The European wool carder bee (Anthidium manicatum) lines her nest with hairs scrapped off the plants like Stachys byzantina or Helichrysum arenarium. Females can be seen with balls of wool under their abdomen, when they carry it back to the nest.
Tag: wildbees
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Potted bees
The majority of bee species nest in the ground. Sometimes a bee chooses a flower pot as her nesting site, digs a tiny burrow and lays her eggs inside. She doesn’t harm plants in the process. If you are a poor gardener, you still have chance for a potted bee – they often prefer pots without much plants and with bare earth inside. Of course they should also have access to some food plants nearby. In areas with seasonality, a pot inhabited by bees should be left outside for winter because they need low temperatures to develop and time their emergence properly.
In my own balcony flower pots the leafcutter bees (Megachile) have been nesting since a few years. Many members of this genus line their nests with cutted leaf parts, so I can see how they repeatedly come home with leaf pieces in their mandibles.
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Vegan
Can you believe that I couldn’t find a photo of the vulture bees which I would trust is properly identified?? So maybe the bee on the cartoon is not a proper necrophagous stingless bee, I apologize for that and if you have a photo of one of the necrophagous bee species, please share it with me!
The vast majority of bees can be considered vegans. Their food, both as larvae and as adults, come exclusively or almost exclusively from flowers. Of course, in biology exceptions are very common 😉 Probably the most notable exception from the vegan-bee-rule are three species of Trigona, called ‘vulture bees’, which feed on carrion. Their ancestors were “ordinary” bees visiting flowers but they specialized in this unusual type of food.
Bees might also feed on honeydew and human tears (which still would make them vegetarian, in contrast to the vulture bees), and maybe they’ll also be portrayed on Non-honey bees some day 🙂
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A laxative for bumblebees
Flowers are the main (and in most cases, the only) source of food for bees. But it’s not their only role in bees’ lifes. They can have also a medicinal value, helping bees to get rid of various pathogens. One of examples is pollen of sunflowers. It helps bumblebees fight the infection by Crithidia bombi, their protozoan pathogen. The mechanism of this beneficial effect was unclear, as scientists could not identify any chemicals present in sunflower pollen which would kill the pathogens. It turned out that there might be none… but the pollen works like a laxative, cleaning the digestive tract from the pathogen’s spores.
Here you can read about the study: Adler, L. S., Fowler, A. E., Malfi, R. L., Anderson, P. R., Coppinger, L. M., Deneen, P. M., … & Stevenson, P. C. (2020). Assessing chemical mechanisms underlying the effects of sunflower pollen on a gut pathogen in bumble bees. Journal of chemical ecology, 46, 649-658.
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Spicy pollen
Pollen is a main food of bee larvae. Adult females and most likely also males need it, too, although in smaller quantities. Not every pollen is the same – they differ in chemical composition, nutritional value, size and shape. It’s not an easy food – the nutritious contents are enclosed inside a hard-to-break cover, and sometimes additionally protected. Asteraceae pollen is an interesting example. It is easily accessible on the flowers but hard to digest by bees. There are some specialist species, feeding exclusively on Asteraceae pollen, but generalists, like bumblebees, don’t develop well on Asteraceae diet. You can find two explanations of this in the literature – one is a chemical defence, ie. some components which are tolerated by specialist bees but harmful to the majority of the others, and the other hypothesis points to the little spines on the surface of the pollen grains which do mechanical damage to bees. I find the idea that pollen pricks the bees eating it, particularly funny.
Here is a paper which was an inspiration to this cartoon: Rivest, S., Muralidhar, M., & Forrest, J. R. (2024). Pollen chemical and mechanical defences restrict host-plant use by bees. Proceedings of the Royal Society B, 291(2018), 20232298.
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Interspecies insect mating
The spring is there (at least in the area where I live!) and each day we can see more and more bees. One of the first thoughts of the freshly emerging males is… mating. They are looking for the virgin and receptive females of their species, alert to their pheromones and to their appearing on the horizon. However, sometimes they make spectacularly misdirected attempt of courtship. They can assault females of other bee species, male bees, and even insects other than bees.
There is an interesting project on iNaturalist.org named “Interspecies insect mating” where you can find a few bee observations. I recommend adding your own, if you are lucky to witness such situation!
