For many years fungi were classified in the Plant Kingdom. Scientists then discovered that fungi show a closer relation to animals, but are separate and unique life forms. The part of the fungi that we see is the fruiting body. The living body of the fungi is a mycelium made from several small filaments called hyphae, which are hidden in the soil, in the wood of a fallen tree, or some other food source.
Fungi acquire the energy they need by absorbing nutrients from the organic material in which they live. Fungi have evolved to use many different organisms for food. Some fungi decompose items such as dead leaves, some cause diseases and infect plants, animals, or other fungi, and others live as partners with plants.
Several of the disease-causing fungi can be used as effective biocontrol agents against crop pests. Crop plants are susceptible to the rapid spread of disease or harmful insects because they are so close together. Chemical pesticides are often used to kill harmful insects, but biological control is cheaper and does not expose the environment to noxious, man-made chemicals. An effective biocontrol of a plant pest would kill the pest without hurting the plant. The biocontrol organism would then die out when the target pest was killed off.
Fungi act as biocontrols by first entering the insect host. Once inside, the fungus multiplies through the entire insect body. The insect is killed due to extensive tissue damage and sometimes by toxins produced by the fungus. Oftentimes the fungus will emerge from the dead insect's body and produce spores that can be carried by the wind, water, or contact with other insectsto spread infection. The spores of several fungi are being used control insect pests such as grasshoppers, house flies, mosquitoes, and gypsy moths.
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