Risk of damage to tomato crops by the generalist zoophytophagous predatorNesidiocoris tenuis(Reuter) (Hemiptera: Miridae)

Abstract

Nesidiocoris tenuis (Reuter) (Hem. Miridae) is a native zoophytophagous predator of the Mediterranean region, and its populations colonize tomato crops when they are not heavily treated with insecticides. This generalist predator has a high capacity for controlling insect pests, and it is currently commercially produced and released in some areas to control Bemisia tabaci (Gennadius) (Hem. Aleyrodidae). However, its status as a pest and/or as beneficial is controversial. Therefore, the aim of this study was to evaluate the risk of damage to tomatoes in extreme conditions of prey scarcity, as well as high predator populations. Three predator densities were tested in a greenhouse cage experiment during a summer tomato crop. The crop did not display any negative effect caused by the predators during the first six weeks of interaction, independently of the density released. However, subsequently, the effect was dramatic, both on the vegetative growth of the plant and on the production of fruits. The reduction in vegetative growth was located at truss eight and it was expressed mainly by a lower number of leaves and a shorter length of the shoot above the truss. There was a significant reduction of yield with a lower number of fruits collected and a smaller mean weight, although this was not observable until truss seven. It seems that feeding on the plant by this mirid bug competed with the vegetative growth and fruiting processes of the plant in the extreme conditions of prey shortage maintained in our experiment.

Enhancing pest management in sweet pepper by the exploitation of zoophytophagy

“…This chemical change in tomato was observed to inhibit the transfer of nutrients in the phloem and negatively affect the fitness of nymphs that develop on those parts of the plant (Sánchez et al, 2016). The intensity of injuries on tomato crops is proportional to the availability of the prey (Arnó et al, 2010a;Calvo et al, 2009b). Describing the damages produced by N. tenuis on greenhouse tomato, Sánchez (2008) found the highest damage incidence (5 necrotic rings on the upper 20 cm of the plant shoot) was produced when about 3 N. tenuis individuals per leaf occurred in a period when the number of the whitefly population was low.…”

“…Hence, as concluded by Castañé et al (2011), these models are appropriate for explaining the behaviour of individual predators and are not mutually exclusive: individuals could behave according to one model or another depending on crop circumstances and plant feeding is essential rather than facultative. Overall, phytophagous behaviour of N. tenuis seems to affect the final number of fruit per plant and may lead to some economic loss (Sánchez, 2009;Arnó et al, 2010a). However, according to Sánchez and Lacasa (2008), such loses might be compensated by the greater weight of the remaining fruit.…”

“…Hence, with such predators, establishment can be prior to pest infestation. The highest density achieved by these kinds of predators before pest outbreak is key to their final successful use as BC agents (Arnó et al, 2010aPérez-Hedo and Urbaneja, 2015;Messelink et al, 2015).…”

Evaluación del riesgo ecológico de insecticidas utilizados contra plagas hortícolas en el agente de control biológico Nesidicoris tenuis Reuter (Heteroptera: Miridae)

“…Sin embargo, muchas de sus especies tienen una dieta zoofitófaga y su interés como agentes de control biológico es cada vez mayor (Lucas y Alomar 2002, Urbaneja et al 2005, Arnó et al 2010). …”

Enhancement of tomato resistance to Tuta absoluta by the expression of two barley proteinase inhibitors

“…Since its introduction, chemical control has been the main method used to control Tuta absoluta leading to a multitude of undesired side effects on non target organisms (Arnó et al, 2010;Biondi et al, 2012a;Biondi et al, 2012b). As an alternative, different integrated pest management strategies with parasitoids and predators have been tested.…”