Taye, Girma (PhD)Gemechu, Bedanie2022-03-292023-11-092022-03-292023-11-092008-06http://10.90.10.223:4000/handle/123456789/30973Maize and Sorghum are the most important food crops in Ethiopia. However, stem borers became the major problem resulting in yield losses. A study was conducted in the cenh'al Rift valley of Ethiopia to find out stem borers infestation, diversity and their parasitoids interaction, to determine the appropriate statistical model that should be used in the analysis of this sort of data. The analysis of stem borers and their parasitoids in maize and sorghum agro-ecosystems was made by generalized linear model using data recorded from eastern Ethiopia in 1999 and 2000. In previous studies, some researchers have used general linear Model (GLM) analysis on the stem borers' data. But, general linear model is used for data satisfying assumption of normality where as there are situations in which non-normal data is treated. This includes using generalized linear model analysis that allows the use of different exponential distributions and non-linear link functions. Furthermore, generalized linear model was found to be relatively better than general linear model for the analysis of data which violate the assumption of linearity and normality. Moreover, the response variables: infestation and diversity of stem borers were found to be discrete and counts. The analysis of the data using this model and appropriate link functions is applied to identify the significant predictors which contribute positively or negatively to the diversity and infestation of stem borers among the explanatory variables. Accordingly, generalized linear model was found to be the best model in identifying the significant predictors. Consequently, infestation and diversity of stem borers were not significantly affected by the season, wild host and the predator species. It was also observed that the infestation was not affected by cropping systems where as the diversity is not affected by year, pest species and crop growth stages. Mean separation was made by using LSD and Duncan's multiple range tests to see the differences with in the explanatory variables. There fore, the effects of vegetation types across locations on the infestation and diversity of stem borers is not significantly different from district to districts at 95% confidence. Besides, there is no significant difference ofinfestation of stem borers with or with out the wild hosts where as diversity does not differ significantly for the main crops (sorghum or maize), cropping systems (mixed or sale), for the parasitoid species (presence or absence) and for the nitrogen contents. But, there is significant difference in infestation of stem borers between the years, 1999 and 2000, between the main crops, more for sorghum (47.812) than maize (19.775), with in the pests species which high for the key species (44.867) than other species (18.639), with in the growth stages of the crops in which more infestation was measure a during the stubble stage (55.00) followed by maturity stage (43.463) the vegetative stage (29.683) at 95% level of significance. The presence of the parasitoids species resulted in more infestation than its absence. The interaction effects of year and location basically implies the difference of infestation and diversity of stem borers in the years 1999 and 2000 across the locations. This is due to the fact that different locations have specific determinant factors such as temperature, altitude and rain fall and etc. which are not included in this study. Finally, it is recommended that generalized linear model is flexible, easy to use for any type of data, due attention should be given to the highly infested areas, control should be devised for the stem borers and great care should be given for the parasitoids during the use of chemicals.enAnalysis of stem borersThesis