By Jon Lamson
As the country continues to squabble about which politicians are the most corrupt, there is a silent tragedy occurring in Washington D.C. and everywhere else, whether or not anyone chooses to acknowledge it. Recent estimates suggest that since 1970, global insect abundance may have fallen over 50%. The importance of these findings is hard to overstate. Approximately three-fourths of all human crops rely on insect pollination. It is simply impossible to feed the 7.7 billion people on this planet without insects. From a slightly less anthropocentric perspective, 87% of all plant species re- quire pollination from other animals, and in the vast majority of cases, insects. Many animals directly rely on insects for food, and their indirect effects spread through entire ecosystems. Furthermore, we simply don’t have a complete idea of how much we rely on insects and the extent of the damage that would occur if this documented decline continues or increases.
Understanding the full extent of the issue is difficult, as insects are far less stud- ied than vertebrates, and their decline is much less visibly noticeable. Scientists es- timate there are 4 million species of insects yet to be discovered (compared to the approximately 1 million we have named and categorized), and for those species we have named, far less is known about them than about the world’s vertebrates. How- ever, there are now indications that this die-off is more extreme than we’ve realized. Earlier this year in a review paper on all prior studies of insect declines, entomolo- gist Francisco Sanchez-Bayo estimated that insect populations are declining by ap- proximately 2.5% each year, on average, and that 41% of all insect species are at risk of extinction.
A long term study in Germany by the Krefeld Society found that insect mass across the country declined 75% since 1989, while another study of a Costa Rican rainforest (that has been essentially unaltered by human activity) by entomologist Bradford Lister found that spider and insect biomass has declined between 75% and 98% since 1976-77, depending on the time of year and type of trap used. Furthermore, it’s important to understand that insect levels in the later 20th Century in many areas were likely already diminished from their natural levels due to the use of a variety of arsenic based insecticides, DDT — used agriculturally in the US from 1945 until it was banned in 1972 in response to massive public protest following Rachel Carson’s book “Silent Spring” — and a variety of other chemical insecticides.
Several factors contribute to this decline. Habitat loss and fragmentation have had an impact, as populations become smaller, more isolated, increasingly inbred, and less resilient to random extinction events. The replacement of natural habitats with vast, monoculture agriculture and with swaths of aggressive, invasive plant species has especially hurt many pollinators and specialists that rely on native plants across the globe.
Pesticides had, and continue to have, a devastating effect on insect populations. Neurotoxins, the most common type of pesticide, will either kill or severely handicap the brain function of the insects that come in contact with them, hurting navigational ability and making them more susceptible to disease. Globally, pesticide applications have doubled over the past 25 years. In a 2017 survey by Mitchel et al., 75% of honey samples taken from around the globe were found to contain insecticides. Other pollutants, such as heavy metals and plastics, are also likely impacting insect life, though these effects have yet to be studied in depth. Finally, climate change is cur- rently hurting and will continue to decimate insect populations globally as timing of pollinators is disturbed, viable habitats change and shift, and desertification and water stress increase. As the earth continues to warm, the effects of these changes on insects will undoubtedly increase.
Faced with this heaping pile of alarming information, it is natural to ask what we are doing as a country to combat this. The answer may not surprise you — essentially nothing. This summer, the Environmental Protection Agency (EPA) rolled back restrictions on sulfoxaflor, a chemical known to be toxic to a wide range of pollinating insects. Since President Donald Trump’s inauguration, the EPA has also reversed a ban on chlorpyrifos, an insecticide known to inhibit brain development, after Dow, the company that marketed the chemical, donated a million dollars to Trump’s inaugural committee. The United States Department of Agriculture has suspended their program in which they track the health and stability of honeybee populations in the U.S. This approach is fated to continue for as long as we refuse to care about these is- sues. The insect die-off may not be a sexy issue, but it is one that we simply cannot afford to continue to ignore.