Phototaxis effect of Oncomelania hupensis hupensis and O . h . robertsoni-- a comparative study / 中国人兽共患病学报

ABSTRACT

The aim of this study was to determine the differences in phototaxis between Oncomelania hupensis (O .h .) hupensis and O .h .robertsoni as well as four related geographic strains of male and female snails and Schistosoma japonicum-infected and-uninfected snails .Field collection of O . hupensis was performed in S . j aponicum-endemic areas of Xingzi and Yushan counties in Jiangxi Province ,China ,as well as Tianquan and Pengshan counties in Sichuan Province ,China .Infected and uninfected snails were screened using the cercariae escaping method ,with artificial separation of male and female snails . The experiment was carried out in an in-house constructed dark phototaxis experiment box using white light as the main source of light at the most suitable light intensity .Under a light intensity of 1 500 Lux for 30 minutes ,all of the snails from the experimental group showed obvious phototaxis .The statistical analysis showed no significant difference in the phototaxis index between male and female snails ,and there was also no significant difference in the phototaxis index between different geograph-ical strains of the same subspecies of snails .A significant difference in phototaxis was observed between the two subspecies during the 30-minute experimental periodO .h .hupensis displayed a higher phototaxis index than that of O .h .robertsoni , whereas S .japonicum-infected snails showed a lower phototaxis index than that of uninfected snails .A difference in phototaxis was found between different subspecies of O .hupensis and within the same subspecies .All uninfected snails displayed the same phototaxis index .When snails were infected with S .japonicum ,phototaxis reduced .