Mortality of the invasive white garden snail Theba pisana exposed to three US isolates of Phasmarhabditis spp (P. hermaphrodita, P. californica, and P. papillosa)

Theba pisana is a serious snail pest in many parts of the world and affects diverse crops including grain, vegetables, grapevines, and ornamental plants and shrubs. Due to its gregarious nature, ability to reproduce rapidly, and the difficulty of controlling it by conventional methods, it has the potential to become a significant pest where introduced. Mitigating this pest is an important challenge that must be addressed. Phasmarhabditis hermaphrodita, is a gastropod-killing nematode that is commercially available only in Europe (Nemaslug ®) and Sub-Saharan Africa (Slugtech ® SP). The use of effective gastropod-killing nematodes in the genus Phasmarhabditis (P. hermaphrodita, P. californica and P. papillosa) in California may provide one strategy for alleviating the potential damage and further spread of these snails, which are currently limited to San Diego and Los Angeles counties. Laboratory assays demonstrated for the first time that US isolates of P. hermaphrodita, P. californica and P. papillosa at 150 DJs/cm(2) caused significant mortality and are equally lethal to T. pisana. Molluscicidal efficacy of these nematodes are comparable with those of iron phosphate, at the recommended high dose of 4.88 kg/m(2). Additional trials are needed to determine their effects at lower dose and whether they are dependent on the size or age of the snails.