Episode 25 of the podcast is up, and I'm diving back into the book review this week! Check it out on Podbean, or wherever you get your podcasts.
Homestead news:
Bubbles (the hen with heat stress/worms) improved enough that I was able to put her back out in the special needs coop on a cool night. She had stopped drinking large quantities of water and responded positively to the panacur with further firming up of her droppings. She had her second and final dose on Monday, and I also treated her flock mates to make sure they’re not passing parasites between each other. I’m very pleased with her recovery! And super relieved to have her out of my house because it was all very messy and smelly.
My corn is flowering! Very exciting, although not all of them have grown to their full height. I think I placed them a little too close together and plan to expand their bed next Spring.
My tomatoes are fruiting but all green so far. I need better stakes to support them as they get heavier.
I had to put out Japanese beetle traps as the milkyspore did not get all of them, alas. Way less than last year but I am still annoyed and will definitely do a Fall application
It was my birthday on the 28th and I had a magical day! Leisurely breakfast, gifts, swimming at the local lake, free birthday drink at my fave coffee place, and then takeout from a new (to us) restaurant. I made my husband watch my fave romcom (‘someone like you’) with me, and drank way too much, which led to drunkenly dancing with my whippet, Chappie. It was wonderful! I felt extremely blessed to spend the whole day with my husband, and it was very special, even though we couldn’t go out and do our usual birthday adventure/meal out/social event.
My bestie also treated me to an early birthday celebration the weekend before, which was amazing. I have been very spoiled this year and feel very loved!
Hive updates:
Not a huge amount to report currently! I was able to take 4 more frames for extraction, and now have replaced the honey that I had bottled so I need to place a much larger order of jars. I had an easier time uncapping the frames this time around, which is nice!
The queen cells in my queenless split have just hatched so somewhere in there is a virgin queen. I am hopeful she survives her mating flight(s) and returns well mated!
My 3 nucs are getting along very well, and I am optimistic about their chances for winter if things continue
We’re in a nectar dearth now and I didn’t notice until I triggered robbing behaviour in my colonies. I posted a 1 minute video on Instagram that shows what this looks like, which I'll share below as well. Thankfully, I was able to prevent further robbing by spraying down the hive.
What is robbing?
Sources:
‘The Backyard Beekeeper’, 4th Ed, Kim Flottum
‘BeeCabulary Essentials’, Andrew Connor
‘Beekeeping for Dummies’, 4th Ed, Howard Blackiston
Robbing is when bees steal food from other hives, usually during a dearth. They become extra sensitive to the scent of nectar/honey, and will descend upon a weaker hive in an attempt to take all of their honey and nectar.
Robbing leads to fighting: the bees being robbed become defensive and will fight to the death to protect their hive. Meanwhile, the robbing bees will be willing to sting in order to help their sisters break through the guard and get to the sweet resources inside. This causes alarm pheromone to quickly fill the air, and nearby colonies will respond with defensiveness. This pheromone can travel quite far, causing numerous colonies to respond defensively, and therefore increasing the chance of someone or some critter being stung should they stray too close to a hive.
How can you tell what is normal behaviour vs robbing?
Normal:
Foragers go to and from the hive with purpose
They fly out, up, and away directly
They return heavy and tend to land solidly on the entrance board
Orientation flights can be seen; lazy figure-8s
Overall, the appearance and feel of the activity is purposeful and calm
Robbing:
Incoming foragers are not weighted down with nectar
They don’t fly directly to the entrance but tend to fly side to side as if looking for something
There’s fighting at the entrance; bees tumbling together, falling onto the ground, tussling and stinging
Robbing bees leave the hives weighted down
Robber bees often climb up the hive before flying away and their weight causes them to dip slightly after take off
Prevention:
Reduce the entrance on weak colonies and don’t place them too close to stronger ones
Don’t use open feeders
Don’t work a colony during a dearth
Don’t dispose of burr comb on the ground near your colonies
When harvesting for honey, make sure to move frames into an airtight container
If removing whole supers, place them on a solid board and cover them tightly
Kim Flottum suggests opening boxes you need to work the day before, breaking the seals and any burr comb, and allowing the bees to clean up overnight. They will not be able to reseal them by the next day but the scent of honey and comb will be less strong when you go back in.
Robbing screens: designed so that the bees of the hive are redirected up as they leave. Robber bees are attracted to the airflow coming from the entrance and remain low; they do not fly up and over the screen to enter.
Stopping robbing behaviour:
Close up entrances of the hives being robbed
Take off covers of the hives doing the robbing; this changes their behaviour from attacking to returning home to defend their colony (last resort, IMO)
Cover robbed hives in a wet sheet that hangs to the ground
Spray hives with water or set up a sprinkler! Bees will return to their own hives.
