I'm back with the book review that never ends! You can listen in over on Podbean, or wherever you get your podcasts.
Homestead News:
Started on weeding
Mulch! Mulch everywhere!
Finally covered over the gravel path and put down mulch. Been meaning to do it for 1-2 years at this point so I’m glad it’s done
Cleared up tomatoes. Applied bone meal for blossom end rot.
Painting a few hive supers
Med change going well (aka hurrah for Lexapro!)
Hive News:
Able to do some quick inspections on 8/12 and felt so much better just to get in there
Took queen excluders off to give more room
Lots of honey frames dispersed through the boxes that I am hoping to extract at the start of the Fall flow (leaving in now to a/ avoid inducing robbing, and b/ they might need the food due to the dearth)
Lots of brood! Some of these queens are particularly prolific: nuc #2, Macha, and Saskatraz queens in particular. I’m so glad I was cautioned not to get rid of Macha last year because she has been so amazing this second year. She is an egg laying machine!
I have a top bar hive to play with! Need to put it together and paint the roof. So excited! Considering placing it out when it’s ready in hopes of attracting a swarm
Nuc #1 is still slow to build but the population looks good. I’m hoping the Fall flow will give them a boost. I gave them 2 frames from other hives to make sure they have enough food during this dearth.
New ‘mentee’; has had hive for 3 years but doesn’t really work it beyond honey super removal to harvest each year. Excited to get in there and figure things out!
A BEE STUNG MY SWEET CHAPPIE. How dare she?!
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The book review continues!!
Chapter 8: Food Collection
Seeley opens this chapter with some nifty facts about honey bee food collection:
Forager bees fly as far as 14 kilometers/9.7 miles to gather pollen, nectar, or both
On average, a colony will have several thousand worker bees in use as foragers (about one third of the total colony population)
A colony must constantly monitor internal and external hive conditions to maximize food collection and storage
This chapter looks into these conditions and how wild colonies meet seasonal challenges
The Economy of a Wild Colony
There are 4 key resources that every honey bee colony requires:
Pollen
Nectar
Water
Tree resin/propolis
Pollen is perhaps the most crucial of these resources as it’s the primary food source for the brood. It contains essential amino acids, fats, vitamins, and minerals. It also prevents the hypopharyngeal glands (that allow bees to produce brood-food) from atrophying in nurse bees. This appears to be why pollen is stored by the brood; it increases access to it by the nurse bees who use it to feed and nurture the developing generation.
A forager who returns to the hive with pollen will go immediately to the brood area, search around the margins for an empty cell, and then spend approximately 10 seconds carefully and thoroughly emptying her pollen pants (not a scientific term!). The result is a neat, tidy band of pollen cells around the brood nest.
For those foragers who have sought nectar for the colony, they will return with noticeably swollen abdomens. Occasionally, foragers will return equally swollen with water. Foragers of both these liquids will disgorge them into the waiting mouths of nest bees, who then take them deeper into the hive for storage. Interestingly, the receiver bees are predominantly middle aged. Those that receive nectar might distribute it to other bees for immediate consumption but most is stored for future use. Water receiving bees will either spread droplets over the combs if the nest requires cooling, or give it directly to the hardworking nurse bees who need it for hydration and brood food production.
In Chapter 5, we learned that honey bees collect tree resin to seal holes and cracks within the nest area, as well as to coat the walls and floors due to its antimicrobial properties (that seems to assist with overall colony health and hygiene). This resin collection is most often seen in late summer and early fall.
Seeley decided to examine just how much pollen and nectar is collected by a colony in a year, and therefore ascertain just how much energy is expended on this endeavour. As has been consistently noted, most studies on this subject have focused on managed colonies so there is very little data on the food collection habits of wild honey bee colonies. To correct this gap in the literature, Seeley decided to focus his study on unmanaged colonies that he calls ‘simulated wild colonies’ (SWC). These consists of colonies kept in hives the size of natural nest cavities that are monitored via weighing once per week for 3 years but are others left entirely unmanaged.
