WHAT YOU NEED TO KNOW ABOUT PESTICIDES

BACKGROUND

What Are Pesticides?

Pesticides are natural or synthetic agents that are used to kill unwanted plant or animal pests...
While the term pesticide is now often associated with synthetic chemical compounds, it was not until relatively recently that synthetic pesticides came into use. Naturally occurring compounds or natural extracts have been used as pesticides since ancient times. The earliest pesticides were most likely salt, sulfurous rock, and extracts of tobacco, red pepper, and the like. It is rumored that the Napoleonic army used crushed chrysanthemums to control lice, with limited effectiveness. Petroleum oils, heavy metals, and arsenic were used liberally to control unwanted pests and weeds until the 1940s, when they were largely replaced for many uses by organic synthetic pesticides, the most famous of which is DDT.

Because the broad term pesticide encompasses a diverse collection of sub-stances, an explanation of pesticide taxonomy and nomenclature is warranted. Pesticides can be classified either by target pest or by chemical identity.

According to FAO (1989) a pesticide is any substance or mixture of substances intended for preventing, destroying, or controlling any pest including vectors of human or animal diseases, unwanted species of plants or  animals causing harm during, or otherwise interfering with, the production, processing, storage, or marketing of food, agricultural commodities, wood and wood products, or animal feedstuffs, or which may be administered to animals for the control of insects, arachnids or other pests in or on their bodies. The term includes chemicals used as growth regulators, defoliants, desiccants, fruit thinning agents, or agents for preventing the premature fall of fruits, and substances applied to crops either before or after harvest to prevent deterioration during storage or transport. The term, however excludes such chemicals used as fertilizers, plant and animal nutrients, food additives and animal drugs. The term pesticide is also defined by FAO in collaboration with UNEP (1990) as chemicals designed to combat the attacks of various pests and vectors on agricultural crops, domestic animals and human beings. The definitions above imply that, pesticides are toxic chemical agents (mainly organic compounds) that are deliberately released into the environment to combat crop pests and disease vectors. Historical background of pesticides use in agriculture and public health.

Pesticides are also natural or synthetic agents that are used to kill unwanted plant or animal pests. While the term pesticide is now often associated with synthetic chemical compounds, it was not until relatively recently that synthetic pesticides came into use. Naturally occurring compounds or natural extracts have been used as pesticides since ancient times. The earliest pesticides were most likely salt, sulfurous rock, and extracts of tobacco, red pepper, and the like. It is rumored that the Napoleonic army used crushed chrysanthemums to control lice, with limited effectiveness.

Type of pesticide Target organism/pest

ALGICIDES:  Control algae in lakes, canals, swimming  pools, water tanks, and other sites.

ANTIFOULING AGENTS: Kill or repel organisms that attach to underwater surfaces such as boat bottoms,

ANTIMICROBIALS: Kill microorganisms

BIOPESTICIDES: Are certain types of pesticide derived from such natural materials as animals, plants, bacteria and certain minerals.

BIOCIDES : kills microorganism

DISINFECANTS AND SANITIZERS : kill or inactivate disease producing microorganism on inanimate objects.

FUNGICIDES : Kill fungi (including blights, mildews, molds)

FUMIGANTS: Produce gas or vapor intended to destroy pests in buildings or soil.

HERBICIDES: Kill weeds and other plants that grow where they are not wanted.

INSECTICIDES: Kill insects and other plants that grow where they are not wanted.

MITICIDES: (Also called acaricides) kill mites that feeds on plants and animals

MICROBIAL PESTICIDES: Microorganisms that kill, inhibit or out compete pests, including insects or other microorganism.

MOLLUSCICIDES: Kill snails and slugs.

NEMATODES: Kill nematodes (microscopic, worm-like organisms that feed on plant roots)

OVICIDES: Kill eggs of insects and mites.

 PHEROMONES: Biochemicals used to disrupt the mating behavior of insects 

The mode of Action of pesticides                    

The mode of action describes how the pesticides is or inactivate a pest. It provides another way of classifying insecticides. Mode of action is important in understanding whether an insecticide will be toxic to unrelated specie such as fish, birds and mammals.

                   Pesticides can be grouped according to the site or mode of action on the undesirable organism on which they act. Several sites or modes of action are known for herbicides, insecticides, fungicides. Here are examples.

 Insecticides control insects:

                   - By interfering on their nervous system, or

                   - By preventing moulting from the larva to the adult stage.

Herbicide control plants:

                   - By inhibiting photosynthesis, or

             -by reproducing effect of plant growth regulators which they produce naturally.

Fungicides control fungi:

                   -by inhibiting amino acid synthesis, or

                        - by interfering in cell division.