Carnivorous plants can have valuable allies in ants, benefiting from their poop and janitor, bodyguard and cutthroat services, researchers say.
The carnivorous pitcher plant Nepenthes bicalcarata dwells in the nutrient-poor peat swamp forests of Borneo. It is not a very effective carnivore by itself — its pitcher-shaped leaves lack the slippery walls and viscous, elastic and strongly corrosive fluid that make those of its relatives such effective deathtraps.
However, N. bicalcarata does apparently have unusual support on its side — the antCamponotus schmitzi. The carnivorous plant has swollen tendrils at the base of each pitcher that serve as homes for the insects, and a food source in the form of nectar secreted on the pitcher rims.
In return, the ants apparently provide a host of services for the pitcher plants. They clean the pitcher mouth to keep it slippery enough to help catch prey. They attack weevils that would otherwise munch on the plant. They cart off the remains of large prey from the pitchers that would otherwise rot. They lie in ambush under pitcher rims and systematically attack any of the plant's prey that attempt to escape the traps. And their droppings fertilize the plants.
Still, while it seemed that both pitcher plants and ants benefited from this alliance, investigators lacked hard evidence. It could be the case that only the ants profited.
Now scientists have compared both ant-inhabited and uninhabited plants, finding those with ants fared much better than ones without.