Dicyphus predatory bugs pre-established on tomato plants reduce Nesidiocoris tenuis population growth

Abstract

Generalist predators are increasingly used in biological pest control for greenhouse crops, as they control multiple pests and persist in crops even when prey is scarce. However, some of these predators may cause plant damage due to their omnivorous feeding behaviour. In many European regions, the omnivorous predator Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is considered to be a serious tomato pest, regardless of the biological control services it offers, and integrated pest management (IPM) strategies are based instead on Macrolophus pygmaeus (Rambur). However, as N. tenuis may competitively displace M. pygmaeus and cause severe damage, growers often resort to pesticide use, disrupting their biological control practice. In this study, we evaluated the competitive interactions of three mirid predators, Dicyphus errans Wolff, Dicyphus bolivari Lindberg, and Dicyphus cerastii Wagner, with N. tenuis. The results showed that pre-establishment of heterospecific mirid species can successfully suppress N. tenuis in the greenhouse; population growth was reduced by more than 90% compared to plants without competing predators. Further laboratory trials revealed reciprocal intraguild predation between these species in the absence of extraguild prey. Dicyphus adults predated on N. tenuis nymphs, while this was not found for M. pygmaeus. In olfactometer bioassays, N. tenuis females preferred plants previously exposed to heterospecifics but not conspecifics, suggesting that this mirid does not avoid competition. These results suggest that the three Dicyphus species could be interesting candidates for preventive releases in tomato crops due to their ability to effectively suppress N. tenuis population growth.