Evaluation of the Pesticide Emamectin and Methanol Extract of Wheat Bran against Biomphalaria Alexandrina Snails, Their Hemocytes and Their Infection with Schistosoma Mansoni

The present study was carried out to evaluate the molluscicidal activity of the pesticide Emamectin (5% aqueous solution) and the methanol extract from the wheat bran (MEWB) against B alexandrina and their infection with Schistosoma mansoni was studied. The LC90 and LC50 values for Emamectin were 50.4 and 22.3 ppm, respectively. Infection of snails with S. mansoni under the effect of the tested agents was evaluated via four experimental groups, each of 50 snails For three consecutive days, one group of snails was exposed to 9.08 ppm aqueous Emamectin solution, another group received 100 ppm methanol extract of wheat bran (MEWB), a third group was administered by a combination of 9.08 ppm Emamectin and 100ppm MEWB, The fourth group was control maintained under similar experimental conditions. After three days, all the experimental groups were infected with S. mansonimiracidia and observed till shedding of cercariae. The physiological and histological changes were assessed before and after the infection.The changes in hemocytes of infected snails after administration with LC25 of Emamectin or wheat bran was significantly (20% and 30%, respectively) suppressed compared to 75% for the control snails. However, the snails treated with joint of Emamectin and MEWB were the least infected snails (10%). On the other hand, the biochemical test results showed a remarkable reduction of GOT (p<0.01) GPT (p<0.05) and total protein (0.05) in the heamolyph extracted from the snails treated with an aqueous Emamectin solution. Yet, the levels of GOT were significantly increased in the groups administered with the MEWB alone (p<0.01) or in combination with the Emamectin (p<0.001). As for the total protein levels, there were slightly declining (p<0.05) in the group exposed to the aqueous Emamectin and to the contrary, theses levels were significantly increased (P<0.05) in the snails of the two other experimental groups when compared to the controls. Moreover, the haemocytes cells showed a differentiation which varied in number when detected under the microscope. Administration of the aqueous Emamectin solution resulted in a significant increase (p<0.05) of the amaebocytes and a considerable decrease (p<0.05) in the number of granulocytes and hyalinocytes compared to the control snails. On the contrary, a remarkable surge (P<0.05) of granulocytes and decrease of the amaebocytes was detected in the haemolyph of snails treated with MEWB.