Abstract

Dockovdia cookarum infection was studied in relation to the abundance and size classes of Lanistes libycus from Omi Stream, Ago-Iwoye, Nigeria, between September 1997 and June 1998. 57.6% of the 262 L. libycus recorded were collected during periods of heavy rainfall. 17.2% (45) of the L. libycus examined had D. cookarum infection. The water mite prevalences were higher in rainy season than in dry season, and ranged between 3.0% and 44.4% monthly. L. libycus in 21-30 mm size class had the highest prevalence (73.3%). Intensity of infection was higher in rainy season than in dry season, and ranged between 1 and 6 mite(s)/snail. 2.6% of the L. libycus specimens in the 21-30 mm size class had concurrent D. cookarum andChaetogaster limnaei infections.

Key words: Dockovdia cookarum, water mites, Lanistes libycus, freshwater molluscs,Nigeria