A Walk in The Park
Winter is reminding us that it's not over yet…but it can't stop me from dreaming of summer and one of my favorite experiences.
Honey bee behavior is a magnificent thing. When I was a graduate student a group of us who were working with honey bees were treated one summer to a drone congregation area. We came to this place on the Marys River not far from where it converges with the Willamette. Armed with weather balloons, queen pheromone, a nitrogen tank and long balloon tethers we headed to a small clearing in the thirty to forty foot trees along the river. It was a lovely, warm afternoon, with clear, calm blue sky above the trees.
We filled the balloons with nitrogen and tied queen pheromone impregnated disks to the tethers below the balloons. The pheromone disks were hung ten to fifteen feet above our heads. I was handed a balloon and told to walk across the open area. Almost immedi- ately a comet like group of drones began following the pheromone disk as I walked. Approaching the edge of the clearing they fol- lowed my imitation queen as I passed a few trees. Suddenly the comet was gone. I turned and took a couple of steps and the drone comet reappeared. It was magical. Defining a drone congregation area is difficult. We do not know how drones delimit such an area because we don't perceive a boundary. These areas persist for the drones for several years and drones will congregate within the bounds and wait for a virgin queen to fly through this zone summer after summer.
But of course drones do not overwinter with the honey bee colony, they die in the fall. It is a puzzle how the new drones of the fol- lowing spring and summer know where to go. They do not have any experienced drones to follow. When a virgin queen appears the drones will follow her and try to mate, but once she crosses the boundary the drones stop following.
The queen must mate with many drones, up to 20 to be able to produce workers with all the necessary abilities to keep the colony fed and healthy. It has been demonstrated that queens who have mated with many different drones produce colonies that are better able to fend off diseases and remain healthy and viable.
We are noticing that queens are mated with fewer drones now than they were 15 years ago. This is adding to the difficulties the honey bees face. Research has shown that on average a queen in the US has mated with only 5 drones, far short of the number she needs to raise a healthy colony.
This process all takes place within the drone congregation area. We know some bits of how but much is not well understood. Mating takes place when these insects are in flight some fifteen to thirty feet above the ground. The male copulation organs are folded up, inside out within his abdomen. To copulate with a queen the organs must be everted and the semen forced through the wall of the everted endophallus. A tremendous pressure, produced by the drone's hemolymph, forces the inversion and extends the organs of copulation outside the drone and into the queen's reproductive tract, where the sprem is transferred. This process paralyses the drone and causes him to tear free of the queen and fall away - leaving behind his reproductive parts, now referred to as the mating sign. The queen manages to maintain flight and with the help of the next drone to mate her removes the mating sign of the previous drone. The sign of the last drone to mate her will stay with her until the workers remove it after she returns home. Her mates will have all fallen to the ground where they will die from dehydration or starvation or a bit of both. This finely tuned process insures that the queen is mated by many drones and has the best chance of producing a healthy well functioning colony.
Today there are problems. Miticides damage the drones, so that they may not even make mating flights. This reduces the number of mates available to a queen. It may also reduce the amount of semen a drone may carry and reduce the efficacy of the mating proc- ess. This problem is worsened by our desire to have early building colonies in the spring, colonies that are gentle and easy to work. Thus there is less diversity in the bees that are kept. More and more colonies are needed by a beekeeper to make a living, so that there are few areas where a different line of honey bees can be successfully bred. It seems to hold true no matter how you look at it…diversity is needed for strength and success. We also see this in nutrition, in both diet sources and how what is eaten is grown. Healthy systems are better sustained with varied sources of both genetics and nutrients.
And with that thought, I'm going to return to my garden preparations. Even in winter there are plans to be made, compost to be turned and insects to be observed. My bees are surely making some cleansing flights. I'll try to encourage some early blooms and wait patiently for a glimpse of this year's drone comets.