There are three types of symbiosis: mutualism, commensalism, and parasitism. Mutualism exhibits a relationship in which both organisms benefit, commensalism is a one sided relationship in which only one organism is helped while the other is not affected, and parasitism is a relationship in which one organism is harmed for the benefit of another.
In parasitism, sometimes a host can develop another symbiotic relationship (mutualism) in order to combat the parasite. Aphids, the most common garden pest insect, are very destructive to plants. Different kinds of aphids specialize in feeding on different types of plants. One of the reasons that aphids are so destructive is that they feed in colonies, easily destroying both garden crops and ornamental plants. A residue known as, “aphid honeydew” is left on the plants as they feed, causing fungi to develop, and leaving the plant to eventually curl up and dry out.
This is where the mutualistic relationship comes in. Ladybugs are a very popular insect all around the world, however, they aren’t native to the U.S.. Ladybugs were first imported from Australia in order to control the aphids on orange trees. Ladybugs are often purchased and released into crops or gardens at sunset, because they’ll fly away in the day, but they won’t fly at night, so sunset ensures that the ladybugs will stick around. The crops also need to be wet because the ladybugs will be dehydrated when they arrive. From here, the adult ladybugs will eat their share of aphids and lay eggs on the plants. The larvae are the real predators of the aphids, so once the adults lay eggs, the infestation is soon to be over.
These relationships are examples of parasitism and mutualism in the way that the aphids feed of off the plants, leaving them dried up and dead, but if the ladybugs are present, they will protect the plants from the aphids, while the plants supply the ladybugs with food and a place to lay their eggs.
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