Combining mirid predators to reduce crop damage and sustain biocontrol in multi-prey systems

With the invasion or local occurrence of Bemisia tabaci and Tuta absoluta in recent decades, they both have become two major insect pests of tomato crops in many countries. The biological control of these two pests through heteropteran predators, e.g., Nesidiocoris tenuis or Macrolophus pygmaeus , is a key pest management strategy. However, by contrast to M. pygmaeus , N. tenuis could usually cause plant damage and yield loss. The joint use of these two mirids for pest management has not been described yet, although it may be helpful in reducing the side effects of N. tenuis on crop (owing to competitive and/or agonistic interactions between the two species). In this study, we compared the abundance of predators and pests in treatments with N. tenuis and M. pygmaeus together versus N. tenuis alone and in the presence of B. tabaci only or B. tabaci and T. absoluta . We also measured necrotic rings and tomato flower production in these four treatments. We found that the joint use of both mirid predators together led to (1) a reduced overall mirid density and (2) a sustained biocontrol efficiency, when compared to the use of N. tenuis alone. In addition, plant feeding activities of mirids were significantly reduced when predators were used jointly (vs. N. tenuis alone). The applicability of zoophytophagous predators as biocontrol agents could be facilitated by simultaneously releasing two (or more) heteropteran predator species instead of a single one.