Pheromone biosynthesis, insects

Wolf W. A. and Roelofs W. L. (1983) A chain-shortening reaction in orange tortrix moth sex pheromone biosynthesis. Insect Biochem. 13, 375-379. 

Abstract Pheromones are utilized by many insects in a complex chemical communication system. This review will look at the biosynthesis of sex and aggregation pheromones in the model insects, moths, flies, cockroaches, and beetles. The biosynthetic pathways involve altered pathways of normal metabolism of fatty acids and isoprenoids. Endocrine regulation of the biosynthetic pathways will also be reviewed for the model insects. A neuropeptide named pheromone biosynthesis activating neuropeptide regulates sex pheromone biosynthesis in moths. Juvenile hormone regulates pheromone production in the beetles and cockroaches, while 20-hydroxyecdysone regulates pheromone production in the flies. 

The site of pheromone production is varied amongst the insects just as there are variable structures in the different orders. Several reviews are available detailing the ultrastructure of these glands [9-11]. Evidence that pheromone biosynthesis occurs in these cells and tissues requires that the isolated tissue be shown to incorporate labeled precursors into pheromone components. In the more studied model insects this criteria has been met. 

Coleoptera comprise the largest order of insects and accordingly pheromone structures and biochemical pathways are diverse [98, 99]. Beetle pheromone biosynthesis involves fatty acid, amino acid, or isoprenoid types of pathways. In some cases dietary host compounds can be converted to pheromones, but it is becoming apparent that most beetle pheromones are synthesized de novo. 

Moths, beetles, flies, and cockroaches have received the most attention regarding pheromone biosynthesis because their members contain prominent pest species and in addition are typically easy to rear in the laboratory. However several other insects have been investigated regarding pheromone biosynthesis, most notably the bees and butterflies. 

The repertoire of chemicals that can be used for communication is limited by the biosynthetic ability of the insect. Compared to other insect orders, pheromone biosynthesis in Hymenoptera has received little study [191]. However, the biosynthetic origins of chemically diverse hymenopteran semiochemicals likely include aromatic, fatty acid, and terpenoid pathways as well as simple modifications of host-derived precursors. Notable recent studies include the biosynthesis of the fatty acid components (2 )-9-oxodec-2-enoic acid 52 and (2 )-9-hydroxydec-2-enoic acid of the honeybee queen mandibular pheromone from octadecanoic acid [192,193], and the aliphatic alcohol and ester... 

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. 

Using the C-terminal hexapeptide of substance P as a model compound, each one of cycloscan diversity parameters have been shown to affect the conformation and hence the biological activity of the peptide.1417,470,4711 This approach has been successfully applied to various peptides such as somatostatin,14191 the insect neuropeptide pheromone biosynthesis activating neuropeptide (PBAN),1420,4311 BPTI,14351 and on the nuclear localization signal (NLS) of the HIV-1 matrix protein (MA),14291 and HIV-1 Tat/Rev.14301... 

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