Bioactivity and genotoxicity effects of certain compounds on Theba pisana and Monacha cartusiana land snails

Theba pisana and Monacha cartusiana, both land snails, are agricultural pests that have caused significant losses in many orchards and fields in various areas of Egypt. In this study, the efficacy of nicotinamide, imidacloprid, and silver nitrate nanoparticles compounds compared to oxamyl were evaluated against these two snail species using residual film and poison bait techniques under laboratory and field conditions to identify alternative, more effective options to conventional pesticides. In addition, the genotoxicity impacts of these compounds on the tested snails were thoroughly investigated. Results showed that, for T. pisana, oxamyl exhibited the highest mortality rate, followed by nicotinamide and silver nitrate, with calculated LC₅₀ values of 0.028%, 0.049%, and 0.120% for residual film technique and 0.546%, 0.971%, and 1.333% for poison bait technique. Similarly, for M. cartusiana, oxamyl exhibited the highest toxicity, followed by nicotinamide and silver nitrate, with LC₅₀ values of 0.054%, 0.063 and 0.103% in residual film method, While in the poison bait method, oxamyl showed the highest toxicity, followed by silver nitrate and nicotinamide with LC₅₀ values of 0.273%, 1.150 and 1.204, respectively. Imidacloprid showed the lowest efficacy in both species with LC₅₀ values of (0.19, 0.14%) and (1.57, 1.48%) for residual film and baits techniques, respectively. The field evaluation of tested compounds against T. pisana and M. cartusiana snails using poisonous baits revealed varying effectiveness in reducing snail populations. Oxamyl showed the highest reduction rates, with 46.31%, 63.63%, and 90.85% for T. pisana and 29.47%, 63.92%, and 92.13% for M. cartusiana after 1, 7, and 21 days of treatment, respectively. Nicotinamide and silver nitrate nanoparticles were also effective, reducing populations by 81.71% and 72.83% for T. pisana and 92.62% and 84.95% for M. cartusiana after 21 days. Imidacloprid compound resulted in the lowest reductions, with 60.64 and 63.26% for two species, respectively. Respecting molecular diagnosis RAPD- PCR, the results demonstrated that the presence of polymorphism in the two types of snails treated with tested compounds.