The location of this 1980s study was New Haven, Connecticut, which is roughly 250 miles east of Ithaca. Seeley noted that his colony populations ranged from a minimum of approximately 8000 adult bees in March to a maximum of 30,000 adult bees in May to June. The biomass for this number of adult bees is around 1 to 4 kilograms or 2.2 to 8.8 pounds. This is a critical data point as Seeley intended to ascertain the colonies food reserves based on the weight of the nest, and would therefore need to know the weight of the bees themselves (and the surrounding hive) to reach an accurate total. He calls the sum of colony mass, food reserves, and nest weight the ‘hive weight’.
From September to April when the colonies collected very little (or no) food, the hive weight naturally decreased at a steady rate as the bees consumed their food stores. On average, the total mass of food consumed over winter was about 25kg/55lbs; 1kg/2lbs being pollen and the rest honey.
Calculating food consumption during the warmer seasons (late April to late September in New York and New England; the areas of study) is much more complicated to ascertain. For one, the colony is expanding rapidly with brood production, and the resources used for this conversion of food to baby bees is not represented in losses of hive weight. Secondly, forage varies considerably over this period, especially due to the vagaries of weather, and thus figuring out exactly what is being used vs stored becomes a little trickier. That said, during this study, the summer had an extended period of cool and wet weather, which allowed Seeley to figure out summertime rate of food storage via the drops in hive weight, which ranged from 1-4kg/2.2-8.8lbs per week, and averaged 2.5kg/5.5lbs per week. If you multiple this average (2.2kg/5.5lbs) by 22 weeks (the summer season of late April to late September), you get a total of 55kg/120lbs, which equals the total mass of resources consumed.
In order to ascertain what portion of this food storage used is pollen, Seeley posits that it can be estimated by considering the fact that it takes around 130 milligrams (0.004 ounces) of pollen to produce a single bee, and the average colony population is 30,000 bees throughout summer. We know that worker bees in the summer live an average of one month, which gives us an estimate of around 150,000 bees produced over the 5 month summer period (if a colony population remains at a steady rate of 30,000 bees then we multiply by by 5 to get the total). 150,000 bees multiplied by 130mg of pollen to produce each bee gives us a total pollen consumption of 20kg or 44lbs over the summer period.
In summary, the yearly food consumption of a wild colony (in Seeley’s study area) is approximately 20kg/44lbs of pollen, and 60kg/132lbs of honey (25kg/55lbs in winter plus 35kg/77lbs in summer). These are estimates, and the numbers will be effected by such things as forage, local climate, and colony size (a larger colony will need more food, etc). What’s interesting is that the estimates of food consumptions for colonies that are managed for honey production are dramatically higher: rearing as many as 250,000 bees annually, and consuming 20-35kg/44-77lbs of pollen, and 60-80kg/132-176lbs of honey per year.
Looking at this sheer wealth of food consumption and storage, how many foraging trips are needed to procure all of this bounty? Again, Seeley wows us with some maths!
The average load of pollen weighs 15 milligrams or 0.0005 ounces. Multiplying this by the yearly pollen total of 20kg/44lbs, we can see that about 1.3 million foraging trips are needed. The average flight distance (there and back) for a forager is 4.5km/2.8 miles, and a flight will cost about 6.5 joules per kilometer. Pollen has an energy value of 14,250 joules per gram, so we can figure out the total flight cost of each trip by multiplying 3.8 by 10^7 joules. This gives an approximate 8:1 energy return ratio when collecting pollen.
Using similar maths, Seeley estimates that the production of 60kg of honey requires about 3 million foraging trips. That gives an energy return ratio of 10:1 when collecting nectar.
Side note: what do we mean by energy return ratio/ratio of energy return? Basically, it’s how much energy is GAINED vs how much energy is SPENT during the collection of honey/pollen. So in the 10:1 ratio, 1 is how much energy a bee burns but 10 is how much they gain during that energy expenditure. This means that foraging, despite being energy intensive over time, provides a net gain for each bee and thus the colony as a whole. Simply put: how much do you have to spend to get something? If you get 10 things but it only cost you 1, that’s a profit vs a loss.
Looking at these figures, we can see that honey bee colonies living in areas with cold winters must do an enormous amount of work in order to find and store enough food for the cold months.
