m48.    What is in pesticides and what do they do?

Pesticides are used for population control. Although labeling an organism as a pest is a human judgment, less than 1% of the animals classified as pests have no predators. Pesticides include insecticides, herbicides, fungicides, nematocides and rodenticides.

There are many forms of insecticides. Chlorinated hydrocarbons are broad-spectrum poisons, causing convulsions, paralysis and death i.e. DDT. Organophosphates can be broad or narrow spectrum poisons, causing death by deactivating the chemical involved in transmitting nerve impulses, i.e. malathion and diazinon.  They are water-soluble. Carbamates can also be broad or narrow spectrum poisons, causing death by deactivating the chemical involved in transmitting nerve impulses, i.e. Sevin.  These are highly toxic to honeybees. Botanicals are broad and narrow spectrum poisons, produced naturally by plants i.e. camphor. Microbotanicals, such as bacteria, fungi, and protozoans selectively kill insects by producing certain toxins.

Herbicides are usually contact chemicals that interfere with photosynthesis. Others, such as Roundup are systemic chemicals creating runaway growth. Soil sterilants kill microorganisms in the soil that are essential to plant growth.

Fungicides prevent fungal spore germination.

Fumigants can kill nematodes, fungi, insects; an example is carbon tetrachloride.  These can bioaccumulate.  

e17.    How do organisms use matter?

e18.    Does water recover from pollution?

e19.    What materials can cause water pollution?

e20.    What are environmental hazards and risks?

e21.    What are chemical hazards?

g17.    Is some matter more useful than other matter?

g19.    Where do you find air pollution?