Evaluating the Effectiveness of Acremonium sp. Protease as a Natural Molluscicide Agent: A Toxicological and Histological Investigation on Land Snails

. ABSTRACT Our goal nowadays is to reduce the use of chemical pesticides and replace them with biocides, aiming to mitigate environmental pollution and minimize the impact of climate change. In this study, we successfully demonstrated the toxic effects of Acremonium sp., a bioagent that produces the protease enzyme, in comparison to the conventional pesticide methomyl, on the land snails Monacha cartusiana and Theba pisana . We also examined the corresponding histological responses of these snails under controlled laboratory conditions. The mortality percentages increased with increasing the concentration of protease derived from Acremonium sp. and the duration of exposure. For the highest concentrations (20%) of Acremonium sp. and (2%) of methomyl, the mortality rates after 96 hrs were 53.33%, 26.67%, 93.33%, and 86.67% for M. cartusiana and T. pisana , respectively, using the poisonous baits technique. Conversely, the dipping technique yielded mortality rates of 100%, 46.67%, 100%, and 100%, respectively. The dipping technique proved to be more effective than the poisonous baits technique, with M. cartusiana displaying greater sensitivity compared to T. pisana . Histological examinations of snails exposed to methomyl revealed significant alterations in the digestive glands, resulting in the loss of their normal architecture. This damage subsequently impaired feeding and movement activities, potentially leading to snail mortality. Microbial agents demonstrated promising results as molluscicides, providing a cost-effective and superior alternative to chemical-based molluscicides for managing snail pests in Egyptian agriculture. Notably, Acremonium sp. induced various histopathological disorders in the treated snails