Genetic analysis reveals multiple introduction events of the Balkanic Reticulitermes urbis (Blattodea,Termitoidae, Rhinotermitidae) in Italy and France.

Biological invasions are a key factor in the ecological changes, and social insects are among the most successful invasive animals. Phylogeography and population genetics can provide detailed information on the introduction routes and invasion biology. Reticulitermes urbis is a subterranean termite native of Balkan Peninsula and introduced in Southern France and Eastern Italy. Introductions in these countries probably resulted from anthropic activities and invasive populations currently live in both forests and urban areas. To identify the source population and to infer the minimum number of introductions, we analyzed mitochondrial (COII) and nuclear (6 microsatellites) loci on 7 native and 39 introduced colonies (15 from France; 24 from Italy). Mitochondrial analysis confirmed the presence of two major lineages in which native and introduced populations cluster together, irrespective of the sampling area (native or invasive range). Microsatellite loci analysis identified two genetic clusters, each including individuals from both native and introduced samples. Moreover the analysis of molecular variance evidenced very low genetic differentiation between the three considered areas (native, French or Italian range). Finally, data showed that introduced populations are less variable in both mitochondrial and nuclear markers, suggesting that introductions might have induced a loss of genetic diversity. On the whole, results supported multiple introductions into the two invasive ranges of France and Italy. This is consistent with links between native and invasive areas protracted in time, as expected in cases of human trades routes. Historical data of human settlement and kingdoms might provide explanations for R. urbis modern distribution.