Combined use of zoophytophagous mirids for sustainable biological protection of greenhouse tomato crops

Abstract

Tuta absoluta and Bemisia tabaci are two key worldwide tomato pests. In response to chemical control limits, the use of zoophytophagous mirid predators as biocontrol agents is being increasingly studied and proposed for the management of these pests. However, the use of some mirid species and in particular Nesidiocoris tenuis, which naturally occurs in European tomato crops, is controversial due to its ability to inflict significant damage on tomato plants (necrotic rings) in parallel of its high predation capacity. Combining other mirid species such as Macrolophus pygmaeus and Dicyphus errans with N. tenuis could reduce the population growth of T. absoluta and of B. tabaci, while maintaining N. tenuis populations below a critical crop damage threshold. In this study, we tested the effect of combining N. tenuis with M. pygmaeus (at two densities: 10 and 15 individuals per plant) and with or without D. errans (five individuals per plant) on the abundance of all insects (predators and pests) for 8 weeks. We also measured leaf damage by T. absoluta and plant and flower damage (necrotic rings, flower abortion rate) by N. tenuis. We found that the combined presence of D. errans, M. pygmaeus and N. tenuis rapidly and significantly reduced the densities of B. tabaci adults, and T. absoluta larvae and damage compared to when M. pygmaeus (with both densities) was only present with N. tenuis. The presence of D. errans was critical to reduce N. tenuis population growth and necrotic rings on tomato plants, while higher densities of M. pygmaeus density reduced the rate of aborted flowers by N. tenuis. The manipulation of M. pygmaeus densities added to the presence of D. errans could provide a sustainable solution to control multiple pests simultaneously while reducing the damaging phytophagous activity of N. tenuis in tomato crops.