Insecticides have been essential in agricultural systems to protect crops from pests. Unfortunately, a recent study reveals how low dosages of insecticides harm essential species such as honeybees, and might be a significant contributor to the decline of insect populations around the world.
The new study was published in the journal Proceedings of the National Academy of Sciences by Australian and American researchers. They discovered how the insecticide imidacloprid affects Drosophila melanogaster or the vinegar fly, commonly known as the fruit fly.
The team observed that the insecticide impairs the vinegar fly's neurological and metabolic functions, affecting its energy production and vision. Professor Philip Batterham from the University of Melbourne explained that while their research only focused on one type of insecticide, there is existing evidence that other types also cause oxidative stress to insect species.
It is critical to better understand how insecticides affect beneficial insects such as bees, ladybugs, and caterpillars. "Without further research, we do not know if other insecticides are any safer," said Professor Batterham.
The European Union has already banned the use of imidacloprid for farming due to the potential harm on honeybees. However, it remains one of the most common forms of insecticides around the world.
Imidacloprid Affecting Fruit Flies
Imidacloprid was created to mimic nicotine which is toxic to insects. It attacks the central nervous system of insects and results in paralysis then death. As plants absorb the insecticide, it spreads throughout its stems, leaves, flowers, and fruits.
In the study, the team observed how imidacloprid affected fruit fly larvae. On farms, the insecticide may be used at high concentrations of 2,800 parts per million (ppm). For their experiment, the researchers only used 2.5 ppm, which was enough to affect the larvae's movement within two hours.
Their results revealed the impact of imidacloprid on the fly's brain function, explained Dr. Felipe Martelli from the University of Melbourne and Baylor College of Medicine in Texas. As insects are exposed to the insecticide, they accumulate large amounts of free radicals in the brain, also known as reactive oxygen species, which cause tissue damage and other harmful effects.
They also tested adult vinegar flies, exposing them to four ppm of insecticide for 25 days. Daily exposure to low doses resulted in blindness and problems in mobility as the result of neurodegeneration.
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Harmful Insecticides
Dr. Martelli shared that this is the first study to uncover how insecticides can "trigger changes at the cellular and molecular levels" as bugs are exposed to low doses of imidacloprid. In conclusion, although there are many reasons why there has been a rapid decline in insect populations around the world, their findings indicate "clear potential for insecticides to contribute and synergize with other stressors."
Moreover, the insecticide is also harmful to people. Farmers have reported dizziness, confusion, vomiting, and skin or eye irritation after exposer to imidacloprid. Pet owners may also be exposed to the substance since flea control products may contain imidacloprid.
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