Hyperactive Drones Prepare for Mating.

Introduction.

Hello Everyone. I hope that you are all well this week. If anyone out there has ever dislocated a shoulder you will know how painful it is till your arm is back where it should be, and how frustrating being temporarily incapacitated is. I’ve just managed to dislocate my left one for the third time and have not been so mobile this week as I bashed my ribs into the bargain. Getting used to the new laptop has been challenging enough without all of that but at least I can still type.

Laptop Care.

Did I tell you that the HP overheated and completely fried while I was engrossed in a particularly good series on Netflix? I later learned that lint/ fluff got into the back of the laptop and the fan blocked. The GPU, whatever that is, failed, and I thought I would share that so you can reduce risks by not taking your laptop to bed, or working on your knee where fluff can easily get inside. I did get the data retrieved from the hard drive but I’ve lost my emails and addresses so please use my new address (front page).

Fan blockage might have caused the laptop fire that all but destroyed a family home in Nairn a couple of years ago. The laptop was recharging overnight on a sofa and it ignited. Fortunately, the smoke detectors worked and no one was injured.

The Drone’s Reputation.

And so, to the drone! I can vividly remember one of my early mentors deriding the drone and relegating him to the role of lazy, greedy, good-for-nothing insect, apart from mating with the queen that is. Is that familiar? I love it that science is dynamic and that people painstakingly study the behaviour of tiny insects to give us new insights into life inside a beehive. What I am about to share knocks the “lazy” theory on the head.

Dr Smith.

Dr Michael Smith and colleagues have recently discovered what drones really get up to inside the hive. Dr Smith is a scientist who takes an interest in researching subjects about which little is already known. Some of you might have heard of Michael’s earlier research on the most painful places to get a bee sting. For this he won an award, https://phys.org/news/2015-09-bee-huh-ig-nobels.html  When I visited Professor Tom Seeley’s lab in 2017,  Michael was studying comb building, and what prompts workers bees to build drone comb, so I was very interested in a recent paper that he has co-authored on what drones do inside the hive¹. Thank you, Gino, for alerting me to this new paper.

Drones at Home.

In the study, the scientists closely observed the activity of drones inside the hive. Previous interest in drones has mostly been around their behaviour outside the hive and their mating flights rather than their behaviour inside the hive. We know that drones do play a small role in keeping the colony warm but that their main role involves mating and passing on genes. We don’t regard drones as a caste because they are not engaged in age related indoor tasks (age polyethism) but this new information is fascinating and we can see them in a new light and revise what we know about them.

Hyperactivity.

The research team tracked 192 individually marked drones using a system called Beesbook, and they found that for most of the time the drones hung around on the edge of the brood nest doing very little. But they had periods of hyperactivity when they moved about faster than any other bee in the colony. In fact, drone speed was several times faster than worker speed on the comb. These bouts of activity started after the drones reached 7 days of age and they occurred at the same time in the afternoons that drones normally start taking short orientation flights. What was interesting was that all the drones of the same age shared this activity at the same time of day. The length of the in-hive activity depended upon the weather, and if it was good and suitable for mating flights then then the time spent inside moving fast increased.

Sexual Maturity.

The beginning of these periods of hyperactivity related to the stages of drone sexual maturity. The sperm moves from the testes to the seminal vesicles at around 7-8 days from emergence with sperm viability peaking at day 7 when the hyperactivity commences. Short orientation flights commence at 6-9 days in preparation for longer flights (1-5km from nest) to drone congregation areas where a lucky drone might mate with a queen when he is over 11- 12 days of age.

Conserving Energy.

By resting on the periphery of the brood nest, before day 7, the drone is conserving his energy for when he needs it most during these energetic mating flights in which only the fastest drone catches up with and mates with a queen. The quiescent phase is an adaptive behaviour in preparation for later, as is the hyperactive phase. What is even more fascinating is that each species of Apis has its own window of time for taking off on mating fights. The reason for this is that they are different species in the same region of some parts of the world and this arrangement of timing means that each is more likely to mate with its own species.

Mating Times Vary for Different Species.

Our Western honey bee (Apis mellifera) drones and queens go out mating in the afternoons around 1pm, but 4 species of honey bee in Thailand have different timetables for mating flights². The difference in endophallus (penis) structure between the species helps prevent them mating outside their own species, but the different mating times are key. The study of three wild colonies from each species came up with the following time frames for mating flights:

Apis andreniformis; 12:15-13:45 hrs

Apis florea; 14:00-16:45 hrs

Apis cerana; 15:15-17:30 hrs

Apis dorsata; 18:15-18:45 hrs

The larger the worker bee the later the drone flights began which is really interesting. 

Scientists in the drone activity study concluded that the visible activity on the comb could be a social cue that helps synchronise the activity of all the drones in the colony so that they all go on mating flights at the correct time when the conditions are best. By moving to the outside of the brood nest the drones get out of the way of workers who can get on unhindered with their tasks. All pretty cool discoveries don’t you think?

References:

¹Louisa C. Neubauer, Jacob D. Davidson, Benjamin Wild, David M. Dormagen, Tim Landgraf, Iain D. Couzin& Michael L. Smith, Honey bee drones are synchronously hyperactive inside the nest, Animal Behaviour, Volume 203, September 2023, pages 207-223.

²Thomas Rinderer, Benjamin Oldroyd, Siriwat Wongsiri, H.Allen Sylvester, Lilia Guzman, Sureerat Potichot, Walter Shepperd & Stephen Buchmann, (1993) Time of Drone Flights in Four Honey Bee Species in South-Eastern Asia, Journal of Apiculture Research, 32 (1): 27-33, 1993.