- Agricultural pests - Pest control methods [SLIDE 1] Agricultural pests are organisms that feed on agricultural crops, ornamental pests or animals. They include insects, fungi, viruses, worms, snails, slugs, rats, mice and birds. Weeds are plants that compete with agricultural crops, forests and grasses for light and nutrients. Insects, plant pathogens and weeds cost the United States $122 billion a year. Disease vectors are pests that transmit diseases. Examples can range from house pests that carry disease found on manure, to mosquitoes carrying dengue, yellow fever and West Nile virus, to beetles that destroy trees such as the emerald ash borer that has bene known to kill roughly 75 million trees in North America. [SLIDE 2] Chemical treatment is the process of treating crops with chemicals to deter and kill pests. DDT is a chemical compound that was used in 1938 to kill pests. It became valuable during World War II where the military used it to control body lice that spread typhus fever. After the water, it was used to spray forests, marshes, agricultural land and even suburbs. Ecological pest control is the protection of people, plants and animals by targeting specific pests or treating entire ecosystems with a natural predator or organisms. Integrated Pest Management (IPM) is the system of controlling pests by using both ecological pest control and chemicals for long-term management.