Cultural and Morphological Characterization of Native Isolates of Entomopathogenic Fungi from Different Locations in Andhra Pradesh, India

Entomopathogenic fungi contribute to insect population regulation, but cultural and conidial traits can vary among isolates. The present study aimed to characterise the cultural and morphological variability of ten native entomopathogenic fungal isolates collected from different locations in Andhra Pradesh, India. The isolates, identified as Beauveria bassiana (five isolates), Metarhizium anisopliae (three isolates), and Metarhizium rileyi (two isolates), were examined for colony characteristics, growth patterns, conidial density, and microscopic morphology. Microscopic observations were performed using lactophenol cotton blue-stained preparations. The B. bassiana isolates produced predominantly white colonies, with variation in growth characteristics and conidial production. Conidial density ranged from 0.73 to 5.12 × 10⁷ conidia mL⁻¹, while mean conidial length and width ranged from 1.93 to 2.78 µm and 1.37 to 1.97 µm, respectively. The M. anisopliae isolates exhibited green to yellowish-green colonies with cylindrical conidia. Their conidial density ranged from 3.34 to 5.91 × 10⁷ conidia mL⁻¹, with mean conidial lengths of 6.07–6.83 µm and widths of 2.25–2.45 µm. The M. rileyi isolates developed olive-green colonies, with conidial densities ranging from 1.64 to 5.11 × 10⁷ conidia mL⁻¹ and mean conidial dimensions of 5.52–5.97 µm in length and 2.06–2.16 µm in width. Overall, the findings document phenotypic variation among the isolates examined and provide baseline information for their preliminary cultural and morphological characterisation. Complementary taxonomic and biological assessments would be valuable to further establish their identity and potential relevance for biological control.