Download - Pesticides Chapter 15 Section 2. AIM Explain the benefits and environmental impacts of pesticide use
PesticidesChapter 15Section 2
AIM Explain the benefits and environmental
impacts of pesticide use
DO NOW
In your EcoLog, discuss at least 2 negative impacts of pesticides
Pest Control-In North America, insects eat about 13%
of all crops-Crops in tropical climates suffer even
greater insect damage because the insects grow and reproduce faster in these climates.
-Worldwide, pests destroy about 33% of the world’s potential food harvest
Pest ControlWhat is a pest?-A pest is any organism that occurs where
it is not wanted or that occurs in large enough numbers to cause economic damage
-Pests can include plants, fungi, and microorganisms
Pest ControlWild plants often have more protection
from pests than crop plants. Why?
Wild Plants Crop Plants
Grow throughout a landscape, so pests have a harder time finding and feeding on a specific plant
Usually grown together in large fields, which provides pests with a one-stop source of food
A variety of pest predators live on or near the plantsEvolved defenses
Pesticides-Pesticides are chemicals used to kill
insects, weeds, and other crop pests-During the last 50 years, scientists
have invented many new pesticides.
Why? Pesticides were extremely effective – some pests have developed a resistance to pesticides therefore new pesticides needed to be developed
Pesticides-Pesticides can harm beneficial plants
and insects, wildlife, and even people
Impacts of PesticidesPesticide resistanceHuman health impactsLoss of biodiversity in the fields:
pesticides kill both target and non-target species
Loss of biodiversity higher up the food chain due to bio-magnification
Pesticide Resistance
-resistance = the ability to survive exposure to a particular pesticide
-more than 500 species of insects have
developed resistance to pesticides since the 1940s
Pesticide Resistance leads to Pesticide Treadmill
Increase tolerance, increase in resistance
What does this mean?
Need this amount of pesticideto Kill 50% x to Kill 90% 10xto Kill 99% 100xto Kill 99.9% 1000x
- hardiest ones live- next generations – very resistant- increase dosage or find new pesticide - time-consuming- costly
Heavy Reliance on Chemical Pesticides to Control Pests and WeedsWhy is this not sustainable?
Pesticide resistance results in a pesticide treadmill
Initial applications of a pesticide may kill 99.9% of the target insect, but the 0.1% left behind will be resistant to the pesticide and their genes will be passed on to each new generation of pest
Very short life spans for crop pests mean that in a short time pesticides will begin to lose their effectiveness (treadmill)
Health Effects of Pesticides
Reported US poisonings: 20,000/yr (est 1% world total)Reported US fatalities: 50/yrThere are > 25,000 brands pesticides registered in US
alone
Acute impacts Wheezing, respiratory distress Diarrhea, nausea, vomiting Blurred vision, salivation, seizures, coma, death
Chronic impacts Neurological effects Cancer (esp childhood cancers) Reproductive and developmental toxicity Endocrine disruption
Human Impacts from Chronic Exposure
95% of reported pesticide exposure cases occur in developing
countries, only acute cases
Reported cases in US typically only include acute poisonings, so
numbers relatively low
Human Health Concerns Pesticides are designed to kill organisms, so
they may also be dangerous to humans High cancer rates and nervous system
disorders Accidental chemical leaks
Endosulfan Cotton, potatoes,
apples, and tomatoes
CA = extinction of mountain yellow-legged frog
FL = contamination of Everglades
Stockholm Convention
Pesticides in ProduceHighest LowestApples Asparagus
Bell peppers AvocadosCelery BananasCherries BroccoliImported grapes CauliflowerNectarines Corn (sweet corn)Peaches KiwiPeas MangosPotatoes OnionsRed Raspberries PapayasSpinach PineappleStrawberries Peas (sweet)
Released 10/21/2003 by EWG
Pesticides and Human Impact
CLOSURE How would you suggest preventing
contamination from pesticides on food?
Michael Pollan Food Fight MOVIE - Ingredients
What have we done to reduce our dependence on pesticides? Biological Pest Controls Genetic Engineering
Pesticides and Biodiversity