Pheromone stimulatory effects

The previously passed over empty comb stimulates hoarding (Rinderer, 1981), so probably a volatile pheromone is involved, the response increasing with the amount of pheromone. Perhaps the pheromone concerned is deposited when cells are prepared for use, and is obscured when they contain brood or stores. Air passed over comb containing honey does not increase hoarding. Providing honey producing colonies with synthetic pheromone instead of abundant empty comb would obviously be advantagous.

Exposing empty comb to isopentyl acetate, an alarm pheromone component from the sting chamber (page 139), diminished hoarding (Rinderer, 1982). This result is difficult to explain because bees soon become adapted to alarm pheromones (page 151) so it is unlikely to keep them in a state of permanent alertness. Perhaps it masked the pheromone present on empty comb prepared for food storage. In contrast, exposing empty comb to 2-heptanone, an alarm pheromone component from the mandibular glands (page 144), increased hoarding (Rinderer, 1982; Rinderer et al., 1982). Perhaps 2-heptanone may normally be used to mark cells for some purpose or other. http://www.lankadirectories.com/pheromones-play-an-important-role-in-animal-behavior/ has a good write up on pheromones.

It is doubtful whether old comb has a special pheromone incorporated in it that stimulates foraging (jaycox and Guynn, 1974), but experiments are needed to compare the nectar and pollen gathering of colonies based entirely on either new or old comb.

Figure 8.1 Stimulatory effect of brood, queen and comb pheromone.

Pheromone stimulatory effects

Comb and the pheromones it contains may have stimulatory effects other than on hoarding and foraging. Jay (1975) showed that the presence of worker comb stimulated the development of ovaries of queenless pheromone worker bees kept in groups of 150 in small cages. Subsequent attempts to demonstrate this in small combless colonies were frustrated because the bees consistently lmilt some comb themselves. Colony defence is also encouraged by the presence of empty comb within the nest (page 145). Learn more about pheromones at http://www.finngas.net/?p=316 and http://www.t-toshi.com/pheromones-produce-familiar-smell/.

Distinguishing between types of cell

Queen cups, the shallow dish-shaped  pheromone precursors of queen cells, are available lo the nest for most of the foraging season, but queens only lay eggs in them some of this time, presumably after the workers have prepared them in some way which may include scent marking. However, no pheromone studies have been done on this.

Queens are able to differentiate between worker and drone cells, and lay in them fertilized and unfertilized eggs respectively. When a chequerboard of drone and worker comb is presented in the brood nest, the relative proportion of each used for brood rearing differs greatly at different techniques in the season, reflecting the amount of drone brood being reared under natural conditions (Free and Williams, 1974, 1975). Workers that have developed their ovaries and are laying eggs (unfertilized) prefer to do so in drone cells (Free and Williams, 1974).

Workers differentiate between pheromone and worker cells for purposes other tltnn egg laying. When a small group of bees was caged with a piece of worker comb and a piece of drone comb they stored more syrup in the worker comb, although that stored in the drone comb was more concentrated (Free and Williams, 1972). When a chequerboard arrangement of drone and worker sections was presented in the hive, or empty drone and worker combs arranged alternately, the bees stored honey in worker cells in preference to drone cells, and stored hardly‘ any pollen in drone cells (Free and Williams, I974. 1975).