During the live broadcasts for Live From The Rainforest a panel of scientists were waiting in the Smithsonian Institution's Electronic Classroom at the National Museum of Natural History in Washington, D.C. to answer questions that were posted by the students. However, we can't rule out the possibility that the presence of algae may play a role in preventing destructive organisms such as fungi or lice from colonizing the sloth. Army ants are predators feeding usually on the forest floor capturing a diverse assemblage of arthropods such as scorpions, cockroaches, spiders and even larger prey such as lizards.
Some species specialize in raiding wasp nests.
This feeding strategy requires a large colony of ants and each must be a rapid runner with a potent sting, powerful mandibles and possess a willingness to use them. If this is what you mean by violent then I guess they qualify. This a tough one. There may be more biomass of ants and termites in rainforests than any other groups. When we were doing our research on animals of the rainforest we had a very difficult time finding information about the katydid especially the katydids that live in the tropical rainforest.