Dear Steve,
I will attempt to answer some of your questions, though I am sure there are others on this list who can provide more information, particularly on the dates of some of the evolutionary stages.
Which evolved from which (according to the fossil record)?
If you look at the evolutionary tree usually printed in books ("Bees of the World" by Christopher O'Toole and Anthony Raw is one of the best introductions to bees), the family Apidae is one of the last to appear. This family contains the major social bees, honey bees, bumble bees, orchid bees and the stingless bees. This shows that social bees evolved from solitary bees. The oldest fossil record of bees that I have read about was of a Trigona stingless bee, found in 90-million-year-old New Jersey amber, though this reflects my reading rather than the fossil record!
Did stinged solitary bees become social? Or did stingless social bees evolve stings?
From the information available, solitary bees became social and they always had stingers, until stingless bees lost theirs. All female bees have the potential to sting. Male bees do not sting. The stinger is an adapted ovipositor. These days bees lay eggs with out it. This may be because bees evolved from wasps, many of whom are parasitic and require an ovipositor to reach into the nest or to the larva. Bees by contrast, make a nest with brood cells into which they directly place an egg. Even the parasitic bees lay eggs by entering the host's nest. No need for a penetrating ovipositor. (Note: in the light of recent discussions on opinion versus fact, I have to say that I don't know this for sure. It is an idea based on reading I have done!)
Honey bees are the only ones that have a barbed stinger and thus are the only ones who die after stinging. Other bees have a smooth stinger and could sting repeatedly if they wanted. Many bees have a stinger that is too weak to penetrate human skin, and if they do their sting is less painful than a honey bee's. And most bees are solitary nesting and unlikely to defend the nest, choosing to flee and start another nest than die defending their existing one. They can sting, though you have to be quite rough with them to make them do it. Often they'll only sting when trapped in clothing or you tread on one.
Are there many solitary stinging bees? Are there many stingless social bees?
There are about 20,000 species of bees in the world, of whom the vast majority are solitary. In America north of Mexico, there are over 4,000 species, of whom the non-native honey bee and the native bumble bees (about fifty species) are the only truly social species. Stingless bees can be found around the world in the tropics. Trigona are wide spread, Melipona are found in Central America, and Dactylurina and Meliponula are African genera.
Stingless bees do have a stinger but it is greatly reduced and effectively useless. This is not say that they cannot defend their nests. Their main enemy are ants trying to raid their food stores, against which they have various defenses, including strong walls and sticky traps in tunnel-like entrances. If a nest is attacked by a larger creature, like a person, they will swarm and bite the intruder. Some species will also secrete irritating fluids into the bites, leading to the name "fire bees."
I hope this is useful. Best wishes,
Matthew
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Matthew Shepherd
Director, Pollinator Program and Publications
The Xerces Society
4828 SE Hawthorne Blvd, Portland, OR 97215
Tel: 503-232 6639 Fax: 503-233 6794
Email: [log in to unmask]
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The Xerces Society is an international nonprofit organization
dedicated to protecting biological diversity through the
conservation of invertebrates.
For information and membership details, see our website:
http://www.xerces.org/
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