Classification of pesticides notes for students
- 1. Crop Protection Weed management using pesticides Definitions of Pesticides The Food and Agriculture Organization (FAO) has defined pesticide as: “any substance or mixture of substances intended for preventing, destroying or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals, causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances that may be administered to animals for the control of insects, arachnids, or other pests in or on their bodies”. Types of Pesticides Pesticides are also referred to by the type of pest they control. Pesticides can be either biodegradable pesticides, that break down into harmless compounds by bacteria and other living organisms, or persistent/Non-Biodegradable pesticides, which can take months or years to break down. Classification of pesticides are according to the types of pests they kill Grouped by the pest types they Kill; Insecticides – Insects Herbicide – Plants Rodenticides – Rodents (rats & mice) Bactericides – Bacteria Fungicides – Fungicide Larvicides – Larvae Depending on how biodegradable they are Biodegradable Pesticides Biodegradable pesticides are those that can be broken down into harmless compounds by microbes and other living organisms within less period of time.
- 2. Non-Biodegradable Pesticides Few pesticides are known as non-biodegradable, also called persistent pesticides. The most long- lived pesticide materials include aldrin, parathion, DDT, chlordane, and endrin, they take a long period of time to break down. These pesticides can survive in the soil for over 15 years or more. Another way of thinking about pesticides is considering the chemical pesticides extracted from a common source or some production method. Chemical pesticides Organophosphates Many organophosphates are insecticides that impact on the nervous system by compromising the enzyme that regulates the neurotransmitter. Carbamate Carbamate pesticides affect the nervous system by compromising the enzyme that regulates the neurotransmitter similar to the organophosphates, but carbamate enzyme effects are usually reversible. Organochlorine Insecticides This type was common in the early years when pesticides came into the market. Many countries have banned organochlorine insecticides from their markets because of their impacts and persistence on health and the environmental factors (e.g., DDT, chlordane and toxaphene). Pyrethroid There are synthetic variants of pyrethrin, a naturally occurring pesticide present in chrysanthemums (Flower). Their development is such a way they can maximize their environmental resilience. Sulfonylurea herbicides The commercial production of sulfonylureas herbicides was for weed control like flupyrsulfuron- methyl-sodium, ethoxysulfuron, chlorimuron-ethyl, bensulfuron-methyl, azimsulfuron, and amidosulfuron, rimsulfuron, pyrazosulfuron-ethyl, imazosulfuron, nicosulfuron, oxasulfuron, nicosulfuron, flazasulfuron, primisulfuron-methyl, halosulfuron-methyl, pyrithiobac-sodium, cyclosulfamuron, bispyribac-sodium, terbacil, sulfometuron-methyl Sulfosulfuron. Biopesticides The biopesticides are a type of pesticides obtained from natural resources such as animals, plants, bacteria, and certain minerals.
- 3. Uses Pesticides are useful in controlling organisms that are toxic or harmful to their environment. Herbicides are useful in controlling algae and weeds. They are useful in grocery stores and food storage facilities to control rats and insects infesting on food. They are in use to kill mosquitoes that can spread life-threatening diseases such as the West Nile virus, yellow fever, and malaria. Also, they are useful in the agricultural sector to prevent or kill insects and other organisms that feed on crops.