Nature has a niche for everything and that everything seems to evolve as evolution evolves. In saying that there is a symbiotic relationship that formed to provided aphids protection from those "evil" Lady Beetles. According to findings, aphids tend to be a gardner's (the human kind) worst enemy amongst many other parasites.
|The honey ants feed on the honeydew secreted/excreted by the aphids while providing protection.|
In order for the aphids to gain an adequate amount of nitrogen from the low-nitrogen producing hosts they must consume a large amount of the liquids found in the host plants. Aphids secrete/excrete a sugary honeydew after sucking on the sugar-rich fluids from the host plants they consume from. As large amounts of sugary waste is produced, the ant who thrives on a sugar nutrient diet then feeds. As the aphids excrete the honeydew, the ants will feed yet in some cases the ant will use their antennae to stroke the Aphids stimulating the secretion of the honeydew. Some aphids actually have evolved to relying on the stimulation of honey ants in order to secrete to save expending additional energy of excreting.
|Ants attack a lady beetle, a known predator of aphids.|
In return, the honey ant provides protection from predators and other parasites. To protect their investment, the ants will also move the aphids to more nutrient filled plants as a plant becomes depleted of its nutrients. Attacking any threat aggressively to protect their well-being honey ants will also go to the extent of destroying predator insects and other parasites eggs. During the cold seasons, ants will stow the eggs of the Aphids in the nests where the humidity and temperature are optimal. As the seasons change, the ants then move the eggs to the appropriate locations for pristine growth.
Although ants appear selfless in their actions of the aphids but in reality are only interested in keeping the aphids around for survival. In some environments, some aphids develop wings for flight to travel to a new location when food becomes to dense or populations of aphids exceeds the limit on that host. Ants will attack those particular aphids in order to keep maintain their investment by either killing them or tearing off the wings.
Watch this link for another symbiotic relationship similar to the aphid-herding ants yet with caterpillars.
|Ants protect and ride caterpillar to gain nutrients|
Styrsky JD, Eubanks MD (January 2007). "Ecological consequences of interactions between ants and honeydew-producing insects". Proc. Biol. Sci. 274 (1607): 151–164.
DeVries PJ (1992). "Singing caterpillars, ants and symbiosis".Scientific American 267 (4): 76.