The feeding behaviour of Rumina decollata (Subulinidae: Gastropoda) raises questions about its efficacy as a biological control agent for Cornu aspersum (Helicidae: Gastropoda)

ABSTRACT

The facultative predatory snail Rumina decollata (L.) has been used as a biological control agent for Cornu aspersum (Müller) in Californian citrus orchards for almost half a century despite there being little laboratory and field evidence of its efficacy. We have demonstrated that R. decollata can only successfully kill C. aspersum that are <13 mm (shell diameter) and if given a choice between a known food plant (carrot roots) and C. aspersum within this vulnerable size range, the majority of R. decollata (∼93%) chose carrots. Adult R. decollata will feed on C. aspersum eggs and mean total consumption per individual was ∼3 eggs over a 7-day period. These experimental results support previous anecdotal suggestions that R. decollata may not be an effective snail predator.

KEYWORDS:

• Rumina decollata
• Cornu aspersum
• biological control
• generalist predator
• vulnerable prey size range
• plant preference

Acknowledgements

We are grateful to Robin Veasey for collecting R. decollata and C. aspersum for our research. We thank William and Holly Stosic for allowing us to collect bucket loads of C. aspersum from their garden for these experiments. Thanks also to Christiane Weirauch for assistance with German translation.

Disclosure statement

No potential conflict of interest was reported by the authors.