Isoamyl acetate pheromone

The GOBPs mainly found in the female moth antennae seem to carry odorant molecules found in plant volatiles (Steinbrecht et al., 1995). In the honeybee, Apis mellifera, ASP2 (AmelOBP2) expressed in the antennae of workers and drones can bind odorant molecules of floral scents such as 1,8-cineol, 2-isobutyl-3-methoxypyrazine, 2-heptanone and isoamyl-acetate but do not bind pheromone components (Danty et al., 1997, 1999 Briand et al., 2001). 

In 1986 the largest ever smell survey was carried out involving 1.5 million people from all over the world. They were given scratch and sniff cards and a questionnaire to answer. The scents tested were androstenone, isoamyl acetate (banana), glaxolide (a synthetic musk), eugenol (cloves), rose, and a mercaptan (the one added to natural gas to make it detectable). Of those who took part, 50% were able to detect all six smells and only 1% could detect none of them. Women were found to be better than men. The smell that was sensed the least was androstenone, and if this really is a human pheromone then it does not operate by having an irresistible odour. 

The nomenclature of esters is relatively simple, because it is similar to the nomenclature of salts. For instance, the ester obtained from methanol and ethanoic acid (acetic acid) is called methyl ethanoate (methyl acetate). Esters are compounds that comprise a large number of structures depending on what the alcohol and acid components are. Esters with a small molecular mass are volatile substances, in most cases with a pleasant odor. For instance, butyl acetate is responsible for the odor of apples. In nature, some esters serve as pheromones for insects, for example isoamyl acetate which attracts butterflies. Other kinds of esters can be large molecules as for instanee waxes and fats where both the alcohol and the acid components can be long-ehained or eomplicated structures. These natural esters will be diseussed in the ehapter on lipids. In industry, esters are used in the fabrication of polymeric fibers for textile materials and plastic materials for various uses. The most common material is polyethylene terephthalate (PET), the ester prepared from terephthalic acid and ethylene glycol. 

Methylbutyl acetate (isoamyl acetate) is best known for the characteristic odor it gives to bananas. It is also one of the more than 40 compounds in the alarm pheromone a honeybee uses to alert other bees that an intruder has arrived. 

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