Toxicity and feeding deterrent effects of selected nutrient-based compounds and soil additives against Theba pisana under laboratory and field conditions

Productivity, stress tolerance, and overall plant health can be enhanced by supplying plants with essential nutrients such as sulfur and phosphate-based compounds. Selected plant chemical nutrients, including potassium dihydrogen phosphate (PDP) and sodium phosphate (SP), as well as the soil additive sodium thiosulfate (STS), were evaluated for their in vitro and in vivo molluscicidal activity against the white garden snail, Theba pisana (O. F. Müller, 1774). Laboratory trials were conducted over 72 h using the toxic bait method. The feeding-deterrent impacts of the tested compounds against the feeding behavior of T. pisana were also assessed. Furthermore, field treatments were applied using the toxic bait technique, and the population reduction percentage was determined after 21 days post-treatments.

Under laboratory conditions, PDP and STS exhibited elevated toxicity toward target snails, with nearly identical LC₅₀ values of 8.67 and 8.99%, respectively. However, SP possessed the lowest toxicity among the tested compounds, with an LC₅₀ value of 19.91%. Treatment with PDP displayed a mean bait weight loss of 2.10 g and a feeding deterrent index (FDI %) of 12.00%, indicating slight feeding deterrent effects on snail feeding behavior. STS and SP had nearly similar bait weight reductions and FDI (%) of (1.94 g, 18.70%) and (1.97 g, 17.50%), respectively. Field treatments revealed that PDP and STS had significant population reductions of 78.43% and 80.87%, respectively, after 21 days post-treatment. Among the tested compounds, STS and PDP showed the highest overall efficacy under both laboratory and field conditions.

The tested compounds exhibited significant toxicity against target land snails. The results indicated slight reductions in bait consumption relative to the control treatment, as indicated by lower bait weight reduction values. Although these compounds do not function as direct neurotoxic or metabolic inhibitors, their secondary environmental effects could influence snail population dynamics and behavior through habitat alteration and physiological stress. These findings highlight the potential of nutrient-based compounds as alternative tools in integrated pest management (IPM) programs for controlling T. pisana, offering a less hazardous approach than conventional molluscicides.