Readers name Earth's overlooked life-savers
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- The Guardian's "Readers reply" column posed the question after John Forward of Brixton described buying Trichogramma evanescens parasitic wasps — ordered online in sachets of 2,000 — to eradicate clothes moths in his home.
- Diatoms were credited by reader MrJustin with producing 50-60% of the free oxygen in Earth's atmosphere.
- Trichogramma parasitic wasps also have a major agricultural role, with Trichogramma chilonis and Trichogramma japonicum deployed as biocontrol agents against crop pests that hurt farmers' incomes, per reader Abinash Das.
- Green lacewing grubs (Chrysoperla spp) are mass-reared in labs and released at 10,000 per hectare to suppress sucking pests and cut chemical dependence, Das added.
- Earthworms were credited by reader JSME with aerating soil and converting it into bioavailable nutrients, making them, in his words, essential to having "enough food."
- Phytoplankton were cited by reader Mike345 as a carbon sink, absorbing carbon from the water and carrying it to the ocean floor when they die.
- Gut bacteria and other microbes drew multiple nominations, with reader d33pf1x noting we have more microbial than human cells in and on our bodies.
Why it matters: The column surfaces concrete, often-overlooked biological workhorses — from 10,000-lacewing-grubs-per-hectare biocontrol protocols to diatoms producing the majority of atmospheric oxygen and phytoplankton driving ocean carbon sequestration — giving gardeners weighing pesticide use and climate-conscious readers a roster of allies that mainstream coverage rarely names.
