Infectivity of a mermithid nematode Romanomermis iyengari (Welch) in different conductivity levels under laboratory and field conditions.

Infectivity of R. iyengari was examined by exposing mosquito (Culex quinquefasciatus) larvae to the preparasite at different conductivity levels. The preparasite infected 63.5, 30, 11, 1.5 and 0.5% of the mosquito larvae respectively at 2000, 2500, 3000, 3300 and 3600 mu ho/cm. Although, 62-69% of the preparasite survived at 4000-5400 mu ho/cm, it did not infect. Application of preparasite to tree-holes resulted in 53-63% infection of Aedes albopictus larvae initially. On 6th day the infection level was 40% which decreased further to 7% by 15th day. The infection reappeared on 38th day indicating that R. iyengari has not only infected mosquito larvae as soon as they were applied to tree-holes in which the conductivity was 600-2800 mu ho/cm but also got established there.