Whilst much has been made over the potential effects certain pesticides could be having on insect pollinators such as bees in recent months, research published this week in the Germany suggests that agricultural chemicals may be having a damaging effect on some of Europe’s iconic mammals.

Researchers from the University of University of Koblenz-Landau have warned that bats are at a greater risk of pesticide exposure than had previously been suspected. The researchers said bats may consume insects sprayed with damaging chemicals, and that due to their long lifespan and low birth rate bats are particularly susceptible to adverse effects on reproduction caused by pesticides.

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The scientists studied bats foraging for insects in an apple orchard which had been sprayed with Fenoxycarb and Chlorpyrifos insecticides. They measured the chemical residues on a range of insects. Although higher residues were recorded on spiders and leaf dwelling insects, with lower contamination levels in flying insects, the scientists suggested certain bat species may still be seriously affected by spraying.

Not only did they discover that bats feeding on tree dwelling insects are at risk of pesticide exposure, the researchers found that current European Union risk assessments did not adequately consider the animals when reviewing the safety of agricultural chemicals. The discovery comes just months after the European Food Safety Authority acknowledged that current pesticide testing does not provide adequate protection for insect pollinators.

The researchers stated, “[bats’] low reproductive rates (usually a single offspring per year) require high adult survival to avoid population declines and dictate slow recovery of impacted populations” and warned that their long lifespan (up to twenty years) meant dangerous chemicals could accumulate within animals which had fed on contaminated insects.

In addition to their iconic status as the only flying mammals, bats are important pollinators and naturally regulate insect populations. The chemicals tested by the German researchers are persistant organic pollutants, the effects of which have been well documented. Fenoxycarb is currently being ‘voluntarily’ retired from use by its manufacturers in the United States.     

The researchers concluded that, as bats can be exposed to chemicals through their diet as well as through drift and inhalation and the effects of exposure can be cumulative and severe for bat colonies, immediate action must be taken to include considerations of bat species in agricultural chemical trials.  

They said, “Although bats are reported as being threatened by pesticides, they are currently not considered in European Union pesticide risk assessments. The reason for that contradiction is probably related to the scarcity of information on bat activity in pesticide-treated fields and the pesticide residues on their food items. The results emphasize the importance of adequately evaluating the risks of pesticides to bats, which, compared to other mammals, are potentially more sensitive due to their ecological traits.”

The study is available here

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