Integrated control in protected crops, Mediterranean climate IOBC-WPRS Bulletin Vol. 119, 2016 pp. 2-6 2 The use of mirids and anthocorid bugs as polyphagous predators in greenhouse crops Cristina Castañé, Nuria Agustí, Oscar Alomar IRTA, Ctra. Cabrils Km 2, 08348 Cabrils (Barcelona), Spain Abstract: Polyphagous predators have shown to be a viable solution for IPM programs in vegetable crops. In this paper advantages and disadvantages of using polyphagous predators are discussed. We also summarize existing experiences on the use of refuge plants to implement conservation programs. Recent experiences conducted by our group for the conservation of mirid and anthocorid bugs in tomato and lettuce Mediterranean crops are explained. The presence of refuge plants in the crop margins can increase the abundance of those polyphagous predators, advance their presence in the crop and facilitate their establishment, contributing to control crop pests, besides to be also beneficial to other neighbouring vegetable crops. Key words: biological control, anthocorid bugs, mirid bugs, polyphagous predators, refuge plants Background Greenhouse vegetables and ornamentals are attacked by a number of pests that are common among several crops, and application of biological control (BC) when based in the use of specific natural enemies (NE) can result in an expensive and complicated puzzle to solve. The release of specific NE was the strategy proposed in the 90’s when companies producing beneficials started to grow up and offered biological solutions for greenhouse pests. They offered extensive lists of NE and the search for new species of beneficials became a race for gaining the market. But, the expansion of the control strategy was limited to few crops and to areas with growers that could afford it. Polyphagous beneficials were thought to be ineffective because their population growth was not perfectly matching that of a specific prey and could theoretically present a risk for other beneficials. However, the use of predatory mirid and anthocorid bugs, which are quite polyphagous, has represented an important step forward in the broad application of BC in vegetable crops in Europe and more specifically in the Mediterranean region (Albajes & Alomar, 1999). Most polyphagous predators consume prey as immatures and as adults, in contrast with parasitoids, therefore both developmental stages are effective in reducing high pest densities that occur in greenhouse crops. Although they have their preferences for certain prey types and plants, they usually consume miscellaneous prey and are present in a range of plants in order to fulfil their nutritional needs. This behavior has the advantage that they can feed on a non-preferred prey up to a certain point when it is present in the crop, and prevent their expansion as a pest. Also, because they are not dependent on a single prey type, they can persist in the crop (agroecosystem) by feeding on other pests or on non-pest prey to maintain their populations. These characteristics enabled their use as BC agents to simplify the pest control in vegetable crops and greatly expanded the application of this control strategy (Leigh et al., 2010).