Now You See Them, Soon You Won’t: Global Insect Numbers in Decline

Face of a Southern Yellowjacket Queen (Vespula squamosa) Credit: Opo Terser

A study on global insect populations published in the April 2019 issue of Biological Conservation sadly reveals that 40 percent of insect species are now threatened by extinction, and that more than two-thirds could soon face similar threats.

Currently, there are nearly one million named species of insects, but many suspect that those represent only about 20 percent of the actual number of insects present on Earth. Insects provide numerous ecosystem benefits, and many insect species have been recognized as keystone species (i.e., species that play a key role in an ecosystem and whose absence would lead to dramatic changes). To take just one example, brown bears in Alaska and the Pacific Northwest would struggle to survive without key insects. The bears depend on berries and salmon, which themselves rely on insects. Without insects, young salmon would lack a primary food source of high protein, and unpollinated berries would not fruit.

Similarly, humans rely on pollination to receive food from agriculture. Estimates currently place the value of insect pollination at $500 billion a year. Without insects, pollination would have to be performed manually, which would lead to an enormous rise in expenses for the agricultural sector. In Maoxian Valley, China, a lack of insect pollinators means farms have to pay $19 an hour to employees who hand pollinate each apple blossom. That process is not only expensive, but it is long and arduous for humans.

The importance of insects in ecosystems can be easy to miss. When cattle were first brought to Australia, their fecal matter would not break down. The stink would drive cows away, forcing ranchers to acquire more land for grazing. Scientists eventually realized that Australian insects were only able to handle marsupial stool, which is more fibrous. Australia had to import dung beetles to ensure its pastures didn't all end up covered in cow pies.

The decline of insect populations is the result of numerous problems occurring simultaneously. A major contributor is the use of pesticides that kill both harmful and beneficial insects; they are unable to bounce back from the damage such chemicals are doing to their populations. In addition, human development has contributed to habitat loss. When humans colonize an area, they also bring non-native plants and animals with them that tend to outcompete the native species. Insects have little time to adapt to these changes and are easily lost, especially if they have a mutualistic relationship with one of the affected organisms. Last, but not least, climate change also is having an adverse impact on insects by destroying their habitats. According to researchers, climate change could make half of insect habitat unsuitable by 2100, and pollinators (like bees) would be especially affected.

The massive die-off of insect populations is an example of what many scientists are referring to as the “sixth extinction.” Five major waves of extinctions have previously occurred throughout history, most due to volcanic eruptions or meteor impacts. This is the first wave of extinctions to be directly caused by humans. In a very short amount of time, humans have managed to alter the geography, climate, and composition of large swathes of Earth.

Many are aware of the threats faced by charismatic megafauna such as rhinos and tigers. These larger animals tend to be liked by humans due to their distinguishing and recognizable characteristics, and so are more likely to be protected. Insects, however, usually get a bad rap and have missed out on much of the protection that benefits larger species, despite the fact that we rely on insects to survive.

There are actions individuals can take to help protect insects from extinction. One solution that is becoming increasingly common is buying organic produce or produce grown through "integrated pest management" practices. By increasing consumer demand for organic products, pesticide use should decrease. Another thing that individuals can do is to plant native flowers rather than exotic species in their yards. This will provide habitats for native bees and other pollinators. Finally, individuals can reduce their overall carbon footprint by eating less dairy and meat products, flying less, and purchasing fewer single-use plastics.

It is important that we inform ourselves on this crucial issue and share these concerns with others. Individual actions help, but political action will still be necessary to prevent widespread insect extinctions. Policymakers can devote more funds to research, to determine the main factors causing the fall in insect numbers. They can regulate the use of pesticides and other chemicals for farming and use on lawns, golf courses, etc.. They can put more land under protection to preserve wild spaces suitable for insects. And, of course, taking measures to slash greenhouse gas emissions is critical.

 

Author: Cameron Bechtold