Different response of two Hemiptera species groups to sown wildflower strips: True bugs and leafhoppers

• Herbivore insect groups can be assumed to respond differently to wildflower strips.
• Heteroptera responded positively and Auchenorrhyncha negatively to wildflower strips.
• Placement of the wildflower strip played a minor role compared to the seed mixture.
• Requirements of target species must be considered in planning of wildflower strips.

Sown wildflower strips should promote the species diversity of several insect groups in order to be an effective tool for the compensation of biodiversity loss in agricultural environments. We studied the responses of two herbivorous insect groups, Heteroptera (true bugs) and Auchenorrhyncha (leafhoppers), to the properties of wildflower strips in a three-year (2008–2010) study in southern Finland. The experiment was replicated in six reed canary grass fields. The insect groups showed opposite responses; the abundance of Auchenorrhyncha was lower while the abundance and species richness of Heteroptera was higher in wildflower than control strips. During succession, both species richness and abundance of Auchenorrhyncha increased unlike Heteroptera. This difference could largely be explained by dietary differences. Auchenorrhyncha, including several grass feeders, could not take advantage of the increasing dicot species richness like Heteroptera species. This was also a likely reason for the unexpected finding that only Heteroptera species richness depended on the placement of the strip, being higher near field margins than in mid-field. We conclude that the optimal planning and implementation of wildflower strips call for the definition of clear goals, the knowledge of the requirements of target species as well as considering the cropping system involved.