Insects are the most numerous animals on Earth, representing more than half of all known animal species, with over a million described types. Their sheer abundance and diversity make them the functional backbone of nearly every terrestrial and freshwater ecosystem. The continuous operation of the natural world depends profoundly on the collective efforts of this massive class of invertebrates.
Pollination: Driving Plant Reproduction and Global Food Security
The reproductive success of many plants is intrinsically linked to the actions of insects, a process known as entomophily. This mutualistic relationship occurs when an insect seeks nectar or pollen from a flower and inadvertently transfers pollen grains to the stigma of the next flower it visits. This service is fundamental to the propagation of over 85% of wild flowering plants, shaping the biodiversity of the plant kingdom.
The economic impact of this biological service is immense, underpinning a significant portion of global agriculture. Worldwide, the value of insect pollination has been estimated in the hundreds of billions of dollars annually. Many major food crops are highly dependent on insect vectors for maximizing yield and quality. Without the activity of bees, butterflies, moths, and beetles, crop production would decline substantially, leading to massive economic losses and increased food costs for consumers.
The Planet’s Cleanup Crew: Decomposition and Nutrient Cycling
Insects break down organic matter, preventing the accumulation of waste material. Species like dung beetles, termites, and fly larvae act as the planet’s primary clean-up crew, rapidly processing organic waste. This decomposition process is the mechanism by which essential nutrients are returned to the soil, supporting new life.
Termites are specialized decomposers of wood and plant material, relying on symbiotic microorganisms to digest complex cellulose. Dung beetles bury and consume faeces, preventing the buildup of waste that could harbor parasites while enhancing soil nutrient content. These actions accelerate the transformation of organic carbon and nitrogen back into forms that can be absorbed by plant roots, while the burrowing and tunneling activities of many insects aerate the soil, improving structure and promoting fertility.
Supporting the Trophic Pyramid: Insects as Essential Food Sources
Insects convert plant matter into high-protein biomass that feeds a vast array of animals. They occupy a foundational position at the base of the terrestrial food web, making the energy stored in leaves and wood available to higher trophic levels. This role as prey is significant for birds, fish, and small mammals that rely on this energy conduit for survival and reproduction.
The reliance of birds on insects is pronounced during the breeding season, as protein is necessary for rapid growth. Studies have found that approximately 96% of all terrestrial bird species feed insects to their young. Similarly, aquatic insects are a major food source for freshwater fish, making up a large percentage of the diet of species like trout. The sheer volume of this transfer is staggering, with wild birds estimated to consume hundreds of millions of tons of insects annually.
Direct Contributions to Human Economy and Science
Beyond their ecological services, insects provide direct benefits to human economies and scientific endeavors. Commercial products derived from domesticated insects include honey and beeswax from honeybees (Apis mellifera). Silk, another historically valuable product, is spun by the larvae of the silkworm moth (Bombyx mori).
Insects also provide natural dyes, such as carminic acid harvested from the cochineal scale insect, used to color textiles, cosmetics, and food products. Furthermore, science relies heavily on insects as model organisms. The common fruit fly, Drosophila melanogaster, is a premier tool for genetic research, yielding fundamental insights into human diseases like cancer and neurological disorders due to genetic homology with humans.
In agriculture, insects are employed as biological control agents. Predatory insects like ladybugs and lacewings, along with parasitic wasps, are intentionally released to manage pest populations naturally. This strategy protects crops while reducing the environmental impact associated with chemical use. The study of insects also holds promise for medicine, as certain species produce unique antimicrobial compounds being investigated as potential new antibiotics.