Biological control
Conservation: Avoid using pesticides, which kill the natural enemies of the pests. Encourage the growth of those things which attack the pests. Use companion planting where possible. In China, the mosquito fern has been used for at least a thousand years, as a companion plant for rice crops. It hosts a special cyanobacteria that fixes nitrogen from the atmosphere, and also blocks out light from competing plants (but not the rice, which grows taller).