Posted on: 02 March, 2017
Author: Alexander P
The pheromone gland is named after the Russian who, in 1883, rst described it; but the function of the gland was then unknown although it was supposed to help in secreting surplus water, possibly fro... The pheromone gland is named after the Russian who, in 1883, rst described it; but the function of the gland was then unknown although it was supposed to help in secreting surplus water, possibly from nectar the bees had collected (Zoubareff, 1883). This erroneous concept was corrected by Sladen (1901, 1902, 1905) who realized that the odour from the gland attracted other bees. This function was conrmed by top pheromone experiments demonstrating that groups of 50 queenless bees were attracted to cluster on small cages containing excised Nasonov glands and that individual bees preferred to move toward excised Nasonov glands in a two-choice olfactometer (Free and Butler, 1955). Nasonov pheromone adsorbed onto lter paper is also effective in an olfactometer (Bach and Shearer, 1962). Bees in the olfactometer were equally attracted to excised Free (1968a) found that whereas some bees that released scent had exposed their Nasonov glands before they landed at a dish and continued to expose them for a few seconds afterwards, others exposed their glands only momentarily, usually soon after alighting. The tendency to scent differed greatly between individuals, some not scenting at all during numerous consecutive trips, and some consistently doing so more readily than others. The impression was obtained that the bees scenting most consistently tended not only to scent while approaching a dish, but also to scent for longer than the others while feeding. This is according to http://pommettmark.doomby.com/blog/the-topic-of-human-pheromones.html The precise pheromone factors associated with the forage that lead to scenting need to be determined. The sugar content of the syrup, an increase in its sugar content, and the ease with which it can be imbibed seem to be important (Frisch, 1967; Pumm, 1969; Pumm et al., 1978). Bees usually do not scent pheromones until after the rst few visits to a source of sugar syrup (Free, 1968a). Such a delay would presumably have the biological advantage of not guiding other bees to a very transient food source or one that is toxic, and would help ensure that there is an absence of predators in the area concerned. Once a bee begins to scent it usually continues to do so on subsequent trips during the day. Bees that dance on their return home from collecting pheromones are more likely to scent on a subsequent trip than those that do not dance (Free and Williams, 1972) and both scenting and dancing are stimulated by an increase in the attractiveness of the forage (Free, 1968a). Data collected by von Frisch (1923) indicates that the longer syrup foragers dance, the longer they circle in the air above the dish — perhaps while circling they are exposing their Nasonov glands. However, dancing and pheromone scenting are not closely correlated (Free and Williams, 1972) and each may therefore be released by a different stimulus or perhaps by different intensities of the same stimulus. Thus, although the presence of a oral odour at a food source encourages dancing (Lindauer, 1948) it discourages scenting by bees collecting syrup (Free, 1968a; Wenner et al., 1969) or water (Free and Williams, 1970). However, it makes no difference to the duration of any scenting that does occur (Wilhelm and Pumm, 1983). Whereas the presence of strong pheromone scents makes bees less likely to add their own, it seems that bees are particularly likely to add their own Nasonov scent to a food source that lacks one, and so facilitate its discovery by others. In contrast to the pheromone behaviour of bees that are clustering, the presence of Nasonov gland odour fails to inuence Nasonov odour release by foragers at a food source (Free, 1968a; Pumm and Wilhelm, 1982). This is not surprising. If Nasonov pheromone odour encouraged scenting the apparent attractiveness of a food supply could be too rapidly magnied and the accidental release of scent could start a false communication: if the odour discouraged scenting it would defeat its own object. Odourless pheromone sources are rare in nature; however, clean odourless water is common. Source: Free Articles from ArticlesFactory.com Alexander P is a blogger from Los Angeles who studies pheromones.