Insects are an important component of agricultural productivity, performing functions that sustain crop yields and farm ecosystems. While some species are pests, the vast majority of insects serve beneficial roles as natural regulators within the farming landscape. These invertebrates provide essential services, from ensuring crop reproduction to managing soil fertility and controlling pest populations. Understanding these functions shifts the perception of insects from nuisances to essential workers that underpin the global food supply.
Essential Crop Pollinators
The reproductive success of many valuable food crops is directly linked to insect pollinators. Approximately 35% of the world’s food crop production, including most fruits, nuts, and vegetables, depends on insects performing the bulk of this work.
The primary group responsible is bees, including managed honey bees and thousands of species of wild, native bees. Flies, butterflies, moths, beetles, and wasps also contribute significantly. Certain crops, like tomatoes, require “buzz pollination,” a specialized technique performed by bumble bees that vibrates the flower to release pollen.
Insect diversity enhances both the quantity and quality of crops. Diverse insect communities can improve the size and shape of fruits and increase the oil content in crops like rapeseed. A mix of species, such as wild bees alongside managed honey bees, often increases pollination efficiency, maximizing yield and quality. This service provides immense global economic value to annual food production.
Natural Pest Management
Insects serve as the primary line of defense against crop pests through biological control. This natural management system involves conserving or introducing beneficial species to suppress pest populations. This service reduces the need for chemical pesticides, fostering a more ecologically balanced and sustainable farming environment.
The two main strategies employed are predation and parasitoidism.
Predation
Predatory insects, such as lady beetles, lacewings, and minute pirate bugs, actively search for and consume a large number of pests during their lifetime. For example, both the adult and larval stages of the green lacewing are voracious feeders on soft-bodied pests like aphids, spider mites, and whiteflies.
Parasitoidism
Parasitoids, predominantly specialized wasps and flies, lay their eggs on or inside a host insect. The developing larva feeds on the host, ultimately killing it. Parasitic wasps, such as the tiny Trichogramma, are widely used because they target the eggs of many major agricultural pests. This host-specific approach makes parasitoids useful in targeted biological control programs.
Enhancing Soil Health
The biological activity of insects beneath the soil surface is fundamental to maintaining healthy agricultural land. Insects that feed on dead organic material, known as detritivores, play a key role in decomposition and nutrient cycling. They physically break down crop residues and manure into smaller fragments, making them accessible to microbial decomposition.
Dung beetles, for instance, rapidly bury and consume animal droppings, preventing nutrient loss and returning elements like nitrogen and phosphorus to the soil. The physical act of burrowing by insects like beetle larvae, termites, and ants acts as natural tillage. These activities create tunnels that improve soil aeration and water infiltration, allowing roots to grow easily and supporting crop resilience.
Targeted Weed Control
Insects can be intentionally deployed as biocontrol agents to manage invasive weed species that compete with crops. This strategy involves introducing insect herbivores that feed exclusively on the target weed, limiting its growth and spread. This insect-based control offers a long-term, self-sustaining, and environmentally focused solution.
A successful example is the use of the Argentine cactus moth to control the invasive prickly pear cactus in Australia. In North America, specific leaf-feeding beetles, such as those from the Galerucella genus, have been effective in reducing the density of invasive purple loosestrife. The insects’ feeding habits reduce the weed’s competitive advantage, allowing desirable native plants to recover.