The life that surrounds us is not only beautiful: it also works in our favor. In the countryside, the forest, or the garden, a silent army of animals and microfauna keeps pests at bay, pollinates crops, recycles nutrients, and stabilizes ecosystems. To ally with that allied fauna of the ecosystem —instead of fighting it— is one of the smartest decisions to produce healthy food and take care of biodiversity.
Over the past few decades, we have seen how the overuse of pesticides, synthetic fertilizers, and intensive farming practices has disrupted fragile balances. However, a growing number of farmers, gardeners, and land managers are turning to biological solutions that prioritize processes over products. Biological control, habitat management, vegetation cover and refuges These are some of the tools that are restoring health to soils and crops.
What does "allied fauna" mean and why is it key to ecological balance?
When we talk about allied fauna —also called auxiliary fauna— we are referring to insects, birds, reptiles, amphibians and mammals that provide essential ecosystem services: natural pest control, pollination, seed dispersal, soil aeration, organic matter recycling and much more. Their work reduces dependence on chemicals and helps to maintain more resilient agricultural systems and gardens.
In organic agriculture, this alliance is strengthened by practices that care for the soil and plants. The use of biostimulants of natural origin—microorganisms, plant extracts, substances that improve plant physiology—can increase crop resistance and indirectly benefit beneficial insects. Vigorous plants and living soils attract and sustain natural enemies that maintain the balance of phytophagous insect populations.
This view fits with a simple idea: pests are rarely the cause of the problem; they are usually the symptom of a stressed system. When the ecosystem is balanced —with a diversity of habitats, nectar sources and alternative prey—, pest pressure decreases without the need for broad-spectrum treatments.
The integrative approach contrasts with “classic” biological control based on buying and releasing exotic pests. Here, the priority is to attract, retain, and enhance the natural population. the already adapted native beneficial fauna to the climate and landscape of the surroundings, with lower costs and stable results in the medium and long term.
Essential allies: who's who and how they help us
Among the beneficial insects, the ladybugs (Coccinellidae) They devour aphids, both adults and larvae; lacewings (Chrysoperla carnea) They are famous for their "aphid lion" larvae; hoverflies They provide pollination and control; and the parasitoid hymenoptera such as Aphidius colemani or Trichogramma spp. regulate populations of aphids and lepidoptera, thus maintaining the balance.
The bees, bumblebees and wasps They are essential pollinators; their activity may be behind one in three bites of food. Many wasps also control caterpillars naturally. In the garden, the butterflies They provide beauty and pollination —although some caterpillars may nibble leaves, their impact is usually minor and offset by their benefits.
The SpidersThese often misunderstood creatures capture a multitude of invertebrates in their webs; and the praying mantis It hunts flies, crickets, and beetles with surprising efficiency. On the ground, the earthworms They are engineers: they aerate, facilitate water infiltration, improve structure and generate vermicompost, a top-quality source of nutrients.
Among birds, there is an irreplaceable cast: insectivores such as robins and blackbirds They clean the orchard of invertebrates; swallows, martins and swifts They hunt insects in flight; and the granivores like the sparrow They take advantage of seeds and remains, even helping to clean human environments. Birds of prey, both diurnal and nocturnal —Imperial eagle, Montagu's harrier, buzzard, kestrels, little owl, barn owl— keep rodents like voles at bay, saving costs and poisons.
In mammals, the mustelids (weasels, polecats, badgers) They are excellent rodent controllers; the zorro It combines micromammal control with seed dispersal; and the lynx It regulates rabbit populations and balances food chains. In the garden, the hedgehog It is a valuable ally against slugs, snails and insects; it is advisable to avoid toxic baits that could poison it indirectly.
The reptiles They also contribute. Lizards and geckos feed on insects and spiders; ocellated lizard It controls small mammals and invertebrates; and snakes such as the bastard or the ladder one They regulate rodents without posing a risk to people. Amphibians —salamanders and toads— consume beetles, moths and gastropods, and appreciate safe water sources.
