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An alarming scientific review has found human activity is driving insects to extinction. When the bottom of the food chain is endangered, so too is everything up the chain—including people. Insect declines threaten birds, fish, reptiles, and amphibians that eat insects, as well as the many plants that require them for pollination. Insects are also crucial to soil health, nutrient recycling, and ecosystem functioning.

"If insect-species losses cannot be halted, this will have catastrophic consequences for both the planet's ecosystems and for the survival of mankind," review coauthor Francisco Sánchez-Bayo, from the University of Sydney, Australia, told the Guardian.

Habitat loss from intensive agriculture and urbanization is the main cause of the decline, according to the review, Worldwide decline of the entomofauna: A review of its drivers, published in Biological Conservation. Agricultural pesticide and fertilizer use, pathogens, invasive species, and climate change are also major factors.

Review authors Sánchez-Bayo and Kris Wyckhuys, from the China Academy of Agricultural Sciences in Beijing, analyzed 73 scientific reports from around the world. Although the authors admit to some limitations with the study, the reports indicate that 40 percent of insect species are declining, one-third are endangered, and the total mass of insects is dropping by 2.5 percent a year. If these trends continue, most insects could be gone within a century—with severe consequences for all life.

The planet is already headed into its sixth mass extinction. Humans—who make up just 0.01 percent of Earth's living biomass—are the major drivers of the current catastrophe. A World Wildlife Fund study concluded that we've wiped out 60 percent of mammals, fish, birds and reptiles since 1970. Another study found people have destroyed 83 percent of wild mammals and half of all plants since the dawn of civilization. As frightening as that is, the rate of insect extinction is eight times that of mammals, birds, and reptiles.

Sánchez-Bayo said insect declines started at the beginning of the 20th century and accelerated in the 1950s and '60s, reaching "alarming proportions" over the past two decades. He believes recent rapid declines are a result of increased use of new classes of insecticides like neonicotinoids and fipronil, which remain in lands and water, sterilizing soils and killing beneficial insects. (Canada has delayed phasing out neonicotinoids.) Butterflies and moths are hardest hit, with bees and beetles also dramatically affected. The researchers found that a few adaptable species are increasing, but nowhere near enough to offset losses or replace services like pollination, animal nourishment, and soil-health maintenance.

People have made great advances over our short history, but we've often failed to apply our unique foresight to understand the consequences of our actions. Industrial agriculture increased our ability to produce more food, internal combustion engines and oil facilitated mobility and trade, and computer technologies brought about efficiencies in many areas, as well as enhanced social connection.

But our lack of care in implementing these many "advances" has led to overpopulation, pollution, habitat loss, extinction, climate change, and more. If we're capable of so much innovation and technological prowess, surely we have what it takes to resolve the growing environmental crises we've caused.

Some solutions can be implemented quickly and relatively easily, such as banning the worst pesticides, implementing the many available and emerging solutions to pollution and global warming, and examining better ways to grow, produce, and distribute food.

Sánchez-Bayo argues that changes in agricultural methods are crucial, noting organic farms and farms that used limited pesticide amounts in the past had more insects. Research also shows organic farms maintain healthier soils, use less energy, emit fewer greenhouse-gas emissions, and produce higher yields than conventional farms, especially during droughts.

Improving soil health is also a way to sequester more carbon and help reduce the threat of global warming.

Many people are repelled by insects or are frightened at the thought of bites and stings. No matter what you think of them, there's no denying they're essential to all life. If insects die out, we won't survive. From banning destructive pesticides to reforming agricultural methods to planting insect- and pollinator-friendly gardens in urban areas, there's much we can and must do to help the critters survive and thrive.