“Each colony can be thought of as an organism that weighs 1-5 kilograms (ca. 2-10 pounds), rears 150,000 bees, and consumes some 20 kilograms (44 pounds) of pollen and 60 kilograms (132 pounds) of honey each year.” Pg. 194-195
This represents some 4 million foraging trips and over 20 million km/12 million miles!!
Knowing this, it’s clear that natural selection has led to this great skill in food collection.
A Vast Scope of Operation
Yah, more maths! (I say while weeping bitterly.)
A honey bee colony can forage over an area of more than 100 square kilometers or 40 square miles. Seeley points out that the ability for a bee to fly around 6km/3.6 miles from home at a rate of 30km/18miles per hour is equivalent to a human flying around 600 km/360 miles!!
Seeley mentions previous studies that tracked honey bee foraging trips by marking foragers in their hives with paint, radioactive isotopes, fluorescent powder, or genetic colour markers. These bees would be captured in the field/wild as they foraged and the distance they had flown from their home hive could then be ascertained by their hive identifying marker. Another study would capture bees in the field and glue a tiny, metal ID disc to them. By installing magnets at the hive entrance, the discs would be removed from returning foragers and enable the researches to work out how far that bee had flown. Pretty nifty stuff!
These studies demonstrated that most foragers examined were traveling within 2km/1.2 miles of their hives. If no closer flowers were available, they would fly as far as 14km/8.7 miles to source pollen and nectar.
In 1979, Seeley and his friend/colleague, Kirk Visscher, started their own study in an attempt to get an accurate view of the foraging activity of a wild honey bee colony. They decided to ascertain where foragers were going by observing the waggle dances of returning foragers. This technique was pioneered by Dr Herta Knaffl in 1948-1950, and is surprisingly accurate. The only downside to consider is that it does not give a reading of all foraging sites as bees will only waggle dance for the most profitable sites (that need more bees enlisted to exploit them). Still, Seeley chose this method because it gives a good spatial scale of a colony’s foraging area.
Seeley set up an observation hive with a volume of 40 liters (10.6 gallons), which is the average volume of wild nest cavities. They set up the hive entrance to direct all returning bees to the glass observation area so that they would be able to see the waggle dances as they were performed. They installed a colony of around 20,000 bees (and queen), and moved the hive to the Arnot Forest, where it was placed within a hut.
Observations were taken from 8am-5pm, and manually recording data from one bee at a time, chosen at random. For each bee, they noted:
The angle (relative to vertical) of her waggle runs
The duration of her waggle runs
The colour of her pollen loads (if any)
The time of day of her dance
This allowed them to estimate where she was foraging, and whether she was sourcing pollen or nectar. They also carefully noted her recruited target on the map, allowing them to eventually ascertain what were the most bountiful areas of forage for the colony.
Overall, 1871 dancing bees were observed during four nine-day periods throughout the summer of 1980. These bees foraged both close to the hive and in a wider area. The most common distance traveled was 0.7 kilometers or 0.4 miles; the average was 2.3km/1.4 miles; and the furthest was 10.9km/6.8 miles. As predicted, the average distance traveled changed throughout the summer in response to the amount of forage available. Bees would travel further when local sources were poor. Most noteworthy was the discovery that 95% of the colony’s food resources covered an area greater than 113 square kilometers or 43 square miles!
One could ask if this study was exceptional in its results but studies conducted by researchers in disparate areas have yielded markedly similar results. One conducted by Herta Kaffl in 1953 showed that 95% of the 2456 dances recorded led to food sources less than 2km/1.2 miles away. She also observed that bees had discovered bountiful food sources as far as 5-6km/3.0-3.6 miles and even 9-10km/5.4-6 miles away.
Similarly, a study conducted in Sheffield, England, by Madeleine Beekman and Francis L.W. Ratnieks, during the ling heather (Calluna vulgaris) bloom, showed that their colony’s foragers would travel as far as 5-10km/3.1-6.2 miles away. Half of all waggle dances observed represented sites of forage more than 6km/3.6 miles away from the hive, and 10% represented areas more than 9.5km/5.9 miles away.
These results demonstrate how important long-distance flying is for a bee colony to source food.
