Empty Calories

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By Dan Wyns July 2, 2019

Foragers gathering fresh sawdust. Photo: Mike Connor

Foragers gathering fresh sawdust. Photo: Mike Connor

Somewhere early on in a “Beekeeping 101” class you’ll learn that honey bees forage for 4 things: nectar, pollen, propolis, and water. The nectar and pollen become honey and bee bread to provide sustenance. Propolis is used as a structural component and also contributes to colony health through immunological activity. Previous blog posts about propolis here and here provide more information. Water is necessary for a variety of purposes including preparation of brood food and evaporative cooling. So in addition to water, bees need 3 substances produced by plants. But do they collect anything else? Of course they do. If you’ve ever seen open syrup feeding, it’s apparent that the bees will forego the flower visitation part of foraging when a sweet liquid is provided. Bees will also readily gather pollen substitute when bulk fed in powder form. While these nectar and pollen surrogates may not be as attractive or nutritious as the genuine articles they are intended to replicate, they can be important in getting colonies through lean times.

Flowers and their surrogates are what the bees should be getting into, but what are they actually getting into? Some beekeepers have a perception that if bees gather it they must need it, but in my time working in and around bees I’ve seen them get into a lot of different things that probably aren’t great for them. One summer we noticed a propolis traps in a yard were yielding a dark brown, almost black propolis with sharp plastic smell instead of the typical red/orange sweet smelling propolis for the area. When we  sat waiting for the construction worker with the Stop/Go sign to allow us through the roadworks where a new topcoat of asphalt was being applied, we noticed bees collecting road tar to use as propolis. This paper detected petroleum derived molecules that matched the chemistry of local asphalt in propolis from urban colonies, confirming that bees will gather sticky stuff other than plant resins. I’ve also seen bees appearing to collect silicon-based caulking product. I’ve often described the physical role of propolis in the colony as bee-glue or caulking, so seeing one bee resort to gathering our version shouldn’t come as a shock if actual resins aren’t available. Bees gather “real” propolis from a variety of botanical sources depending on geography and climate. Some of the most common propolis sources in temperate climates are members of the genus Populus which includes poplars, aspens, and cottonwoods. For more about the role of propolis in the colony and an overview of botanical sources around the world, check out this article.

It’s not just propolis collection where bees make mistakes, sometimes they get it wrong when seeking pollen too. While building woodware in the shop, I’ve seen bees take a lot of interest in the sawdust from both treated and untreated lumber. I’ve never actually seen a forager pack it onto her corbicula, but beekeepers report bees gathering a variety of powdery materials when pollen is scarce. An early study on pollen foraging noted this tendency,  “During periods of pollen scarcity bees are reported to seek substitutes, such as bran, sawdust, and coal dust, which are of no known value for brood rearing.

Just about any sweet liquid is going to get the attention of honey bees, and I’ve seen them investigate many kinds of sodas and juices. This tendency may be a little unnerving to picnickers, but it isn’t really a problem unless there is a more permanent stationary source of sugary liquid that the bees find. One such case happened when some urban bees in NYC found a bit of runoff syrup from a maraschino cherry factory which was only the beginning of the story.

https://beeinformed.org/2019/07/02/empty-calories/

Drift

      By Dan Wyns     June 12, 2018

     Drift




Bees have incredible navigation abilities that allow them to fly miles away from the colony to forage and return home with enough precision to locate the entrance to their colony, even when there are dozens of nearly identical hives within a small apiary site. The current understanding of navigation is that a combination of position relative to the sun and landmarks across the landscape get them close and then a combination of visual cues and pheromones to precisely locate the colony entrance. When a returning forager ends up returning to the wrong colony, she is typically not attacked as a robbing bee but accepted into the colony due to the pollen or nectar she carries. This process, known as drift, can lead to significant variations in colony strength over time and increase the potential for the spread of diseases and parasites within an apiary. Drift is generally not viewed as a huge problem, but there are some steps beekeepers can take to mitigate the amount of drift happening in their apiaries.

When colonies are aggregated in large numbers and placed in rows of pallets, as is common in a commercial setting, there is potential for excessive drift. Many beekeepers elect to paint all of their woodware white, and this decision may be based on tradition, aesthetic, or other considerations. Others use a variety of colors, which creates a more vibrant apiary and may also help returning forages with orientation. While bees do not see the same spectrum of colors as humans, they are able to distinguish between different shades, assisting them in orientation. In general dark colors should be avoided, particularly in excessively warm and sunny locations, so colonies will not become excessively hot. However, a mix of pastel colors and tones can provide some variation to help bees distinguish individual colonies without adding the potential for thermal stress.

In addition to variations in color, placement relative to other colonies and objects in the landscape can offer navigational aids that limit drift. Many beekeepers have observed that when a number of colonies are placed in a long line the colonies at the downwind end of the line accumulate more bees and yield greater honey harvests while those at the upwind end of the line are often short on bees and lighter in honey stores. By placing an array of hives in circles or arcs, with entrances pointed in different directions, the downwind drift effect can be lessened.  Prominent landscape features can also be helpful in providing orientation assistance. In addition to potentially providing a windbreak, a structure, tree line, or hedgerow close to hives can reduce drift. Orientation landmarks can be particularly important when setting up yards for mating nucs. It is essential that queens return to the correct nuc after orientation and mating flights so extra consideration should be given to visual cues in order to minimize drift in mating yards.

Drift is not something that most beekeepers give a lot of thought and it is certainly not among the most critical factors impacting colony health. Nevertheless, there is a growing understanding of the impacts of horizontal transmission of varroa mites between colonies and the ability to control varroa levels within and between apiaries. Phoretic varroa on drifting foragers are one way that ‘clean’ colonies may become reinfested. Given the ever-increasing number of challenges to bee management, reducing drift represents one area where beekeepers can potentially reduce colony stress for a minimal amount of effort.

https://beeinformed.org/2018/06/11/drift/