Ants are one of the most numerous and widespread insect groups globally, inhabiting virtually every terrestrial environment from rainforests to arid deserts. Current estimates suggest there are nearly 20 quadrillion individual ants on Earth, a staggering number that speaks to their ubiquity. This collective population represents a total biomass of approximately 12 megatons of dry carbon, a mass greater than the combined biomass of all wild birds and wild mammals. Despite their small size, the sheer volume and constant activity of ant colonies mean they play large roles in maintaining ecological balance, profoundly impacting human environments and economies.
Ants as Ecosystem Engineers
The constant tunneling and excavating activities of ant colonies fundamentally alter the physical structure of the soil, earning them the designation of “ecosystem engineers.” As they construct their subterranean nests, ants aerate the soil, increasing its porosity and improving the flow of oxygen and water. This action enhances water infiltration, ensuring moisture is distributed more deeply into the ground rather than running off the surface.
Ants move vast quantities of soil, often turning over more earth than earthworms do in certain habitats. This bioturbation mixes different soil layers, helping to break up compacted earth and facilitating the movement of nutrients to plant roots. The resulting tunnels contribute to overall soil health and stability, supporting robust plant growth and preventing soil erosion.
Ants also play a role in nutrient cycling by acting as decomposers and recyclers of organic matter. Foraging workers collect dead insects, shed leaves, and other debris, transporting this material back to their nests. Once inside, this matter decomposes, enriching the surrounding soil with essential nutrients like nitrogen and phosphorus. Waste products, often deposited in refuse piles or “middens,” function as natural fertilizer depots, making the soil around ant nests measurably richer than the surrounding earth.
Ants in Seed Dispersal
A specialized process known as myrmecochory describes the dispersal of seeds by ants, a mutually beneficial relationship found in an estimated 11,000 to 23,000 plant species worldwide. Many of these plants produce seeds with a fleshy appendage called an elaiosome, which is the specific reward for the ants. The elaiosome is rich in lipids, amino acids, and other nutrients, making it highly attractive to foraging workers.
Ants carry the entire seed-elaiosome package, known as a diaspore, back to their nest. The elaiosome is removed and fed to the ant larvae, and the intact seed is typically discarded in an underground waste chamber or a refuse pile. This disposal location is favorable for germination, as it is protected from seed predators and naturally enriched with the colony’s discarded organic material and nutrients.
Although ants generally disperse seeds within a few meters of the parent plant, this short-range movement provides advantages. Dispersal helps the seeds escape immediate predation and reduces competition with the parent plant. By burying the seeds, ants also protect them from surface hazards like fire, aiding in the successful reproduction and biodiversity of myrmecochorous plant species.
Ants as Natural Pest Controllers
The predatory nature of many ant species makes them effective natural pest controllers in both natural and agricultural settings. Ants are opportunistic generalist predators, constantly foraging and consuming a wide variety of insect pests, including eggs, larvae, and adult forms. This constant predation helps regulate insect populations, preventing outbreaks that could devastate crops or native flora.
In agricultural systems, ants have been shown to be effective biological control agents, sometimes achieving efficacy comparable to chemical pesticides in certain crops. They prey on many pests that damage fruits, seeds, and leaves, such as caterpillars and beetles. This service has been recognized for centuries, with records indicating that Chinese farmers were using weaver ants for pest control as far back as 1200 B.C.
However, the role of ants in farming is complex due to a “disservice” they provide to certain insect groups. Some ants “farm” sap-sucking insects like aphids and mealybugs, protecting them from natural predators in exchange for consuming their sugary waste product, known as honeydew. Management strategies, such as providing alternative sugar sources, can interrupt this relationship, allowing the ants to continue their beneficial predation on other crop-damaging pests.
Direct Human Uses of Ants
Beyond their ecological services, ants have a long history of direct use by human cultures around the world, particularly as a food source and in traditional medicine.
Ants as Food
The practice of entomophagy, or eating insects, includes many ant species, which are valued for their high protein, fat, and mineral content. Ant larvae and pupae are consumed as a delicacy in parts of Africa, Latin America, and Asia.
In Mexico, the large, edible larvae and pupae of certain ant species are known as escamoles, sometimes referred to as “insect caviar” due to their texture and desirability. The bodies of some adult ants, such as the weaver ant (Oecophylla smaragdina), are also eaten for their distinct, sharp, citrus-like flavor, which comes from the formic acid they contain.
Traditional Medicine and Research
Ants have been used in traditional entomotherapy to treat conditions like rheumatism and certain types of pain. Leaf-cutting ants (Atta species) have been used in Latin America to address ailments such as abdominal pain and sore throats. Modern research increasingly explores the biochemical components of ants, including their antimicrobial and anti-inflammatory compounds, which may offer future pharmaceutical benefits.