By James Gamble via SWNS
Pesticides used to protect growing crop seeds are detrimental to the health of earthworms, warns a new study.
Researchers found that even minor exposure to certain insecticides and fungicides resulted in poor weight gain and DNA damage in worms.
Some of the worms exposed to the pesticides were seen to gain up to 80 percent less weight than those that were not.
The authors say their study, published in the American Chemical Society’s Environmental Science & Technology Letters journal, highlights the unexpected risks of using such pesticides in treating seeds.
While pesticides protect crops from irritant animals, insects, or even microbial infections, they also impact other vital organisms including bees and earthworms.
By their activity in the soil, earthworms offer many benefits including increasing nutrient availability as well as providing better drainage and a more stable soil structure – all of which help improve farm productivity.
Pesticide treatment can be introduced at several different stages of a plant’s life, either by covering seeds before they’re sown or spraying already-grown crops to protect them.
Different chemicals are often applied at the same time to maximize their efficiency.
Neonicotinoids, known as neonics, are one common class of insecticides used in the US and other countries, though many of these neonics are banned across the European Union.
Recent research has shown these insecticides and many fungicides to persist in groundwater and soil where earthworms could encounter them.
A research team from the University of Washington monitored the health of impacted worms by observing changes to their weight and mitochondrial DNA (mtDNA) damage.
Unlike DNA held in a cell’s nucleus, mtDNA can’t repair itself as well and can therefore help to indicate less obvious effects of particular environmental toxins.
The researchers used this approach to investigate how realistic amounts and combinations of neonics and difenoconazole (DIF) fungicide affected earthworms.
In lab experiments, groups of juvenile earthworms were exposed to individual pesticides and combinations of neonics and DIF in concentrations that mimicked residues left behind by pesticide-treated seeds.
After 30 days, the worms were weighed and their mtDNA damage was examined.
Whilst all the worms survived, the researchers found the earthworms in single pesticide-treated soil gained between 30 and 80 percent less weight during that period than a control group living in untreated soil.
Worms exposed to one of the four tested neonicotinoids and DIF at the same time also gained considerably less weight than those exposed to a single compound, whilst pesticide exposure also resulted in a significant increase in mtDNA damage.
Because mitochondria generate most of the energy within cells, damage to their DNA could interrupt cellular functions and other metabolic processes.
The researchers say their findings establish a link between neonics and fungicide mixtures that are likely present in the environment and earthworm health, which could inform the unexpected risks of using neonics in seed treatments.
