Vegetable growers with an aphid problem might be used to seeing ants around their aphid-infested crops as well. That is because aphids are sometimes protected by ants, because they have a mutualistic relationship.ant farming aphids

Aphids produce a sweet substance called honeydew, which ants collect as a food source. The ants “milk” the aphids by stroking them with their antennae. The ants in turn protect the aphids from predators and some ants even transport aphids between plants for re-establishment when the ants move to new nesting sites.

Although mutualistic, the feeding behaviour of aphids is altered by ant attendance. Aphids near ants tend to increase the production of honeydew in smaller drops with a greater concentration of amino acids.

A Symbiotic Relationship

Some farming ant species gather and store the aphid eggs in their nests over the winter. In the spring, the ants carry the newly hatched aphids back to the plants. Some species of dairying ants manage large herds of aphids that feed on roots of plants in the ant colony. Queens leaving to start a new colony take an aphid egg to found a new herd of underground aphids in the new colony. These farming ants protect the aphids by fighting off aphid predators.

Ants therefore compound the aphid control problem by actively participating in the infestation. Be on the lookout for large masses of ants running the length of your plants, as this is indicative of an aphid farm underway. So managing ants is a key component of aphid management.

Another variation in ant-aphid relationships involves lycaenid butterflies and Myrmica ants. These butterflies lay eggs on plants where ants tend herds of aphids. The eggs hatch as caterpillars which feed on the aphids. The ants do not defend the aphids from the caterpillars, since the caterpillars produce a pheromone which deceives the ants into treating them like ants, and carrying the caterpillars into their nest. Once there, the ants feed the caterpillars, which in return produce honeydew for the ants. When the caterpillars reach full size, they crawl to the colony entrance and form cocoons. After two weeks, the adult butterflies emerge and take flight. At this point, the ants attack the butterflies, but the butterflies have a sticky wool-like substance on their wings that disables the ants’ jaws, allowing the butterflies to fly away without being harmed.

 

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