We have talked a lot about invasive species here. Many of the impacts are obvious. Burmese pythons (Python bivittatus) have drastically altered Florida’s ecosystem. They have killed up to 90 percent of some species of mammals in the Everglades. Big headed ants haven’t killed a single lion (Panthera leo) but they are changing the African landscape and forcing lions to adapt by hunting other prey.
The big headed ants (Pheidole megacephala) are not native to east Africa and the impact of their arrival is now being felt. They are believed to have originated along the shores of the Indian Ocean and have spread widely around the world, including the United States.
According to the Terminix pest control website:
- “:Size: This type of ant has two distinct sizes of workers. The larger ones, called major workers, typically range in size from one-eighth of an inch to one-fourth of an inch in length, depending on the species. The major worker is easily identified by the extremely large size of its head in comparison to its body. The head of the minor worker is in proportion to its body.
- Color: Most are reddish-brown in color.
- Behavior: Big-headed ants, like all ants, establish well-defined trails between the nest and food and water sources. They feed on a wide variety of foods including dead insects, plant materials and garbage. The workers are partial to the sweet honeydew produced by aphids, scales and mealybugs found feeding on many trees and plants. Fruit trees, roses and many shrubs serve as hosts for aphids and may contribute to ant infestations in homes and other buildings. One species, Pheidole megacephala, establishes large “supercolonies” consisting of dozens, if not hundreds, of subcolonies connected by interlocking trails. These supercolonies have been found to extend over large portions of a city block, making control efforts on a single property quite difficult to achieve. This species is more common in Florida and Hawaii but can be encountered all along the southeast Gulf Coast. They have been known to construct mud tubes that can resemble those made by subterranean termites, although this behavior is not common.”
According to Scientifc American the changes begin at the micro level. Big headed ants out compete the native acacia ants (genus Crematogaster). Those ants have a relationship with acacia thorn trees. The ants protect the trees from predators by attacking them. Elephants and other animals try to eat or uproot the trees. The acacia ants live in and protect the trees. The big headed ants kill and eat the acacia ants.
The ants live underground and make no effort to protect the trees. Studies show that the acacia thorn trees provide cover for lions stalking zebras (Equus quagga). Fewer acacia trees mean lions have less success hunting zebras. So research now shows lions in Kenya are switching to African buffalo (Syncerus caffer) for food. The buffalo are more difficult to hunt. But research shows the cats are adapting well. Lion populations have not declined as a direct result of the ant invasion.
Ants, meanwhile, are iportant wildlife. There are at least 10,000 species and some have direct benefit to humans. Recent research says they may have a benefit in the war on cancer. These ants may be able to detect cancer early.