Terellia serratulae in Lebanon : host adaptation in Picnomon acarna

Abstract

Terellia serratulae is a flower head infesting tephritid fly, which is commonly found in Lebanon from April to October at all elevations. It is a polyphagous species that infests flower heads of six thistles belonging to Cirsium, Carduus, and Picnomon genera. In a previous study, molecular and morphometric variations were detected between flies associated with the different host plants and showed that flies associated with P. acarna may be distinct. In this study, the extent of genetic divergence between host populations of T. serratulae was investigated using both mitochondrial and nuclear loci. The results showed that the Terellia serratulae populations associated with Cirsium lappaceum most likely constitute a genetically distinct host race compared to the other host populations and that the majority of flies associated with P. acarna clustered alone in a clade but also grouped with flies of the other host plants. The ultrastructure of the ovipositor of T. serratulae females was studied using scanning electron microscopy. Differences in the arrangement of central sensilla found at the very tip of the ovipositor were found between females of the different host populations. Further sampling is needed to shed light on the dynamics of gene flow between the different host populations in Lebanon.