Later, the queen returns to the eggcup and eats the worker-laid eggs, ensuring that resources aren't 'wasted' on rearing worker-produced offspring.pic.twitter.com/taCnq0vXJe
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Cool example of kin conflict in one of my Tree Bumblebee colonies. Here, the queen catches worker #3 laying eggs and gives her a rather nasty telling off.pic.twitter.com/AHop2WIBvD
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Didn't expect this to do so well and I'm getting a lot of questions in the comments so here's a thread to explain why we observe this behaviour in bumblebee colonies:
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1. In the Hymenoptera (the insect order containing bees, wasps, ants, and sawflies), sex is determined by haplodiploidy.
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2. This means that females develop from fertilised eggs and are diploid (i.e. possess two sets of chromosomes, with one set inherited from the father and the other set from the mother).
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3. In contrast, males develop from unfertilised eggs and are haploid (i.e. they possess only one chromosome set inherited directly from the mother).https://images.app.goo.gl/KYyJe22GPcJRtXFT8 …
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4. Colonies of bees, wasps, and ants are family units, usually consisting of a single queen (who has stored sperm from a previous mating in a reproductive organ called the spermatheca) and her daughter workers. Males are produced only for reproduction.
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5. Since the colony is a family unit, everyone inside is related to one another. However, haplodiploidy has an interesting effect on relatedness between colony members (here, we define relatedness as the percentage of genes that two individuals share via common descent).
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6. Since the workers all inherit the exact same genetic material from their father (he is haploid and can therefore only pass on one set of gametes), they share 75% of genetic material with one another (r = 0.75).
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7. However, since queen-produced males are haploid and derive from one half of the queen's genetic material, workers only share 25% of their genetic material with their brothers. The queen shares 50% of genetic material with her offspring, regardless of sex.pic.twitter.com/ds2zjzSrLA
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8. These relatedness asymmetries manifest in various conflicts between individuals in a colony (reviewed nicely here: https://www.annualreviews.org/doi/full/10.1146/annurev.ento.51.110104.151003 …) but, for present purposes, we are only interested in conflict over male production.
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9. In many social insect species (including bumblebees), workers cannot mate but are capable of activating their ovaries and laying unfertilised eggs, that, as we know, develop as males.
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10. The queen is more related to her own sons (r = 0.5) than she is to her workers' sons (r = 0.25). In contrast, workers are more related to their own sons (r = 0.5) than they are to their brothers.pic.twitter.com/R3hbE3l5Xp
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11. Thus, the queen and egg-laying workers are in direct conflict with each other over who gets to produce males, and will attempt to 'police' one another through aggressive behaviour and egg-eating.
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12. In annual social insects, where colonies only last for one year (such as bumblebees and wasps), conflict may eventually lead to workers killing the queen to gain control over male production. Here's a really nice demonstration of this in a wasp: https://www.sciencedirect.com/science/article/pii/S0960982215011756 …
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13. In these situations, workers are able to kill the queen with few fitness impacts to themselves, since in annual colonies, queens tend to produce female offspring (workers and new queens) first before switching to male production.
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14. Thus, as long as their timing is correct and workers do not kill a queen who's still producing females, workers are able to potentially increase their own fitness by removing the queen altogether, allowing them to lay male eggs unhindered. Viva la revolución!
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15. Also, for those concerned, worker #3 is still alive, although I haven't seen her lay eggs again since this happened!
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End of conversation
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how is 3 able to lay eggs? is her ovipositor not modified for stinging?
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yep the ovipositor is modified for stinging but still maintains its egg-laying function, with the vagina at the very base of the sting. You can tell when they're laying eggs since they have to poke their sting all the way out!https://images.app.goo.gl/4KKy8fLrnKSn5ghP6 …
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ooohh!!! thank you!! please, is this unique to this species or is this typical to hymenopterans? i didnt know this!! im sad for 3. she just wanted babies and she got beaten up u__u
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this is typical for the stinging Hymenoptera, although not all social species have workers that retain the ability to lay eggs
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ooohh, i didnt know!!!! thank you for sharing your expertise with me
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