Presentation on theme: "1 Pesticides Section 1:11 pp34-37. 2 What are pests? Pests are living organisms that are not wanted around us. Organisms that people consider to be harmful."— Presentation transcript:
8 3. Fungicide kills moulds Example: Captan lingers for days
9 4. Bactericide kills bacteria Example: Penicillin lingers for days
10 Early Pesticide Use Early pesticides: lead salts, arsenic, or mercury. Killed beneficial organisms, and polluted water and soil resources. Non-biodegradable..... not broken down within the ecosystem. Accumulated in the environment, contaminating water and soil resources, eventually poisoning humans.
11 Modern Pesticide Use Chemists developed organic pesticides …less toxic to humans and the intended pests. Organic pesticides also caused unexpected environmental effects.
12 Bioaccumulation Bioaccumulation. As each organism feeds on one lower in the food chain, the fat soluble pesticide began to be concentrated in ever higher amounts as one moved toward the top of the food pyramid.
13 Bioaccumulation Example: damage done to predatory birds as a result of bioaccumulation of DDT. DDT has been banned from use in North America.
15 Water Soluble Pesticides Newer pesticides are soluble in water. These pesticides are broken down by organism’s liver and excreted. They are also broken down in soil a lot faster.
16 Water Soluble Pesticides…Problems 1. More applications because they decompose faster in the soil 2. Insects becoming more resistant to the pesticide
17 Water Soluble Pesticides…Problems 3. Affect other organisms in the ecosystem 4. Bioaccumulation may occur in many different food chains when the dead pests or other non-specific organisms are eaten.