Recruitment of native parasitoids by the exotic pest Tuta absoluta in Southern Italy

The tomato borer Tuta absoluta (Meyrick) is an invasive pest native to South America and since its arrival in Europe the tomato production has faced severe yield loss. The complex of indigenous parasitoids that colonized this new host species was monitored in Southern Italy during 2009-2011, in some of the regions where T. absoluta was initially detected (Campania, Sardinia and Sicily) with the aim of identifying the parasitoid complex of the tomato borer as well as finding potential biocontrol agents of this invasive pest. The survey was carried out by sampling the tomato borer on open field and protected greenhouse crops, on wild secondary hosts and by exposing sentinel infested tomato plants. A quick shift of native parasitoids to the new invasive host was observed and the parasitoid complex associated to T. absoluta seems to follow the typical pattern of colonization on exotic pests. The recovered species were, in fact, mainly generalist idiobiont parasitoids causing low levels of parasitism in open field. The species found belong to 13 genera and 6 families (Ichneumonidae, Braconidae, Eulophidae, Elasmidae, Pteromalidae and Trichogrammatidae). In particular, the 10 identified species were: Diadegma pulchripes (Kokujev), Bracon osculator (Nees), Bracon (Habrobracon) nigricans Szepligeti, Necremnus sp. near tidius (Walker), Necremnus sp. near artynes (Walker), Neochrysocharis formosa (Westwood), Pnigalio soemius s.l. (Walker), Pnigalio cristatus (Ratzeburg), Pnigalio incompletus (Boucek) and Halticoptera aenea (Walker). For seven of these species, the finding on T. absoluta is the first host-parasitoid association report. This survey highlighted that conservation of indigenous natural enemies, also by means of habitat management techniques, should be taken seriously into account when planning integrated management strategy of the tomato borer in the Mediterranean area.