In addition, the insecticidal treatments required to control specific outbreaks give short term control of the problem, but eliminate, or greatly reduce, the abundance of their natural enemies thus making subsequent outbreaks more severe (Solomon et al. 2000). Participants in Äppelträffen identified the study of natural enemies, and possible management strategies to foster their ecological service, as a research priority. Strategies fall in two categories according to Eilenberg et al. (2001): (1) the protection of natural enemies, and (2) the provision of adequate resources to improve their abundance and fitness. Both strategies require, as a starting point, detailed phenological data on natural enemies and pest’s trophic relationships. In the first case it allows for a correct product choice and application (Murchie, Williams & Alford 1997; Wilson, Bauer & Lally 1998). In the second, it is essential to identify which natural enemies, and when, should be provided with additional resources in order to improve their performance. From 2014, integrated production is mandatory in EU apple orchards (91/414/EEC). One of the main objectives of integrated pest management (IPM) is to maximize the effectiveness of natural enemies for pest control. In apple production, biological control promotion is regarded as the main focus of advanced IPM (Blommers 1994). Aphids are along with tortricids the most relevant pests in European apple orchards (Blommers 1994) and other homopteran pests, such as the woolly apple aphid, Eriosoma lanigerum Hausmann, and the mussel scale, Lepidosaphes ulmi (L.) have increased in the past years and therefore can be locally relevant in Swedish apple orchards demanding additional control to suppress their damage. Through this project we intent, in the first place, to provide information on the state of the ecosystem service provided by natural enemies through the regulation of these relevant pests in Swedish apple orchards. Secondly, to establish the knowledge required for the development of strategies aiming at the conservation and increase of this pest regulation function allowing, in the long term, for a reduction in insecticidal interventions. Se sluttrapport under "relevante dokumenter" til høyre.