Pesky snails pick food by smell not taste

"Finding ways to protect young crops without causing lasting pollution is a major challenge," says Guy Poppy. (Credit: ansel117/Flickr)

Natural smells might offer a more environmentally safe way to protect seedlings from hungry snails. A new study shows snails choose the plants they eat based on scent rather than taste.

“Slugs and snails are two of the key pests threatening crop production, and they can be particularly damaging to seedlings, since they cannot regrow in ways that older plants can,” says Guy Poppy, a professor of ecology at the University of Southampton.

“But common prevention methods—such as slug pellets—can have a major environmental impact, and finding ways to protect young crops without causing lasting pollution is a major challenge.”

Poppy and colleagues presented several different cultivars of oilseed rape seedlings to hundreds of snails and recorded which ones they preferred.

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Then they characterized each of the seedling cultivars based on the presence of glucosinolates and volatile organic compounds (VOCs), both types of naturally produced chemicals, to determine whether the snails’ choices were linked to either type of defense.

The results showed there was no relationship between the snails’ choices and the presence of glucosinolates, but that seedling acceptability was strongly related to VOCs.

“Crop plants are often bred for various desirable characteristics, but most often priority is given to increased yield and disease resistance over traits favoring herbivore resistance. Increased agro-chemical inputs are often used to maintain productivity; however pesticides can have adverse effects on key non-target species such as pollinators and cause wider contamination.

“But at a time when increasing demands for food security are in conflict with concern over pesticide use, we show that for one major crop species at least, plant protection could be developed without ecotoxic side effects.”

Other researchers from Southampton, Plymouth University, and the German Centre of Integrative Biodiversity Research contributed to the study, which appears in the Annals of Botany.

Source: University of Southampton