Pesticides Science 1206

Pest Pests are living organisms that are not wanted around us. Examples of pests include unwanted dandelions growing in the lawn; rodents or insects that eat fruits, vegetables or other crop species; micro-organisms that cause disease in forest, fish, or crop resources, etc.

A pest is any organism that man believes is undesirable, has a negative impact on the human environment, or is in competition with human use of a resource, either natural, or cultivated.

4 types of Pesticide Herbicides: kills plants Insecticides: kills insects Fungicides: kills fungi Bactericides: kills bacteria

Early Pesticide Use: First generation pesticides the use of toxic inorganic metallic salts such as copper sulfate, lead salts, arsenic, or mercury. These substances were generally effective against the intended pest, but also created some environmental problems: –they also killed other beneficial organisms, –polluted water and soil resources used by man. –Most early pesticides were non-biodegradable (meaning that they were not broken down within the ecosystem). Therefore, they began to accumulate in the environment, contaminating water and soil resources, eventually poisoning humans.

Modern Pesticides: Second generation pesticides organic pesticides that were designed to be less toxic to man and more specific toward the intended pests. Some of these pesticides were fat soluble. This characteristic lead to a problem known as bioaccumulation. Toxins become more highly concentrated at higher trophic levels.

One example of this problem is illustrated by the damage done to predatory birds as a result of bioaccumulation of DDT. As a result of this problem DDT has been banned from use in North America.

Pesticide Resistance When pest become resistant to pesticides which means the pesticide no longer effects them.

Development of pesticide resistance There is a chance that some pest will have genes that allow them to survive a first application of pesticides. They are resistant to the pesticide.

The survivors then have offspring which are mostly resistant. These individuals survive the next spraying. If a similar pesticide is often used, resistant pest will soon make up most of the population. See fig. 5 pg. 55

Read page 56 and write a short paragraph answering the question in (l) Read “the Bald Eagle” section, pg 57, answer (r ) and (s) Pg. 58 understanding concepts #7 a and b Homework: Read p 52-57

1. Which statement is generally true regarding DDT? a. DDT is not a serious problem since it is biodegradable. b. DDT will kill all the pests it is used against. c. DDT tends to accumulate in the tissues of top predators. d. DDT is water soluble so it is normally excreted in urine. 2. Which statement best describes the problem associated with continued use of the same pesticide? a. The pests are completely eliminated from the ecosystem. b. The pesticide kills a greater number of pests with each application. c. The pesticide kills fewer of the pests with each application. d. Pesticides are generally highly specific and rarely harm beneficial organisms. 3. Which statement regarding early pesticide use is false? a. Early pesticides made use of heavy metals such as mercury. b. Early pesticides contaminated soil and water. c. Early pesticides were biodegradable. d. Early pesticides were toxic to humans. 4. What is the most common problem associated with fat soluble pesticides? a. They tend to contaminate the ground water supply. b. They are highly specific to a single pest species. c. They are prone to biomagnification. d. They must be sprayed more often than water soluble pesticides. 5. Which is most likely to contain the highest concentration of pesticide in its body tissues? a. wheat b. frog eating birds c. frogs d. grasshopppers

1. Which statement is generally true regarding DDT? a. DDT is not a serious problem since it is biodegradable. b. DDT will kill all the pests it is used against. c. DDT tends to accumulate in the tissues of top predators. d. DDT is water soluble so it is normally excreted in urine. 2. Which statement best describes the problem associated with continued use of the same pesticide? a. The pests are completely eliminated from the ecosystem. b. The pesticide kills a greater number of pests with each application. c. The pesticide kills fewer of the pests with each application. d. Pesticides are generally highly specific and rarely harm beneficial organisms. 3. Which statement regarding early pesticide use is false? a. Early pesticides made use of heavy metals such as mercury. b. Early pesticides contaminated soil and water. c. Early pesticides were biodegradable. d. Early pesticides were toxic to humans. 4. What is the most common problem associated with fat soluble pesticides? a. They tend to contaminate the ground water supply. b. They are highly specific to a single pest species. c. They are prone to biomagnification. d. They must be sprayed more often than water soluble pesticides. 5. Which is most likely to contain the highest concentration of pesticide in its body tissues? a. wheat b. frog eating birds c. frogs d. grasshopppers