Geographic distribution of Bemisia tabaci species in Sicily and patterns in facultative endosymbiont community composition

Bemisia tabaci is a group of cryptic and morphologically indistinguishable species able to cause severe damage to many agricultural and ornamental plants. Among the various species of this complex, the Mediterranean (MED) and Middle East Asia Minor 1 (MEAM1) species stand out as they are highly polyphagous, invasive, easily in acquiring resistance to many insecticides and reproduce quickly. Considering how (1) the geographic distribution of B. tabaci is changing with the ongoing global climate change and (2) no knowledge is presently available on phylogenetics of whitefly endosymbionts in Sicily, a population survey was conducted in the most important horticultural production areas of the island to assess the species composition within the B. tabaci complex, including their endosymbiont community and their geographic distribution. Our results show that the MEAM1 species and two mitochondrial variants of B. tabaci MED are present in pure or mixed populations, the MED Q1 presents the highest level of genetic variability within the MED populations in Sicily, having been found almost across the island and, MED Q2 was nearly exclusively detected in the Ragusa province. MEAM1 individuals were rare and exclusively detected in two localities in the Trapani province. The survey on endosymbionts community revealed the existence of a species specific composition, showing the lowest endosymbiont diversity in MED Q2 populations, typically characterized by only Rickettsia. Moreover, except for Portiera in MEAM1, no sequence variation was found within any endosymbiont sequence. Co-infection patterns of different endosymbiont species are discussed in the context of their needs for host cell metabolites. The present study defines an updated distribution map of cryptic species and phylogenetic groups of the B. tabaci complex and the first status on the endosymbiont community in Sicily; but it also represents the first report of whitefly endosymbionts sequences not only from Sicily but from Italy as a whole.