The Jekyll and Hyde case of Nesidiocoris tenuis (Reuter) in the management of Bemisia tabaci (Gennadius) on tomato plants under greenhouse conditions

Abstract

The rise of Nesidiocoris tenuis (Reuter) as a natural enemy of various greenhouse pests in protected systems is widely reported around the globe, mainly in the Mediterranean basin, Asia, and North and Central America. In-vitro studies on improving its growth and reproduction using artificial and factitious diets, and banker plants for its breeding and propagation, and the use of violet-light (LEDs) as the attraction mechanism are well established. However, field studies are lacking in integrating these biological control components to promote N. tenuis predation on greenhouse pests. First, we performed toxicity assays in-vitro and in field conditions. Results revealed that neonicotinoids and spinosyns were toxic to N. tenuis. Avermectins & milbemycins, pyridine azomethine derivatives and diamides, in contrast, were less to moderately toxic against N. tenuis but toxic to Bemisia tabaci, a known, widespread greenhouse pest. Field tests under greenhouse conditions were performed to evaluate the role of violet-LEDs in relocating N. tenuis from banker plants to tomato plants and their augmentative effect on the densities of B. tabaci. Results showed that the movement of N. tenuis from banker plants to tomato plants was accelerated when supplemented with violet-LEDs. The accelerated resettlement of N. tenuis on tomato plants aided by selective pesticides significantly reduced B. tabaci egg, nymph and adult densities, densities that were relatively the same compared to those of the greenhouse with conventional pest control strategies. Overall, comparable outcomes in managing a pest are possible when biological control agents are integrated with environmentally safe and cost-effective approaches.