The invasive tomato pest Tuta absoluta can transmit the emergent tomato brown rugose fruit virus

Abstract

The tomato brown rugose fruit virus (ToBRFV) currently represents one of the most significant threats to tomato crop worldwide. Its transmission occurs mainly through contact between plants and infected surfaces, and only one case of mechanical transmission by arthropods has been reported. Here, we aim to assess the role of an invasive tomato pest, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in ToBRFV transmission. Laboratory tests demonstrated the presence of the ToBRFV in adult moths obtained from larvae developed on ToBRFV-infected plants. Infected adults of T. absoluta were able to infect healthy tomato plants. In order to evaluate whether the occurrence of ToBRFV on T. absoluta adults was internal or external to the pupae, as results of larvae feeding on infected plants, pupae obtained from larvae fed on infected plants were externally disinfected and then analyzed for the presence of ToBRFV by RT-qPCR. Adults obtained from disinfected and not-disinfected pupae were also analyzed. Both adults and pupae were positive for the virus, suggesting its presence in the inner surface of the pupal exuvia. Electron microscopy, western blot analyses and hemolymph bioassay showed the absence of ToBRFV virions and viral coat protein in the hemolymph collected from disinfected pupae, demonstrating that the ToBRFV is not circulative in the progeny of T. absoluta adults obtained from larvae fed in infected plants, but probably adults got contaminated during their emergence, due to virus presence in the inner surface of pupal exuvia. This study demonstrates for the first time that T. absoluta can carry an infectious primary inoculum of ToBRFV, highlighting a potential epidemiological role of T. absoluta in spreading ToBRFV in the field.