Recent advances in conservation biological control of arthropods by arthropods

Conservation biological control (CBC) aims at improving the efficacy of natural enemies and can contribute to safer and more effective biological control practices. Considerable progress in this field has been made during recent years, and it is therefore justified to review key findings in a special issue of Biological Control. The following topics, with primary emphasis on CBC of arthropods by arthropods are covered in this issue: (1) honeydew as a food source for natural enemies, (2) artificial food sprays, (3) shelter habitats, (4) chemical ecology and CBC, (5) natural enemy diversity and CBC, (6) CBC at a landscape scale, (7) CBC as provider of multiple ecosystem services, and (8) economics and adoption of CBC. These reviews present substantial evidence that CBC can attract and/or improve the fitness of natural enemies. However, studies showing that this translates into decreased pest damage, increased crop yield or quality and improved economic profit for growers are still rare. We conclude that future researchers should investigate the effect of CBC at these levels, but also that we need a better understanding of which conditions CBC will reduce pest populations in the field. CBC has the potential to increase ecosystem services other than biological control and consideration of the economic benefits of this will increase the likelihood of adoption of CBC.