Bioassay of Some Indigenous Entomopathogens for Controlling Rhynchophorus ferrugineus, Olivier in Saudi Arabia

Nagdy F. Abdel-Baky, Khalid E. Hamed, Nader D. Al-Otaibi and Mohammad A. Aldeghairi

Background and Objective: The red palm weevil is a dangerous date palm pests that cannot be controlled with chemical pesticides only. As a result of the justified concerns of the negative use of synthetic insecticides on human health and the environment. So on, candidate eco-friendly micro-organisms isolated from KSA agri-ecosystems were evaluated in controlling RPW. Materials and Methods: Some indigenous entomopathogenic fungi and bacteria were isolated from naturally infected RPW larvae and adults and evaluated as alternative control methods. Results: The infection of RPW larvae with entomopathogenic fungi and bacteria under natural conditions was higher than in adults. Beauveria bassiana was the most prevalent followed by Aspergillus sp., Metarhizium anisopliae, Mucor sp., Cladosporium chlorocephalum. In contrast, both Bacillus thuringiensis and Bacillus popilliae formed 73.9 and 26.1%, respectively. From the 7th day, mortalities (%) increased gradually and recorded the highest mortalities with 21st days after treatment and recorded 93.33, 66.70, 53.36, 46.69 and 60.00% when treated with B. bassiana, M. anisopliae, C. chlorosphalum, Mucor sp. and Aspergillus sp., respectively. Conclusion: Although there was evidence indicating midgut damage and feeding inhibition among larvae that survived the treatments, instead of lower activity of B. thuringiensis against R. ferrugineus immature stages may refer to that, Both species of Bacillus were more virulent as the days 15-21 post-treatment.

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