Biological characteristics and pathogenicity of entomopathogenic Beauveria bassiana (Bals.-Criv.) Vuill (Hypocreales: Cordycipitaceae) isolated from soils in Northern Kenya against desert locust (Schistocerca gregaria) (Forskål) (Orthoptera: Acrididae)

Abstract

The Horn of Africa has witnessed an episodic upsurge in invasion by desert locust (Schistocerca gregaria Forskål). In Kenya, unusually larger swarms of desert locust were reported in 2019 and 2020. Entomopathogenic fungi, specifically the genus Beauveria, a cosmopolitan teleomorphic and anamorphic group of fungi, effectively control several insect pests. However, there is less information concerning their morphological and molecular characteristics and potential pathogenic characteristics on desert locust during upsurge in the more vulnerable regions of the Horn of Africa. In this study, we characterized isolates of Beauveria bassiana from two agro-ecological zones (Isiolo and Laikipia Counties) in Northern Kenya through morphological and molecular techniques and test their potential pathogenicity against adult desert locust. Samples were isolated using the Galleria bait method and cultured on solid Sabourand Dextrose Agar Yeast (SDAY). A total of 24 isolates were identified in 120 soil samples based on morphological characteristics such as colour of the colony, colony shapes, elevation, and shapes of the conidia. Seven isolates were positively identified using genetic technique based on rDNA-ITS regions. The isolates growth rates ranged from 1.6 to 2.5 mm/day with marked significant differences (P < 0.05). All isolates of B. bassiana were pathogenic to S. gregaria in cages, causing mortality ranging from 63 to 100% after 14 days post-inoculation. This study demonstrated variations in characteristics of B. bassiana isolates from a region heavily infested with desert locust, with potential high pathogenicity of the fungi on the insect pest.