“I’m worried about my bees. They are very busy and the brood frames are full but the bees are so different; some are yellow, some brown or gray, and some are almost solid black. Is my hive being invaded by robbers? What should I do?”
Good question. What you are most likely seeing is a strong colony with a good variety of genetic material. Far from being a bad sign, a mix of colors is an indicator that your queen is sufficiently mated.
As you know, a queen bee mates many times before she begins to lay eggs. The sperm from all the different drones is mixed together and held in a storage organ called the spermatheca. For the rest of her life, the queen draws from this supply to fertilize the eggs which will become workers or new queens.
Each female bee in the colony will get half of her genetic material from her mother (the queen) and half from her father (one of the drones). For the sake of argument, let’s say this particular queen mated 16 times.
A subfamily for every drone
Sixteen matings means that the queen’s offspring can be divided into 16 different subfamilies. Each of these subfamilies has the same mother, but a different father. In human terms, the offspring are very much like half siblings: one mother, different fathers.
All the bees in one subfamily (that is, all bees having the same mother and father) will be very similar to each other, even though they are not identical. They are not identical because the genes from the mother (who has two sets of chromosomes) will sort out in different ways when she is producing eggs (which have one set of chromosomes). The genes from the father will all be the same since he has only one set of chromosomes to begin with. Overall, however, the bees within one subfamily will be very similar to each other.
Bees belonging to different subfamilies will be less similar to each other because, even though the mother is the same, the father is different. These bees have thousands of traits you cannot see, but one you can see is color. So when you open your hive and see different colors and patterns, you know you are seeing the offspring of different drones.
Multiple matings can strengthen a colony
It is well known that multiple matings lead to strong colonies, and it is easy to see why. Let’s say, for example, that one of the 16 drones is a strong, fast flier but he’s allergic to apple pollen. One whiff and he keels over dead. (I’m making this up, so don’t fret over apple trees.)
He will pass this bad gene to all of his offspring. At this point, I don’t want to get into dominant and recessive genes or the regulation of genetic expression by other factors. Suffice it to say that, depending on the mother’s genetics, this defect may show up in some of his progeny.
For the sake of argument, let’s say it shows up in 50% of his children, and that those bees will die at the first scent of apple pollen. Because of multiple matings, those that die will be only 50% of 1/16 of the colony (half of one subfamily) or 1/32 of the entire colony (about 3%). A colony can survive a loss of 3%. If, however, that drone was the only father, the colony would lose half the bees—a very different story.
Mitigating the bad genes
Although I used an on/off, all-or-nothing example to illustrate my point, many real-life negative traits are suppressed by multiple matings. Disease resistance, overwintering ability, foraging distances, stress regulation, and thousands of other things are genetically controlled, and damage to the colony by so-called “bad genes” can be mitigated by multiple matings.
So next time you see bees of many colors, know that the wonders of nature and genetic inheritance are helping your colony along. Celebrate! Everything is working according to plan.