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Size (not always) matters
In most bee species, there is not much size variation within one sex, and body size is often useful character in the process of species identification. Bumblebees belong to the exceptions from this rule. In females, there is huge size variation not only within a species but even within a single family. You can see this clearly in the spring – the first ones to emerge are queens which are big. Then very small wokers appear – these are the first brood reared by the queen herself. Then, the next “generations” of workers consist of both big and small ones, and the difference can be even tenfold!
In this paper, the effect of interaction between size of a bumblebee and size of a flower was studied. It turned out that there is not much effect of the sizes of the interacting parties on effectiveness of pollination. It is a good news because it allows us to assume that these interactions are resilient to size changes which might be a result of various environmental factors, like climate change. In the warmer temperatures, organisms tend to get smaller but not every species and population must change their size at the same pace.
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Hard life
Some bee species can use many various plants as their pollen sources (but still, they can have preferences) but there are others which are more or less specialized. The pollen specialists use plants belonging to only one family, sometimes their diet is restricted to just a few genera or a few species. They can’t live in areas where their food plants are absent. It shouldn’t surprise us, then, that pollen specialists are often rare or endangered.
On the drawing you see a pair of Clarke’s mining bee, Andrena clarkella, which collects pollen exclusively from willows.
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Nest box
Bumblebees nest in various places, like abandoned rodent burrows, clumps of grass, tree holes or old bird nests. Some species can inhabit nest boxes intended for birds. Sometimes a bumblebee queen finds a nest box already occupied but somehow likes it so much that she throws the bird out. It can happen at the stage of nest building, egg laying or even when there are chicks in the nest!
Bumblebee queen cares for her offspring in a way surprisingly similar to birds in some respects. In spring, when temperatures are often quite low, she may incubate their brood, to make them develop faster. Bumblebees, even though they are insects, can be effectively endothermic, generating heat inside their body when necessary. It proves useful not only for brood incubation but also during warm-up before setting off to forage in cold weather.
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Cellophane bee
Bees belonging to the genus Colletes are solitary, usually nest in the ground and line their nests with a cellophane-like substance which is an evolutionary achievement of their family, Colletidae. This family was once considered the most “primitive” of bee families but genetic analyses showed quite the contrary – they should be placed on the top of bees’ phylogenetic tree.
And here you can see a portrait of Colletes fodiens. It specializes in collecting pollen from plants belonging to Asteraceae family.
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Stockholm syndrome
I’m very fond of cuckoo bees. They don’t build their nests and have amazing adaptations to make other bee species raise their children. Many of them, “true” cuckoos, just lay their eggs in the nests of solitary bees, and their success depends on making it so that the nest owner doesn’t know of the parasite’s egg in her nest. Others, like the cuckoo bumblebee pictured on the cartoon you see, invade nests of social species and usurp the title of the queen. After succesfully establishing its position in the nest, the cuckoo bumblebee female begins laying her eggs and host workers care for them like for their own sisters. The cuckoo keeps discipline by biting and dominating the workers (and the old queen, if she survived) but usually doesn’t kill the workers, as they are precious workforce for her young.
On the cartoon you can see the Field cuckoo bumblebee (Bombus campestris) in the nest of the Common Carder bumblebee (Bombus pascuorum). The cuckoos are picky when it comes to host choice, and usually parasitize only one or a few host species.
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The suspect
Bee species identification is considered quite a hard job. There are some easily distinguishable species, but others demand looking closely at the specimen under a magnification. Some bumblebees take it to an even higher level. Bombus terrestris, B. lucorum, B. cryptarum and B. magnus are four closely related species living in my area, whose males and queens are often very difficult to separate, and workers, especially old and worn ones, are considered inseparable in many cases, and I mean inseparable at all by the means of looking at a specimen – even if you take it to the laboratory and look under the microscope. How on earth do these bumblebees recognize each other?! Well, they have more senses than just vision at their disposal. For example, males’ pheromones differ between these four species. When scientists are very determined to be sure which species they caught, they can do chemical analyses of these substances, or just do genetic analysis.
Fun fact: if you are eg from UK or Iberian Peninsula, you might have far less trouble recognizing your Bombus terrestris than me in Central Europe. In UK it tends to have more or less buffish tail (instead of pure white), and in Iberian Peninsula the corbiculae of females are reddish.
Non-honey bees 