Potential of the Snail-Parasitic Nematode Phasmarhabditis eagyptiaca Azzam 2023 to Control Terrestrial and Freshwater Snails Under Laboratory and Field Conditions

In Egypt, over 20 species of freshwater snails, 16 land snail species, and three slugs attack approximately 64 plant types. All terrestrial and freshwater snails cause significant damage to crops, in addition to serving as intermediate hosts for numerous parasitic diseases that afflict humans and livestock. The interactions between nematodes and gastropods range from accidental phoresis to parasitic or pathogenic relationships. Eight species of snail-parasitic nematodes have been identified in Egypt: Phasmarhabditis tawfiki Azzam, P. eagyptiaca Azzam, P. eobaniae Azzam, P. hermaphrodita (Schneider, 1859), Rhabditis sp., Diploscapter sp., Cephalobus sp., and Agfa sp. Consequently, these nematodes must be researched further to determine their potential for biological pest control. Phasmarhabditis eagyptiaca Azzam 2023 was recently reported, and its capability to kill various terrestrial snails, slugs, and aquatic snails was investigated. The present study examines the effect of the nematode P. eagyptiaca on snail mortality across terrestrial and freshwater species under laboratory and outdoor conditions to clarify its potential role in snail control. This investigation showed a significant positive correlation between nematode concentration and mortality rates for both terrestrial and aquatic snails. The time required to reach total mortality decreased as nematode concentration increased. Furthermore, this nematode affects immature snails more rapidly than mature snails. Infected terrestrial snails yielded a higher recovery of nematodes at lower concentrations than at higher ones, though the time of recovery was shorter at higher concentrations. According to the study's findings, this nematode could play an important role in the biological control of terrestrial and freshwater snails.