According to a study produced in the UK, over 400,000 insects are at risk of extinction due to heavy pesticide use. Insects such as bees and butterflies play significant roles in our ecosystem. They help pollinate, recycle nutrients, and serve as food for other animals. 23 bee and wasps species have become extinct over the last century while the number of pesticide applications has doubled over the last 25 years.
Pesticides are harmful to our ecosystems and to our health. They contaminate soil, water, and other vegetation. Pesticides are meant to kill insects and weeds, but can also be toxic to birds, fish, and other wildlife or plants. These chemicals are harmful to humans as well. They can cause short-term, immediate effects such as rashes, diarrhea, nausea, dizziness, and flu-like symptoms, and they can also cause long term effects such as cancer or tumors.
Certified organic foods are grown without the use of pesticides. Each time you buy organic, you are voting to stop the use of pesticides. Save our ecosystem, eat organic. Here's the article on the insect extinction studies: