Can essential oils be used as novel drench treatments for the eggs and juveniles of the pest snail Cornu aspersum in potted plants?

Abstract

The horticultural trade is an important pathway for the introduction and spread of invasive gastropods because potted plants are essentially portable microhabitats, which protect snails and slugs, especially buried eggs and juveniles, from desiccation and molluscicides. The identification of a drench or dip treatment would therefore be an important development in helping to manage this pathway. We assessed the potential of using eleven essential oils and one terpene against the eggs and juveniles of the quarantine snail pest, Cornu aspersum. Clove bud oil was most efficacious and based on Lethal Concentration 50 (LC50) values it was 22 times more toxic than the commercially available product Snail and Slug Away® which has cinnamon oil as its active ingredient. Importantly, at a concentration of 0.116 %, clove bud oil caused 100 % mortality of C. asperum eggs and juveniles in potted plants after 24 h and was not phytotoxic. Although more expensive than a widely used metaldehyde product (Slug-Fest All Weather Formula) clove bud oil causes rapid mortality, is pleasant smelling, is non-toxic to humans and is exempt from pesticide registration requirements and pesticide residue tolerance requirements under federal law in the United States. This exemption would decrease the time and costs associated with bringing a new molluscicide to market, which has clove bud oil as its active ingredient.