IF PARASITES threaten an ant colony鈥檚 food supply the colony throws more ant power into fending off the attack. 鈥淚t鈥檚 a kind of immune response,鈥� says Adam Hart at Sheffield University, who discovered the response. The finding backs up the notion that ant colonies behave as a 鈥渟uper-organism鈥�.
Hart and his colleagues studied leaf-cutter ants (Atta columbica), which bring leaves to underground chambers to fertilise their food鈥攁 growing fungus. But this food supply can be devastated if it is infected by the parasitic fungus Escovopsis. Hart showed that infected colonies increase the number of workers throwing out the infected waste.