They act quickly and are then degraded to non-toxic substances by chemical or microbial processes. This helps prevent their build-up in crops or other organisms. How quickly a pesticide breaks down depends on its chemical properties, how much is applied and how it is distributed, as well as environmental factors such as temperature, moisture, soil pH and the availability of microorganisms. How pesticides can control pests Physical toxicity pesticides These may block the cellular processes of target organisms in a purely mechanical way. Examples include spray oils that clog the respiratory mechanism of insects, petroleum oils that dissolve protective waxes on some insects and plants, or the bypyridylium herbicides that destroy the membranes of plant cells leading to their desiccation.
Some petroleum oils can deter feeding or egglaying in some insects.
Metabolic system inhibitors Metabolism is the transfer of energy within the cells of organisms, which is essential for the growth and survival of all living things. Sometimes a pesticide has to be metabolised into the toxic form before it becomes toxic to the target pest. This happens when the animal eats the bait containing the 1080. Proteins are the basic building blocks of all cells. Proteins such as enzymes control many important cell functions.