'The Lives of Bees', Thomas Seeley.
Chapter 7: Colony Reproduction
‘An individual is fit it its adaptations are such as to make it likely to contribute a more than average number of genes to future generations.’
-George C.Williams, Adaptation and Natural Selection, 1966
The chapter opens with a comparison between the reproduction of apple trees and honey bee colonies. Both produce male and female ‘units of reproduction’; queens/seeds, and drones/pollen. Both send out their females within a larger structure; the apple with seeds tucked safely inside, and the queen bee leaving her old colony in a swarm of some 10,000 bees. Similarly, both invest less in the male units; both pollen and drones leave their home unprotected. Just as a colony will produce only a few swarms each year but thousands of drones, the apple tree produces far less fruits than the millions of pollen. This comparison will become more clear later in the chapter.
To begin, Seeley reminds us that colony reproduction has usually been approached from an agricultural view point, i.e. one aimed at maximizing honey production. This often entails actively trying to prevent colony reproduction through the natural process of swarming. How we tend to manage our colonies also limits drone production to some extent as we prioritize worker cell production over drone. For this reason, Seeley looked to wild colonies to see how they regulate their production of swarms and drones throughout the year.
Drone Production Peaks Before Queen Production
A study by Robert E.Page Jr in Davis, California, that examined 13 colonies demonstrated that drone production peaks early in the Spring (early April), while swarm production peaks 30 days later in early May. This makes sense if you consider both the biology of drones and the process of queen mating. First, drones take 24 days to emerge and then require another 12+ days to reach sexual maturity. This fits nicely within that 30 day (give or take) window. Second, knowing that a queen bee will mate during a fixed period of time before spending the rest of her life laying eggs, it makes sense that maximum drone production would be beneficial before swarming season as this dramatically increases the number of drones available for mating, thus maximizing genetic diversity.
Two studies looked at how much drone comb is made by colonies that are left unmanaged; the study by Robert E. Page that was just referenced, and one by Michael L.Smith et al in Ithaca. Page measured the area of capped drone comb, whereas Smith measured areas of drone comb that contained all stages of life (egg through to capping). Page’s 13 colonies consisted of 10 frame Lansgtroth boxes, each containing 2 frames of drone comb, whereas Smith studied 4 colonies in observation hives with natural comb they had made the previous year.
Both studies had similar results. Over a summer, the average number of drones produced was 7,812 (Page) and 6,949 (Smith). These 2 numbers will be important for later in the chapter so we will revisit them.
Drone comb serves two primary purposes within a colony; the rearing of drones, and honey storage. In the Fall, drone comb is used for honey storage. By Spring, this can mean that these cells are potentially still full of honey when the colony needs to start raising drones. As a result, it has been noted that colonies will preferentially remove honey from drone comb in the Spring. This was clearly demonstrated in a study by Michael L. Smith where frames of drone and worker cells were pre-filled with thick sugar syrup and placed within hives each month from April to September. In the Spring months, the average area cleared of syrup was larger for drone comb than worker. In late summer and early Fall, little syrup was removed from the drone comb as drone production was no longer a priority; honey storage was instead.
Queen Production and Swarming
This section opens with a quick rundown of queen production within a colony. In the Spring, a colony builds its population of worker bees and begins to create queen cups; “tiny inverted bowls made of beeswax” (pg.161). The queen lays upwards of a dozen fertilized eggs within these special cells, which are then drawn out by the workers into the distinctive queen cells that are positioned vertically on the frame. The larvae within are fed the royal jelly, and will emerge as virgin queens within 16 days.
While these new queens are developing, the original/mother queen is going through her own changes. The workers feed her less over time, which causes her egg production to decline and her abdomen to decrease in size. The workers will also grab hold of the queen and shake her violently, which appears to keep her moving throughout the day. All of this results in the queen losing 25% of her original body weight.
Not long after the first queen cell is capped, the mother queen leaves the colony with round 10-20,000 workers in a swarm. Once a suitable nest cavity has been found, the swarm will follow the scout bees to this location, which is “rarely less than 300 meters (ca. 1,000ft) from the bees’ original residence, and can be 3,000 or more meters (more than 2 miles) away.” (pg.162)
On average, the first virgin queen will emerge 8 days after the prime swarm has departed. If the original colony was greatly weakened by the swarm’s departure, the workers will allow the first emerging queen to seek out and kill her sisters. If, however, the colony has maintained or returned to full strength, workers will guard the remaining queen cells from destruction, exercise the first queen to emerge, and eventually depart as an ‘afterswarm’.
