Pathogenicity of Beauveria bassiana (Balsamo-Crivelli) and Metarhizium anisopliae (Metschnikoff) isolates against life stages of Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae)

Abstract

Background Entomopathogenic fungi are primary pathogens that naturally affect insect pests by suppressing their populations and considered as an ecofriendly agents. The present study aimed to evaluate in vitro activity of different isolates of Beauveria bassiana and Metarhizium anisopliae against the development of larval stages of the Cucurbit fruit fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae). Results Larval mortality was significantly high with B. bassiana isolate Bb337 (5.82–21.70%) and with the lowest in M. anisopliae isolate MaD (1.49–6.33%). Pupal mortality rate was comparatively higher with more than 50%. The cadavers of all host instars produced conidia (sporulation). Sporulated dead larvae were significantly higher in Bb337 (61.10%) than at the least in MaD (18.60%) at 105 conidia/ml. At 108 conidia/ml, MaD induced the highest pupal cadavers with mycosis (32.42%). Regardless of applied fungal species, host instars mortality significantly increased with increasing concentration of B. bassiana isolates, suggesting a concentration-dependent response of Z. cucurbitae. Conclusion The tested isolates demonstrated their pathogenicity through vertical transmission of mycosis from one instar to another, regardless of the concentrations used.