Pesticide characteristics Many plant-derived pesticides(e.g, pyrethrin from chrysanthemums)or their derivatives are easily broken down by microorganisms and do not persist long in the environment Most of the second generation man-made pesticides (e.g., DDT)are broad spectrum and slow to degrade(half-life 15 years in soil and as much as 150 years in aquatic environments)
Pesticide Characteristics Many plant-derived pesticides (e.g., pyrethrin from chrysanthemums) or their derivatives are easily broken down by microorganisms and do not persist long in the environment. Most of the second generation man-made pesticides (e.g., DDT) are broad spectrum and slow to degrade (half-life 15 years in soil and as much as 150 years in aquatic environments)
Pesticide risks Pesticides can kill desirable organisms as well as pests. For example, broad spectrum insecticides may kill pollinators such as bees or lady bugs, which eat garden aphids Pesticides enter the food network and through biological magnification may concentrate to toxin levels in secondary and tertiary consumers
Pesticide Risks Pesticides can kill desirable organisms as well as pests. For example, broad spectrum insecticides may kill pollinators such as bees or lady bugs, which eat garden aphids. Pesticides enter the food network and through biological magnification may concentrate to toxin levels in secondary and tertiary consumers
Pesticide Benefits Disease control -e.g, malaria caused by female Anopheles mosquitoes Crop protection -reduce loss from competition with weeds, consumption by insects, and disease caused by fungi and bacteria. Part of reason for large numbers of agricultural pests is emphasis on monoculture in large tracts of land
Pesticide Benefits Disease control - e.g., malaria caused by female Anopheles mosquitoes. Crop protection - reduce loss from competition with weeds, consumption by insects, and disease caused by fungi and bacteria. Part of reason for large numbers of agricultural pests is emphasis on monoculture in large tracts of land
Effects of Long 500. Term Use of E400 Pesticides 00 Insect pest Insect predator or parasite 100 195019601970198019902000 Natural population fluctuations Pesticide application Tt
Effects of Long Term Use of Pesticides
Effects of Long Term Use of Pesticides In addition to selection for pests with genetic resistance long term use of pesticides causes imbalances in ecosystemS. Beneficial organisms and even natural enemies of the pests may be among the species 1400 1.300 eliminated by pesticides. May lose 1,100 1.000 keystone species. May develop new 800 DDT treated trees dominant pest species Untreated control trees 50 ∠ conomic injury leve 1967
Effects of Long Term Use of Pesticides In addition to selection for pests with genetic resistance, long term use of pesticides causes imbalances in ecosystems. Beneficial organisms and even natural enemies of the pests may be among the species eliminated by pesticides. May lose keystone species. May develop new dominant pest species