Potential of Trichogramma achaeae (Hymenoptera: Trichogrammatidae) in Biological Control of Tuta absoluta (Lepidoptera: Gelechiidae) in Azorean Greenhouse Tomato Crops

Abstract

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is an important pest of tomato crops. It is native to South America and has rapidly extended its range into Mediterranean countries. The parasitoid Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) has been recommended as a possible biological control agent of this invasive pest. The pest and parasitoid were accidentally introduced into the Azores Islands and became well-established owing to the climate conditions of the region. During an undertaken survey to determine the presence of natural parasitism, 2.5% of the T. absoluta eggs were found to be parasitized by Tr. achaeae, and no other egg parasitoid was observed. Other Trichogramma species, Trichogramma cordubensis Vargas & Cabello, was also selected to test, along with Tr. achaeae, against T. absoluta on caged tomato plants (microhabitats), and the effectiveness of these parasitoids in limiting the T. absoluta populations was assessed. The results revealed that Tr. achaeae had a high parasitism and emergence rate (29.6% and 65.9%, respectively), relative to those rates observed for T. cordubensis (6.1% and 39.3%, respectively). Greenhouse assays were also carried out between May and July in 2013 and 2014 on commercially produced tomatoes with the aim of evaluating the potential of Tr. achaeae mass releases for the control of T. absoluta under these conditions. In the second year, we observed a reduction in the mean number of leaf mines and of eggs, larvae, and pupae of T. absoluta per leaflet, and an increase in the Tr. achaeae parasitism rate.

Keywords: Tuta absoluta; egg parasitoid; field experiment; integrated pest management; parasitism.