Beyond agriculture, there are species that provide formidable environmental services. Los Murciélagos They control pests and even diseases; a colony of 20 million Mexican free-tailed bats can eat 220 tons of insects in one night (each individual eats around 1.000 insects per hour), providing billions in services to agriculture. Protect their shelters and reduce pesticides It is vital, even more so with threats such as habitat destruction (which affects 98% of species in North America) and white-nose syndrome, which has decimated populations.
The beavers They are true landscape engineers: their dams retain water during droughts, mitigate floods, create wetlands, and reduce the risk of fires by maintaining damp areas. Despite this, they are sometimes perceived as a problem, and their dams are destroyed, thus losing their benefits. Changing that perception and managing conflicts It prevents damage and preserves its services.
The bees They deserve a separate chapter because of their pollinator role in crops and wild flora; the birds They disperse seeds and control insects; vultures They clean up carrion, preventing disease outbreaks. Butterflies, although less efficient than bees, pollinate flat flowers in meadows and gardens; Its presence indicates environmental health..
In tropical ecosystems, the Elephants They dig dry riverbeds during droughts to create waterholes and disperse seeds in their dung; they also tend to eat younger trees, leaving the trees with the most stored carbon standing. At sea, the otters They control sea urchins and save kelp forests; Sharks They eliminate diseased fish, slowing the spread of pathogens; and the fish feces They can sequester carbon for centuries, a process now threatened by overfishing.
There are allies with surprising uses: the flames They protect flocks of sheep from predators, reducing the need for traps; narwhals They carry sensors that have made it possible to measure salinity, depth, and temperature in inaccessible areas of the Arctic; and the giant African rats Trained robots detect landmines —one example, Magawa, cleared 2,4 million square feet and located 71 mines and 38 devices in four years—, with a huge human impact.
Other great forest regenerators are the tapirs, which deposit thousands of seeds with their manure, especially in burned areas where their presence doubles and the number of seeds in their feces triples; the squirrels They bury and "forget" seeds, reforesting as they go; and earthworms maintain fertile soils essential for food production. They all contribute to food security discreetly but decisively.
How to attract and retain allies on your farm, orchard, or garden
The first step is to design the habitat. Floral borders with nectariferous plants (sweet alder, umbellifers, sunflower)Mixed hedges, safe ponds, islands of spontaneous vegetation and plant cover create food, shelter and microclimates. Staggered flowering throughout the year It is key for parasitoids and predators to find nectar and pollen always available.
To bees and bumblebeesPlant lavender, sage, thyme, sunflowers, and cosmos; install shallow waterers with stones and avoid insecticides. ladybugs They appreciate marigolds and areas with aphids (prey), as well as wooden shelters. The butterflies They look for brightly colored flowers and, sometimes, ripe fruit; reducing chemicals is essential.
The insectivorous birds They respond well to feeders in winter and waterers all year round, as well as dense bushes for nesting. Do not destroy swallow and martin nests, protected and invaluable as natural “insecticides”; and place nest boxes for kestrels, little owls and barn owls if you want them to help with rodents.
Bats feel right at home with high-rise shelter boxes and vegetation that attracts nocturnal insects; lizards and geckos They thrive with dry stone walls, rocks, and wood; and for toads and salamanders It's advisable to provide ponds with ramps for entry and shaded areas. The hedgehog needs piles of leaves, hedges and clear passages between plots; if you put food out, make sure it is safe and without toxic baits around.
In agriculture, crop rotations, polycultures, and diversified margins increase the stability of the system. Fertilization management, avoiding excess nitrogen which softens tissues and attracts aphids and thrips, Reduce outbreaks before they startIt also helps to plan pruning and harvesting to maintain flowering strips and shelter, especially in greenhouses.
Habitat management and biological control for conservation
Habitat manipulation—or conservation biological control—consists of conditioning the environment to increase the survival and effectiveness of native natural enemies. Cultivation margins with specific flower mixtures, Plant cover in olive groves and vineyards, and bands of uncultivated vegetation are “ecological infrastructures” that support lacewings, hoverflies, parasitoids and predatory mites.
