Invasive land snails have emerged as significant horticultural pests in Australia, inflicting considerable damage on agriculture and the environment. Snails can also act as vectors of parasites and pathogens, which can in turn impact agriculture, human health, and biodiversity. Despite the potential impact of these organisms, little is known of the role snails play as vectors in an invasion context. We need to address this gap to assess and understand fully the risks invasive snails pose to Australia. The risks snails pose as vectors of other harmful organisms (either native or introduced) as well as direct crop pests can then be prioritized. Knowing the organisms vectored by snails is also necessary for assessing whether we need diagnostic tests for the vectored pests and pathogens.
This project will initially focus on exotic snail species which have already become established in Australia. Species include Theba pisana (the white or Italian snail, introduced about 100 years ago and now a major pest of grains, horticulture, grapes and pastures over a wide area of southern Australia), Cornu aspersum (also known as Helix aspersa, the brown garden snail, introduced about 200 years ago to the mainland but more recently to Tasmania and now a very common garden, amenity and citrus pest), Cantareus apertus (the green garden snail, introduced about 40 years ago, with a restricted distribution owing to internal quarantine controls), and Bradybaena similaris (the oriental tramp snail, introduced about 60 years ago and a horticultural pest over a range which is expanding). Thus, the initial targeted snail species for this study represent diverse geographic origins and ecologies, which will enable comparisons across broad groupings that are highly relevant for biosecurity planning and risk assessment.
The parasite and pathogen communities will be characterised for each species using a range of morphological and molecular techniques and will be compared with those of native snails occurring in the same areas. Where possible, snails intercepted at the border will also be included. Common interceptions include Lissachatina fulica (the giant African snail), Pomacea canaliculate (the golden apple snail), Caracollina lenticula (the lens snail), Massylaea vermiculata (the chocolate-banded snail) and Monacha spp. (the hairy snails). Combined with a review of the literature, and potentially collections from overseas, the studies will provide a greater understanding of the differences in parasite and pathogen loads in the recipient and origin countries. These data will allow determination of the parasites and pathogens that have likely been introduced along with their exotic snail hosts, assessment of the risks associated with interceptions of exotics (including those already here but perhaps without all their parasites and pathogens, as well as those still absent from Australia) their associated parasites and pathogens, and identification of potential biocontrol agents from the geographic origins of the snails.
Aim: Assess the parasite and pathogen loads of invasive snails in Australia, and the potential of genomic technologies for their diagnosis and detection, to improve knowledge of vectoring and how it should be incorporated in biosecurity planning.
Meet the PhD student for this project
Bethany Perry
“My name is Bethany, I am 24 and have recently moved from the UK to start my PhD with the ARC Training Centre in Plant Biosecurity.
“My passion for parasitology evolved during my Masters at the London School of Hygiene and Tropical Medicine where I studied MSc Medical Parasitology. I particularly enjoy delving into the biology underlying parasitic diseases and how they can be effectively diagnosed and controlled. Completing my Masters project overseas at the Hospital of Tropical Diseases in Thailand, really stimulated my interest in entomology and molecular biology research.
“This PhD is of particular interest to me as it encompasses both parasitology and entomology and incorporates aspects of my BSc Biological Sciences from modules focusing on wildlife and farming, pest management and plant sustainability. This project is enabling me to tailor my knowledge into a new area of research focusing on invasion risks and biosecurity which is a very unique aspect of parasitology.”
Supervisors and advisors
Professor Dianne Gleeson, University of Canberra.
Senior Research Fellow Alejandro Trujillo-Gonzales, University of Canberra.
Dr Mike Hodda, CSIRO.
Dr Daniel Huston, CSIRO.
Approach
The following is a suggested approach which may change depending on the results of the project.
- Review of general & specific records of local & exotic snails and their parasites, with particular emphasis on the information available for each. Review of the methods of their detection, diagnosis and host relationships. Flowing from this, an assessment of initial methods for field trials.
- Collection of introduced snails (probably starting with the very abundant brown garden snail), conventional isolation, identification and sequencing of individual parasites and hosts. This will provide baseline data.
- Comparison of parasites in introduced and original locations. Many important considerations of what constitutes different species and lineages, and their host or geographic specificity will likely arise in these considerations leading to a need for integrative taxonomy. There will be opportunities to test some of these depending on the results and material available.
- With the background of information and material now available from numbers 1, 2 and 3, test and assess different genomic methods for detection and diagnosis: eDNA, transcriptomics of parasites, pathogens and hosts.
- Summary of biosecurity risks (what it all means in practice).
Want to know more? Email Sarah Adams, Chief Operating Officer, at plantbiosecurity@anu.edu.au or +61 459 341 281.