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The study examined the effects of larval trematode infection on the neutral lipid and phospholipid content of Biomphalaria alexandrina infected with Schistosoma mansoni. Uninfected snails were used as matched controls. As determined by qualitative high-performance silica gel thin-layer chromatography (HPTLC), the major neutral lipids present in the whole bodies and digestive gland-gonad complexes in both infected and uninfected snail populations were free sterols, free fatty acids, and triacylglycerols, and the major polar lipids were phosphatidylcho-line and phosphatidyl ethanolamine. Quantitative analysis by HPTLC with visible and UV scanning reflectance densitometry showed the snail's digestive gland lipid level was found to be almost halved in 20 days post infection; a more then 80% reduction being visible after the subsequent 40 and 60 days.

The excessive use of pesticides in agriculture has sparkled the interest of scientists in investigating the harmful effects of these compounds. The present study evaluates the pesticides Atrazine and Roundup (glyphosate) on biochemical and molecular aspects of Biomphalaria alexandrina snails. The results showed that LC 10 of these two pesticides caused considerable reduction in survival rates and egg production of treated snails. Additionally, Atrazine proved to be more toxic to B. alexandrina snails than Roundup. In treated snails, glucose concentration (GL) in the hemolymph as well as lactate (LT) and free amino acid (FAA) in soft tissues of treated snails increased while glycogen (GN), pyruvate (PV), total protein (TP), nucleic acids (DNA and RNA) levels in snail’s tissues decreased. The activities of glycogen phosphorylase (GP), superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), succinic dehydrogenase (SDH), acetylcholinesterase (AChE), lactic dehydrogenase (LDH) and phosphatases (ACP and ALP) enzymes in homogenate of snail’s tissues were reduced in response to the treatment with the two pesticides while lipid peroxide (LP) and transaminases (GOT and GPT) activity increased ( P B. alexandrina snails, and have adverse effects on its reproduction.

Four plant species, as a dry powder of their leaves, were tested against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni . The bioassay tests revealed the plants Datura stramonium and Sesbania sesban to be more toxic to the snails than the other two ones. Therefore, they were tested against snails’ fecundity ( M x ), reproduction rate ( R o ) and their infection with S. mansoni miracidia. In addition, total protein concentration and the activities of the transaminases (AsT and AlT) and phosphatases (AcP and AkP) enzymes in hemolymph and tissues of snails treated with these plants were determined. As well, glucose concentration in snails’ hemolymph was evaluated. Exposure of snails for 4 weeks to LC 10 and LC 25 of the plants D. stramonium and S. sesban dry powder markly suppressed their M x and R o . The reduction rates of R o for snails exposed to LC 25 of these plants were 62.1% and 76.4%, respectively. As well, a considerable reduction in the infection rates of snails exposed to these plants either during, pre- or post-miracidial exposure was recorded. Thus, infection rates of snails treated during miracidial exposure with LC 10 of D. stramonium and S. sesban were 41.7% and 52.2%, respectively, compared to 92.6% for control group ( P 25 of these plants shed 372.8 and 223.2 cercariae/snail, respectively, compared to 766.3 cercariae/infected control snail ( P The results, also, revealed that glucose and total protein concentrations in hemolymph of snails treated with LC 10 and LC 25 of these plants were decreased, meanwhile, the activities of the enzymes AsT, AlT, AcP and AkP were elevated ( P 25 of the plants D. stramonium and S. sesban negatively interferes with biological and physiological activities of B. alexandrina snails, consequently it could be effective in interrupting and minimizing the transmission of S. mansoni .