DEATH BY A THOUSAND CUTS is how professor Rodolfo Dirzo sums up the situation of the plight of insects on the planet Earth in the 21st century. Dirzo is a Bing Professor in environmental science at Stanford and a senior fellow at the Stanford Woods Institute for the Environment. He is not alone in his dire observations.
In an article titled “Insect populations suffering death by a thousand cuts, say scientists,” Damian Carrington sums up the findings of a group of scientists investigating the bugs’ situation. The article is sub-titled “Frightening global decline is ‘tearing apart the tapestry of life’, with climate crisis a critical concern” and appears on The Guardian website (January 11, 2021).
Carrington continues ():
“Insect populations … face multiple, overlapping threats including the destruction of wild habitats for farming, urbanization, pesticides, and light pollution. Population collapses have been recorded in places where human activities dominate, but there is little data from outside Europe and North America and in particular from wild, tropical regions where most insects live.
Insects are essential to the ecosystems that humanity depends upon.
The scientists are especially concerned that the climate crisis may be causing serious damage in the tropics. But even though much more data is needed, the researchers say enough is already known for urgent action to be taken. Insects are essential to the ecosystems that humanity depends upon, pollinating plants, providing food for other creatures, and recycling nature’s waste.
The studies show the situation is complex, with some insect populations increasing, such as those whose range is expanding as global heating curbs cold winter temperatures and others recovering from a low level as pollution in water bodies is reduced.
The good news is that the raised profile of insect declines in the past two years has prompted government action in some places, while a ‘phenomenal’’ number of citizen scientists are helping with the huge challenge of studying these tiny creatures.”
To read this article in its entirety, click here.
Featured insects are the Regal fritillary (Speyeria idalia, in the center), the rusty patched bumble bee (Bombus affinis, in the center right), and the Puritan tiger beetle (Cicindela puritana, at the bottom). The illustration is by Virginia R. Wagner from the PNAS website.
A thousand cuts
Carrington’s article is effectively a summation of a lengthier and denser piece, “Insect decline in the Anthropocene: Death by a thousand cuts” by
“Nature is under siege. Much of Earth’s arable lands are already in agriculture, millions of acres of tropical forest are cleared each year, atmospheric CO2 levels are at their highest concentrations in more than 3,000,000 years, and climates are erratically and steadily changing from pole to pole, triggering unprecedented droughts, fires, and floods across continents.
Ongoing losses have been clearly demonstrated for better-studied groups of organisms. Terrestrial vertebrate population sizes and ranges have contracted by one-third, and many mammals have experienced range declines of at least 80% over the last century.
Most biologists agree that the world has entered its sixth mass extinction event.
A 2019 assessment suggests that half of all amphibians are imperiled (2.5% of which have recently gone extinct).
Bird numbers across North America have fallen by 2,900,000,000 since 1970. A 2020 United Nations report estimated that more than a million species are in danger of extinction over the next few decades.
Indeed, most biologists agree that the world has entered its sixth mass extinction event, the first since the end of the Cretaceous Period 66,000,000 years ago, when more than 80% of all species, including the nonavian dinosaurs, perished.
Although conservation efforts have historically focused attention on protecting rare, charismatic, and endangered species, the ‘insect apocalypse’ presents a different challenge. In addition to the loss of rare taxa, many reports mention sweeping declines of formerly abundant insects.
Insects comprise much of the animal biomass linking primary producers and consumers, as well as higher-level consumers in freshwater and terrestrial food webs. Situated at the nexus of many trophic links, many numerically abundant insects provide ecosystem services upon which humans depend:
• the pollination of fruits, vegetables, and nuts;
• the biological control of weeds, agricultural pests, disease vectors, and other organisms that compete with humans or threaten their quality of life;
• and the macrodecomposition of leaves and wood and removal of dung and carrion, which contribute to nutrient cycling, soil formation, and water purification.
Clearly, severe insect declines can potentially have global ecological and economic consequences.”
To read this article in its entirety, click here.Many numerically abundant insects provide ecosystem services upon which humans depend. Clearly, severe insect declines can have global ecological and economic consequences Click To Tweet
FEATURED IMAGE: Insects such as damselflies are particularly susceptible to drought, one expert warned, because they’re all surface area and no volume. (Photo by blickwinkel/Alamy.)