Getu, Emana(Professor)Djirata, Ofgaa2018-07-232023-11-092018-07-232023-11-092017-04http://etd.aau.edu.et/handle/123456789/9820Mango (Mangifera indica L.) is the third most important fruit crop in the tropics following citrus and banana. It is consumed as a fresh fruit and different forms of preparations for its contents of sugar, vitamins, minerals and protein, among others. Mango is produced in Ethiopia and Kenya for domestic consumption and export market. Mango production in these two countries is currently constrained by infestation of white mango scale, Aulacaspis tubercularis Newstead (Homoptera: Diaspididae). In Ethiopia, white mango scale was recorded for the first time in 2010, from mango orchard located at Loko Village in East Wollega Administrative Zone of western Ethiopia. It constrained mango production in the region and released panic among mango farmers. Occurrence of white mango scale in Kenya was much earlier. These studies were designed and conducted to know the distribution, population dynamics, and host range of white mango scale for designing management options of the pest. The studies were conducted in western Ethiopia, and some mango growing counties in central and eastern Kenya, from May 2013 to July 2016. Randomized Complete Block Design was used for sample collection from the total of five study orchards in Ethiopia and Kenya to determine population dynamics and, screen insecticide in Ethiopia. Purposive sampling method was employed for white mango scale survey. It was known from the results that, in western Ethiopia, white mango scale showed population peaks in April at Arjo and in May at Bako orchards, with marked decline with decreased precipitation. Abundances of eggs, crawlers and sessile stage white mango scale showed significant differences among the study months (P< 0.05). Abundance of sessile white mango scale was significantly higher at Bako orchard than Arjo (P< 0.05).In the entire study orchards in both Ethiopia and Kenya, white mango scale population was significantly more abundant on upper mango leaf surface than lower (P< 0.05). At Bako orchard population of male white mango scale was found to be significantly higher than that of the female (P< 0.05). In the current study, larvae of Chilocorus sp. (Coleoptera: Coccinellidae) was recorded preying on live white mango scale, a new association reported for the first time with this study, of a native natural enemy with the exotic white mango scale in Ethiopia. This study revealed the presence of statistically significant (P<0.05) positive correlation between populations of white mango scale and the predatory larvae in both study orchards in western Ethiopia. In the Kenyan study orchards, population peaks of white mango scale were found to be in February and April, with general trend of decline towards the colder dry months. The variation among the study months were statistically significant at both Kimani and Samuru (P<0.05) whereas that at Kenyatta vii University mangos showed no significant difference (P>0.05).Sessile stage white mango scale population was found to be significantly more abundant at Samuru orchard than Kimani (P<0.05). Some mango varieties were found to be more susceptible to white mango scale infestation than others with significant difference (P<0.05)White mango scale distribution was found to have covered 189km east-to- west and over141km north-to-south air distances, with more of high and very high severity status of infestations in west Ethiopia. In central and eastern Kenya, white mango scale was recorded from all of mango farms visited except only four with level of infestation being mild in most cases. White mango scale distribution was uneven within each county in Kenya and each administrative Zone in Ethiopia. Implementation of chemical and cultural control methods could help some mango farmers in Kenya to manage white mango scale infestation. The result of this study showed that white mango scale had no alternative host plant apart from mango tree, in western Ethiopia. Performance of Folimat 500 SL in reducing number of the insect pest on mango tree was significantly higher (P<0.05) than Closer 240 and D-C-Tron plus. The current investigations concluded that temperature and rainfall were the main factors that determine population dynamics of white mango scale. Chilocorus sp. was newly associated with white mango scale but couldn’t control the pest yet. White mango scale infestation on mango can be mitigated by the use of indigenous knowledge of pest management combined with insecticide application. Key words: Population dynamics, Distribution, Orchard, Infestation, Mangifera indica.enPopulation DynamicsDistributionOrchardInfestationMangifera IndicaThesis