In vitro assessment of entomopathogenic potential of indigenous Clonostachys rosea CR 02 against the whitefly Bemisia tabaci in Potato

Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) are economically important polyphagous pest species causing severe yield losses in Potato. To develop a biopesticide in an environmentally safe manner, the virulence and pathogenecity of the indigenous Clonostachys rosea CR 02 (Ascomycota, Hypocreales: Bionectriaceae) was assessed against whitefly under laboratory condition. The mortality was assessed at varying conidial concentrations and exposure times. Both factors, along with their interaction had significantly influenced, where the higher concentrations and longer exposure times increasing the mortality rate. Maximum mortality of B. tabaci nymphs of 75.83% at 1.0 × 108 conidia/mL on day 10, with median LC50 values of 3.24 × 106 and LT50 values of 1.0 × 108 was 6.82 day. For adult B. tabaci, mortality increased exponentially, reaching 52.5% by day 10 at a concentration of 1.0 × 108 conidia/mL. However, C. rosea CR 02 showed lower virulence against adults compared to nymphs. Scanning electron microscopy (SEM) images of infected nymph B. tabaci revealed conidial adherence, hyphal growth, hyphal penetration, conidiophore formation and completely colonized the host’s surface (24-96 hours post-inoculation). For adult B. tabaci, mycelial colonization observed 7 days after treatment. This study highlights the entomopathogenic potential of indigenous C. rosea CR 02 against B. tabaci and suggests their use for the environmentally sustainable pest management.