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Potential of Beauveria bassiana and Metarhizium anisopliae as Biological Management Agents of Phytolyma fusca (Hemiptera, Psylloidea)

V. M. Nwaokolo
S. G. Jonathan
J. A. Ugwu
E. I. Eziashi


Iroko gall bug Phytolyma fusca (Walker) is a major insect pest of Milicia excelsa militating against Milicia excelsa plantation establishment in West Africa. The efficacy of Beauveria bassiana (Bals.) Vuill. strain Bb S41 and Metarhizium anisopliae (Metsch.) Sorokin strains F123 and IC30 against adult P. fusca was evaluated at the pathology laboratory of Nigerian Institute of Oil Palm Research (NIFOR) Benin City, Nigeria using conidia suspension. Using Direct Contamination Assay method, 1g conidia of each fungal strain was applied to petri dishes containing ten newly emerged adult insects and no treatment was applied to control. Each treatment was replicated three times in a complete randomized design (CRD) and adult mortality was recorded daily for five days. All the treatments evaluated were effective against adult P. fusca under laboratory conditions. However, M. anisopliae strain IC30 was more effective than other strains giving 100% mortality of adult P. fusca at four days post-inoculation. M. anisopliae strain F123 recorded 100% mortality at five days post-inoculation; while B. bassiana strain Bb S41 recorded 90% mortality at five days post-inoculation and only 23% mortality was observed on the control experiment. The pathogenicity test results showed that only B. bassiana was pathogenic to adult P. fusca by forming mycosis on the cadaver of the insects. Metarhizium anisopliae and B. bassiana strains evaluated have shown great potential for biological control of P. fusca, hence, their use could be incorporated in the integrated pest management of P. fusca for sustainable establishment of Milicia excelsa plantation in the region.