@article{Bancole_Laing_Yobo_Togola_2020, title={Establishment of Beauveria bassiana isolates as endophytes in rice cultivars and their biocontrol efficacy against rice stem borer, Sesamia calamistis}, volume={116}, url={https://sajs.co.za/article/view/7914}, DOI={10.17159/sajs.2020/7914}, abstractNote={<p>Possible endophytic colonisation of rice cultivar parts (leaves, stem and roots) by <em>Beauveria bassiana</em> isolates and their potential as biocontrol agents against <em>Sesamia calamistis</em> Hampson (African pink stem borer) were investigated. Five promising B. <em>bassiana</em> isolates were evaluated for their endophytic colonisation, the effectiveness of the inoculation methods and the efficacy of the isolates as biocontrol agents against <em>S. calamistis</em>. The plant part colonised is often dependent on the inoculation method. Colonisation of plant parts was assessed at 30 and 60 days after seed inoculation and foliar spray. For the pathogenicity activity, third instar larvae of <em>S. calamistis</em> were fed with rice stems that were previously inoculated with endophytic isolates of <em>B. bassiana</em>. Both inoculation methods led to the colonisation of the rice cultivar tissues, but were affected by the interactions of cultivars x isolates x inoculation methods. The colonisation of the cultivar plant parts varied over time (30- and 60-day intervals), and was affected by the inoculation method used. For both inoculation methods, highly significant differences were observed in the roots and the leaves over time (<em>p</em>=0.0001). However, with seed treatment, there was no significant difference in levels of colonisation in stems by the isolates x time (<em>p</em>=0.32). The <em>B. bassiana</em> isolates were pathogenic on the third instar larvae of <em>S. calamistis</em>, causing mortalities of more than 50% at 28 days after treatment. However, the virulence of the isolates varied. According to the isolates and the inoculation methods, <em>B. bassiana</em> formed an endophytic relationship with rice plants, and produced various mortality rates.</p> <p><strong>Significance:</strong></p> <ul> <li><em>Beauveria bassiana</em> could be a potential biocontrol agent of rice stem borer, <em>S. calamistis</em> as there is no report of endophytic isolates of <em>B. bassiana</em> for the control of rice borers.</li> <li>Currently there is no commercially registered biocontrol agent against rice borers; hence further studies into <em>B. bassiana</em> could lead to the registration and commercialisation of <em>B. bassiana</em> as a bio-pesticide for rice stem borers.</li> </ul>}, number={11/12}, journal={South African Journal of Science}, author={Bancole, Wonroo B.A. and Laing, Mark D. and Yobo, Kwasi S. and Togola, Abou}, year={2020}, month={Nov.} }