Growing the crops and raising the animals that feed civilization is a ceaseless battle against spoilage induced by pests. Farming produces an unnatural bounty of calories, stored in a single location: a treasure far too tempting for a great many pests. Humans have been battling the causes of crop spoilage and loss for over ten thousand years. However, only in the last few hundred years have agricultural science and technology been able to tip the balance in the struggle against spoilage substantially in human favor. The annals of history are packed with examples of pest-induced crop spoilage and crop loss, often resulting in widespread famine and immiseration.

Between 1845 and 1850, for example, a virulent late blight mold took hold in Ireland’s potato fields, swiftly destroying nearly the entire crop. Hunger was immediate, and without access to a large and varied trade network for foodstuffs and a more varied source of available foods at home, famine set in swiftly. The late blight that ravaged Ireland in the mid-1800s resulted in more than a million fatalities. Between 20 and 25 percent of the population either perished in the famine or immigrated to the United States or other countries. The application of modern fungicides to the fields of Ireland would have entirely prevented the famine. Unfortunately, it would be another hundred years before such fungicides would be invented.

Pesticides are an extremely broad range of chemical compounds, both naturally occurring and synthetic, that humans utilize to control infectious or destructive plants, insects, animals, fungi, bacteria and a wide range of microbes. The advent of experimentation with natural pesticides and herbicides began modestly in 2000 BCE in southern Mesopotamia, with the application of powdered sulphur to vegetable crops. By 1550, a number of naturally derived but highly toxic pesticides were in use across Europe, including arsenic, mercury and lead. These naturally-derived chemical pesticides were used widely until the first laboratory synthesized pesticides were developed, starting in the 1940s.

From the 1950s onward, new and innovative synthetic pesticides were developed and tested with a progressively increased focus on reducing the chemical toxicity, the volume of pesticide required to achieve a given effect and the overall cost to the farmer. All three of these driving performance indicators helped farmers produce more crops, and feed more people and animals at a lower cost — thus leading to less land clearing.

The application of pesticides to agricultural crops has been transformative for farmers and those who buy farmed products alike. Dramatically improved yields have kept the real cost of food significantly lower than would otherwise be possible without the use of pesticides. The modern use of fungicide in the United States, for example, prevents between 50 and 90 percent of crop loss among fruits and vegetables. Globally, responsible usage of modern herbicides, insecticides and fungicides prevents an average annual crop loss of roughly 50 percent. In 2005, global pesticide application helped to prevent a crop loss totaling nearly half a trillion dollars. Along with modern fertilizer and industrial equipment, pesticides have been, and will remain, an integral part of feeding a growing human civilization.

The application of pesticides is not limited to large-scale industrial agriculture, as the use of natural and synthetic pesticides have a role to play in organic farming as well. Far too many people believe that organic food is produced without the use of pesticides. That’s false. Organic farming is heavily reliant on a number of naturally occurring pesticides that are at least as toxic, if used incorrectly, as their synthetic counterparts. Naturally occurring copper sulphate, for example, is used extensively in the organic production of grapes, potatoes, tomatoes, apples, and other fruits and vegetables.

Over the last five decades, researchers have worked diligently to improve the positive characteristics of pesticides, while reducing the negative externalities resulting from their use. However, it is still important to recognize that the use of modern pesticides is not without risk. When used excessively and/or applied incorrectly, pesticides can have an undesired impact on plants, animals and human health.

The good news is that researchers and farmers have continued to work on methods to reduce the amount of pesticides required to protect crops, through more accurate and efficient systems of GPS guided spraying and advanced modes of pest detection. The two allow farmers to fight small and localized pest occurrences before the infection or infestation becomes widespread. In the coming decades, the role of genetically engineered (GE) crops in the reduction of pesticide use will revolutionize agriculture. The incorporation of selected infection and infestation combating genes into key crops has the potential to help many agricultural crops resist pests and diseases, without the application of external pesticide treatment.

Today pesticides remain a very thin, but strong layer of defense against the ravages of nature that would otherwise seek to consume or destroy the crops, feedstocks and animals that feed humanity. Their use has been one of the few truly transformative agricultural technologies that have helped to bring about our current state of food abundance.