Abate Dawit (PhD)Seyoum Emiru (PhD)Aysheshim, Seneshaw2018-07-102023-11-082018-07-102023-11-081998-05http://etd.aau.edu.et/handle/123456789/7575Ten native fungal isolates were collected from the different regions of Ethiopia. Eight of the isolates were identified at International Institute of Tropical Agriculture, UTA, Benin. Five of the isolates were identified as Beallveria, two were Paecilomyces and one belonged to Metarhizilllll species. Eight of the tested fungal isolates showed pathogenecity to fifth instar Schistocerca gregaria. The Beallveria spp. isolate FF and MetarhiziulII spp. EE were more virulent compared to the rest. Thus two isolates were further assayed in peanut (Arachis hypogaea) and noug (GlIizotia abyssinica) oil formulations, and compared with a known entomopathogen, M anisopliae ICIPE 30. The results indicated that there were strong doseresponse patterns. Peanut oil formulation enhanced infectivity of both FF and EE. Infectivity of EE was significantly (P<0.05) reduced in noug oil formulation. Comparison of virulence revealed that isolates FF and EE were more pathogenic than ICIPE 30. FF in peanut oil formulation had the lowest LCso value of2.02xlOs conidia/ml followed by EE, 2.93x10s and ICIPE 30 with 4.98x10s conidia/m!. The highest mortality was achieved by FF at Ixl08 conidia/ml, resulting in 50% and 100% mOliality in 4.2 days and seven days, respectively. The median lethal time taken to fOUlih, fifth and adult FF treated insects were 3.47, 4.14 and 4.83 days; respectively that indicated fourth instars are more susceptible. Insects killed as a result of FF infection developed red pigmentation and produced white powdery mass of spores on the external surface. The Metarhizilllll isolates EE and ICIPE 30 produced green sporulation on the integument when the cadavers were kept at high humidity. FF and EE grew at a temperature range of 24°C and 37°C, with peaks at 24°C and 28°C for FF and 28°C for EE. Malt extract agar favoured growth and sporulation of FF, whereas EE grew and sporulated faster on sabouraud dextrose agar. Germination of both isolates was significantly (P<0.05) high in peanut oil formulation than in noug oi!.enBiologyThesis