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.

Benefit of the project

The primary objective of the research project was to investigate the effects of the agricultural mowing techniques used on insects under - in agriculture - as practical a time and conditions as possible. In addition, "protection and scaring devices" were tested on mowing equipment and investigated to see if 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 during mowing in farm grassland.

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

The double-blade mower proved to be the most gentle 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 significantly improve the results. However, due to the tendency of the "harrow" to perform better, further development appears to be sensible.

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; due to natural development, insects are also very large at this time. Not using a conditioner can have a particularly insect-friendly effect here.

Different insect groups also showed different mortality rates, so wild bees and honey bees were observed comparatively less frequently. The low numbers indicate, in comparison with other insect groups, that the mowing techniques tested have a relatively low damaging effect on wild bees and honey bees.