Survey on indigenous parasitoids of the invasive exotic pest Tuta absoluta (Meyrick) in Southern Italy

The tomato borer, Tuta absoluta, is an invasive pest native to South-America and since its arrival in Europe the tomato production has faced severe yield loss. The composition of the indigenous parasitoid complex of the leafminer was monitored in Southern Italy (Campania, Sardinia and Sicily) during 2009-2011. The parasitoid collection was carried out by exposing sentinel tomato infested plants and by sampling open field and protected greenhouse crops, as well as Solanum nigrum, a T. absoluta wild host. The parasitoids found developing on the leafminer were mostly generalist idiobionts belonging to 12 genera and 6 families (Ichneumonidae, Braconidae, Eulophidae, Elasmidae, Pteromalidae and Trichogrammatidae). A prompt shift of native parasitoids to the new invasive host was observed and the parasitoid complex recovered on T. absoluta seems to follow the typical pattern of parasitisation on exotic pests, being characterized by a relatively low number of species mostly represented by generalist idiobionts, performing low levels of parasitisation in open field. This study highlighted the suitability of sentinel plants for indigenous parasitoids surveys in case of heavily treated crops, since the majority of the species were collected on sentinel plants (16 out of 23 totally recovered). The data recorded up to now lead to be rather optimistic with reference to the perspective of T. absoluta natural biocontrol in the Mediterranean basin.