Certain pesticides and other phytosanitary products, while useful to agricultural production, can have negative impacts on the environment that exceed the benefits of their use. Because of this, France has taken the initiative to reduce pesticide use by 50 % by 2025 through its Ecophyto plan. Reducing the use of pesticides is great news for the environment, but it is not without consequence for farmers. What, then, should farmers use to replace phytosanitary products without harming the environment? Bio-control, the practice of using solutions already present in the environment, is a potential solution (using living organisms, like insects or bacteria, or natural substances like plant extracts). The leading French National Institute for Agricultural Research, INRA, has played a major global role in developing solutions. The institute recently released a report highlighting the various methods that can be used to fight off pests using natural methods that are not harmful to the environment. What follows is a brief summary of the different bio-control solutions for replacing harsh chemicals in agriculture brought to light in the report.
For more than 40 years, INRA has been studying the chemical ecology of pest insects and has been developing bio-control strategies that include the use of pheromones to fight against these insects, by playing off their natural behavior or through the disruption of the reproductive cycle. For example, researchers have developed methods that allow to reproduce the same pheromones emitted by female species of pest insects that can then be used to draw away males and prevent them from reproducing. Another method is to recreate an odor that incites a pest to flee, such as that emitted by a predator. Yet another strategy consists of identifying and recreating the natural odors that attract mother insects to the types of plants where they usually lay their eggs. Using these smells, farmers can then apply the pheromone to an area away from the plants they are trying to protect, and trick the insect into laying its eggs elsewhere, protecting the plant and preventing the pest from laying viable eggs.
The most widely used bio-control tool is the use of macro-organisms, and several are as efficient – or more so – than phytosanitary products. Certain ones, such as the genus Trichogramma, are parasites of pest insect eggs. Others, like certain nematodes, attack pest larvae, and other, such as bats, eat the adult insects, meaning that these organisms can provide a three front attack against pests. Yet another method, used in the case of invasive pest species, consists of introducing carefully and sustainably a natural predator of the invasive species from its original environment to fight off the pest insect.
A third natural method of warding off pest species is the use of micro-organisms like viruses, bacteria, or fungi. This consists of identifying species that pose no risk to the host plant but that infect or repulse the pest species. For example, researchers are currently finalizing a project that identified a certain species of fungi that is sometimes naturally found on tomato plants and that provides nearly 100% protection against the fungal infection of tomato plants caused by Botrytis cinerea. Plants are not the only things that can be protected this way: Fish species are also frequently confronted with infections by pests. Researchers at INRA have discovered a family of naturally occurring fungal species that can be used to protect fish from infection by microorganisms called Oomycetes.
Beneficial natural substances
Finally, natural substances – whether they be animal, plant or mineral – can also be beneficial in the fight against pests. One example can be taken from the world of animal husbandry. Goat and sheep are sometimes stricken with infections caused by parasitic nematodes that take up residency in the intestinal track of the animals, reducing their milk production, slowing their growth, and sometimes even killing them. Researchers have discovered that by raising the goats and sheep on plants high in tannins, they can provide a natural anti-worm defense to the animals, protecting them from infection. Additionally, it has been found that these plants can reduce the greenhouse gas emissions produced by sheep and goats.