Developing ecologically based pest management programs for terrestrial molluscs in field and forage crops

Terrestrial molluscs are some of the most important herbivores in temperate habitats. They tend to be generalists and can be serious pests in agricultural fields, particularly no-till fields used for field and forage crops; however, farmers have access to few commercially available solutions, and the existing ones present many disadvantages (e.g. reliability, cost, environmental concerns). In this paper, we review these current management options with a focus on agronomic crops, as well as the biotic factors that influence mollusc feeding, such as natural enemies, plant nutritional content, and chemical defences. These biotic factors all have important direct consequences on mollusc fitness and can be manipulated in agricultural settings. We then review evidence from the latest research in the field of nutritional ecology to propose the use of the Geometric Framework, a well-established nutritional approach, to measure nutrient regulation and performance of terrestrial molluscs and develop ecologically based management programs that also relies on susceptibility to natural enemies. To illustrate our point, we detail a specific strategy being used by farmers in the Mid-Atlantic US to manage slug populations; in this system, farmers are using cover crops terminated after the cash crop is planted (also called “planting green”) and this approach appears to harness slug nutritional preferences and natural enemies to manage slug populations.