E. In addition to the introduction of predators, several microbial pathogens are effective against nematodes. They consist of a microorganism as the active ingredient. They can control many different kinds of pests, although each separate active ingredient is relatively specific for its target pest . For example, there are fungi that control certain weeds, and other fungi that kill specific insects. The most widely used microbial pesticides are subspecies and strains of Bacillus thuringiensis, or BT. Each strain of this bacterium produces a different mix of proteins, and specifically kills one or a few related species of insect larvae. While some BTs control moth larvae found on plants, other BTs are specific for larvae of flies and mosquitoes. The target insect species are determined by whether the particular BT produces a protein that can bind to a larval gut receptor, thereby causing the insect larvae to starve.

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