insecticides
The plight of the bumblebee Spotlight on: insecticides
The good
A
rthur C. Clarke once wrote that “any sufficiently advanced technology is indistinguishable from magic.”
If one were to explain to an early Neolithic farming community the many benefits accrued to humanity via the use of pesticides, accusations of sorcery would surely soon follow. And yet, since their introduction, these often-disparaged chemicals have led to increased crop yields, improved food safety and human health, and a worldwide boost in quality of life. Since their humble origins more than 4,000 years ago in ancient Sumer, pesticides have diversified into a broad portfolio of more than 80,000 chemical substances, classified depending on their application. Herbicides (weed killers) are the largest subcategory, making up around 40% of global use, whilst insecticides designed to eliminate pest insects like beetles, mites, moths, aphids, and flies make up around 33%.
The bad Whilst insecticides have proved effective against pest insects, they have also proved harmful to the wider ecosystem, including to beneficial insect life such as pollinators. Pollinators are not usually targeted by farmers, but they can still end up ingesting insecticides due to contamination. For example, phorate –an organophosphate used to control a wide range of insects and nematodes- can produce metabolites that can persist in soils, ultimately leaching into waterways and contaminating floral plants.
nectar and pollen in crops are sufficient to impact substantially on colony reproduction in.” Insecticides can also pose a serious threat to human beings. Long-term exposure to pyrethoids, for example, has been associated with a higher risk of all-cause and cardiovascular disease mortality, whilst acute oral phorate exposure can cause blurred vision, nausea, convulsions and, at high doses, death. In recent decades, pesticide use worldwide, including the use of insecticides, has grown. Brazil, Canada, and Argentina have shown particularly strong growth, whilst China and the USA have consistently used high amounts of insecticides since 1990. This year, at least 3.5 million tonnes of pesticides will be used worldwide, with some estimates as high as 4.6 million tonnes.
The legislative landscape A 2013 report concluded that insecticides are likely to be impacting a broad range of non-target taxa. “Reported levels in soils, waterways, field margin plants and floral resources overlap substantially with concentrations that are sufficient to control pests in crops, and commonly exceed the LC50 (the concentration which kills 50% of individuals) for beneficial organisms,” the study found. “Concentrations in
técnicas de LABORATORIO
Because of the risks posed by insecticides and other pesticides, legislators around the world have imposed regulations on their use. The European Union has set strict limits on acceptable residue levels of phorate in various foodstuffs –as low as 0.01 mg/kg– and issued outright bans on many other insecticides, including three neonicotinoids in 2017 –clothianidin, imidacloprid, and thiamethoxam– and another –thiacloprid– in October 2019.
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Nº 469 MARZO 2022
