Pathogenicity and horizontal transmission of Beauveria bassiana and Metarhizium anisopliae isolates used against Sahlbergella singularis, ccoa pest in Cameroon

Mahot Hermine Claudine, Hanna Rachid, Bagny-Beilhe Leïla, Bilong Charles Félix Bilong. 2017. Pathogenicity and horizontal transmission of Beauveria bassiana and Metarhizium anisopliae isolates used against Sahlbergella singularis, ccoa pest in Cameroon. In : Livre des résumés de la 22ème Réunion et Conférence de l’Association Africaine des Entomologistes : “Vers une amélioration du bien-être humain grâce à la gestion de la diversité des insectes dans un monde en mutation”. Omondi Aman Bonaventure (ed.), Kekeunou Sévilor (ed.), Ouali-N’goran Mauricette (ed.), Salah Faiza Elgaili Elhassan (ed.), Tanga Mbi Chrysantus (ed.), Getu Emana (ed.), Zanou Elisabeth (ed.), Ayelo Pascal (ed.). Wad Medani : AAIS, Résumé, 86-87. 22nd Meeting and Conference of the African Association of Insect Scientists, Wad Medani, Soudan, 23 Octobre 2017/26 Octobre 2017.

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Résumé : The brown cocoa mirid, Sahlbergella singularis (Heteroptera: Miridae) has been named the most economically important insect pest of cocoa across West African and it is capable to cause yield loss of about 30 to 70%. The pathogenicity of six indigenous isolates of Beauveria bassiana and Metarhizium anisopliae to fourth and fifth nymphal stage of mirid was evaluated. The mirid-87 to-mirid transmission of conidia of those fungal isolates was the investigated under laboratory conditions. Pathogenecity was tested using two assays: contact and by ingestion at various conidial concentrations. Tween 80 (v/v) of 0.1 % was used as a control. For contact application method, the six isolates showed mortalities significantly higher than the control. In ingestion method some isolates (BIITAC6.2.2, BIITAC8.1.5, MIITAC11.3.4 and MIITAC6.2.2) were not significantly different from their control (p˃0.05). Corrected mortality ranged from 35 to 100% in contact application and from 16 to 94.28% in ingestion method. Mycelial out growth and sporulation on some dead insects after seven days in dark conditions demonstrated that much of the death was due to the fungal infection (mycosis).We observed a mycosis ranged from 19.73 to 91.66%. On Mirid to Mirid transmission, 20, 50 and 80% of mirid population were infected by fungi. At the end of experiment, mortality obtained in treated batch and untreated one could reach 100%. Mortalities of untreated mirids started before the death of all treated-fungus insect. No difference has been found between the mortalities of treated-fungus mirids and untreated ones. These results showed that, Cameroonian entomopathogenic fungi strains of B. Bassiana and M. anisopliae can be used as biocontrol agent disseminated by insect and they appear to be excellent candidates for further development of biopesticide targeting cocoa mirids.

Classification Agris : H10 - Ravageurs des plantes

Auteurs et affiliations

• Mahot Hermine Claudine, IITA (CMR)
• Hanna Rachid, IITA (CMR)
• Bagny-Beilhe Leïla, CIRAD-BIOS-UPR Bioagresseurs (CMR)
• Bilong Charles Félix Bilong, Université de Yaoundé 1 (CMR)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/587261/)

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