Potential role of rice cultivation and fish aquaculture in the transmission of schistosomiasis and the effect of pesticides and fertilizers used in rice cultivation on the snail Biomphalaria alexandrina and schistosome larval stages | ||
| Egyptian Journal of Aquatic Biology and Fisheries | ||
| Article 6, Volume 22, Issue 3, July 2018, Pages 71-87 PDF (444 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/ejabf.2018.8769 | ||
| Authors | ||
| El- Khayat, H. M. M.; Mahoudm, K. M. A.; Eissa, F. I.; Mostafa, M. A.; Flefel, H. E. | ||
| Abstract | ||
| The present investigation aimed to study the potential role of rice cultivation and fish aquaculture in the transmission of schistosomiasis in Kafr El-Sheikh governorate. This study accomplished in four non-governmental rice fields; three non- governmental fish aquaculture and one governmental of each about one year. It was found that B. alexandrina established in all watercourses next to nongovernmental farms in the whole study, while B. truncatus was observed in certain watercourses next to non-governmental farms. The toxicity of six pesticides (lampada, sylian, saturn, karasay, mancozeb and machete and two fertilizers urea and mixed nitrate) which used in rice cultivation against B. alexandrina and their egg masses and schistosome miracidia and cercariae showed that all pesticides had strong molluscicidal properties and are far toxic than fertilizers. Lampada and karasay were the strongest pesticides against snails where their LC50 & LC90 were 0.8 & 1.0 and 0.7 & 1.1 ppm, respectively. Also, fertilizers LC50 & LC90 were 2754 & 4092 ppm for mixed nitrate and 9636 & 15937 ppm for urea. Effect of LC25 and LC50 of pesticides and fertilizers on mortality of B. alexandrina eggs explored that fertilizer mixed nitrate more potent effect on the eggs that killed 97.6% and 98.2%, respectively. Followed by Pesticides mancozeb and machete witch caused 94.7 & 95.9% and 94.2 and 97.9% mortality, respectively. The current data indicated that death rates of S.mansoni miracidia and cercariae were started after minutes of exposure to LC5 of both pesticides and fertilizers. It is concluded that accidental introduction of such pesticides to snails' habitats through plant pests control, low concentrations of the pesticide mancozeb and mixed nitrate inhibited the hatchability of B. alexandrina eggs, also suppressed vitality of S. mansoni larval stages within a short exposure period. As well; they disturb the compatibility of B. alexandrina snails to S. mansoni miracidia. | ||
| Keywords | ||
| Schistosomiasis; B. alexandrina; B. truncatus; Rice cultivation; Aquaculture; Pesticides; fertilizers | ||
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