A New Isolate Beauveria bassiana GxABT-1: Efficacy against Myzus persicae and Promising Impact on the Beet Mild Yellow Virus-Aphid Association.

Simple Summary: Investigating new microbial control agents to overcome the use of chemical insecticides is of utmost importance to control Myzus persicae, the main vector of Beet Mild Yellow Virus (BMYV). Our study explored the efficiency of two Beauveria bassiana isolates (GHA and GxABT-1) against M. persicae and on the transmission of BMYV. After 8 days (post fungal spray), a mortality rate of more than 90% was registered among treated M. persicae. The impact of these fungi as endophytes on the BMYV-M. persicae association was assessed by (1) treating sugar beet seeds with fungal suspensions, (2) proving the ability of the fungi to colonize the plant, (3) studying the impact on the aphid's life cycle and its attraction towards plants, and (4) evaluating the virus load in treated plants. The fungi were able to colonize all parts of the plant, which led to alterations in the aphids' life cycle and their attractiveness to the plant. Although the fungi were not able to prevent virus transmission, the viral load appears to be reduced. We suggest performing the experiments on a larger scale and using different methods to inoculate the plants to explore whether the efficiency of the tested fungi could be enhanced. Within the context of ecofriendly alternatives to neonicotinoids, we explored the direct and endophytic potential of two Beauveria bassiana isolates, GHA from BotaniGard and the new endemic isolate GxABT-1, against the Sugar Beet Mild Yellow Virus (BMYV)-Myzus persicae pathosystem. A mortality rate of 96 and 91% was registered after 8 days of treatment with GHA and Gx-ABT-1, respectively. To assess the endophytic impact, sugar beet seeds were treated, and the ability of the fungi to colonize the plant was assessed and correlated with the aphids' (1) life cycle, (2) attraction towards the plants, and (3) ability to transmit BMYV. Both fungi colonized the plants, and the GxABT-1 isolate impaired the aphids' life cycle. Myzus persicae were more attracted to leaf discs from non-treated plants than to the fungal-treated ones. Interestingly, when the choice test dealt only with the fungal treatments, aphids were more attracted to leaves from plants harboring Gx-ABT-1 than those with GHA. Moreover, no significant impact was observed for BMYV transmission despite the slight decrease in the viral load in GxABT-1 isolate-treated plants. Our findings constitute a baseline to delve more into the performance of the new endemic isolate B. bassiana in other pathosystems using different treatment methods. [ABSTRACT FROM AUTHOR]