Ants and birds prevent insects from causing serious plant damage

Recently, in conservation biological control of insects, researchers has become more interested in generalist predators that do not specialize in a particular pest. This is due to the fact that generalists are better at limiting pests in the early stages. Christer Björkman, project leader and professor of forest entomology at the Department of Ecology, wanted to develop a method to monitor variations in predation pressure over time and space.

The work began with a workshop where goals were defined that resulted in:

• A review article in which the advantages and disadvantages of existing methods to measure predation was summarized. It has been sent to a scientific journal.
• A field study where predation was measured in different environment with the help of artificial insect pupae and larvae and compared with natural insect pupae and larvae.

The ambition was high in the field study and the method had not been used before. Unfortunately, the use of natural pupae did not succeed, but the study was carried out with artificial larvae and pupae. Preliminary results show that green larvae are most attractive to predators and they were attacked by arthropods (eg, insects, spiders and centipedes). Pupae were attacked mostly by birds and white larvae mostly by small mammals.

To reach the long term goal of the research project, to develop a general method to measure the predation pressure over time, more method development is required.