Factors affecting the molluscicidal activity of Asparagus densiflorus and Oreopanax guatemalensis plants and Difenoconazole fungicide on Biomphalaria alexandrina snails

Abstract

Many factors may enhance or suppress the molluscicidal activity regardless of their origin. The present study aims to determine the molluscicidal activity of two plants, namely Asparagus densiflorus and Oreopanax guatemalensis besides, Difenoconazole fungicide against Biomphalaria alexandrina snails, miracidia and cercariae. The most effective agent was Difenoconazole followed by A. densiflorus and O. guatemalensis against B. alexandrina snails, where the LC90 values after 24 h of exposure reached 2.5, 102, and 188 ppm, respectively. Toxicity of tested agents was more pronounced at high temperatures. A. densiflorus and Difenoconazole showed no changes in their activities after their exposure to sunlight for 6 h. Also, neutral and acidic media were favorable for maintaining their toxic action. The presence of aquatic plants, mud particles, and storage period had negative effects on the activities of the tested agents. Both A. densiflorus and Difenoconazole had a fast effect against miracidia and cercariae of Schistosoma mansoni after 3 h of the exposure. Moreover, the tested agents recorded adverse impact on the total reproductive rate of exposed snails. Such effects were supported by histopathological examinations of the hermaphrodite gland. It showed an abnormal necrosis in male and female gametogenic cells, besides a decrease in the number of ova and other gametogenic stages.