Kapama,Juma Tuwelango2025-10-022025-10-022001https://www.suaire.sua.ac.tz/handle/123456789/7069DissertationThe populations of white grub pest of sugarcane, and that of Cordyceps, a naturally occurring fungal pathogen of white grubs, were determined in the four fields of the TPC sugarcane estate. The effects of ethylene dibromide (EDB), a commercially Cordyceps. Also the contribution of Cordyceps as the biocontrol agent of white grubs was evaluated both in fields and in the laboratory. White grubs populations (in the four fields) varied significantly among four selected Fields with grub densities varying from 25 000 to 93 000 grubs per hectare. These variations were possibly due to differences in field location and soil types and also the number of crop ratoons. Similarly the populations of Cordyceps differed significantly between fields ranging from 600 to 4000 Cordyceps clavac per hectare. The variations were attributed by initial population of white grubs, and soil properties. Ethylene dibromide significantly reduced the populations of both white grubs and Cordyceps in the treated plots, with maximum impacts al the third week after EDB application. In the laboratory, reduction in the population of white grubs by EDB was consistent to the sliding scale of concentration. Although EDB reduced significantly the germination of the Cordyceps clavae from infected cadavers, its effect on fungal growth and the branching of germinated clavac were not significant. Although estimated mortality of white grubs caused by Cordyceps in stress rearing experiment was low (0.27-27%), from field surveys the contribution of the fungus as a natural control agent of white grubs was very high (54-94%). Studies on the effect of EDB on non target organisms used soil fumigant, was assessed in controlling the white grubs and its impact on in sugarcane fields, and development of alternative white grubs control strategies which are sustainable and less harmful to the environment have been recommended.enEthylene dibromideWhite grubsCordycepsSugarcaneThesis