Posted on: 02 March, 2017
Author: Alexander P
In combination with the evolution of glands that secrete and emit pheromones, bees have developed olfactory receptors of high sensitivity, capable of rapid and precise discrimination. Consequently, bi... In combination with the evolution of glands that secrete and emit pheromones, bees have developed olfactory receptors of high sensitivity, capable of rapid and precise discrimination. Consequently, biologists are usually able to produce a satisfactory bioassay for use in the development of a synthetic pheromone. Lack of complete chemical identication of a pher- omone is usually the prime constraint to progress in bee pheromone research. Until recently the minute quantities of material available for chemical analysis have made this task extremely difcult. Hopefully recent develop- ments in the techniques and devices associated with the employment of the coupled gas-chromatograph and mass-spectrometer will help overcome the problem. Many of a pheromone’s components release different behaviour patterns and so have different functions or different combinations of functions. Most bioassays have investigated the components in isolation. There is less information on the ability of bees to detect and respond to a component in a mixture, and on whether the response to it is the same as when the component is presented alone. The relative proportions of the different components of a pheromone must vary at different distances from the source of secretion according to their volatility. Perhaps there is a corresponding variation in the type of response elicited. The absence of certain components in a synthetic mixture may be partially compensated for by an increased amount of some of the others, but the correct blend is necessary to elicit the full response. It is essential to test mixtures of the different components of the same pheromone, as well as the individual components, in order to determine any additive or synergistic effects. But so far studies of bee pheromones have provided little evidence of either. The effect of two components in combination rarely seems to equal the sum of the effects of each acting on its own, and certainly has never exceeded it. Whereas a single component of a multi-component pheromone can serve multiple functions there is no evidence yet that it ever does so unaided. The queen pheromone component 9-ODA may approach the effectiveness of the complete mandibular gland secretion in attracting drones and indeed may be the sole mandibular gland component involved, but 9-ODA alone is insuf- cient to induce normal court formation, and to inhibit queen rearing or ovary development. Other components of the mandibular gland secretion or other pheromones are probably always involved in these latter activities. The method of dispersal of 9-ODA may also differ in the different circumstances according to http://youthbruce.com/ Because non-social insects communicate by pheromones during mating, this is likely to be their earliest evolutionary use by eusocial bees. It is signicant that 9-ODA occurs in all honeybee species. Probably 9-ODA developed as a sex attractant and as the honeybee colony evolved it combined with additional chemical secretions to produce other signals. Perhaps its extended use was originally associated with aggressive behaviour as some- times exemplied by honeybee and bumblebee laying workers; the capability of inhibiting reproduction by chemical means alone evolved later. Although many alarm pheromone components release more than one behaviour pattern, like 9-ODA each always normally acts only in conjunction with other components. Such a multi-functional role of queen and alarm pheromone components allows an economic use of the existing chemical repertory to produce the required output of signals. It is tempting to suppose that bees of different physiological conditions, or with different behavioural repertoires, respond preferentially to different components of a pheromone mixture, or that different components of a pheromone may be responded to in different behavioural contexts. Source: Free Articles from ArticlesFactory.com Alexander P is a blogger who studies pheromones and lives in Los Angeles.