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  • In 1845, Ireland's vast potato fields were struck by an invasive fungal disease

  • that rapidly infested this staple crop.

  • The effect was devastating.

  • One million people died of famine,

  • and over a million more were forced to leave Ireland.

  • Nowadays, we avoid such agricultural catastrophes with the help of pesticides.

  • Those are a range of manmade chemicals that control insects,

  • unwanted weeds,

  • funguses,

  • rodents,

  • and bacteria

  • that may threaten our food supply.

  • They've become an essential part of our food system.

  • As populations have grown, monoculture, single crop farming,

  • has helped us feed people efficiently.

  • But it's also left our food vulnerable to extensive attack by pests.

  • In turn, we've become more dependent on pesticides.

  • Today, we annually shower over 5 billion pounds of pesticides across the Earth

  • to control these unwanted visitors.

  • The battle against pests, especially insects,

  • has marked agriculture's long history.

  • Records from thousands of years ago

  • suggest that humans actively burned some of their crops after harvest

  • to rid them of pests.

  • There's even evidence from ancient times that we recruited other insects to help.

  • In 300 A.D., Chinese farmers specially bred ferocious predatory ants

  • in orange orchards to protect the trees from other bugs.

  • Later, as large-scale farming spread,

  • we began sprinkling arsenic, lead, and copper treatments on crops.

  • But these were incredibly toxic to humans as well.

  • As our demand for more, safer produce increased,

  • so did the need for effective chemicals

  • that could control pests on a grander scale.

  • This ushered in the era of chemical pesticides.

  • In 1948, a Swiss chemist named Paul Hermannller

  • was awarded a Nobel Prize for his discovery

  • of dichlorodiphenyltrichloroethane, also known as DDT.

  • This new molecule had unparalleled power to control many insect species

  • until the 1950s, when insects became resistant to it.

  • Worse, the chemical actually drove dramatic declines in bird populations,

  • poisoned water sources,

  • and was eventually found to cause long-term health problems in humans.

  • By 1972, DDT had been banned in the United States,

  • and yet traces still linger in the environment today.

  • Since then, chemists have been searching for alternatives.

  • With each new wave of inventions, they've encountered the same obstacle -

  • rapid species evolution.

  • As pesticides destroy pest populations,

  • they leave behind only the most resistant individuals.

  • They then pass on their pesticide-resisting genes

  • to the next generation.

  • That's lead to the rise of super bugs,

  • such as the Colorado potato beetle,

  • which is resistant to over 50 different insecticides.

  • Another downside is that other bugs get caught in the crossfire.

  • Some of these are helpful predators of plant pests or vital pollinators,

  • so erasing them from agriculture wipes out their benefits, too.

  • Pesticides have improved over time

  • and are currently regulated by strict safety standards,

  • but they still have the potential to pollute soil and water,

  • impact wildlife,

  • and even harm us.

  • So considering all these risks, why do we continue using pesticides?

  • Although they're imperfect,

  • they currently may be our best bet against major agricultural disasters,

  • not to mention mosquito-born diseases.

  • Today, scientists are on a quest for alternative pest control strategies

  • that balance the demands of food production

  • with environmental concerns.

  • Nature has become a major source of inspiration,

  • from natural plant and fungal chemicals that can repel or attract insects,

  • to recruiting other insects as crop bodyguards.

  • We're also turning to high-tech solutions, like drones.

  • Programmed to fly over crops,

  • these machines can use their sensors and GPS

  • to carry out more targeted sprays

  • that limit a pesticide's wider environmental impact.

  • With a combination of biological understanding,

  • environmental awareness,

  • and improved technologies,

  • we have a better chance of finding a holistic solution to pests.

  • Chemical pesticides may never shake their controversial reputation,

  • but with their help,

  • we can ensure that agricultural catastrophes

  • stay firmly in our past.

In 1845, Ireland's vast potato fields were struck by an invasive fungal disease

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B2 TED-Ed resistant crop agricultural pesticide environmental

【TED-Ed】Do we really need pesticides? - Fernan Pérez-Gálvez

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    Jenny posted on 2016/11/15
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