Effect of dietary diversification on growth and development of the exotic terrestrial mollusk, Deroceras reticulatum

Due to increases in global trade, biological invasions by non-native gastropods into North America are of concern to regulatory agencies, agriculturalists, and conservation organizations. The goal of this research was to quantify the quality of hostas on growth and development parameters in the invasive slug Deroceras reticulatum (Müller) with a view to testing the hypothesis that dietary diversification promotes development rates in this species. Generalist arthropod predators such as carabid beetles, the major biological control agents of slugs, are widely recognized as diversifying their diet to enhance their fecundity, but there is little information pertaining to plant-feeding mollusks. Deroceras reticulatum hatchlings were randomly assigned to one of thirteen single- or multiple-plant treatments including cabbage, romaine lettuce, and Hosta (Fragrant Blue, Guacamole, Red October, So Sweet, Sun Power). Leaf thickness, toughness, and water, carbon, and nitrogen contents, were measured and correlated with slug growth parameters. Interestingly, despite highly significant variation in plant nutrient content, no significant differences in weight gain were recorded between treatments for hatchlings, but dietary diversification positively affected weight gain in older slugs. Furthermore, a diverse ad libitum diet positively influenced survival, with single-plant diets causing high levels of mortality. Examining the role of dietary selection on the dynamics of population growth in invasive gastropods contributes to our understanding of the impact of such invasions upon plant growth and establishment in urban environments. Furthermore, it enables greater understanding of the role of habitat diversification on population growth and ultimately biological control potential of generalist arthropod predators.