Squeeze it or leave it? An ecological-economic assessment of the impact of mower conditioners on arthropod populations in grassland

Abstract

This study addresses the use of conditioners as a driver of arthropod loss in agricultural landscapes. Conditioners compress the freshly cut mowing material mechanically to destroy the evaporation-inhibiting wax layer of the grass material. This compression potentially increases the physical damage to several arthropod groups during the mowing process. We have combined an ecological field study on the impact of conditioners on arthropods at the plot level with an analysis of the economic rationale of applying conditioners in differently managed grasslands in the study region, in order to understand the impact of applying conditioners on the damage to arthropods at the landscape level. The use of conditioners in the mowing process significantly increased the overall percentage of damaged individuals by 18% from 52% without to 70% with conditioner use. Aphids and plant lice, beetles, thrips and mites were most severely affected by additional damage. We also found that the use of conditioners takes place on substantially more than 20% of all grasslands in the study region. Depending on the respective grassland area managed with conditioners in the future, grasslands could be losing an additional 4% to 18% of their overall arthropod numbers only due to the use of conditioners compared to a scenario without conditioners. As the damage due to the use of conditioners is presumably higher in extensively managed grasslands, and the profit of their use is higher in intensively managed grasslands, we suggest, as an implication for insect conservation, concentrating measures to disincentivise the use of conditioners on extensively managed grassland.