Bats can prevent pest insect damages

In a new study, researchers at the University of Turku and the University of Helsinki identified the diet of the most common Finnish bat species. The diet of the bats included a considerable amount of various invertebrates, including ground dwelling beetles, gnats, mosquitoes, and a wealth of moths. The researchers were able to determine a total of over 500 different prey species from the approximately 1,200 bat droppings collected for the study.

​In this new study, the researchers focused extensively on the diet of the most common Finnish bats, i.e. the northern bat, Daubenton’s bat, Brandt’s bat, the whiskered bat, and the brown long-eared bat.  The goal of the study was to accurately determine the potential differences and similarities between Finnish bats for the first time.

The findings revealed that the bats eat various insect pests, thereby potentially limiting the damage they cause. As previously demonstrated, bats consume a considerable amount of mosquitoes, something people should to be thankful for. Based on the diet of bats, the researchers were able to determine surprisingly accurately where and how the bats have foraged.

– Some of the moths had been consumed at the larval stage, and other prey species only live close to water. Thus, we can indirectly – yet relatively accurately – deduct a fair amount of information on the predatory behaviour of bats, says recently graduated Master of Science, Project Researcher Anna Puisto from the University of Turku.

The findings confirm earlier conceptions on the division of bats into different feeding guilds.

– Some of the bats catch their prey primarily in flight, others trawl over bodies of water, while a third group has specialised in gleaning for food from different surfaces and from the ground, for example. In this study, all of these groups were represented well, explains Adjunct Professor Thomas Lilley from the University of Helsinki.

The majority of earlier studies have mainly focused on single species or vicarious species. This time, the researchers wanted to ascertain the predatory behaviour of Finnish bats.

– The five species we studied represent over 90% of all bat records in the country, so in that sense the data set is extensive, says Anna Blomberg, who also studies bats in her doctoral thesis at the University of Turku.

Bats Studied with Consideration

What makes the new study exceptional is the fact that the researchers did not have to physically catch any bats, as all of the samples were collected from their daytime roosts.

– Therefore, we first analysed the DNA to verify the bat species that produced our samples, says Puisto.

Thanks to modern molecular procedures, several species can be identified accurately from almost any material. Thus, a bat’s diet, for example, also reveals the state of natural biodiversity. The information provided by bat droppings and other environmental samples is a valuable addition to other biodiversity research.

– As a whole, this study is a great example of how much information can be gathered from the environment and nature without disturbing the targets species of the study, says Blomberg.

– We are constantly hearing about new research results across the globe stating that natural biodiversity is diminishing at an alarming pace, says Postdoctoral Researcher Eero Vesterinen, who works at both the University of Turku and the University of Helsinki.

Traditional intrusive or even destructive collection methods could already be relatively easily replaced by neutral processes that do not disturb the studied populations, as this study shows. The new methods are also cost-efficient, although they might sound complex and expensive.

– The methods also offer good opportunities for varied research. I have always emphasised that every single detail of the painstakingly collected samples should be studied, especially seeing as utilising DNA methods will not require extra effort, says Vesterinen.

The research article is based on a Master's thesis written at the Department of Biology of the University of Turku. The study has been published through the international Ecology and Evolution publication series.

Original article on Wiley Online Library; Ecology and Evolution: Table for five, please: Dietary partitioning in boreal bats