Abstract:
This study extended over a period of three years, from July 1995 to June 1978. This project was financed by Pakistan science foundation and was carried out in the laboratories of the Zoology department, university of the Punjab, Lahore.
Eighteen thousand five hundred snail specimens belonging to the nine freshwater species obtained from fifty-four localities from all over Pakistan were examined for the presence of larval trematodes. As a result of survey fifty-seven species of cercaria were recovered, studied and identified. Out of these thirty-eight are new to science and eleven are new records from Pakistan. For every cercaria its behavior, emergence and the structure of the ratio or the sporocyst, as the case may be, was also studied.
An attempt was made to study the life histories of five cercariae but we were able to study the life histories of only two species in the laboratory.
The histochemistry of five cercaria, three belonging to xiphidiocerous group, one to echinocytes group and one to pleurolophocercous group and one to pleurolophocerous group was studied. A comparative assessment of thehistorichemical nature of different glands has been made and possible functions have been assigned them.
Two species of cercariae and two species of snails were exposed to various concentration of some of the commonly used insectaries. some of these insecticides have been found to be highly toxic to both cercariae and snails at very low concentrations.
The effects of PH and industrial waste om cercariae and snail hosts was also studied.
