THE PHENOLOGY OF BEMISIA-TABACI (HOMOPTERA, ALEYRODIDAE) POPULATIONS ON CASSAVA IN SOUTHERN COTE-DIVOIRE

Population phenologies of the whitefly, Bemisia tabaci (Gennadius) (Ho moptera: Aleyrodidae), in young cassava crops in Cote d'Ivoire, West A frica, are described for three field seasons. Populations of all stage s were consistently greatest 6-12 weeks after the crop was planted. Th e number of adults on plants as well as on attractive and non-attracti ve sticky traps displayed cycles of buildup and decline each year, the periodicity of these cycles corresponding to the generation time of B . tabaci under field conditions. Adult population declines were probab ly caused by emigration from the crop. Rainfall was negatively correla ted with both nymph and adult populations, possibly due to reduced ovi position after rain. B. tabaci is the vector of African cassava mosaic geminiviruses (ACMV) and the observed B. tabaci population trends fit well with the pattern of ACMV buildup in the crop.