Pheromone cuticular

Legendre, A., Miao, X.-X., Da Lage, J.-L. and Wicker-Thomas, C. (2008). Evolution of a desaturase involved in female pheromonal cuticular hydrocarbon biosynthesis and courtship behavior in Drosophila. Insect Biochem. Mol. Biol., 38, 244-253. 

The site of pheromone production in flies and cockroaches that utilize hydrocarbons is similar to that of the moths. Oenocyte cells produce the hydrocarbon pheromone which is transported by lipophorin in the hemolymph to epidermal cells throughout the body for release from the cuticular surface in general [20,21]. 

Several families of moths utilize hydrocarbons or epoxides of hydrocarbons as their sex pheromone. Oenocyte cells produce hydrocarbons that are transported through the hemolymph by lipophorin [71]. In a study using arctiid moths it was shown that sex pheromone hydrocarbons are transported on the same lipophorin particle as the hydrocarbons destined for the cuticular surface [ 17]. Therefore, specific uptake of the sex pheromone hydrocarbon occurred in pheromone glands [17]. Similar findings have been found with other moths [72-74]. The mechanism behind this specific uptake of one hydrocarbon from a potential pool of other hydrocarbons is unknown. 

One of the sex pheromone components of the housefly, Musca domestica, is Z9-21 H that is found on the cuticular surface of the fly. This compound is formed by the elongation of Z9-18 CoA using malonyl-CoA and NADPH to Z15-24 CoA which is decarboxylated to form Z9-21 Hc (Fig. 3) [78-80]. Other pheromone components include an epoxide and ketone that are produced from Z9-21 Hc by a cytochrome P450 [81,82] and methyl-branched alkanes that are produced by the substitution of methylmalonyl-CoA in place of malonyl-CoA at specific points during chain elongation [83,84]. A novel microsomal fatty acid synthase is involved in production of methyl-branched alkanes in most insects [85-87]. This fatty acid synthase is different from the ubiquitous soluble fatty acid synthase that produces saturated straight chain fatty acids in that it is found in the microsomes and prefers methylmalonyl-CoA. The amino acids valine and isoleucine can provide the carbon skeletons for methylmalonyl-CoA as well as propionate [83]. 

As with the other insects studied that utilize hydrocarbon sex pheromones, once Z9-23 H is produced by oenocyte cells it is released into the hemolymph. Lipophorin is the transport protein that will move the hydrocarbon to cuticu-lar tissue [21]. It was found that about 24 h were required once Z9-23 H was induced to actual deposition on the cuticular surface [237]. As is the case with other insects selective partitioning of the sex pheromone was observed with relatively larger proportions of Z9-23 H being found on the cuticular surface than in other tissues [21]. 

Largely, the insect detectors for pheromones and other semiochemicals are arrays of hair-like sensilla distributed over the surface of the antennae and palps. In some species, such as scarab beetles [3, 4] and the honeybee [5], semiochemicals are received by olfactory plates. The more ubiquitous hair-like sensilla typically consist of hollow cuticular hairs (10-400 pm long, 1-5 pm thick) innervated by one or several olfactory receptor cells (neurons) and three auxiliary cells [6]. 

The female produced sex pheromone of Aleochara curtula has been described to consist of a mixture of (Z)-7-henicosene and (Z)-7-tricosene [114]. The same compounds are reported to be used by young males as a kind of camouflage to avoid aggression from older males. Similarly, chemical camouflage by using hydrocarbons plays a role in the relations between the myrme-cophilous staphylinid beetle Zyras cones and the ant Lasius fuliginosus. The host worker ants never attack these beetles which show the same profiles of cuticular hydrocarbons as the ants [115]. 

Recently, two new facets have been added to scarab chemistry. A suite of unusual A9 10-allenic hydrocarbons like 86 has been identified among the cutic-ular hydrocarbons from several Australian melolonthine scarab beetles [184]. Though very low-level components in the related cane beetle Antitrogus parvu-luSy the major cuticular hydrocarbons in this species proved to be oligomethyl-docosanes like 87. Only the relative configurations of these compounds could be determined [185]. Whether these interesting hydrocarbons have a function as pheromones needs to be established. 

Another contact sex pheromone was identified as a component of the cuticular lipids of females of Psacothea hilaris [350,351]. Extracts of the elytra contained (Z)-21-methyl-8-pentatriacontene 189. The synthetic compounds (both enantiomers were synthesized [352,353]) induced precopulatory behaviour in males, however, its biological activity was considerably lower than that of the natural extract. 

Volatile sex pheromones provide the first specific information about mating partners. Cuticular contact pheromones provide a second step in species and sex recognition and, in most cases, they function as courtship-inducing pheromones... 

A non-volatile contact pheromone contained in the cuticular wax of females elicits a wing-raising courtship response from males (Roth and Wilhs, 1952 Ishii, 1972). Nishida and co-workers obtained three active chromatographic fractions from hexane extracts of 224000 females. The major active component was identified as... 

Table 6.3. Chemical structures of the principal identified contact sex pheromones of cockroaches, listed by the species and sex that produces it contact pheromones are localized on the cuticular surface... 

The third, and perhaps least understood, mechanism regulating contact pheromone production involves its transport to the cuticular surface. The detection of large amounts of hydrocarbons and pheromone internally, within the hemolymph, prompted an examination of lipid transport in B. germanica. Gu et al. (1995) and Sevala etal. (1997) isolated and purified a high density lipoprotein, lipophorin, that carries hydrocarbons, contact pheromone, and JH within the hemolymph. The accumulated evidence supports the idea that the hydrocarbons and contact pheromone components are produced by oenocytes within the abdominal integument, carried by lipophorin, and differentially deposited in the cuticle and ovaries (Fan et al.,... 

Jurenka, R. A., Schal, C Burns, E., Chase, J. and Blomquist, G. J. (1989). Structural correlation between cuticular hydrocarbons and female contact sex pheromone of German cockroach Blattella germanica (L.). Journal of Chemical Ecology 15 939-949. 

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