Phytophagy of Nesidiocoris tenuis triggers the response of Trichogramma achaeae to tomato plants infested by Tuta absoluta

The generalist predator Nesidiocoris tenuis, an effective biological control agent of numerous pests of the tomato crops, can also trigger plant defence mechanisms (direct and indirect) due to its phytophagous behaviour. In southern Europe, Nesidiocoris tenuis is frequently released in tomato greenhouses to control the invasive pest Tuta absoluta, sometimes combined with another biocontrol agent, the egg parasitoid Trichogramma achaeae. In this study, using olfactometer bioassays, we showed that the modification of the volatile chemical profile induced by the plant feeding activity of the mirid made tomato plants more attractive to T. achaeae, both in the absence and in the presence of T. absoluta eggs or larvae. This result was discussed in relation to difference observed among the chemical profiles of the volatile organic compounds released by tomato plants punctured by N. tenuis, without or in combination with T. absoluta infestation. We found that a few compounds (e.g.beta-pinene and myrcene) could play a role in the foraging behaviour of T. achaeae in this scenario. Overall, our data support the emerging idea of an ecological role of N. tenuis, in addition to its predatory activity, in making tomato crops more resilient against the attack of pests, including T. absoluta.