A Beauveria bassiana Balsamo Vuill. strain for Macrosiphum euphorbiae (Thomas) control and plant growth promotion in tomato

Abstract: Entomopathogenic ascomycetes have been successfully employed as endophytes for
systemic plant protection. These fungi have demonstrated to protect several crops against insect pests, plant pathogens, and abiotic stresses. In this study, an endophytic strain of Beauveria bassiana (EABb 01/33-Su) was applied to tomato plants to protect them from the aphid Macrosiphum euphorbiae.
Three application methods (foliar spray, soil application, and seed dressing) were
evaluated to determine the most effective approach for achieving high colonisation rates. Based on the results, foliar spray emerged as the optimal method for applying the B. bassiana strain. Additionally, fungal suspensions with concentrations of 104, 106, and 108 conidia/ml were tested to identify the concentration that maximized plant colonisation while minimizing fungal product. While 108 conidia/ml achieved the highest colonisation rate in target leaves (52.0 %), no significant differences were observed between 106, and 108 conidia/ml in the colonisation of non-target leaf tissues (2.0 %).
The impact of B. bassiana endophytic colonisation on M. euphorbiae was assessed by
measuring aphid mortality and fecundity over one week of exposure to colonised tomato plants. The treatment resulted in aphid mortalities of 88.75 % on target leaves and 78.8 5% on distant leaves. Furthermore, total fecundity was reduced by 36.0 % and 24.0 % on target and distant leaves, respectively. These findings highlight the potential of B. bassiana endophytic treatments for effective control of M. euphorbiae populations.
Finally, it was observed that endophytic colonisation enhanced plant growth parameters,
including root length and chlorophyll content, which are critical for improving overall crop
production.