Treasure Hunting by The Bees
To maximize the benefit of foraging within their range, honey bees must be able to find the most bountiful sites, and do so before other colonies have done so (returning home with 100s of competitor bees). This led Seeley to ask how capable is a colony of surveying its environment? How quickly can they detect a new patch of food-rich flowers?
To answer this question, Seeley took 4 colonies and set up a ‘treasure hunt’ using lush patches of flowering buckwheat (the treasure). He dispersed these patches within a large forest and then measured each colony’s success in finding these rich food sources. The forest in question was Yale Myers Forest, which is 7,840 acres/3213 hectares in size, and is very similar to the Arnot Forest.
Seeley clustered his 4 hives close together and dispersed a total of 6 buckwheat patches, each of which was 100 square-meters/1078 square-feet in size. These were placed a varied distance of 1.0-3.6km/0.6-2.2 miles from the hive cluster. The bloom of these buckwheat patches was timed so that it happened when little other forage was available; late June and again in mid-August. Choosing a colour to mark each patch, Seeley would mark foraging bees found on these flowers; around 150 in total for each area, and then returned to the hives to see which foragers returned to which hive.
His results showed that the colonies had high chances of discovering those patches at 1000 meters/0.6 miles and 2000 meters/1.2 miles but none found the patches at 3200-3600 meters/2.0-3.7 miles.
To put these results in perspective: a patch of flowers about half the size of a tennis court represents less than 1/125,000 of the area within a 2km/1.2 mile circular area (from the hive), and that the 4 colonies studied had a 50%+ chance of discovering a flower patch of this size located with 2km of the hive.
Choosing Among Food Sources
Discovering food sources is clearly an important trait of the honey bee but how does a bee choose which patch to visit and how frequently? In order to maximize their resources, a foraging bee must choose the richest food sources after discovery.
In the previous study mentioned where Seeley and Visscher observed the waggle dances of foragers returning to an observation hive, they noted the time of each dance, and it is now known that the longer the waggle dance, the richer the food source. These longer dances were noted on the map, indicating the colony’s most attractive food areas for each day.
These results demonstrated that the richest food sources can change on a daily basis. I won’t compile all the results here (although you can find them on pg. 205 if you’re interested) but, to give an example, one day they noted that the main area of recruitment was 0.5km/0.3 miles SSE and SSW of the hive, with one site being 2-4km/1.2-2.4 miles SSW. The very next day, however, the main focus of the foragers was an area 0.5km/0.3 miles NW, with a previous day’s area of interest now resulting in few, if any, waggle dances. This makes sense if we consider the nature of flowers; how nectar and pollen is affected by weather, and previous pollinator visits.
Although this study yielded fascinating results, Seeley decided to enact a separate study that looked at the amount of foragers exploiting various forage sites. To do this, he marked all 4000 worker bees from a colony and then moved them 240 km/150 miles to Cranberry Lake Biological Station (CLBS). This area consists primarily of forests, bogs, and lakes, and therefore is not a rich source of food for the bees. In fact, no wild colonies live in this area due to this lack of food. Seeley needed an area with no natural food sources so that his colony of carefully labeled bees could not be lured away from the 2 feeders he set up as part of his study method.
These feeders were set up north and south of the hive at a distance of 400 meters/0.25 miles. Initially, they were filled with a 30% sugar syrup; attractive enough to lure in foragers but not so rich that it would trigger recruitment behaviour. Once the bees had been ‘trained’ to find these feeders, Seeley then began his experiment. Starting at 7.30AM, he set up the North feeder with the 30% solution and the South feeder with a 65% sugar solution. By noon, the colony had 91 bees returning from the South site and just 12 from the North. They then switched the feeders so the richer solution is now in the North; by 4pm, the bees had switched their focus to this feeder. This was repeated again the following day.
The results show that a colony does, in fact, track the richest forage sites, and can switch focus quite quickly; taking just 4 hours to completely reverse their original focus of forage.
Honey Robbing in the Wild
This section seems particularly timely for me as I spoke last episode about robbing behaviour in honey bees, as well as my recent experience with it (and we are still in a dearth, sadly, although I have noticed an increase in pollen forage so fingers crossed the next nectar flow isn’t too far away!).
