Sex pheromones are chemical signals that mediate sexual attraction&mating in animals. Among moths, these signals are usually secreted by females and are perceived by males. Pheromone detection involves chemosensory hairs (sensilla) on the male's antennae. A hypothesis concerning mechanisms involved in moth olfactory sensing of pheromones proposes that the lipophilic pheromone enters olfactory sensilla on a male's antennae through pores in the cuticular wall of the sensilla and that the pheromone is solubilized in the hydrophilic lumen of the sensilla by binding with pheromone-binding protein. The bound pheromone is transported across the sensillar lumen and transferred to a membrane-bound pheromone receptor protein on sensory dendrites within the sensillum. Binding of the pheromone with the receptor leads to generation of an electrical response in the neurons that make direct inputs into the macroglomerulus of the moth central nervous system. This ends in the display of sexual behavioral reactions by the male. The receptor-bound pheromone is then removed from the receptor and catabolized to ready the system for a fresh incoming stimulus. The thrusts of our research concern the discovery and study of new compounds that resist the processes of pheromone catabolism and thereby debilitate sensitivity of males to pheromone detection. Such compounds could be useful in pest insect control. We have discovered that two fluorinated sex pheromone analogs of the European corn borer moth [2-fluoro-Z-11-tetradecenyl acetate (2F-Z-11) and 14,14,14,-trifluor-Z-11-tetracenyl acetate (F3-Z-11)] are potent inhibitors of insect pheromone sensing and mating in the species. In 1993, we synthesized racemic tritiated 2F-Z-11 at the NTLF and used it to study how it was processed by catabolic enzymes on the insect antennae. The study showed the fluorinated analog was resistant to catabolic degradation. This fact may explain the mechanism by which the compound inhibits. In subsequent behavioral studies using enantiomers of 2F-Z-11, we found that the R-antipode inhibits moth mating but the S-antipode does not. We now wish to determine comparatively how these antipodes are processed catabolically by using tritiated R-2F-Z-11, S-2F-Z-11 and F3-Z-11. Results of the study should provide valuable insight into the mechanism of mating inhibition and lead the way to design of other insect mating inhibitors with greater inhibitory potentials for use in suppression of pest populations.
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