Olfactory response of the zoophytophagous mirid Nesidiocoris tenuis to tomato and alternative host plants

It has been proved that the omnivorous predator Nesidiocoris tenuis (Hemiptera: Miridae) is attracted to and can develop successfully on sesame (Sesamum indicum). In this study, the potential of this plant, compared with Dittrichia viscosa and tomato (Solanum lycopersicum), to attract the mirid bug was assessed. A Y-tube olfactometer was used to test the olfactory preference of the mirid in dual-choice bioassays comparing healthy tomato, S. indicum, and D. viscosa plants, and tomato plants infested by eggs and larvae of Tuta absoluta (Lepidoptera: Gelechiidae). To understand the biochemical basis of the attraction of the omnivorous predator toward the alternative plants, headspace solid-phase microextraction combined with gas chromatography–mass spectrometry was performed, with the aim of identifying potential volatiles responsible for mirid attraction. S. indicum was the most attractive plant; T. absoluta infestation did not significantly increase N. tenuis attraction. We identified 57 volatiles belonging to the classes of hydrocarbon and oxygenated monoterpenes, sesquiterpenes, C13-norisoprenoids, aliphatic aldehydes, esters, alcohols, and hydrocarbons. Sesame plants emitted the lowest amount of hydrocarbon monoterpenes but a higher rate of oxygenated terpenes. Green leaf volatiles, known for attracting mirids, were emitted at higher levels by sesame plants, whereas tomato plants infested by T. absoluta larvae showed the highest levels of monoterpene hydrocarbons. The potential applications of plant volatiles in integrated management of tomato pests are discussed in the framework of mirid ecology.