Remember the gliding ant Cephalotes?
This ant lives in tropical forests in South America. They eat many things, one of them being bird-poop. However, it turns out that the eating of this poop carries some risks with it! In it, nematodes (roundworms) sometimes occur. When the ants eats from this poop, they also ingest the nematodes.
When the ants feed their young, they transfer the nematodes to them. These nematodes then infect the unfortunate ants. As a result, when the young ants grow to adulthood, their abdomen turns red (normally it’s black), and the ant starts holding up it’s abdomen, so that it looks like a nice ripe red berry. This red abdomen is full of the eggs of the roundworm.
In turn, the birds see the ‘berries’ and want to eat them. After eating the ant’s abdomen, the eggs end up in the bird’s stomach. Here they don’t get digested, but pass through the intestines unscathed. The bird poops out the parasite eggs, the ant finds and eats the poop, bird eats the ant, bird poops again…and so the cycle continues.
By manipulating its host to look like a berry, as well as making sure the ant holds up its abdomen to look even more like a real berry, the parasitic nematode makes sure it can complete its life cycle every time.
Source:Yanoviak, S.P. et al. (2008). Parasite-induced fruit mimicry in a tropical canopy ant. The American Naturalist 171(4): 536-544