many global insect populations suffering death by a thousand cuts

Es­ti­mated reading time is 4 min­utes.

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).

Most bi­ol­o­gists agree that the world has en­tered its sixth mass ex­tinc­tion event.

Car­rington con­tinues (edited for brevity and styl­istic con­ti­nuity with this blog):

“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.

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.


A Thousand Cuts: illustration of a chart adressing plight of insects.
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 David L. Wagner, Eliza M. Grames, Matthew L. Forister, May R. Beren­baum, and David Stopak. It ap­pears on the Pro­ceed­ings of the Na­tional Academy of Sci­ences of the United States of America web­site (Jan­uary 11, 2021). That paper opens with these para­graphs (edited for brevity and styl­istic con­ti­nuity with this blog):

“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.

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.

The insect apocalypse

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

A Thousand Cuts: photo of a damselfly.

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.)



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