Plant damage to vegetable crops by zoophytophagous mirid predators

The use of plant-feeding predators for biological pest control has traditionally been neglected, mainly due to the risk of them feeding on crop plants and causing economically significant damage. Yet, these predators offer advantages for biological pest control. They are mostly generalist predators that have an impact on several crop pests. They may also be able to establish on crops early in the growing season, when pests colonize them, and can remain on the target crop when prey is scarce. Therefore, management programs must seek to minimize risks while maximizing benefits. In vegetable crops, most of the literature on zoophytophagous predators has focused on four species: Dicyphus tamaninii, Dicyphus hesperus, Macrolophus pygmaeus and Nesidiocoris tenuis (Heteroptera, Miridae). The capacity of these species to produce crop damage in tomatoes varies. This damage has been related to relative predator-to-prey abundance, with damage increasing at high predator abundances and low prey densities. In this review, we analyze the use of these species in biological control programs and the associated benefits and risks. The differences in the damage caused by the four predatory species examined could not be attributed to either stylet morphology or saliva composition. However, feeding on specific plant structures where they may find the resources required for their development is what probably determines feeding damage. Understanding when and why these predators increase their feeding on plants or on certain plant parts is of crucial importance for integrating them in biological control programs. (C) 2011 Elsevier Inc. All rights reserved.