Whether a colony produces afterswarms depends entirely on its population of workers and brood. A number of studies have been conducted on swarming behaviour, including the production of afterswarms. From these (most notably a study conducted by David C. Gilley and David R.Tarpy), we learn that the probability that a colony that has already produced a prime swarm will have an afterswarm is 0.70; the probability that there will be a second afterswarm is 0.60; and the probability that a third daughter queen will then remain in the original nest is 1.00. (pg.164)
In terms of survivability, the daughter queen who inherits the original nest, with all its rich resource of comb and food stores, has a much higher rate of winter survival: 0.81 (aka 81%). For all the queens that left the original colony, including the mother queen, their winter survival rate is usually less than 0.20.
Looking at these statistics, Seeley wonders why a mother queen would risk leaving the colony to face possible winter failure? He believes it is due to the higher probability that she would be killed if she remained in the colony with the newly emerging daughter queens. A study conducted by Gilly, Tarpy, and M.Delia Allen in Aberdeen, Scotland, in the 1950s, demonstrated that a colony will usually have one virgin queen depart in a prime swarm, one virgin queen inheriting the original colony, and 5.3 virgin queens killed by their sister(s).
“Clearly, the mother queen does well to flee the killing field of her old nest before her murderous daughter queens emerge from their cells.” (pg.164)
How A Population of Wild Colonies is Persisting
In Chapter 2, we learned that the population of wild honey bee colonies within the Arnot Forest had been relatively stable since they developed resistance to the varroa mite. We have since read about how weather, forage, colony build up, wax production, and swarming all directly affect survival rates. In this section, Seeley details 2 long term studies he conducted (1974-1977, and 2010-2016) on colony generation (swarming) and colony loss.
For these studies, Seeley worked with simulated wild colonies (SWCs) that had been set up in movable-frame hives, and wild colonies located in natural nesting sites. 20 SWCs were established in individual, secluded area, using 10 frame Langstroth hives. Swarms were then captured and housed within these SWCs. Each hive contained 2 frames of drone comb and 8 of worker, and the entranced was reduced to a small, natural sized opening. The queens were labeled in order to track them (as they swarmed, were superseded, etc). Colonies were inspected in early May, late July, and late September; before and after the primary swarming season for the area. The main focus of these inspections was to assess whether the mother queen had swarmed, and to check the colonies for disease.
The wild colonies used for this study were located by Seeley directly via bee-lining, or by others who had been told that he was looking for trees occupied by honey bees. Once colonies were located, Seeley visited them on the same schedule as he did the SWCs, and noted whether the colony was still alive. He also tracked whether a nest that had been empty due to colony death had been repopulated by a swarm. 42 nest sites were ultimately examined: 26 in trees, and 16 in rural buildings (barns, cabins, etc) from 1974-1977. For the later study (2010-2016), 33 sites were monitored: 20 in trees, 13 in rural buildings.
Both studies yielded similar findings about colony survival and reproduction. These results are summarized best in a table that I’ll post on the blog but a few key points: in regards to whether a colony will swarm, the probability is much higher (0.87) than the possibility that it will not (0.13). Similarly, the probability that the monther queen will leave with the prime swarm is 100%, as is the probability that a daughter queen will inherit the original nest. There is then a 70% chance that a daughter queen will leave in an afterswarm, and a 60% chance that a second daughter queen will leave in another afterswarm. The survival rate of the prime swarm is about 23%, compared to 81% survival rate of the daughter queen that remains in the nest, and a mere 12% for the afterswarms.
Seeley identifies 2 key points from these results:
Although 87% of wild colonies will swarm, even producing multiple swarms in one season, the overall growth rate of colony population is low: just 0.14 of new colonies are added to the overall population each year. This rate appears to be sufficient to replace any losses caused by poor forage or hard winters.
The population appears to be at “carrying capacity” (pg.168); aka at the maximum sustainable population
How Long is a Bee Tree Alive With Bees?
This section looks at how long a nest cavity will be continuously inhabited by honey bees. Seeley calculated the average lifespan of a nesting site using the results from the previously discussed studies. Assuming that each site was founded by a prime swarm, that nest site’s probability of survival to one year of age is 0.23. For each year after that, he added 0.81 (the survival rate for an established colony, aka one that has survived its first winter). Based on these calculations, the average occupation of a bee tree as a nest is a mere 1.7 years. This low number reflects the fact that newly swarmed colonies have such a low survival rate their first winter (23%).
