How does the habit of eating dead animals evolve in a group of insects that feed on plant products?
The Vulture Bees seek out rotting carcasses, creep inside them, and then salivate on the horrid mess and suck it all up. They take this stuff back to the nest and pass it on to colleagues who digest it a bit more. The resultant goo is then placed in little pots and fed to the young.
Evolution
How did this way of life evolve among the Stingless Bees? There are only three known species of Vulture Bee (that eat dead flesh), all the other members of this large group are nourished by plant products. It is difficult to imagine a direct ‘switch’ from nectar to corpses – perhaps there was an intermediate habit. If there was – what could it have been?
Stinkhorns
A French entomologist (with a very French sense of humour) christened one of the stinkhorn fungi Phallus impudicus, for obvious reasons if you look at the images. They smell horrible and seem very attractive to many insects. Another species (Phallus hadriani) has been observed to attract bees (Stinkhorns and Bees). This stinkhorn smells a bit better, more like a flower, and maybe here is a clue?
From Nectar to Carrion
Maybe some ancient Stingless Bees developed a taste for these fungal products, eventually preferring them to nectar. As the fungi developed smellier products (largely to attract flies which help disperse the fungal spores) the bees adapted and began to associate rotting smells with food. Eventually the switch to feeding exclusively on dead animals could have taken place. This is pure conjecture on my part, but it does seem plausible.
On to Predation
Recently Vulture Bees have been observed eating the living larvae of wasps (abandoned and therefore not protected by the adult wasps). Is this where evolution is taking descendents of the Vulture Bees next - to become predators of wasps? If so it would be a complete ‘turn around’. Bees (nectar feeders) are thought to have evolved from predatory wasps millions of years ago (see ‘Bees in General’) and it would be ironic if some bees went on to eat the descendants of their own ancestors.
Our Ignorance
The curious behaviour of the Vulture Bees was only discovered in 1982, and it highlights how little we currently know about most insects. This should not be surprising since there are many, many more insects than entomologists! But it should be taken as a warning. Until we know an awful lot more about the workings of the natural world we should be very cautious when we do things that disrupt it.
Like this? – see what else I have written.
