Biological control of Monacha cartusiana “glassy clover land snails” by microbial biopesticides Biozed and Biogard, using bait technique

Abstract

Abstract The effectiveness of microbial derived insecticides (Biozed and Biogard) were tested for controlling the subversive clover snails causing wastage of economic plants at Sharkia Governorate, Egypt, using poisonous baits technique. The toxicity index, LC50 and relative potency values reveals the potential activity of Biozed (fungal) than Biogard (bacterial) against M. cartusiana snails. Biogard caused no mortalities among treated clover snails at all at the first day of exposure. Mortality percentages appeared after one week and increased gradually with increasing concentrations and time of treatments. The highest concentrations of Biozed (0.75%) and Biogard (3.9%) caused 66.6% and 40% mortalities respectively after 28 days of exposure. From the biochemical parameters, an increment of total proteins, AST, ALT, α-esterase levels while a strong reduction on the total lipids, β-esterase and Phenoloxidase levels were observed after treatments with LC25 of biocides for three weeks. Histopathological investigations on the digestive and hermaphrodite glands revealed that sublethal concentration of Biozed produced tubular disruptions, vacuolation, excessive luminal secretions in digestive gland tissues. Malformed sperms and oocytes were spotted in ovotestis acini treated with Biozed. Biogard caused extensive luminal secretions, hemocytes infiltration and lysis of peripheral cells of digestive tubules while hermaphroditic acini showed disrupted sperms and oocytes.