Chemical Control

What is chemical pesticide control?  Chemical pesticides use chemicals (synthetic or natural) to kill the targeted pest.  When using chemical pesticides you must consider the persistence, toxicity, and specificity of the chemical Why do these matter when thinking about pesticide use?  But what do these terms mean?

Vocabulary Building  Persistence : describes the length of time a chemical remains active in the ecosystem. Persistent chemicals are problematic because they do not break down quickly and continue to kill organisms in the ecosystem.  Toxicity : is the degree to which a substance is harmful.  Toxicity depends on  Dosage amount  Number of times exposed  Size/age of organism exposed  Ability of body to detoxify substance  Organisms sensitivity  Synergistic effects

Vocabulary Building cont.  Specificity : describes how many organisms the pesticide will kill.  Broad spectrum pesticides kill a wide range of organisms  Narrow spectrum pesticides focus on specific pest.

Bioaccumulation and Biomagnification  Bioaccumulation : increase in concentration of a pollutant from the environment to the first organism in a food chain  Biomagnification : increase in concentration of a pollutant from one link in a food chain to another  A pesticide can bioaccumulate in an organism and biomagnify up a food chain  We are concerned about these phenomena because together they mean that even small concentrations of chemicals in the environment can find their way into organisms in high enough dosages to cause problems. In order for biomagnification to occur, the pollutant must be:  long-lived  mobile  soluble in fats  biologically active

 DDT is a classic case of a pesticide biomagnification  How might this impact humans?

Types of Pesticides  First-generation pesticides used before 1940  Inorganic compounds (minerals)  Lead (neurotoxin)  Mercury (neurotoxin)  Arsenic (honey and arsenic were used to kill ants)  Highly toxic  Persistent  Accumulate  Non-specific Minerals would accumulate in the soil and cause infertility  Botanicals  Nicotene  Pyrethrum  Rotenone  Usually non-persistent  Highly toxic

Types of Pesticides  Second generation pesticides  Synthetic chemicals created after 1940  Persistent  Toxic Short lived  Result in biomagnification (chlorinated hydrocarbons like DDT)  Water Soluble

Rachel Carson ( ) Before there was an environmental movement, there was one brave woman and her very brave book Peter Matthiessen Time Magazine elected her “one of the 100 most influential people of the century”

Advantages of Chemical Pesticides  save human lives by decreasing insect-related diseases such as malaria, typhus, plague, etc.;  help increase food supplies;  increase profits for farmers;  they work fast, have a long shelf life, can be shipped; can be safe if properly used

Disadvantages of Chemical Pesticides  Accelerate the genetic resistance of pests (pesticide treadmill)  put farmers on a financial treadmill having to pay more and more for new pest control programs to beat genetic resistance that can cost more and become less effective over time;  can kill natural predators/parasites that help control pest populations and/or pollinators;  can pollute the environment (soil, water, sediments, non-target organisms, humans, food chain, etc.)

What are the regulations governing pesticide use?  How can laws help protect us from the harmful effects of pesticides?  Specifically, describe how the following laws regulate pesticide use: FIFRA, FQPA, Clean Air Act, Clean Water Act, FFDCA, ESA, and PRIA