Improving the efficiency of Trichogramma achaeae to control Tuta absoluta

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), commonly known as the tomato borer, is native to South America and has rapidly spread in various European countries becoming one of the major threats of tomato crop. The parasitic wasp Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) has been suggested as a possible biological control agent of the invasive pest and several aspects of its taxonomy have been elucidated. As for other egg parasitoids, the parasitism rate of this species is influenced by the rearing host and by the biotic environment, especially temperature. Starting from commercially available material, we assessed the influence of different rearing host eggs on T. achaeae longevity and fertility. We found that a single generation of the parasitoid on Tuta absoluta eggs laid on tomato leaf significantly improved T. achaeae attack rate against the tomato borer. Moreover, we found a positive effect between temperatures during development (acclimation) and the fertility of the parasitoid at different temperatures. This was particularly evident at 15 °C which was optimal for parasitoid fertility at low temperatures. We conclude that the combination of rearing system (plant + host egg) and temperatures (during development and use) are crucial factors for optimizing efficiency in terms of longevity and fertility of this species as a biocontrol agent of the tomato borer.