A Study of the Weather Variability Influence on Occurrence and Damages of Mononychellus tanajoa Bonder (Acarina: Tetranychidae) on Selected Cassava Varieties in the Lake Zone, Tanzania

A study was conducted in the Lake Zone, the leading cassava producing Zone in Tanzania during the 2015 and 2016 dry seasons. It was aimed at establishing the influence of the weather variables on occurrence and damages caused by Cassava green mites (CGM), Mononychellus tanajoa on commonly grown cassava varieties. Cassava is a subsistence food to 200 million poor people in the African continent and also plays an important role in the generation of employment and income, especially for small and medium producers. The experiments were laid out in a Split plot design with varieties as sub plots and locations as main plots. The three locations were; Ukiruguru, Ng’ombe and Kishiri, the former two being in Misungwi and the other one in Kwimba districts respectively. Infestation of M. tanajoa was allowed to occur naturally. Results suggested that mites population and damage varied significantly (P<0.05) among varieties, data collection dates and locations in both years. Generally, Kwimba in 2015 and Ukiruguru in 2016 recorded the highest population of M. tanajoa while N’gombe had the lowest counts in both years. The highest root yield was recorded at Ukiriguru in both seasons. In both years, Liongo Kwimba and Naliendele were comparatively the most susceptible varieties while Suma and Kyaka were found to have tolerated/resisted the pest. Rainfall, relative humidity and temperatures contributed either positively or negatively to the survival, perpetuation of and damage by M. tanajoa in both seasons.