October 23, 2023

In 1478 the farmers of Berne, Switzerland, had had enough. A plague of beetles was wreaking havoc in their crops. Finally, after all attempts to remove the beetles had failed, a complaint was raised to the bishop of Lausanne. The bishop put the beetles on trial and, after finding them guilty, sentenced them to excommunication.

The trial was not unusual. During the Middle Ages insects and other pests were routinely tried by ecclesiastical courts. A plague of crop-destroying beetles could be a matter of life and death, so it may be no wonder that desperate citizens sought help from higher powers.

Perhaps the farmers of Berne could have looked closer to home for help, however. Today, regenerative farming techniques have shown that one of the best defences against insects is other insects. A single ladybird, for instance, can consume 5,000 aphids in its lifetime. They aren’t fussy eaters and will consume many of the most damaging pests in agriculture.

Ladybirds are, in effect, a natural pesticide. Yet, like most insect species, native ladybird populations are under threat,1 often they are unintended casualties in our escalating war on pests.

Ladybirds are, in effect, a natural pesticide. Yet, like most insect species, native ladybird populations are under threat

 The age of agro-chemicals

History is full of inventive approaches to pest control. As long ago as 2,500 BCE, the Sumerians were using sulphur to kill off insects. In 19th century UK, the Victorians had a no-nonsense approach to protecting their apple trees against aphids and birds – they smeared the trees with arsenic. “Wash the apples well afterwards,” was the advice.

More recently we have sought less toxic alternatives. Since the 1950s, modern monoculture farming techniques have relied on carefully formulated agro-chemicals – fertilisers, insecticides, bactericides, fungicides and herbicides. In a roundabout way these chemicals even dictate what we eat – for example, most soya beans and corn now come from plants genetically engineered to resist weed killer2.

These innovations have led to extraordinary increases in crop production. Often dubbed the ‘Green Revolution’, between 1960 and the start of the new millennium cereal yields more than doubled despite the amount of land given over to growing them staying relatively stable.3 According to the UN’s Food and Agriculture Organisation, each year we now spray more than a third of a kilogram of pesticides for every person on Earth.4

Is pest control out of control?

Pests, it turns out, don’t take this chemical onslaught lying down. Over time, they evolve to tolerate particular products. In turn, farmers resort to ever more toxic formulations that can have wider negative environmental impacts. Neocotinoids, for instance (a branch of insecticide largely banned in the UK and EU but still widely used elsewhere), are up to 10,000 times more deadly to bees than earlier insecticides.5 In effect, we are engaged in a game of whack-a-mole on a planetary scale, only the moles and the hammers are getting bigger.

For the environment, this escalating battle can have dire consequences. In Germany, researchers found that the total number of flying insects such as ladybirds and wasps fell by around 80% between 1990 and 2017– unintended exposure to pesticides is thought to be largely to blame7. (For birds, this fall in insect numbers has been calamitous – across Europe, the bird population has fallen by more than 500 million over the last 40 years.8)

Pesticides’ indiscriminate impact is felt below ground, too, where years of accumulated spraying make life miserable for earthworms and other invertebrates

Pesticides also linger in the environment. In the Canadian province of New Brunswick, DDT, the now-banned grandfather of modern insecticides, was found in high concentrations in some lakes fifty years after it had last been sprayed onto neighbouring forests. Despite the passage of half a century, researchers believed that the DDT was still causing algal blooms and reducing fish stocks.9

Pesticides’ indiscriminate impact is felt below ground, too, where years of accumulated spraying make life miserable for earthworms and other invertebrates. Earthworms are essential for soil health, but fungicides and insecticides can stunt their growth and hamper their ability to reproduce.10

Read also: Soil: food’s forgotten superhero

Restoring the natural balance

In the early 2000s, Alvarro Nietro, a vegetable farmer in Central Mexico, stumbled upon a natural solution. Nietro had been forced by food production regulations to set traps for mice in his field. Nietro discovered that the mice being killed weren’t interested in his crops: they just wanted the water which he had diverted to irrigate the crops. He decided instead to make small ponds outside the fields: “If they want water, why not give them water?” he reasoned. The mice stopped coming into the fields and the traps lay empty.

It was a simple solution, but, according to Nietro, “it changed everything.” Soon, owls and eagles came to feed on the mice. Inspired by the resurgence in life, Nietro planted 10,000 native trees in areas which weren’t being actively farmed. These ‘wild, bio-corridors’ became host to bats, squirrels, deer and even a cougar.

The need for pesticides was almost entirely eliminated since the wildlife in the bio-corridors controlled pests naturally, saving money and labour. “Once you help nature restore the balance, you restore everything, even your economy,” Nietro says. “I tell all the growers: do it for the love, or do it for money, but do it.”11