Beauveria bassiana Enhances the Growth of Cowpea Plants and Increases the Mortality of Cerotoma arcuata.

Cowpea (Vigna unguiculata) crops stand out for their efficient adaptation to edaphoclimatic conditions. Insect pests, such as the leaf beetle Cerotoma arcuata, are among the main factors that limit cowpea yield. Chemical control methods are commonly used to control such pests; however, biological methods are an alternative to reduce the indiscriminate use of conventional pesticides. This study aimed to evaluate the effects of Beauveria bassiana inoculation on the growth and physiological parameters of the cowpea plant and assess the influence of the inoculation on the feeding performance and survival of C. arcuata adults. Colonization by B. bassiana was recorded in the stems (63.89%), roots (45.83%), and leaves (25%) of the cowpea plant. It was found that B. bassiana enhanced the plant height, number of leaves, and the dry mass of the inoculated cowpea plants as compared to the control. The treated plants exhibited higher net carbon dioxide (CO2) assimilation rates in the gas exchange evaluation as well as higher stomatal conductance, evapotranspiration rates, and chlorophyll (a + b) content than the control plants. Moreover, the Kaplan-Meier survival analysis showed that the B. bassiana negatively affected the survival of the insect in the leaf disc assays.