Lesson 1.4 - Costs of Pesticides

You learned that scientists have developed pesticides to help increase food production.  You learned that insecticides are used to control insects and herbicides are used to control plants.  You also learned that some negative things happen when pesticides are used.  These "bad" things are called costs; they do not mean money.

One of the costs of using DDT is that some birds are failing to produce offspring.  Because of biological magnification, the chemical becomes highly concentrated in the bodies of the birds.  As a result, their eggs have shells that are too thin to withstand the birds sitting on them to hatch them.  The shells break, and no young birds hatch.

When insecticides are used to control one particular insect, other insects are usually killed also.  Beneficial insects such as honey bees are killed along with the pest insect.  The same thing can happen with herbicides.  Beneficial plants can be killed along with the pest plants.

Another cost of pesticides results from natural resistance.  Using pesticides results in a temporary reduction in the pest population.  The pesticide resistant population continues to grow, resulting in a pest population that cannot be controlled with the pesticide.  Then, new and stronger pesticides have to be developed.  Have you heard of "super bugs"?  These are not bugs as in insects; rather, they are bacteria that are resistant to existing medicines.  These super bugs evolved in a similar way: drug resistant bacteria survive and reproduce, forcing drug companies to make new and stronger drugs to kill them.

Now, answer the following questions.

Question 1. What is a cost of using DDT?

Question 2. What is a cost of using insecticide to control the potato beetle population?

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What is a cost of using DDT?

One cost of using DDT is a decrease in predatory birds such as the falcon. 

Question 2. What is a cost of using insecticide to control the potato beetle population?

The insecticide resistant potato beetles survive and reproduce, forcing the chemical companies to make new, stronger insecticides.  These stronger insecticides may have serious consequences for other organisms.

Another cost is that beneficial insects may be killed as well as the potato beetles.

 


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