Project description

In 2023, over 720,00 ha of permanent grassland were mown in Austria. These areas are not only important for the production of high-quality food and feed, but also serve as a habitat for insects. In recent decades, the number of insects has steadily declined. Meadows that are located in a heavily agriculturally used environment, but also forest and protected areas, are particularly affected by the decline in species. Depending on the mowing equipment, up to 88 % of the insects are destroyed during each mowing operation. Insect-friendly mowing techniques are a simple and effective way to protect insects and contribute to biodiversity conservation.

Insect-friendly mowing techniques aim to maintain and enhance insect habitat and living conditions. If adaptations to the mowing units succeed in reducing insect losses during mowing, the insect population can be maintained at a higher level and thus have a positive impact on the subsequent food chain (e.g. bird population) and the entire environment.

Benefits of the project

The primary aim of the research project was to investigate the effects of the agricultural mowing techniques used on insects at times and under conditions that are as close as possible to real-life conditions in agriculture. In addition, "protection and deterrent devices" were tested on mowing equipment and analysed to see whether they could reduce insect losses. The results were also to be used to derive possible improvements in the design of mowing technology in order to minimise insect losses when mowing grassland.

For two seasons, five different mowing variants and their influence on insects in grassland were compared over the course of the year: Double-blade mower, disc mower, disc mower with conditioner, disc mower with conditioner and protective/scouring device harrow, disc mower with conditioner and protective/scouring device deflector plate. On eight test days, the different mowing variants were tested on grassland that is mowed four to five times (four to five-mow) and on one to two-mow nature conservation areas. Mowing dates took place at the usual local times in the trial year. Insect occurrence was recorded before mowing and insect losses after mowing. Flying insects were caught with nets and the mown material was analysed. The insects that were still alive or damaged were counted and the results statistically analysed.

The double-blade mower proved to be the gentlest variant with less than 5 % insect losses. With the disc mower, mortality was twice as high at 10 %.

The three mowing variants with conditioners to accelerate the drying process of the mown plants showed values of 15 to 20 %. The "harrow" and "deflector plate" protection and scouring devices did not bring any significant improvements. However, the tendency for the "harrow" scouring device to perform better means that further development would appear to make sense.

It was also found that large insects were exposed to a higher risk of injury during the mowing process than smaller ones. The number of insects was highest in the summer months, and insects are also very large at this time due to their natural development. Not using a conditioner here can have a particularly insect-friendly effect.

Different insect groups also exhibited different mortality rates, with wild bees and honey bees being observed comparatively less frequently. This is mainly due to the fact that both wild bees and honey bees were rarely found in the meadows at the time of mowing and were therefore hardly affected.