Bumblebees are animals of colder climates than most bees, and climate change can affect them negatively in various ways. One of dangers are heatwaves. They can not only simply kill the individuals but also impair their memory.
Tag: bumblebee
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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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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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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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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.
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Robbers and thieves
Yesterday I read a very interesting article by Andreas Müller and Paul Westrich about Andrena lathyri, a mining bee species specialized in nectar robbing. I learned from this paper, among other things, that there is more than one way of obtaining nectar without pollination. Two of them I portraited on the cartoon. The first method, nectar robbing, involves damaging a flower, eg. piercing a hole in its side, like Bombus wurflenii, the famous nectar robber, is doing. On the other hand, nectar thiefs don’t damage flowers but are so small that they sneak past the reproductive organs straight to the nectaries, and as they don’t touch stamens or pistil, it doesn’t pollinate.
If you want to read the paper about Andrena lathyri, which I recomend, here you have the citation: Müller, A., & Westrich, P. (2023). Morphological specialisation for primary nectar robbing in a pollen specialist mining bee (Hymenoptera, Andrenidae). Journal of Hymenoptera Research, 95, 215-230.
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Skrócinka białonoga, mamrzyk skrócinkowiec
As I told you, I’m preparing portraits of Polish bees, and here is another one which I’d like to show you. Epeoloides coecutiens and Macropis europaea are both cute, and their parasitic relationship is interesting (like every relationship between a cuckoo bee and its host!). Did you know that Epeoloides coecutiens was once told to be the rarest species of bee in Europe? It is not the rarest, in fact, but in general cuckoo bees tend to be quite uncommon because of their lifestyle.
And fun fact: the Polish names of these bees are real tongue-twisters: skrócinka białonoga and mamrzyk skrócinkowiec
I just checked that if you paste these names into Google Translate, it can read it properly. So if you are courious how to pronounce these names, you can check there 
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The variable bumblebe
I’ve just began drawing a series of little portraits of bee species living in Poland. The drawings are referring to distinctive features of the species or their Polish names (or both
). Meet the pretty Bombus humilis, “trzmiel zmienny” in Polish, which translates into “the variable bumblebee and refers to extreme colour variability of this species.By the way, have you known that “nacked” bumblebees (ie, under their fur) are glossy black?
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Crossword
I spent last few days on a short vacation with friends. In the evenings we were solving crosswords. My fiancé came out with a great idea of a crossword for bee lovers – see for yourself!
A little hint – this is an European version 🙂
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Cell phones
Bee nests are usually divided into sections, called “cells”. Each cell contains one developing larva and a pollen-and-nectar provision for it.
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Plagiarist
Anyone who ever tried to learn bumblebee identification, knows that there are species which are very similar in colouration to each other. Moreover, there are some strange species where one colour morph is similar to one species, and another morph – to a different species. Bumblebees form mimicry rings, which are groups of species which are visually similar and live in more or less the same area. The advantage of this similarity is that predators more quickly learn which insects are not worth attacking (bumblebee females have stings which makes them a rather unpleasant lunch).
Non-honey bees 