Sourcing effective biological control agents of conical snails, Cochlicella acuta, in Europe and north Africa for release in southern Australia

Authors: JOURDAN, MIREILLE - CSIRO EUROPEAN LABORATORY; THOMANN, THIERRY - CSIRO EUROPEAN LABORATORY; KRITICOS, KAREN - COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION (CSIRO); BON, MARIE-CLAUDE - EUROPEAN BIOLOGICAL CONTROL LABORATORY (EBCL); SHEPPARD, ANDY - COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION (CSIRO); BAKER, GEOFF - COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION (CSIRO)

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2019
Publication Date: 7/1/2019
Citation: Jourdan, M., Thomann, T., Kriticos, K., Bon, M., Sheppard, A., Baker, G. 2019. Sourcing effective biological control agents of conical snails, Cochlicella acuta, in Europe and north Africa for release in southern Australia. Biological Control. 134, 1-14. doi.org/10.1016/j.biocontrol.2019.03.020.
DOI: https://doi.org/10.1016/j.biocontrol.2019.03.020

Interpretive Summary: The ‘European’ snail, Cochlicella acuta, is an invasive pest of grain crops in southern Australia. A parasitoid fly, imported from France, has performed poorly as a biocontrol agent. Molecular genetics suggests that the pest did not originated from France but from the Iberian Peninsula or Morocco. Moreover, climates within the Australian distribution match closely with these same regions. The combination of genetic data from the snails and climatic matching analyses point to the need for future searches for effective biological control agents for use against C. acuta in Australia being best focused in southern Spain, southern Portugal and Morocco.

Technical Abstract: The conical snail, Cochlicella acuta, is a major introduced pest of grain crops in southern Australia. Previous attempts to control this snail pest included the release, during the early 2000s, of parasitic flies (Sarcophaga villeneuveana) sourced from southern France, within the perceived native distribution of C. acuta. The flies established in southern Australia, but only in very low numbers, such that there was no significant reduction in the snail’s pest status. Sequencing of mitochondrial genes has now identified three main maternal lineages within C. acuta, across its distribution in south-western Europe and Morocco. All the C. acuta found in Australia belong to the 3rd lineage found in the U.K., western and southern France, northern, eastern and southern Spain, Portugal and Morocco. A plausible explanation for the poor performance of the biological control agent previously released to control C. acuta in Australia is a mismatch between snail host and selected parasitoid. A different biotype or sub-species of S. villeneuveana, or even a different parasitoid species altogether, that attacks the 3rd lineage of C. acuta in south-western Europe or Morocco, could prove to be a more effective biological control agent than the S. villeneuveana previously released from southern France. Climates in southern Spain, southern Portugal and northern Morocco also best match those areas in southern Australia where C. acuta is a pest, suggesting further searches for effective natural enemies should be focused there.