Wednesday, April 8, 2009

Ant Wars- continued.

In grade school one of my favorite things to do was watch the black and red ants wage war in the playground. Later, I thought the coolest organisms on earth were the fungus and parasites that hijack ant brains. I wish they'd make a movie with human-targeting variants of them. Guaranteed bio-gore!
Now check this out. Further proof of the awesomeness of ants. You know that ants take prisoners of wars as slaves and force them to take care of the larvae. Well the slaves can become rebellious motherfuckers:

Achenbach and Foitzik collected 88 colonies of the slave-making P.americanus ant that had abducted workers from three species of Temnothorax. They found that the workers clearly care for the larvae, and nearly all of them were raised until their pupated. But at that point, the slaves' behaviour changed dramatically, taking on a more homicidal bent.

Two-thirds of pupae died before they hatched. The mortality rate was even higher (83%) for pupae containing queens, but very low (3%) for those containing males. The duo saw that the captives were deliberately killing the healthy pupae. In about 30% of cases, as in the photo, the workers would gang up to literally pull the developing ants apart. Another 53% of the pupae were killed by neglect, by workers who moved them out of the nest chamber.

These murders were solely the acts of the slaves. No P.americanus worker ever lifted a mandible against its own pupae. Nor are the deaths a reflection of a generally poor standard of care on the part of Temnothorax. In their own colonies, the majority of pupae hatched, with just 3-10% dying before that happened.

This rebellion takes its toll on the slave-makers and may explain why the nests of P.americanus tend to be very small. The captives may never reproduce themselves, but they do their part for their relatives back home by crippling the workforce of the slave-makers. These indirect benefits are particularly pertinent to Temnothorax ants because a single colony can occupy many different nests - a family of sisters spread out over a large area. If one nest is raided, it pays to ensure that none of the related nests are targeted later.

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