In contrast, Seeley learned that a colony that survived its first winter will likely occupy that nest site for another 5.2 years. During his 6 year study (2010-2016) of 33 nest sites, 8 of those sites were occupied for all 6 years, with 1 site having a 7 year record of continuous occupation as of May 2017.
Investment Ratio Between Drones and Queens
“The most striking feature if the reproductive biology of honey bees is their astonishingly skewed sex ratio.” (pg.171)
As discussed earlier in the chapter, a wild colony will, on average, produce 7,500 drones each year, compared to 2.3 swarms (1 prime, 1.3 afterswarms). Despite this vast disparity in male and female reproduction, Seeley notes that evolutionary theory predicts an equal allocation of resources to male and female production since half the genes come from the male units and half from the female units. This means that each sex functions equally as a means to genetic success. So when we see 7,500 drones vs 2.3 swarms, it initially appears that honey bee colonies defy this prediction. However, to truly assess this apparent disparity, one has to assess a colony’s total reproductive investment in it’s reproductive males and females. For drones, we can examine how resources are utilized to produce and support drones throughout their lives. For females/queens, allocation of resources is far more complex.
Seeley suggests that one should calculate a colony’s total expenditure of resources on queens by taking into account every aspect that leads to the production of a swarm. This takes us back to the opening chapter’s comparison of honey bees to apple trees: how each sends forth the female unit protected within a complex, protective structure (swarms for bees, apple fruit for seeds).
Seeley then narrows this look at resources spent by assessing the dry weight of the bees that the colony produces for drones and swarms. Using previous studies on the average number of drones produced in a year (7,380) and the average dry weight of a drone (45mg), Seeley calculates that the average total investment of a colony each year is 332g/11.7oz of dried drones. To calculate the dry weight of a swarm, Seeley looks at the average number of workers produced over a summer (23,024) and the average dry weight of a worker (17mg), multiplying these two figures together to get an average colony investment of 391g/13.8oz of dried workers. Looking at these figures (332g vs 391g), we can see that they are roughly equal.
Seeley also proposes that calculating the cost of fueling workers and drones would yield similar results. Although drones will be fed throughout their lifespan by their sisters, the workers that will swarm eat less until right before swarming, where they gorge themselves. It is Seeley’s suspicion that the amount of food consumed by each sex would be approximate.
Optimal Swarm Fraction
This section looks at how natural selection has affected the percentage of a colony’s workforce that leaves with the prime swarm (called the ‘swarm fraction’ here). This aspect of colony life is of particular interest because it is not manipulated by beekeepers; it is an innate part of honey bee biology, and thus under their total ‘control’.
Knowing as we do that the swarm’s workforce will face the energy intensive task of building comb for its new home, we could assume that a swarm needs a large amount of workers to succeed. The question, though, is what percentage of the colony population is optimal? What will maximize genetic success?
To answer this question, Seeley used previous studies on the subject to come up with a mathematical model that would allow one to calculate the optimal swarm factor of a colony using 3 key, measurable factors. He then compared these results to observations of wild honey bee colonies. The purpose being to demonstrate whether this model yields an accurate result.
This next section looks rather scarily like my old algebra textbooks so I’ll do my best to sum up the model/formula used.
There are 3 key factors to this model:
Genetic relatedness of a worker to the offspring of each queen
Winter survival probability of each colony (mother and sister) if x amount of workers leave with the mother queen
The expected reproductive success of each colony if x amount of workers depart with the mother queen
In this model, x is called the “swarm fraction”. It refers only to the adult workers of a colony (nurse bees would have no use for a swarm as they cannot fly yet and would not leave the brood).
To determine the winter survival probability for the mother and sister queen colonies, Seeley started with 15 colonies in June 2008, from which he produced an artificial swarm (or split) from each. The mother queen and some portion of workers was removed in each swarm. The portion of workers taken was split into 3 groups: 90%, 60%, or 30%, with 5 colonies for each group. So 5 colonies had 90% of the work force removed for the artificial swarm; 5 had 60, and 5 30.
Each swarm was placed in a 10 frame Langstroth hive with empty frames (just as how wild swarms would need to build comb in their new nest). Colonies were checked once a month from July 2008 to April 2009, only to see if they were still alive.
More eye-crossing math happens here but the gist is that this model’s results demonstrated that a colony’s optimal swarm fraction is between 0.76-0.77, aka 76%-77% of workers leaving the colony yields the greatest success. When wild colonies are observed, this optimal swarm fraction comes to 0.72. This closeness in results demonstrates that worker bees are maximizing their genetic success by preferring to leave with the mother queen rather than stay with the sister queen, and that the model is an accurate way to assess the swarm factor of a colony.
