New study on International Bat Appreciation Day

Study shows that island bats are valuable allies for farmers - University of Oxford

The 17th April is international bat appreciation day and a new study has highlighted how these secretive mammals can be valuable allies for farmers, by feeding on important agricultural pests. The findings demonstrate that encouraging bat species can be a win-win for both conservation efforts and local farmers.

Thanks to their ability to fly, bats have successfully colonized many different oceanic islands. A newly-published study in the Journal of Mammalogy has finally revealed what is on the menu of these secretive mammals living on the sub-tropical island of Madeira (Portugal), and it is good news for local farmers.

Bats account for about one-fifth of all mammal species and are particularly important in island ecosystems, which typically have far fewer mammals than mainland areas. But up to now, the specific diets of island-dwelling bat species have been poorly studied.

The new study investigated the three bat species that live on Madeira: the Madeira Pipistrelle (Pipistrellus maderensis), the Madeira Lesser Noctule (Nyctalus leisleri verrucosus), and the Grey Long-eared Bat (Plecotus austriacus). 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. This revealed that all three bat species had highly diverse diets – eating over 50 different species between them, including beetles, butterflies, flies, moths, and spiders. Overall, 40% (23) of the identified species were likely or confirmed agricultural or forestry pests.

Lead author of the study Angelina Gonçalves (University of Porto, Portugal) 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.’

The pest species found to be eaten by the bats included banana moths (Opogona sacchari) - a well-known agricultural pest that, as the name indicates, impacts banana trees, an important crop for the local economy. Other pests eaten by the bats included turnip moths (one of the most damaging insects to vegetables and cereals) and the golden twin-spot moth (Chrysodeixis chalcites), which is one of the four most important pests 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.