In many mythologies, the coming of locusts is a sign of the impending apocalypse. The flying insects are symbols of carnage and destruction. Ironically, it is not the coming of insects that might bring about our grisly end, but rather the absence of them.
A study published this past October in the Proceedings of the National Academy of Sciences has described a startling reduction in insect numbers in Puerto Rico’s Luquillo rainforest. The researchers, who conducted a similar study in the Luquillo rainforest in the late 1970s, recognized the difference in the forest even before taking any measurements. “Boy, it was immediately obvious when we went into that forest,” Dr Bradford Lister, a biologist at Rensselaer Polytechnic Institute and author of the study, told the Washington Post. But it was only after measuring the biomass, a measure of the overall weight of certain animals in an area, that Lister and his colleague Andres Garcia could see just how dramatic the change was.
Between 1977 and 2013, the insect biomass had declined by up to 60 times.
This study comes a year after an equally distressing report published in PLOS ONE that showed a more than 75 percent decline in insect biomass over 27 years in protected German nature preserves. The results of this study prompted Dr Dave Goulson, a researcher at Sussex University who authored the paper, to warn The Guardian that we are “currently on course for ecological Armageddon.”
At first, that statement may seem alarmist. After all recent figures show that there are around 1.4 billion insects for each human on our planet, so what if a few billion are missing from German nature preserves?
In fact, some people probably feel the fewer insects the better. Without bugs, insect-borne diseases such as Malaria and Zika would be all but eradicated saving countless lives each year. All of our produce could be grown without the need for harsh chemical pesticides. And think of the picnics we could have without those annoying ants or buzzing bees ruining the serenity of a temperate spring day.
But before we begin boycotting bugs, what else would happen in a world without insects?
Within the first few weeks, millions of individual animals would die and thousands of species would go extinct. In most environments insects, due to their abundance and high protein content, form the base of the food web. In fact, it is estimated that around 60% of all birds rely on having insects in their diet. Without insects, the animals that eat them – aptly named insectivores – will starve. In turn, the animals that eat the insectivores will also starve. After several more weeks the apex predators of the world’s ecosystems, such as tigers, lions, and bears, will perish as well – oh my.
This both literal and metaphorical butterfly effect is called a bottom-up trophic cascade and it is already being seen in the Luquillo rainforest. Dr Lister and Dr Garcia found that there was a synchronous decline in the insectivorous lizards, frogs, and birds in the study area, which they characterized as a “collapse of the forest’s food web.”
However, animals will not be the only victims of the bug apocalypse.
According to a 2011 study, over 80% of wild plants depend on insects for pollination. Bees, butterflies and other pollinators allow many flower-bearing plants, called angiosperms, to reproduce by distributing pollen from the male organs of one flower to the female organs of another. These insect-dependent plants include around 35% of global food crops including many fruits and vegetables, such as avocadoes, coffee, and apples.
While certain crops can survive without pollination, insects provide another key ingredient to plants: nutrient-rich soil. One way that insects do this is through soil aeration. In order for plants to thrive, they not only need plentiful oxygen in the atmosphere but also in the soil to nurture their roots. Currently, this aeration process is largely dependent on burrowing bugs that create tunnels on the surface of the soil that oxygen can travel through.
Moreover, insects do not just aerate the soil they help create it.
Insects such as Adonis blue butterflies and earthworms are adept at breaking down detritus, organic matter from decaying plants and animals, turning it into arable soil. In most environments, fungi will be able to pick up much of the slack, as they are usually the primary decomposers anyways.
However, the surplus of deceased animals due to the bottom-up trophic cascade will overcome their valiant efforts, leaving behind tons of decay for us to deal with. And we better move quickly to make sure the bacteria-infested rot does not infect our streams, wells, and other water sources.
Conveniently, humans already have some solutions to the problems we would face in a world without insects.
For example, the pollination problem can be resolved by hand pollinating crops. Hand pollination is already used on crops in rural China as a response to decimated bee populations. Unfortunately, the inefficacy of hand pollination would mean much of the produce we eat today would be gone. Moreover, as we lose the crops used to sustain our livestock, meat would no longer be an option.
As for soil aeration, farmers have been using aerating tools for centuries. Although, aerated soil is not much good without the nutrients left behind by insects breaking down organic matter.
However, when scaled globally these solutions would come at a steep cost and for many countries, they would be impossible. In the United States alone it is estimated that insects provide equivalent ecological services valued at USD $57 billion per year.
So could we survive the “ecological Armageddon?”
The short answer is no.
The collapse of food webs and ecosystems across the planet would start a wave that we would never be able to get in front of. The Earth’s surface would be littered with dead animals and plants with no one to remove it except for overworked fungi and us. Meanwhile, we would be busy figuring out how to prevent our food production infrastructure from coming to an inevitable halt. Whether by disease or starvation, we do not survive the insect apocalypse.
Luckily, bugs are still here. But what is happening to them?
While there is disagreement about what is causing the declines, there is a consensus that human activity is largely to blame. The fragmentation of natural habitats has forced many species into new environments where they may not survive. Furthermore, the widespread use of pesticides frequently contaminates the areas surrounding farms, killing or displacing native insects.
Finally, insects are extremely well adapted to the environments they live in. Therefore, variations in temperature as a result of climate change can have a massive impact on their survival. In the Luquillo rainforest, Dr Lister and Dr Garcia found that there had been an increase in temperature of 2° Celsius, a change that they say is responsible for the drastic insect decline.
Even though these recent studies have been jarring, they have also brought much more awareness to the plight of our six-legged friends. However, it will take more than awareness to prevent the worst of this dystopia.
The next time you find yourself imagining a world without bugs, try to remember that insects do not plague our lives…they make them.
This article was originally published in I, Science Magazine and may be found here.