Enduring Understanding:

• When humans use natural resources, they alter natural systems.

Learning Objective:

• Describe the benefits and drawbacks of different methods of pest control.

Essential Knowledge:

• One consequence of using common pest-control methods such as pesticides, herbicides, fungicides, rodenticides, and insecticides is that organisms can become resistant to them through artificial selection.  Pest control decreases crop damage by pest and increases crop yield.

• Crops can be genetically engineered to increase their resistance to pests and diseases.  However, using genetically engineered crops in planting or other ways can lead to loss of genetic diversity of that particular crop.

• A week is any plant that is deemed undesirable by humans

• Remember that some weeds or pests can have resistance and become stronger, persevering against pesticides

  • This leads to the need to use more pesticide

  • The pests get stronger, and we use more pesticide, then they get stronger…

  • This is the pesticide treadmill

Impacts

• Runoff can kill species in downstream ecosystems

  • Will not cause eutrophication like fertilizers but has a different kind of detrimental effect

• May infiltrate drinking water

• Can be carried by wind and affect other areas

• Can be taken up into the rain and spread very far

• May end up in residential areas, affecting humans

• Pesticides don’t go away, they have an impact everywhere they go

• They have components that do not break down

• They may build-up in certain areas and reach fatal levels of toxicity

• Biomagnification can also occur, affecting all parts of the food chain, but especially apex predators (including us)

  • This will be covered in unit 8

Why Use Them?

• Decreasing a pest’s impact on crops can increase yield and subsequently profits

• Products that are in any way damaged by pests or weeds cannot be sold

Genetically Modified Organisms (GMOs)

Process

• The gene from a completely unrelated organism is spliced into the genetic material of the crop

• This may the ability to produce insecticide, be pesticide or herbicide resistant so you can spray indiscriminately, produce more yield, etc.

• This is talked about more in 5.3

Complications

• The new produced insecticide could kill nontarget species

• It can cause resistance in pests

• Monocultures will limited genetic diversity may be susceptible to catastrophes that sweep through the environment

• The use of a single variety may lead other varieties to die out

  • Remember the issues that come with a decrease in biodiversity