A series of tests in semi-balanced tub aquaria and in the field indicated that sodium-pentachlorophenate should be applied at 15 to 20 p.p.m. to assure year round efficient control of Biomphalaria and Bulinus in the irrigation waters of Egypt. Temperature is an important factor in snail control and exerts a great influence on the molluscicidal activity of this toxicant, especially when employed at concentrations of 2 to 10 p.p.m. The concentration of the snail-killing agent should be maintained for 12, and preferably 20 to 24 hours. The molluscicidal activity of the compound against Bulinus and Biomphalaria, and the eggs of the latter, in Egypt was lower than that reported for sodium-pentachlorophenate used with other species of schistosome vectors in different geographical localities and under different environmental circumstances.
Investigation conducted while Head, Department of Parasitology, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt.
The author wishes to acknowledge the technical assistance of G. M. Malakatis, HM, 1/C, and B. H. Randall, HM, 1/C, U.S. Navy.