Parasitism of the conical snail, Cochlicella acuta , by the fly, Sarcophaga villeneuveana , in south-western Europe

The conical snail, Cochlicella acuta , is an introduced pest of grain crops in Australia. Biological control of C. acuta has been attempted using the parasitoid fly, Sarcophaga villeneuveana , sourced from southern France, but has failed. Molecular genetics of the snails and climatic matching have suggested greater success might be realised using flies from southern Iberia (Spain and Portugal) or Morocco. We measured levels of parasitism of C. acuta by S. villeneuveana at several sites within southern Iberia, and near the previous fly release site in Australia. Emergence of flies was slightly higher in Iberia, compared with Australia, but 31% of the S. villeneuveana that reached pupal stage within C. acuta in Iberia were hyperparasitised (up to 63% at individual sites). No hyperparasites emerged from Australian collections of C. acuta . These data encourage further searches in southern Iberia for more effective populations of S. villeneuveana for use as biological control agents.