic importance have been most intensively studied for example, pheromones or sex attractants are known for hundreds of tortricid species, whereas few or no pheromones at all have been identified for members of other families (Ando et al., 2004). 

Second, the decarboxylase enzymes required to produce hydrocarbons apparently are not present in lepidopteran pheromone glands, but these enzymes are present in oenocyte cells where most insect hydrocarbon synthesis takes place (Blomquist et al., 1987). Thus, Lepidoptera that produce Type II pheromones must have a mechanism for transport of hydrocarbon pheromone components from the oenocytes to the pheromone gland, where... 

Hai, T.V., Vang, L.V., Son, P.K., Inomata, S. and Ando, T. (2002). Sex attractants for moths of Vietnam field attraction by synthetic lures baited with known lepidopteran pheromones. J. Chem. Ecol., 28,1473-1481. 

Soulie, J., Ta, C. and Lallemand, J.-Y. (1992). Access to unsaturated chiral epoxides. I. Bisallylic chiral epoxides. Application to the synthesis of lepidopteran pheromones. Tetrahedron, 48,443 452. 

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