Insect Fat Body Tissue & Queen Bee Dissection.

It’s been a mild week here in Nairnshire with sunshine and rain showers. Falling oak leaves are blowing in the strong wind and larch leaves pile up along either side of the road in thick yellow lines. Despite the rain, the bees have been flying and collecting yellow pollen. The colony on the left is the hardiest of my colonies. The bees are dark and came in from the west in a late spring swarm. They are out in all weathers when the other colonies are indoors. When I took this photograph, the sky was not yet fully light at 8:30 am and yet they were out flying. They continued their work when the rain came later. I’ve seen them along the road on a neighbour’s heavily scented pink viburnum bodnantense with yellow pollen-packed baskets. However, yesterday the temperature dropped from 13 to 4 degrees Celsius over night bringing the first snow to the hills and has probably kept them indoors. I didn’t see them as I had the day off and walked at Evanton on the Cromarty Firth till it was nearly dark on my return at 4pm.

Fat Body Tissue.

A couple of weeks ago I explained the physiology of winter bees and the role of fat body tissue. I’ve dissected out the abdominal contents of a queen wasp preparing for hibernation to show you what it looks like. Initially, I was surprised to find the body stuffed so full of fat body tissue which was much larger than in any winter worker bee bodies I’d seen previously. Then I remembered that queen wasps hibernate alone with no external food stores, just as brown bears do, so they must have large built in fat and food reserves to survive, and thus it makes sense.

Queen Betty the Bad.

Connie was keen to dissect Queen Betty the Bad who was a 2020 queen that her colony decided to supersede at the end of summer. It was hardly a colony though and still in a nucleus box so I decided that they were unlikely to survive winter if they had to wait for the production and mating of a new queen. So, I removed queen Betty to the freezer and united her colony with another nucleus to give them the best chance of surviving winter.

At the moment, Connie (nearly 9) wants to be a vet and was fascinated by the process of embedding specimens in wax for dissection. I’d partially filled a polish tin with bees wax. The whole process involves heating a metal rod over a spirit lamp flame and making a crater in the wax that the bee is pressed into to prevent it moving when you dissect and remove the upper (dorsal) part of the cuticle exoskeleton with a scalpel blade. The legs and wings are removed first to give a clear working area. Once a few bees are embedded, a 50/50 mixture of water and isopropanol alcohol is poured over the bees so that the body parts don’t collapse when you cut open the bees and expose the abdominal contents. If you used water only you would end up with lots of bubbles and poor visibility in the tin.

You can see the spermatheca which is where the mated queen stores the sperm from the 7-17 drones that she mates with. Notice the white snake-like tube running across the surface which is one of 2 spermathecal glands that supply secretions essential for the health of the sperm which can survive for the life of a queen, perhaps up to 4 years. Usually in a mated queen the spermatheca is crisscrossed with tiny tracheal branches that supply oxygen and contribute to sperm survival. A virgin queen has a clear spermatheca. Queen Betty’s was not transparent but neither was it covered in a rich network of white tracheae so I am not sure how well mated she was. The bees must have known.

Getting Bees for Dissection.

Having stored worker bees in the freezer, I’ve decided that they are not easy to dissect because they deteriorate and the abdominal contents are often brown and friable, and the thoracic collars don’t come off easily when you want to inspect the tracheae. Freshly killed bees are easier to work with. A friend suggested that I leave a tray out in front of a hive and collect newly dead bees thrown out of a hive in the mornings. I tried that this week and was surprised at the easy collection and success. Only one of 6 bees was too old to dissect. A couple of the bees had obviously become cold and revived somewhat indoors so I put all the collected bees in a jar with killing fluid on a tissue to ensure that they did not come to at the critical moment. I hope that the photos have been useful to those of you studying bee anatomy for exams or just general interest.