Ants protect plants better than toxic pesticides
Harnessing the natural power of insects can, with proper management, be more effective than using harmful chemicals.
New research shows that ants can help farmers produce food more effectively than pesticides.
They are better at killing pests, reducing plant damage, and increasing crop yields, according to the first systematic study of ants’ contribution to plant production.
Ants are generalist predators that hunt pests which damage fruits, seeds, and leaves, leading to a decline in crop yields. According to the study, greater ant diversity generally provides better protection against a wider range of pests.
The study examined 17 crops, including citrus fruits, mangoes, apples, and soybeans in countries such as the USA, Australia, the United Kingdom, and Brazil. «In general, ants can be useful pest control agents with proper management and can increase crop yields over time. Some ant species have similar or greater effectiveness than pesticides, and at lower cost«, the researchers write in the study published in Proceedings of the Royal Society B.
The Brazilian team examined 26 species, most of which are arboreal ants that nest on plants or on the ground but often also climb plants. They found that ants thrive best in diversified farming systems such as agroforestry (where trees and crops are grown on the same land) and shaded crops, because these environments offer more nesting sites and food resources.
Lead researcher Dr. Diego Anjos of the Federal University of Uberlândia said: «Our study encourages farmers to adopt more sustainable practices such as biological control by ants and the cultivation of shaded crops to naturally promote ants in farming systems«.
The role of ants in agriculture has not yet been fully clarified, as they can also pose a problem. Pests such as mealybugs, aphids, and whiteflies, which produce a sugary liquid known as honeydew, tend to occur more frequently when ants are present. This is because ants feed on the honeydew and essentially keep aphids like livestock, protecting them from predators in return.
Researchers say that nature-friendly management practices such as providing an alternative sugar source (on the ground, near the tree trunk, or on the branches) can disrupt this relationship. The ants are distracted and can continue to reduce the numbers of other pests such as caterpillars and beetles, which do not produce honeydew.
Scientists in the Fiji Islands have discovered an ant species that grows, fertilizes, and guards its own coffee.
The study examined most insect species considered pests worldwide and encompassed 30 species across 52 studies. The data came from studies comparing groups of plants with ant infestations to plants from which ants had been removed (mechanically or chemically), strongly suggesting that the ants were responsible for the observed changes.
There are more ants than any other insect; they make up half of the planet's insect biomass. There are at least 14’000 known ant species, and many more are likely still undiscovered. Citrus farmers in China have been using ants in agriculture for centuries, and the insects are also used to combat forest pests in Canada, cocoa pests in Ghana, and crop pests in Nigeria.
Ants living on the Pacific islands of Fiji can cultivate and grow at least six plant species as part of a mutually beneficial relationship dating back 3 million years, as published research shows.
Dr. Patrick Milligan from the Pringle Lab at the University of Nevada was not involved in the study but described the findings as «encouraging and by no means surprising«. He added: «They offer a clean and tidy description of the ant-derived benefits that are ubiquitous in ecological and agricultural systems.»
«This is essentially another option in our agricultural toolkit that can enable farming to move away from pesticides – which genuinely harm neighboring insect communities – while still improving crop yields.«
Prof. Adam Hart from the University of Gloucestershire, who was also not involved in the research, said that this confirmed the important role of ants as pest controllers. «Many of us have talked about ants as natural pest controllers. But as with everything, the matter is usually more complex than we think once we start digging deeper.«
The research findings suggest that it could be worthwhile to relocate ant colonies to other areas.
«However, we need to be careful – it is not about all ants or all cultivation systems. It is about developing a better understanding of how ants interact with plant pests and other organisms.»
