Susceptibility of the Rice Weevil, Sitophilus Oryzae (Coleoptera: Curculionidae) to Native Entomopathogenic Fungal Isolates

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2010

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Addis Ababa University

Abstract

The experiments on susceptibility of the rice weevil, Sitophilus oryzae (coleoptera: curculionidae) to native entomopathogenic fungal isolates were conducted at Addis Ababa University Insect Science Research Laboratory. The initial cultures of Sitophilus oryzae were obtained from Holeta Agricultural Research centre. Five different local fungal isolates were used in the study. The isolates obtained from Addis Ababa University Insect Science Research laboratory and Desert Locust Control Organization for East Africa (DLCO-EA) Addis Ababa. The target concentrations of 1x104, 1x105, 1x106, 1x107, and 1x108 conidia ml-1 were adjusted for liquid formulations. All experiments were replicated three times. The fungal isolates were evaluated by direct spraying of spore suspensions over the target insects. All fungal isolates used in the present study were able to infect and cause death in adults of Sitophilus oryzae at all concentrations ranging from 1x104 to 1x108 conidia ml-1.The present study showed that Sitophilus oryzae treated with 1x108 conidia ml-1, AAU D is observed to be virulent with the least LT50 value 3.52 days and 96.6% mortality in day 10, DLCO 131 killed 83.33% of the target insect in day 10 with LT50 value 4.45 days, DLCO 141 with LT50 value 5.32 days and 76.67%mortality , DLCO 26 with LT50 value 6.53 days and 70.00% mortality 7 and DLCO 91 with LT50 value 6.21 days and 60.00 % mortality in day 10. The present study suggests that biological control of Sitophilus oryzae with local entomopathoges make in Ethiopia. Key words: Sitophilus oryza;, Entomopathogen; pathogenecit;, Metarhizium ; Beauveria

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: Sitophilus oryza;, Entomopathogen; pathogenecit;, Metarhizium ; Beauveria

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