Anatomy Book Review & Queen Attraction Research.

Introduction.

Winter is here and the temperature is below zero. The sun is low and doesn’t make it over the treeline. I see it clearly when it slides round the edge of the forest, but, even then, it makes only a brief appearance in our garden. So, the snow remains out front all day and the hedge sags under its weight.

A surprise parcel arrives from Switzerland. Its contents include chocolates and this beautiful honey bee anatomy book. A friend is thanking me for proofreading his thesis and I am delighted.

This is one of the nicest books on bee parts that I have seen. I enjoy looking at bees under my microscope during dissection as I try to learn more about how this wonderful insect functions. Making slides of bee parts is fiddly and time-consuming and I am too busy to do much these days. Now I don’t even need to try; I can just open this reference book.

Book Review.

It doesn’t matter that I can’t read German, because these impressive photographs tell the story for me perfectly. But I do hope that Anatomie der Honigbiene might be translated into English. I’m going to add the English text to my copy.

Anatomie der Honigbiene is the work of photographer and beekeeper von Ruedi Ritter and published by Beinen Schweiz Appenzell. The ISBN number is 978-3-9523866-9-9 and it costs CHF 32:00. Sadly, the website link refused to connect here.

This is a hardback book with 48 pages of clear and intriguing photographs of bee parts under a microscope. The only text describes briefly each photograph. The back cover displays pictures on both sides. As bee-buddy Cynthia pointed out yesterday, this book is high quality and each page comprises hard card making it more durable and reader-friendly.

Queen Pheromones & Attractiveness.

Still on the subject of bee biology, I always prick up my ears when I hear of new research by Canadian scientist Dr Alison McAfee who is also one of the best science communicators today. She is an expert on honey bee queens and helps beekeepers try to understand and manage the problems of queen failure. In this recent paper published in iScience, https://doi.org/10.1016/j.isci.2024.110906, McAfee et al. look at queen pheromones.

Pheromones are chemical messengers and part of the exocrine glandular system which secretes substances to the outside of the animal body. Pheromones are volatile chemicals that disperse in the air and give information to other member of the same species. A commonly known bee example is the Nasanov gland pheromone which is released from the end of a worker scout bee’s abdomen as she waits at the entrance of the new home after swarming. The pheromone wafts through the air and lets the rest of the swarm know that they should land and settle here. It smells a bit like geraniums to me and does contain geraniol, geranic acid, nerol, citral, farnesol, and other smelly substances.

Queen Pheromones.

Back to the queen though. She doesn’t produce Nasanov pheromones but she does make queen substance or queen mandibular pheromone (QMP) in her mandibular glands. The main acids produced in these glands are called 9-oxodecenoic acid (9ODA) and 9-hyroxy-(E)-2-decenoic acid (9HDA) but there are at least 15 other major chemicals in this complex mixture. Recent studies show that that there are additional chemicals not specific to these glands. QMP has a varied role including a sex attractant for drones in the congregation area. You may have heard of the queen retinue pheromone (QRP) which is mainly composed of mandibular gland secretions but does contain three fatty acids not found in these glands. As the name suggests, this QRP attracts nest bees to form a retinue around the queen and touch her with their antennae.

Honest Signals.

The purpose of the McAfee study was to reassess something called the “honest signal hypothesis”. This hypothesis asserts that social insect queens give pheromone signals which inform worker bees of their fecundity which is their potential to produce lots of offspring. This intelligence helps workers decide if they should invest in this queen or not. Will she be good for colony function and wellbeing?

The scientists studied several groups of queens comprising; virgin queens with underdeveloped ovaries, young mated queens, older mated queens, and older mated queens with smaller underdeveloped ovaries. QRP was measured using liquid chromatography-tandem mass spectrometry and related to queen age, laying status, and worker acceptance.

Ovary Mass & Acceptance.

I found this interesting because literature suggests that workers are most attracted to queens with larger ovaries. This study found that queen pheromones and attractiveness did increase with age and ovary size. Older queens produced more of certain QRP components compared to younger queens, and the chemicals correlated to ovary mass but this was not an important factor influencing worker decisions about queen acceptance. The study asserted that it was an “honest signal” but not one that was primarily influenced by ovary mass which turns out not to be constant, and is a poor measure of fecundity. Here is the interesting part, ovary mass can change throughout the life of a queen and only measures fecundity at one point. Poor nutrition can reduce ovary mass. Better quality food (more protein), increased feeding rates due to better care and worker attendance can make the ovaries larger. On the other hand, the number of ovarioles, sperm count and viability are not reversible and they can only remain constant or decline. So, ovary mass is not a good indicator of reproductive status due to the adaptability (plasticity) of this organ to environmental changes. Another reason for a reduction in ovary mass is caging queens for too long. There are implications here for beekeepers caging queens for several weeks as part of varroa control. Some beekeepers report supersedure following caging and this is one of the reasons that I haven’t tried it myself. That, and the fact that all my colonies have brood breaks in June during swarm season.

Banked Queens.

Queen breeders will be reassured to know that queens banked for up to 18 days had the same high introduction success as free-range queens. The paper reports queen acceptance level increases with age (7-35 days post emergence) quoting another study and stating that worker sensitivity to QMP varies throughout the season. There is also consistently better acceptance of queens of the same subspecies.

Conclusion.

It was good to be reminded that good nutrition is key to colony success at all levels. I’m fortunate to live in an area with good pollen sources all year round, and I’m able to monitor forage easily and make up any shortfall if I have to. I’ll not keep more than 6 colonies in the home apiary so, despite an increase in local beekeepers and colonies, there should be enough available forage through the season.