Genetic variability in the parasitic fly, Sarcophaga villeneuveana, in south-western Europe and Morocco

The snail, Cochlicella acuta (Muller), is an introduced pest of grain crops in southern Australia, and native to Europe and north-west Africa. Parasitoid flies (Sarcophaga villeneuveana (Enderlein)) have previously been sourced from France to attempt biological control of the pest in Australia, but have failed. Cochlicella acuta has three mitochondrial lineages (CO1 & 16S based) within its native distribution. The snails now found in Australia belong to just one of these lineages. Their origins most likely lie in the southern Iberian Peninsula or Morocco, not in France. We collected S. villeneuveana attacking C. acuta in France, Spain, Portugal, Morocco and Australia. Genetic structure (CO1) was not found within the fly that aligned with the lineages recorded for the snail host in the same regions. However, geographical patterns were detected amongst haplotypes of S. villeneuveana which encourage further, better targeted searches in Morocco and the southern Iberian Peninsula for a more effective biological control agent(s).