Insect Decline

Tim Iverson

(8/2019) People generally aren’t very fond of creepy crawlies. Bugs usually elicit a reaction ranging from "gross!" to "kill it!" There are very few charming critters among the insect ranks - butterflies, lady bugs, and honey bees to name a few. The rest we could do without, right? Wrong. Not even close. We’d be goners without them. Which makes the global decline of insect populations all the more troublesome.

If you lumped all the insects together collectively they’d weigh more than all the fish in the ocean or the mammals on land. They outweigh all of humanity by 17 times over. Insects are the basic foundation upon which much of the food chain is built upon. Unfortunately, a few recent studies have put their numbers into a staggering downward spiral. An October 2018 paper from the National Academy of Sciences documented a 30 year decline of insects within a Puerto Rican rainforest. Over the course of the longitudinal study survey net traps had a decline of up to 8 percent, while sticky traps pegged a decline of up to 60. A similar longitudinal study conducted in Germany, and released in 2017, showed a decline of up to 75 percent.

These were two separate studies conducted to within two separate protected forest environments half a world apart. Within these national forests populations are insulated from either widespread insecticide use or habitat loss. The conclusion the authors came to is that the staggering losses within these safe spaces is a result of human driven climate change that is precipitating a global extinction event.

When you start pulling foundation stones out from under a structure the rest becomes shaky. That’s a concern that bugs more than just entomologists. Most people are relatively well acquainted with the services that honey bees and similar pollinators provide. When we lose large sections of the insect biomass more than just our food supply starts to unravel, entire ecosystems suffer.

Climate change was always bound to take out some specialist plants and animals. As sea levels rise rare plants on isolated islands end up underwater. The specialist pollinators for the specialist plant have no choice but to go down with the ship. Researchers expect this, but the unexpected findings of these studies have shown that it’s also generalist insects that are also suffering. Insects that are well adapted to all sorts of conditions are also suffering the same fate as their less adaptable brethren. The loss of the building blocks of the food web ripples upwards. In some cases it’s even correlated to the population decline of their respective predators like reptiles and birds.

Biodiversity (the diversity of species, genetics, and ecosystems) relies on a rich multitude and variety of life. The sudden and stunning initial reports of declines among insect species in separate parts of the globe should give everyone pause. The reasons why are largely the same no matter where they occur.

The main reasons for these loses stems largely from habitat loss. Land use is central to threats against many other species, insects are no different. Climate change is an additional factor spurning more biological varieties of tougher more infectious diseases that affect insects. Finally, better and better insecticides have ripple effects throughout the entire insect community. They indiscriminately affect all insects, not just what they are intended for.

Pollinators serve a vital and irreplaceable role in our world. The word pollinator immediately conjures up images of bees, specifically honey bees. While bees are an important pollinator they don’t have the market cornered. Other pollinators include bats, birds, beetles, moths, butterflies, and small mammals. Pollination is the process by which pollen from flowering plants is spread. In a recent report from the USDA it is estimated that, "Pollinators, most often honey bees, are also responsible for one in every three bites of food we take, and increase our nation’s crop values each year by more than 15 billion dollars." With the sudden inexplicable loss of a significant pollinator we should be alarmed.

The honey bee has been most notably the face of these losses. They are susceptible to insecticides sprayed on crops, with the intent not to kill bees, but other insect pests. This in turn has wrought havoc on their immune system. Plagued by varroa mites they become sick. With the additional compounding factors of less wild land space and warmer drier conditions they have seen less and less stability within their colonies.

Over the past few years neonicotinoid pesticides have been under intense scrutiny and examination as a potential factor in declining bee populations. Most research scientists agree that a host of factors are creating the perfect storm that is crippling bee populations. However, the link between this type of pesticide and the effect it has on pollinators is beginning to be understood. Pollinators are intricately interwoven into our food system and economy. Simply, their importance can’t be overstated. Pollinators are directly responsible for 85% of flowering plants, 35% of global food production, add more than $15 billion to the US economy, and provide $26 million worth of pollination services in Maryland alone. Maryland has been a leader on this issue, having banned the use of these pesticides in 2016.

By planting native plants in homegardens homeowners can personally and directly combat the issue. Native plants require no fertilizer or pesticide. As a result, they protect both pollinators and a homeowner's budget. These plants have evolved to live right here in our local ecosystems and require little attention for survival. They have grown accustomed to the weather and climatic patterns and have natural defenses against predators and disease. The Maryland Native Plant Society (www.mdflora.org) and the US Fish & Wildlife Service www.fws.gov/chesapeakebay/ offer resources on native plants for our region and locations where they can be found for purchase.

Potentially as many as six to ten million species of insects, comprising almost 90% of animal life, exist on earth today. We consider many as pests because they live in our homes, feed on our food, or worse - feed on us. However, many more prey on those insects, and other even larger animals feed on them. Some of them work to feed us by spreading pollen to ensure vegetables and fruits continue to flower.

While more research into the issue is underway there are meaningful avenues we can take to mitigate losses. Native pollinators contribute billions to the economy and ecosystem and are too significant to idly let them vanish. Human intervention is likely required to tackle a human caused problem, and an all hands on deck approach is important to protect and encourage these species. By being proactive, being responsible, and being stewards we’ll be okay.