A study conducted by the University of Oxford has concluded that bats can be “valuable allies” for farmers by feeding on important agricultural and forestry pests.

The study was released today (Wednesday, April 17), on International Bat Appreciation Day, and the findings demonstrate that encouraging bat species can be a win-win for both conservation efforts and local farmers.

The study analysed the diet of the three bat species living on the sub-tropical island of Madeira, Portugal, and the research revealed that they were feeding on over 50 different species between them.

Overall, 40% (23) of the identified species were likely or confirmed agricultural or forestry pests.

These pests include banana moths (Opogona sacchari), an agricultural pest that impacts banana trees, an important crop for the local economy in Madeira, researchers said.

Other pests eaten by the bats included turnip moths and the golden twin-spot moth (Chrysodeixis chalcites), which is a prominent pest of European greenhouse crops.

In addition, the bats were also found to feed on a parasite of humans: Psychoda albipennis, which can cause urogenital myiasis, resulting in abdominal pain, diarrhoea and burning sensations.

Associate Prof from the University of Oxford’s biology department, Ricardo Rocha, said: “Bats often get a bad rap.

“Our study highlights their significance, revealing that while their nocturnal habits and secretive lifestyle make them elusive to many, insectivorous bats play a crucial role in the ecosystems they inhabit and, through the ecosystem services they provide, they can help humans in multiple ways.”

Rocha said an increasing number of farmers are now using bat boxes to attract insectivorous bats to their fields.

“During our study, we experimented by placing some in the protected area where we were working, and to our excitement, some of these are now inhabited by the vulnerable Madeiran Pipistrelles.

“This suggests that deploying simple artificial bat roosts might lead to win-win outcomes for both conservation and local farmers.”

Bats study

The study investigated the three bat species that live on Madeira: the Madeira Pipistrelle, the Madeira Lesser Noctule and the Grey Long-eared Bat.

The research team captured then collected droppings from over 100 individual bats, before extracting DNA from the faeces to work out which species the bats were eating.

As well as the agricultural and forestry pests, the bats were also found to eat beetles, butterflies, flies, moths, and spiders.

Lead author of the study, Angelina Gonçalves of the University of Porto, said: “We anticipated that all three species would primarily feed on nocturnal butterflies; however, we did not expect that over 40% of the species detected in the bats’ diet are likely or confirmed agricultural or forestry pests.”

Collecting the bats for the study initially proved highly challenging for the research team.

The process involved using mist nets (which resemble volleyball nets) to temporarily capture individuals until their faecal samples could be collected.

However, with their echolocation abilities, the bats were easily able to evade the nets.

Gonçalves said: “Fortunately, we discovered that the bats lowered their guard when they came to drink so we changed tactics slightly and waited at strategic water points.

“In this way, we were then able to capture enough individuals to conduct our research.”

The paper ‘A metabarcoding assessment of the diet of the insectivorous bats of Madeira Island, Macaronesia’ has been published in Journal of Mammology.