Out of many doom and gloom topics, biodiversity decline may be the gloomiest, or at least the gloomiest that the global political system and public by and large are not thinking about. With climate change, at least we all know something is going on even if we are bickering about it and not doing enough 50 years after we needed to start acting in a concerted way. Anyway, global insect decline is just beyond shocking. Here is just one article hot off the presses:
Long-term decline in montane insects under warming summers
Widespread declines in the abundance of insects portend ill-fated futures for their host ecosystems, all of which require their services to function. For many such reports, human activities have directly altered the land or water of these ecosystems, raising questions about how insects in less impacted environments are faring. I quantified the abundance of flying insects during 15 seasons spanning 2004–2024 on a relatively unscathed, subalpine meadow in Colorado, where weather data have been recorded for 38 years. I discovered that insect abundance declined an average of 6.6% annually, yielding a 72.4% decline over this 20-year period. According to model selection following information theoretic analysis of 59 combinations of weather-related factors, a seasonal increase in insect abundance changed to a seasonal decline as the previous summer’s temperatures increased. This resulted in a long-term decline associated with increasing summer temperatures, particularly daily lows, which have increased 0.8°C per decade. However, other factors, such as ecological succession and atmospheric elevation in nitrogen and carbon, are also plausible drivers. In a relatively pristine ecosystem, insects are declining precipitously, auguring poorly for this and other such ecosystems that depend on insects in food webs and for pollination, pest control, and nutrient cycling.
For a more general overview of the insect decline issue, I suggest this paper: Insect decline in the Anthropocene: Death by a thousand cuts.
There is some debate about which causes are more important than others, but like climate change, the causes are pretty much known (and one of them is climate change). Destruction of natural ecosystems to clear land for urban areas and agriculture is the biggest and most obvious. Massive use of pesticides and other agricultural chemicals. Heat and drought. The spread of invasive species.
The destruction of nature is just sad for everyone who values nature for its own sake. For those who don’t, it’s a little harder to come up with the elevator pitch for why this matters. Pollination has huge and obvious economic value, but maybe we can replace natural pollinators with domesticated bees for the most critical crops.
Beyond pollination, insects are the base of the food chain. Their disappearance is actually a symptom of loss of plant life, since many of them are herbivores and depend on plants. We should be able to help a little bit just by conserving or replanting some of the native trees and other plants we know they depend on in our urban areas and on farms. A guy I know wrote a paper about this.
Insects, in their function as herbivores, are also critical in transferring energy, biomass (i.e. carbon), and nutrients up the food chain to everything from birds to amphibians to fish. So their loss is a direct cause of the loss of a lot of these other animals. But in terms of the food supply, we can probably produce chickens and pigs and cows without them I suppose. So it’s a little hard to tell that “conservative” uncle at the Thanksgiving table that there is some imminent tipping point where the bugs dwindle to a certain level and then we all starve to death. (“Conservative” is in quotes because a true conservative would be interested in, well, conserving things not destroying them.)
