الفهرس 
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Abstract
This study is an attempt to search for a fungal control agent for the desert locust, Schistocercagregaria (Forskål), based on naturally associated fungi with such insect pest and originally isolated from it. A colony of S. gregaria was reared under laboratory conditions (30 ± 2°C, 70- 80 % R.H and 8 D: 16 L). Naturally infected nymphs and adults were collected, together with the locust eggs were checked for entomopathogenic fungi. A total of 33 fungal species, belong to 12 genera were isolated. The highest total count of isolated fungi was that fromlocust nymphs (33.8CFU / nymph), and the lowest total count was isolated from egg stage (7.39 CFU/egg). Among the fungal isolates,Aspergillus (39.0%) andMucorspecies(31.1%) showed relatively high rates of incidence followed by Penicillium (17.0%), Fusarium (9.6%) and other genera (3.3%). After preliminary tests, 13 fungal isolates and a commercial product, B. bassianawere selected to determine their virulence against1stinstar nymphs. The fungus, P. aurantiogriseum(Dierekx) 800 (AUMC) spores significantly(p≤ 0.05)caused the highest rapid lethal effect, with nymph mortality of 96.6 ± 3.3 %,LT25 of 3.5days and LT50 of 5.4 days. Higherspore concentrations of P. aurantiogriseum producedsignificantly (p≤ 0.05) higher mortalities and speed insect mortality.