Seeley points out that stealing honey, despite the potential fatal consequences for the robber bee, is worth the risk when you consider that nectar has an average sugar concentration of 40%, compared to 80% in honey. Similarly, a forager might need to visit hundreds of flowers to gather a full load of nectar, whereas a robber bee need only go to one area and consume as much honey as they can.
Robbing is an example of intraspecific kleptoparasitism; aka parasitism by theft. Seeley notes that it is also a mechanism for interspecific parasitism by fostering the transmission of parasites and pathogens between colonies. Varroa mites will readily hitch a ride on a robber bee, and American foulbrood spores can also be transmitted in this manner. Seeley points out that to truly understand how much robbing behaviour is contributing to the transmission of disease and parasites between colonies, one must first ascertain how long these agents of disease can survive in dead or dying colonies, as well as how quickly they will be found by robber bees.
In an attempt to answer the question about discovery of weakened colonies, Seeley and one of his PhD students, David T. Peck, set up an experiment to determine how quickly unguarded honey is discovered by honey bees. He chose two sets of test subjects: wild colonies within the Arnot Forest, and 5 managed apiaries at Cornell University.
The wild colonies are spaced an average of 1 colony per kilometer/0.6 miles, whereas the managed apiaries are arranged in pairs on hive stands spaced less than 1 meter/3 feet away from the next pair. Unguarded honey was provided in ‘robbing test boxes’ (RTBs) made by cutting Langstroth hive bodies in half, and adding a wall, floor, and lid. The entrance opening of each RTB was just 2.5cm/1inch in diameter and spherical in shape, drilled into each end of the box. Each RTB was given one frame of capped honey, and 3 frames of older, aromatic comb.
During October of 2015, frost had killed off most of the flowers in the area so the bees were keen to find another food source (and thus more likely to begin robbing from other hives). 10 RTBs were placed in the Arnot Forest at this time, as were 10 at the apiary site in Ithaca. The RTBs were hung from high tree limbs to avoid being discovered by bears, and all boxes were placed about 1km/0.6 miles apart (mimicking the spacing of wild colonies). At the apiary, the RTBs were hung in trees or placed on cement boxes (as bears were not a risk).
Every RTB that was placed at the apiary site was robbed within 24hrs on the first day of good weather. All the RTBs in the Arnot Forest were also discovered but it took 10 days of good weather for this to happen. Seeley had expected the result seen in the managed apiary but did not anticipate that all of the RTBs would be located in the forest by the wild colonies. This leads to the conclusion that, even in the wild, parasite and pathogen transmission can occur via robbing.
Seeley goes on to mention a time he had the opportunity to observe robbing bees in May 2017. He had left out a hive with 2 frames of capped honey in the hope of attracting a swarm, and instead discovered it being robbed by visiting honey bees. Seeing his chance to observe their behaviour more closely, he moved the frames of honey into an observation hive, which he set up in a shed nearby. Rapidly, the robber bees found this hive and began to take from it.
What Seeley observed over a 2 day period is that robber bees will not uncap a honey cell in order to have a personal honey source; she will walk over capped cells and join a group of other robbers drinking from an opened cell. When open cells have been fully plundered, capped cells are opened carefully; in fact, the worker will cut open a tiny hole just large enough for her tongue to enter the cell. Over time, other bees will join her. This means that robber bees spend the largest time in a hive standing closely together, often touching, and rarely moving at all as they drink. On average, Seeley noted that the robber bees spent an average of 12 minutes inside the hive on each trip. Being so close together, and standing so still, we can easily see how varroa mites can move from the comb onto the waiting bees.
If we wondered how varroa mites moved from our managed colonies to those in the wild, here is a good example of transmission. Seeley notes that he was initially surprised to find that varroa had managed to entirely infiltrate wild colonies of honey bees in the Arnot Forest. Now, knowing what he does about the ability of bees to so quickly locate colonies that are ripe to be stolen from, and how long these bees spend inside said hives, he will henceforth only be surprised to find a wild colony without varroa mites.
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And that's it for this chapter! Next episode will cover chapter 9, which is all about temperature control and absolutely fascinating. I'm looking forward to sharing it with you all!
As always, you can find me on the various social media platforms, and you can drop me a line over on those, or email me at homesteadhensandhoney@gmail.com
I love to hear from you!
Stay safe out there.
