The Connecticut State Museum of Natural History and the Connecticut Entomological Society hosted a lecture by Dr. David Wagner titled “The Collapse of Nature: Insect Decline in the Anthropocene” on Friday, Feb. 23. Wagner is a professor of ecology and evolutionary biology at the University of Connecticut and his research “focuses on the biosystematics of Lepidoptera and invertebrate conservation,” according to his Entomology Lab website.
Many of the audience members had prior knowledge of entomology and the current situation for invertebrates. To begin, Wagner highlighted a few unsettling facts that have contributed to the decline of insect populations. Some of these included that five million acres of rainforest are cut and lost to agriculture every year, the American West is facing the worst drought in the last 12,000 years and there have been unprecedented fires in Russia, Australia, the Amazon and the United States in recent years. All of these factors have been caused by human activity and impacted the population of many insect species. “We’re in a biodiversity crisis,” Wagner stated.
The extinction of insects differs from mammals, not just because of their size but because of their nature. “We know that [insects] are declining, but at a faster rate because they’re so specialized, and pesticides that work on them don’t work on mammals,” Wagner said. Not to mention that insects have shorter lifespans and reproduce quicker, so their decline has been very dramatic compared to animals like bears or wolves.
Wagner displayed how insect biodiversity is measured through biomass, abundance, species richness and range (occupancy). Biomass refers to the organisms’ total quantity or weight in a given area. Aspects like abundance and species richness are closely related to this. Range refers to where these insects live or where they are moving to. An example of this that Wagner mentioned is the movement of moths in Great Britain, which are moving north due to climate change. Unfortunately, Wagner warned that none of these indicators directly address how the individual species perform in these areas. “Don’t just care about the rare and endangered species, but also abundant ones,” Wagner stated. “It’s the abundant species that are important to their ecosystems,” he said.
Wagner then moved on to a real-world example of how these measurements can fail. He mentioned the monsoon in southeast Arizona in July 2021. It was the third wettest monsoon in the last 100 years, making barren desert flourish with greenery and life. There were spikes in butterfly sightings in these areas, but Wagner noted that the species found were not native. Instead, the species — like the sleepy orange and cloudless sulphur — had moved up with the rain from Mexico. “Native species are getting wiped out due to long droughts,” Wagner said. “This is not just a drought; droughts have ends, we’re seeing eradication.”
Despite the grim data, Wagner told the audience that more can be done to prevent further declines in insect populations. “The sky is falling, of course, but all we have is solutions,” he said. The Lights Out movement and a push for using fewer pesticides do address some of the issues that insects face. Light pollution is a serious problem for moths. Wagner displayed photos from a colleague who regularly worked outdoors and had a bug net surrounding him at night. At first, his net was completely covered with moths who were attracted to his light, but as the decades went, on there has been a sharp decrease in the amount of moths he’d see, so much so that he has been unable to collect as many as he did before.
On a larger scale, agriculture has been a major component of insect decline. Even though hundreds of acres of farmland appear green and ecological, Wagner said that “industrial agriculture is a biological desert.” For these large plantations, there is only one or a few different crops, making it impossible for insects to thrive or even pass through on their migration routes.
Wagner urges everyone to do their best to encourage biodiversity around their homes and towns, and he stated that the best way to address the decline of insects is through policy. “If we do the right thing, we can bring them back,” Wagner said. Even though many believe it’s too late to act or that it wouldn’t amount to much, Wagner asserted that “insect populations can increase twofold or threefold in only one or a few generations.”