The potential of entomopathogenic fungal isolates as an environmentally friendly management option against Acanthoscelides obtectus

Abstract: The bean bruchid, Acanthoscelides obtectus is a major threat to bean production. In Ethiopia, where this study was performed, the damage by bruchids on stored beans has been reported to reach up to 38%. To use the isolates Beauveria bassiana and Metarhizium anisopliae in the management of A. obtectus can be an environmentally safe alternative for controlling the pest. In the present work the aim was to examine if the four chosen fungal isolates, B. bassiana DLCO 43 and M. anisopliae DLCO 91, 76, 28, would provide an effective way of managing A. obtectus. To test the impact of each of the fungal isolates on A. obtectus mortality, insects were placed in a Petri dish and sprayed with the spore solutions in three concentrations; 1x105, 1x106 and 1x107 conidia/ml. All the fungal isolates had a high level of mycosis, ranging from 85-97%, meaning that a majority of the dead insects died of fungal infection. The control group had 0% in the mycosis test. The results show that all the fungal isolates, but especially the Metarhizium isolates, are effective against A. obtectus and achieve a high mortality.