P ESTICIDES

N ATURAL C APITAL : S PIDERS ARE I MPORTANT I NSECT P REDATORS

W E U SE P ESTICIDES TO T RY TO C ONTROL P EST P OPULATIONS (2) First-generation pesticides Second-generation pesticides – Paul Muller: DDT – Benefits versus harm Broad-spectrum agents Persistence

W E U SE P ESTICIDES TO T RY TO C ONTROL P EST P OPULATIONS Pesticides Insecticides Herbicides Fungicides Rodenticides Herbivores overcome plant defenses through natural selection: coevolution

M ODERN S YNTHETIC P ESTICIDES H AVE S EVERAL A DVANTAGES Save human lives Increases food supplies and profits for farmers Work quickly Health risks are very low relative to their benefits New pest control methods: safer and more effective

Fig , p. 295 TRADE-OFFS Conventional Chemical Pesticides Save livesPromote genetic resistance AdvantagesDisadvantages Increase food supplies Kill natural pest enemies ProfitablePollute the environment Can harm wildlife and people Work fast Safe if used properly Are expensive for farmers

M ODERN S YNTHETIC P ESTICIDES H AVE S EVERAL D ISADVANTAGES (1) Accelerate the development of genetic resistance to pesticides by pest organisms Expensive for farmers Some insecticides kill natural predators and parasites that help control the pest population Pollution in the environment Some harm wildlife Some are human health hazards

C HARACTERISTICS OF AN IDEAL PESTICIDE

A N IDEAL PESTICIDE WOULD Kill only the target or targeted pests thus NOT affecting beneficial insects. It would be cost effective. It would break down quickly and NOT accumulate in the ecosystem.