Studies support this approach: in protected horticulture, Amblyseius swirskii, Orius laevigatus and Encarsia formosa They have reduced the need for broad-spectrum insecticides by controlling thrips, mites, and whiteflies; and in farms where sunflowers are intercropped, a higher influx of beneficial insects is observed even at short distances (≈1 meter), resulting in fewer pests and treatments.
In contrast to the traditional model of mass acquisition and disposal, the integrative approach seeks stable processes. Attracting and retaining auxiliary fauna adapted to the local climate It is more economical and robust. Even so, some farms combine both approaches, freeing up, for example, Cryptolaemus montrouzieri against mealybugs or Aphytis melinus for citrus red scale, while improving habitat to retain them.
Some are exploring novel tools such as mother tinctures and biological signals that “modulate” plant-insect interactions; these are combined with plant extracts, enzymes, or metabolites to to disadvantage the pest and favor the beneficial organismThese methods must be accompanied by observation and fine-tuning: without habitat or food, no helper will stay for long.
Some useful pest species: Orius laevigatus (trips), Amblyseius swirskii (mites, thrips, whitefly), Leptomastix dactylopii and Anagyrus pseudococci (cottonnet), Citrostichus phyllocnistoides (citrus miner) or Aphidius spp. (aphids). The combination of shelters, flowers, and crop management makes a difference in their success.
Risks, threats and how to minimize them
The main threats to allied fauna are habitat loss, broad-spectrum pesticidesElectrocution on power lines, falling into wells or dead-end pools, and collisions with infrastructure are among the threats. In the case of bats, diseases such as white-nose syndrome and the impact of poorly located wind farms are also risks.
Protect nests and shelters, install escape ramps on raftsMarking or burying hazardous power lines, and reducing chemicals are high-impact measures. Let's remember that there are protected species—like swallow nests—that should never be removed. Wildlife-friendly management It is compatible with profitability and improves the image of the agricultural sector.
Some of these allies are in decline or in danger: elephants, sharks, certain bees, birds and bats They suffer from human pressure. Losing pieces of the ecological web has domino effects that are difficult to reverse. That is why, in addition to taking action on farms and gardens, it is important to support conservation policies and projects. consume responsibly.
A common recommendation is to adjust the diet towards more plants and less industrial meat and dairy: this reduces pressure on habitats and pollution associated with certain production models. Animals cannot compensate on their own Deforestation, overfishing, or soil degradation; our part is unavoidable.
Fauna as a “thermometer” of the agroecosystem
Observation is a management tool. Aphid or thrips infestations may indicate excess nitrogen or tender tissuesA low diversity of beneficial insects suggests a deficit of nectar or shelter; compacted soils and poor earthworms reveal problems of structure and organic matter. Pests signal imbalancesCorrecting the source is usually more effective than "putting out fires" with chemicals.
Modern management relies on science and field experience: adjusting pruning dates to maintain flowering, combining companion species, planning irrigation to promote healthy soils, and introducing infrastructure such as Nest boxes for kestrels, barn owls and little owls that help with rodents. In areas with vole infestations, these boxes have proven to reduce populations at lower costs than poisons, and without their side effects.
One guiding principle of this approach: nature rarely eliminates everything; regulates and leaves genetic “reserves”Attempting to eradicate a pest often generates resistance and new problems. The goal is not zero individuals, but densities below the economic damage threshold, with allies who work for free as long as the system is well designed.
For more in-depth lists of allied species, fact sheets and practical recommendations, you can consult technical materials from specialized entities. Guide to biological control and conservation of beneficial fauna. Train, observe, and test It is the shortest path to successful and sustainable management.
Looking at the whole picture, it is clear that betting on allied fauna is a decision with long-term implications: more biodiversity, lower recurring input costs, resilience against droughts, heat waves or occasional outbreaks, and healthier food. From the home garden to the olive grove or the greenhouseThe principle is the same: create conditions for life to do its work and avoid anything that hinders it. When done right, the ecosystem responds, and the difference is visible—and rewarded—season after season.