Pheromone transport contact pheromones

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.,... 

Transport of pheromones. Two major routes for translocation of pheromones have been considered in this chapter (a) from the secretory cell directly through the cuticle overlying it and (b) indirectly through the hemolymph. Cockroaches share with even the most studied lepidopterans an almost complete lack of information on the former pathway. Transport of hydrocarbons and contact sex pheromones, on the other hand, has been extensively studied in cockroaches, commencing with the work of Chino and colleagues. It has... 

Indirect delivery little contact with female. In some aquatic species, a male courts a female by relying on water currents to transport his pheromones to her. This describes courtship in Triturns and Cynops (Salamandridae). Excellent analyses by Halliday (1974, 1975, 1977) of the courtship of the smooth newt, Triturus vulgaris, show that the male moves his tail in a fan-like fashion to create a water current from the male s clocal glands towards the female s nares (see Halliday, 1975, Fig. 4). 

Drosophila melanogaster is another dipteran where pheromone biosynthesis has been studied [92]. Adult sexually mature female D. melanogaster utilizes primarily Z7,Z11-27 H as a contact sex pheromone. The biosynthesis of this compound follows the biosynthesis of other hydrocarbon-derived pheromones (Fig. 3). It is biosynthesized in oenocytes [93], transported through the hemo-lymph by lipophorin [94], and deposited on the cuticle surface. Biosynthesis in the oenocytes follows a similar pathway [95] as that described for the house fly... 

Regulation of contact sex pheromone production in B. germanica operates at several levels, including (i) production of the 3,11-dimethylnonacosane precursor, (ii) its metabolism by female-specific oxidases to 3,ll-dimethylnonacosan-2-one, and (iii) transport and distribution of the pheromone to the epicuticular surface. Early in the life of an adult female, it appears that food intake is a major regulator of hydrocarbon production. Females produce hydrocarbons only when they feed, and experimentally starved females, or gravid females that feed less, produce significantly less hydrocarbon (Schal el al., 1994). Because a pool of precursor 3,11-dimethylnonacosane is required for pheromone to be made, little pheromone is produced when less hydrocarbon is available, for example in starved females. 

Gu, X., Quilici, D., Juarez, P, Blomquist, G. J. and Schal, C. (1995). Biosynthesis of hydrocarbons and contact sex pheromone and their transport by lipophorin in females of the German cockroach (Blattella germanica). Journal of Insect Physiology 41 257-267. 

In contrast, the hydrocarbon contact sex pheromone of the German cockroach is synthesized in Class II oenocytes associated with the abdominal stemites (Young et al., 1999 Fan et al., 2002). These large oenocytes, ranging up to 50 p in in diameter in B. germanica, have abundant mitochondria and extensive smooth endoplasmic reticulum (Fan et al., 2002). Although the oenocytes are associated with abdominal stemites, the hydrocarbons are released into the hemolymph and loaded, probably across a plasma membrane reticular system, into high-density lipophorin. The lipophorin then likely transports the hydrocarbon to epidermal cells for release onto the cuticle (Fan et al., 2002). 

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