Fungal endophytes as promising tools for the management of bean stem maggot Ophiomyia phaseoli on beans Phaseolus vulgaris

摘要

Common bean, Phaseolus vulgaris, is an important food and cash crop in Africa. Its production is seriously affected by the bean stem maggot (BSM), Ophiomyia spp., which attacks seedlings. We evaluated the ability of eleven fungal isolates to colonize bean plants and the effects of inoculation on BSM feeding and oviposition, pupation, and adult emergence. All fungal isolates were able to colonize different bean plant parts (root, stem, and leaves), except isolates of Metarhizium anisopliae and Beauveria bassiana isolate ICIPE 273. Colonization was generally higher on the roots than on the stem and leaves and varied significantly between the fungal isolates. BSM feeding and oviposition were significantly reduced in all the fungus-inoculated bean plants which in turn affected pupation and adult emergence as compared to the control. Metarhizium anisopliae ICIPE 20 outperformed the other isolates in interfering with BSM lifecycle. Although M. anisopliae ICIPE 78 recorded a high number of punctures similar to the control, a significant reduction in the number of pupae and adult emergence was observed, suggesting possible BSM growth inhibition. This study clearly demonstrates that fungal endophytes can be considered as promising tools for the management of BSM in East Africa.