Today is Earth Day, a day to reflect on our effects on the planet and put in some work to ensure that we leave the planet as good or better than we found it. So without further ado, I’ve written a blog post to fulfill the foreshadowing I set up in our post about gigantic bees. At Guardian, we work with insects and related arthropods all the time, often reducing or eliminating their populations at a local level to protect people’s food, property, and health from the harm that pest species may cause. But lately there have been some alarming research papers coming out in the field of insect conservation biology. There is evidence that insect populations as a whole are dropping the world over.
At first glance, this decline may seem like a good thing. Insects are pests, right? Indeed, some species of insects are pests in some situations. But insects are crucial components of ecosystems. Flies, beetles, cockroaches, and crickets are decomposers, rapidly accelerating the breakdown of poop, dead animals, leaf litter, and wood. There is even evidence that some insects can consume and digest Styrofoam and plastic. Insects are also major pollinators. Not just the charismatic European honey bees pollinate; native bees (the US is home to about 4,000 bee species), flies, butterflies and moths, beetles, and even some true bugs pollinate to some extent. Many insects and arachnids also control the populations of more pestiferous species, with wasps, parasitic flies, predatory beetles, predatory true bugs, and spiders being some of the most prominent natural pest controllers. In addition, insects represent a vital food resource for a huge range of vertebrate animals. Amphibians, reptiles, birds, and small mammals all rely on insects as a major protein source. Altogether, Losey and Vaughan have estimated the economic value of wild insects in the US to be at least $57 billion.
So what exactly is the state of insect declines? Unfortunately, insects are not studied well enough to know the exact extent of their declines everywhere, so we have to make use of examples and extrapolate out from there. However, a particularly alarming review by Sanchez-Bayo and Wyckhuys (2019) surveyed 73 historical reports of insect declines from across the globe and explored the proposed causes of the declines. They found that the four main drivers were habitat loss, pollution (including by pesticides and fertilizers), biological factors like pathogens and introduced species, and climate change. Two examples are particularly poignant: Hallman et al. 2017 found that flying insect biomass dropped by over 75% over 27 years in German protected wilderness areas, and Lister and Garcia 2018 found that insect biomass fell 10 to 60 times in a Puerto Rican rainforest. These two examples are troubling because they show that even in protected wilderness areas, insect populations are not safe – and neither are the populations of the animals that depend on those insects. If insect populations continue to decline, so do their ecosystem services, as discussed by Dr. John Losey and Emma Pelton in this podcast. Therefore, this should be something we all worry about.
How can I sleep at night knowing I work for a company that kills insects, that insects on the whole are declining, and that insect declines are a major problem? For one thing, there are still too many unknowns. The Entomological Society of America has issued a position statement highlighting that the scariest part of this whole decline is how much is still unknown. The media is certainly not helping – do a Google search for “insect decline” and you will be greeted by headlines of “Insect Apocalypse,” even though we don’t know that the declines have hit that point, how widespread or severe the consequences will be, the causes of the insect declines, or the best corrective action to take. Reading news articles on insect declines certainly brings back memories of the news articles of the “Bee-mageddon” when Colony Collapse Disorder caused higher-than-normal die-offs of European honey bees (note – Colony Collapse Disorder is still poorly understood, killed far fewer honey bees than Varroa mites, and seems to have essentially vanished as mysteriously as it arrived; also, honey bee populations are currently high and rising). Much like the Bee-mageddon, this may turn out to be an anomalous blip rather than portents of doom and gloom to come. There are even a few articles (here and here) suggesting that this decline is “fake news,” though the evidence toward insect declines at least warrants further research.
Furthermore, the insects we treat are primarily invasive species or pose a legitimate threat to people, food, or property. By using careful integrated pest management techniques, we can target our pest management practices to minimize effects to non-target arthropods. By educating our clients, we can also promote tolerance for non-pest arthropods while treating for pests. Because pest management is necessary, I find it preferable to work in this industry and help keep it safe and environmentally responsible than to not be involved and trust someone else with this important work.
What can you do about insect declines? Answering this question is difficult, because the declines are so ecologically complex. A good starting point is to create habitat on your property for insects. Plant a variety of native flowering plants that bloom throughout the season to support pollinators. Keep in mind that most bees nest in the ground or in hollow stems, so consider leaving patches of bare ground and old stems from plants like raspberry to house nesting bees. Have some areas with mulch, stones, or leaf litter to provide cover for ground-dwelling arthropods. Maintain a buffer between the insect habitat and your home or business so that insects do not readily spill over into the building, and keep the plantings trimmed and thinned out to both protect them from fungal infections and prevent them from sheltering mosquitoes. Only use pesticides when needed, use them carefully, and follow the label instructions – or better yet, hire a pest management professional who has been trained to use pesticides safely. Be careful to avoid moving hitchhiking arthropods, keeping in mind that wood and water can easily harbor insects but are difficult to inspect. Finally, take action to fight climate change; make lifestyle changes to reduce your carbon footprint, and be an environmentally responsible voter who supports legislation that supports research and protects the environment. For more information, please check out the Xerces Society for Invertebrate Conservation.