Labora\ol'j trials for Ihe controlling two snails species namely Blomphlada
alexandrina and Bulinus truncatus were carried out. Three carbamate compounds
(Trimelhacarb' Thiodicarb and Melhlocarb) and three organophosphorus compounds
(Trichloroton; Pnormothion and Phorate) were tesled fOf their mollusc\clda\ activilies
at intervals wilh time up 10 10 days. On basis of LD5J values after 24 h. or 48
h.exposure, the toxicity order fOt' the carbamates compounds were trimethacarb >
thiodicarb ~ methlocarb and that of organophosphorus compounds was trichlorofon >
formolhion :> phorata, Biomp < /em>halaria alexandrina was found to be more sensitive to all
the eesuclces tested than Bulinus truncates, snails. Also the Chemical stability or the previous pesticides in water was determined
using HPLC method for all pesticides tested. This wa~ done by allowing Ihe expected
Lego values for 24-hours exposure to stand for varying pertods before testing thsrn
against snails. The stability of the previous pesticides were ranged as follow:
trlmethacarb > Itliodicarb > msthlocarb > formolhion ,. phorate > tliChlocofon that with
HPlC method and wilh toxicity test against Blompha/aria a/exandrina. snails,