While some insects are declining, others might be thriving

The German Centre for Integrated Biodiversity Research is located in Halle-Jena-Leipzig.

Observations of abundance changes in one group of insects, for example, but they don't tell us much about how other insects are doing. Different groups of insects may show different trends in different places. The findings of a new meta-study examining long-term data on insects from more than 900 locations worldwide. The study was led by a team of researchers from the German Centre for Integrated Biodiversity Research (iDiv), the Martin Luther University Halle-Wittenberg (MLU), the Friedrich Schiller University Jena and the Helmholtz Centre for Environmental Research. The importance of monitoring multiple groups of species at the same time is highlighted.

The decline in insect numbers became part of the global conversation in 2017, when scientists reported the loss of three-quarters of the flying insect biomass from western German nature reserves over 30 years. People realized that there were not as many bugs as there used to be. Hundreds of popular articles have been written about the insect decline problem after an explosion of studies from across the world.

A group of scientists led by iDiv, MLU, the University of Jena and the UFZ have been analyzing a database of studies from across the world that had monitored the abundances of groups of insects. The group is led by Dr. van Klink, a researcher at iDiv and MLU.

Monitoring insects is difficult due to their small size. There are 30,000 species of insects in Germany. Most monitoring programs only study one insect group, but no one has investigated whether the status of the group under study tells us anything about the well-being of other insects.

Van Klink and colleagues wanted to know if changes in one type of insect could predict changes in other types of insects. Does the decline of butterflies mean beetles, flies and bees also decline? Changes in one group of species can be used as indicators, which is useful because not all insect species need to be monitored. If this is the case, scientists and policymakers would be able to use information from one group of insects to make conclusions about all insects.

In their analyses, van Klink and colleagues found no evidence for indicator species. The trends of beetles and butterflies were the same, but their relationship was poor.

The results of this study emphasize what the team has been saying for a long time.

Nature is not as simple as we would like it to be, says van Klink. No doubt humans are having unprecedented impacts on the natural world around us, and it is our job to find out exactly how, why and where these changes occur, and to which kinds of insects.

The scientists hope that their work emphasizes the need to monitor and better understand changes in abundances of a broad range of insect groups through time.

Diana Bowler says that we need to care about the diversity of insects.

More information: Roel van Klink et al, Long-term abundance trends of insect taxa are only weakly correlated, Biology Letters (2022). DOI: 10.1098/rsbl.2021.0554 Journal information: Biology Letters Provided by German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Citation: While some insects are declining, others might be thriving (2022, February 22) retrieved 23 February 2022 from https://phys.org/news/2022-02-insects-declining.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.