Monday, 12 April 2010

The Importance of Pheromones to the Sustainable Bee Keeper

by Ali Twigg

Definition: A pheromone is a substance that is externally secreted to induce a behavioural or physiological response in other animals of the same species.

Bees use pheromones as their primary means of communication because in the hive it is dark, so they can’t use their eyes effectively and it’s noisy, so their sense of hearing is no good either.

It is the unique formula of each queen’s pheromones that gives her colony its identity and cohesion. If you imagine people from a different area having a different accent that identifies them to that area, then the same can be said of the queen’s pheromones in identifying her colony as coming from her hive.

Two Kinds of pheromone:

Primer: (more liquid)                Releaser: (more gaseous)
-causes physiological change     -causes behavioural change
-has low vapour pressure          -has high vapour pressure
-long tem control                       -short term control

Bees transmit and receive pheromones.

  • Nasonov gland (at rear end) 
  • Mandibular gland 
  • Cuticle 
  • Koschevnikov gland (in sting) 
  • Dufour gland (in Queen’s vagina; deposits a pheromone on Q eggs so they can be distinguished from eggs laid by workers, which are not required and are therefore not looked after) 
  • Amhart gland (produces foot-print pheromone in Qs and Ws. Not necessary in drones.) 

Bees have chemoreceptors to detect and decode pheromones.

Queen-3,000  Worker-5,000  Drone-30,000 (so drones can detect Queen when she’s on her mating flight-she only does this once in her lifetime. 
Queen pheromones tell drones which Queen is their mother so they do not mate with her. Conventional bee-keeping practice of artificial insemination cannot and does not take this factor into account.

Two kinds of chemoreceptors:
  1. Plates (responsible for detecting smell) Found on antennae only. Can recognise the direction of smell 
  2. Pegs: (responsible for detecting taste) Found on antennae, mouth and legs. Thought possibly to be ingested partly. 
Swarming and pheromones. 
Swarming is started by scout bees and is controlled by pheromones: Q mandibular gland pheromone and Nasanov gland pheromone.

Scout bees also leave an odour trail (NasGPh) for others to follow when they have decided on a new home for the colony.

If no pheromone is present in the cluster of bees that forms the swarm (because the Q is not present), the swarm collapses and returns to the hive.

Conventional bee keeping practice of clipping the Queen's wing causes Queen to fall out of hive when she wants to swarm. Obviously she can’t fly! The resulting lack of her pheromone within the swarm causes the swarm to return to the hive and begin feeding a larva/larvae with Royal Jelly to produce a new Queen(s). It is the Queen’s pheromones that knit the entire colony together and give it cohesion. Lack of Queen pheromone causes both behavioural and physiological change within the colony. Conventional bee keeping practice is to prevent or ‘manage’ swarming because the workers fill their honey stomachs before they swarm and thus deprive the conventional bee keeper of his/her honey. No honey, no profit.

Mandibular gland pheromone is secreted as a warning to others to stop what they are doing or else!

Koschevnikov gland pheromone and nonanol (produced in other glands, esp. nasonov gland) are secreted when a bee feels so threatened that it attacks. Conventional bee keepers advise new-comers to ensure that their bee suits are washed regularly to remove any traces of these pheromones so that new bee keepers are not attacked unwittingly and therefore put off beekeeping.

Bees use pheromones to communicate the mutual exchange of food: adults-adult and adult-larvae. This is termed trophallaxis.

Foraging bees bring home nectar which is regurgitated and reingested by themselves and the house bees until its water content has been reduced significantly to change it into honey.

Larvae produce pheromones to tell the workers what food is needed and to encourage workers to develop their hypopharyngeal gland, which produces a super-rich protein food for the larvae. It also produces Royal Jelly for Q larvae. The workers ‘bathe’ the larvae in food within the brood cells.

Capping pheromone also comes from the larvae to signal to the workers when the larvae are ready to pupate. Their brood cells are capped with the porous waxy substance that will seal larvae in their cell but will still allow air to pass through the cap so they can breathe.

Unfortunately, varroa mites can also detect capping pheromone and will invade brood cells to lay their eggs just before capping takes place. They are especially fond of drone brood.

Pheromones are also secreted by the non-living organism! In order to maintain hygiene within the colony, undertaker bees detect apneumones from the dead bodies of bees and larvae; apneumones conveying the signal to get rid of the dead to prevent the spread of disease.

Pheromones are produced by drones to attract each other to the drone collection area; the place where drones gather to catch the virgin queens on their mating flight. It is my supposition that the queens must also be able to detect the drone collecting area pheromone in order to know where to go to become successfully mated and thus continue their genetic line but I’ve no proof nor anybody else’s research to back this idea up. In fact, as my ‘knowledge’ of pheromones is my interpretation of other people’s research and my lecture notes from various speakers, please don’t take any of the preceding information as accurate. I’m neither a chemist nor an entomologist. Also, where I have mentioned ‘conventional bee keeping practise’ I am referring to what I have been taught is conventional practise on the BBKA ‘Introduction to Bee Keeping’ course I have attended (as outlined by the BBKA) and I am not suggesting that every conventional bee keeper adheres to everything I have been taught.

Having said all of the above, it is my understanding that conventional bee keepers open their hives every seven days in order to inspect them for disease and to see how the stores are progressing. Bees work extremely hard to maintain the temperature, humidity and pheromone content in the atmosphere of the hive, all of which are vital to the health and well-being of the colony. By opening up the hive from the top, which is how WBC, National, Commercial and their hybrid hives are opened, with frames of brood and supers being removed for inspection, and with the knowledge that hot air rises with cold air rushing in to take its place, the carefully controlled atmosphere of temperature, humidity and pheromones nurtured by the colony is allowed to escape, causing the bees to have to start this work all over again. This causes them unnecessary stress and must put their brood in danger of chilling and possibly lack of feeding, since the bees that would be feeding them are having to shiver to raise the temperature, fan to spread fresh pheromones throughout the colony and possibly send forager bees out for water to increase the humidity within the hive. The sustainable bee keeper, using a Warré or Top Bar Hive, does not open up their hive for such inspections, believing in a policy of non-interference (or as minimal as is possible). The resulting continuation of internal harmony has to be of benefit to the health and general well-being of the colony and is, after all, what would most likely happen in nature. Mimicking nature is what I believe sustainable bee keeping is all about.

Pheromones are a fascinating subject. I hope what I have discovered has whet your appetite to find out what you can for yourself. Happy hunting!

1 comment:

YABeeP said...

Thanks for doing this Ali - it's volunteers like you giving time that really makes YABeeP a success.