Floral herbivory of an invasive slug on a native weed

Abstract

Effects of floral herbivory (grazing flowers) by slugs on production and quality of seeds of herbaceous plants have been rarely quantified. We studied consequences of grazing by an invasive slug Arion lusitanicus (Mabille) for inflorescences of dandelion (Taraxacum officinale Weber ex Wiggers). In May 2008, a grassy site in Prague-Ruzyně (Czech Republic) was densely populated by dandelion inflorescences. Of the 40% of the flowers grazed by the slug, 70% died before seed dispersal and seed was eaten from 10% of the closed mature inflorescences. Viability of seeds from inflorescences that survived slug grazing was not affected. In addition to seedling predation, grazing of flowers may be an important source of dandelion mortality at sites where this slug is abundant.