Parasites spark swarm of ZOMBIE BEES
California infestation grave, declare buzz boffins
Researchers have found a type of parasite that turns bees into zombies, causing them to exhibit strange behavior before dying.
The discovery was made by accident, after San Francisco State University professor of biology John Hafernik collected some bees he found outside his office so that he could feed them to a praying mantis he had collected on a recent field trip.
“Being an absent-minded professor, I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees," he told AFP.
After zombification, the bee dies and
its murderous parasite burrows free
The parasites were identified as Apocephalus borealis, a phorid fly native to North America, and they attack bees by injecting eggs into their abdomens. Once hatched, the parasites kill the bees within a couple of weeks and emerge from the body when they have finished feeding – but it’s the behavior they induce in bees that scientists have found fascinating.
Infected bees exhibit jerky limb movement and general weakness, then leave the hive and congregate around bright lights – behavior more akin to moths. The scientists are trying to determine whether the bees leave the hive of their own accord, or are forced out by healthy members of the swarm.
"When we observed the bees for some time – the ones that were alive - we found that they walked around in circles, often with no sense of direction," said Andrew Core, a graduate student in Hafernik's lab. "They kept stretching [their legs] out and then falling over. It really painted a picture of something like a zombie."
The zombie problem looks to be severe, with infected bees found in 77 per cent of the samples collected in the San Francisco Bay Area. The team suggests this might be one cause of the collapse in bee populations seen in the last five years. Mobile phones have been fingered as one culprit, but scientists are coming to the conclusion that more than one factor must be involved. ®
COMMENTS
But...
... can a bee be said to be or not to be an entire bee when half the bee is not a bee, due to some unsavoury larvae?
re: why has this not been spotted, with a 70% infection rate?
By way of a reply, I would guess because we’d not been looking, or we’d been looking at the wrong bees and for the wrong thing. Bees have a complex lifestyle, but once pupated and out of the cell they are “house bees” for the first section of their lives, not leaving the hive at all. Eventually they graduate to “guard bees” who hang around at the entrance, and then, having learnt where the hive entrance is, they go off and forage. They then forage for the rest of their short little lives, usually dying in the field.
It would seem this fly attacks foragers, while they out and about, not while in the hive. It’s difficult as an insect to get in to a hive (wasps try, and after a short spell will usually reappear as a corpse), if the colony is strong. A weak colony will soon be overrun with other colony’s bees, wasps, or any number of other nasties).
Usually when you open a hive, even to check for disease, you do so during the day when the foragers (i.e. the infected ones) would be off foraging. The majority of the bees you see are young house bees. You do this because there are less bees there, so it’s easier to see what’s going on, and you get stung less. It also tends to be warmer, so the bee brood (bee eggs, pupae, larvae) won’t chill too much.
If the infection causes disorientation, then infected bees can’t return to the hive, so they won’t be collected for any sampling. As a rule bees out and about are not caught for examination, you have no idea where they are from. I do think the light thing is a red herring though, I once took a hive on the back seat of my car, it tipped and burst open as I went round a corner. The bees, all 50,000 or so, were a bit upset and flooded out. It was night, and I absconded from the vehicle at high speed. The guy behind me stopped, and the bees all made for his headlights, so I could scoop them back into the hive fairly easily. So, I think they may do it anyway. They don’t usually fly at night, so bright lights probably just confuse them.
Standard disease checks don’t look for these things, the big ones are all “external” so you look at the brood, or for mites you can see on the bees (varroa) or elsewhere in the hive (hive beetles and wax moths). If you suspect an “internal” disease you ask for that to be looked for, or just grab some bees and open them up. BUT you look for the disease you think they have, such as nosema (spores in the gut) or acarine (pull off the head and look for black marks in the trachea).
HTH. Interesting work in any event.
Resident weevil?
"Then the next time I looked at the vial, there were all these fly pupae surrounding the bees,"
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