It makes sense that natural selection would favour a large percentage of workers leaving with the mother queen as they face the task of building comb and helping shore up the numbers before winter arrives.
Wild Mating
Honey bee mating habits have been known since the 1950s, when researchers realised that virgin queens do not have chance meetings with drones, but instead travel to drone congregation areas, which are often 30-60ft in the air. Drones arrive at these areas first, circling each site, until a queen arrives. Virgin queens fly alone, without a protective group of workers, and is therefore vulnerable to predation. Due in part to this, most queens will take just one mating flight, pairing with an average of 10-20 drones.
Study of these drone congregation areas indicates that their location remains consistent. One such location in the Austrian Alps has persisted since the 1960s! Both queens and drones will fly long distance to reach these areas. Studies indicate that queens fly an average of 1.2-1.9 miles from their hive to mate, with drones flying an average of 3-4.2 miles. Seeley references a study conducted in Austrian Alps by Friedrich and Hans Ruttner that worked with 19 apiaries, capturing drones, and marking them with a specific colour for each apiary. They then captured drones at known congregation areas and identified which hives they came from, thus being able to work out how far the drones had flown from their home. For the 2 congregation areas studied, the average flight distance was 1.9 miles and 1.4 miles.
These numbers line up with another study on drone flight distance conducted in Canada by Donald F.Peer in the 1950s. The area he chose for his study had no honey bee colonies but those he established himself. He set up 20 colonies with drones that had the Cordovan allele (a recessive colour mutation), as well as mating nuclei that contained only workers and a virgin queen, each that was homozygous for the Cordovan mutation. These mating nuclei were placed at sites away from the 20 drone producing colonies, all positioned at varying distances. 22 queens were placed more than 12-14 miles (19.3-22.6km) from the colonies, and none of them were mated. Those queens placed 10 miles (16km) or less away did mate successfully, and exclusively with drones carrying the Cordovan allele (those in the study group). Bear in mind, the nature of this study means that these results indicate maximum range, not typical or average range. However, the sheer distance traveled by drones indicates that outbreeding is clearly the norm for honey bees.
Is Polyandry Weaker in the Wild?
Polyandry: a female mating with multiple males
Interestingly, polyandry is not common among insects but is seen in all species of honey bees. But how was it discovered that a single queen mates with multiple drones? What methods were used to assess the genetic diversity of bees within a colony?
Basically, scientists studied the heritable genes of worker bees, identifying the genotypes, in order to assess how many sperm donors would have been needed to explain the genetic diversity of these results. From these studies, it’s known that queens will mate with an average of 12 drones.
Seeley asks the question: why are queen bees so promiscuous?
It is not an issue of sheer sperm volume. We know that queens typically store about 5 million sperm, whereas the typical ejaculate of a drone contains 10 million sperm. So clearly this is an issue of genetic diversity, especially if you consider that of the 100 million sperm (or more!) that a queen receives during her mating flight, the 5 million that she keeps is a completely randomized mix. Genetic diversity within a colony can lead to such things as improved resistance to disease, enhanced food acquisition, better temperature stability, etc.
Historically, studies that looked at the genetic diversity of a honey bee colony used colonies managed by beekeepers. Seeley wondered if this level of diversity would be reflected in wild colonies, especially considering the increased distance and lower population between unmanaged colonies.
To answer his question, Seeley worked with David R.Tarpy and Deborah Delaney to determine the mating frequencies of queens within his study area of the Arnot Forest. In August 2011, Seeley and one of his students located 10 colonies living within bee-trees, and collected 100 workers from each colony. They also collected an equal sample number from the 20 managed colonies within the study area to use as a comparison. These managed colonies belonged to a commercial beekeeper who bought their queens from a queen producer in California, making these genes distinctive and easy to identify within the samples.
Looking at the paternal genes of workers from all 30 colonies, no significant difference in number of fathers was found. The 2 managed apiaries (with 10 colonies each) had an average of 19.8 drones and 16.6 drones, which is not statistically distinguishable from the wild colonies that had an average result of 15.9 drones. This indicates that, even in areas where colonies are fewer and widely spaced out, queens do not mate with less drones than in managed apiaries where the queens and colonies are kept close together.
Knowing as we now do that both drones and queens will fly wide distances to reach drone congregation areas, this result is not entirely surprising. In fact, it seems likely that natural selection favoured those bees that flew long distance to mate.
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And that's it for this episode! Next up: Chapters 8&9; Food Production & Temperature Control. So be sure to check back here in 2 weeks, and subscribe to the podcast so you never miss an episode!
Stay safe out there; remember to wear your mask! And, as always, hug your hens and then wash your hands.
Take care!