Bee nests are usually divided into sections, called “cells”. Each cell contains one developing larva and a pollen-and-nectar provision for it.
Tag: insects
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Which way to the exit?
I’d like to tell you about one of experiments I did during my PhD studies. I worked with the red mason bee (Osmia bicornis), a common solitary bee species. I was particularly interested in topics related to their reproduction. The red mason bees’ nests are linear, with individual cells in a row, which is common to many cavity nesters. Typically, there is only one entrance, and the other end of the nest is blind. The larvae must know the direction to the exit, and they do. Important source of information is the shape of mud partitions separating the individual cells. I pictured this on the cartoon – the nest entrance is to the right, and you can see that the side of the wall which should be chewed by the bee to go out is rough. The other side is smooth and concave. When you open the nest in winter, you can see the cocoons (each of them has a young adult bee inside) most of which are directed with bee’s head towards the exit. So, in the spring all that the bee has to do is to chew the cocoon wall, and then cell wall, all the time moving forward.
But my older colleagues from the lab observed that some cocoons are oriented in the other direction. Those misoriented bees are more often males than females. What happens to such individuals? Do they emerge from the cocoon and go forward, blocking and killing their siblings inside the nest, and eventually dying unable to exit? Or can they find out that they made mistake, and correct it? In order to check it, I prepared “artificial nest cells” which had the real cell walls attached, put the cocoons inside, and checked which way the misoriented bees will emerge.
The results were quite surprising. The majority of misoriented males turned around in the cell after emerging from cocoon, and exited their cells in the right direction. In contrast, most females didn’t turn around and got out the wrong way. Females are typically larger than males in the red mason bee but it was not the difficulty with maneuvering that prevented my females to choose the correct exit. The artificial cells were large enough for them to turn around – I checked.
It looks like the decision about which way to go out of the nest is made at the different moment by each of the sexes. Females position themselves already as larvae spinning their cocoons, and in spring they simply follow the chosen direction. Males are less rigorous in positioning their cocoons but before emergence they check where they should go. It’s quite reasonable strategy, as big females in real nests (in contrast to my artificial cells) can have difficulty with turning around as adults. If they postponed choosing direction for spring, it could turn out that they are not able to turn and are doomed. In contrast, smaller males don’t face such problems, so they can look for the correct exit later.
Here you can read a paper from my experiment.
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Wash your hands
Bees, like all other organisms, suffer from various diseases. Among the causes are RNA viruses, which can evolve fast and thus quickly change host species (between bees but sometimes also to other insects). These viruses can be transmitted via flowers, the latter compared to “dirty doorknobs” by Burnham et al. in their article from 2021.
On the cartoon you can see a pair of red mason bees (oops now I see that I forgot to picture horns on female’s face!). Males in this species have quite sophisticated courtship, involving stroking of mate’s eyes with front legs. One would assume they should wash their hands before doing that. Oh wait…
Transmission of RNA viruses, and also other pathogens, to the wild bees is one of the risks associated with mass breeding and transport for large distances (eg between countries or continents) of the honeybee, bumblebees and other bees.
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Listening
I did such a drawing of a bee (which was meant to be male Hoplitis cristatula, with his lovely bright blue eyes), and when I put it on my Facebook page, a friend of mine asked me if bees can hear.
Yes, they can! But not too well. They can receive frequencies between 20 and 500 Hz, so far narrower range than humans. Their hearing organs are located on their antennae, at the base of flagellum. These informations apply to honeybees, I don’t know about other bees being studied in this respect but I suppose it is pretty much the same between species.
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Bodyguards
Male bees usually don’t take part in any parental care. There is, however, an interesting exception. Males of Ceratina nigrolabiata guard nests when females forage. They defend it against parasites or small predators. What is interesting, males usually don’t stay in one nest forever but they switch between nests every couple of days.
If you want to know more, you can read the paper: Mikát, M., Matoušková, E., & Straka, J. (2021). Nesting of Ceratina nigrolabiata, a biparental bee. Scientific Reports, 11(1), 5026.
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Orchid love
Orchid bees (Euglossini) are unusual not only because of their metallic colouration. Males pollinate certain species of orchids, but visit them not for food but for fragrances. They use them to mix their own perfumes with which they court females. Not only orchid oils are used but even as unexpected sources of perfumes as… feces.
I like to think that females not always choose their mates on the basis of their perfume quality but sometimes they just fall in love 😀 (yes, just joking, but then, it’s a page with funny cartoons, isn’t it)
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Accepted or rejected?
I read this interesting article about decision-making by honeybees. The research shows that bees are faster to accept a flower than to reject it. In other words, the bee hovers in front of the flower for short time before eventually landing on it, but making decision not to land requires (on average) more time. The decision about accepting flower is made with high accuracy: bees rarely land on a flower which is not rewarding (provided they can know about it, of course, that is, they have experience with this type of flower, which was the case in the study), but some rewarding flowers are “mistakenly” rejected. When they have difficulty with making a decision because of limited evidence available, they’ll rather reject a flower than accept it. I think that would make them quite good review editors!
I must add that the flowers in the experiments were artificial ones, but I don’t think it matters much for the results 😉
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Attenzione, pickpocket!
Have you heard of that recently published report of honeybees stealing pollen directly from scopa of wild bee species? Although competition between honeybee and wild bees is an often studied and debated topic, there are only few observations of direct agressive interactions. What is interesting, the victims of theft seem indifferent to what is happening to them, and only rarely try to resist in any way.
And by the way, this cartoon was inspired by a viral movie from Italy. I’m curious if you also saw it, or was it not as much viral as I thought?
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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).
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Mating ball
It’s such fun to look at the bees in an aggregation at the beginning of their flight season – let’s say, Colletes cunicularius in early spring – when males are flying like crazy and looking for virgin females. When they spot one, a mating ball forms immediately around her, with numerous males trying to get their chance.
I must add, in the real life males rather can’t be so easily fooled like on this cartoon, but quick escape of the successful male with his mate can be practiced in some species.
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Proudly announcing my little paper
As you might figured out already, my favourite bee is, for now at least, Nomioides minutissimus, one of smallest bees in my coutry. It is not only sooo small but also quite rare. The most recent published observations I could find were from 90s, and there were only three places in Poland where it was known to live. After actively looking for it, and collaborating with other scientists and citizen scientists in the process, I learned that there are more localities where Nomioides minutissimus was seen in last twelve years. We just published an article which you can read here, with photos of the beautiful bee and her habitat.
Non-honey bees 