An insecticide commonly used on crops seems to impair navigation in big brown bats by altering the levels of brain proteins involved in memory.
Big brown bats (Eptesicus fuscus) support agriculture by eating large amounts of pest insects found on crops. However, the effects of insecticides 鈥� such as chlorpyrifos 鈥� on bats is unclear. Due to its harmful effects on people鈥檚 nervous systems, chlorpyrifos was banned by the European Union in early 2020. The US followed suit in early 2022, banning the chemical from food crops, but it can still be used in the country for non-food crops, such as grass and trees. It is also widely used in tropical regions, where bat diversity is high.
To test the effects of chlorpyrifos on bat nervous systems, at the University of Toronto in Canada and her colleagues first allowed 12 bats to explore a corridor that split into two paths, one that rewarded bats with a shelter they had been trained to consider safe and another with no reward.
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The team fed half the bats with mealworms that had been injected with a mix of chlorpyrifos and vegetable oil daily for seven days, to mimic the pesticide levels previously detected in crop insects. The researchers fed the remaining six bats mealworms that had been injected with oil only.
They then tested how well the bats could remember the path to the shelter. Those exposed to the pesticide chose the correct path less than half as often as control bats.
鈥淭he pesticide-treated bats will either stay in the middle, confused. Or they will go to the wrong side more and, in general, they are more lethargic,鈥� says Sandoval-Herrera.
By analysing the bats鈥� brains, the team found that pesticide exposure altered the abundance of proteins related to inflammation, spatial navigation and memory, potentially explaining the effects.
However, in the real world, bats are going to be exposed to pesticides for longer time periods, so the effects seen in the study are likely to be smaller than those in the wild, says Sandoval-Herrera.
鈥淗opefully, this information can help pesticides to be regulated so that we are not harming bats while they are doing something good for us,鈥� she says.
搁别蹿别谤别苍肠别:听bioRxiv,
