Egg Disease in Spodoptera litura Caused by Aspergillus ochraceus and Its Metabolic Phenomic Characterization

The fungus was isolated from unhatched egg masses of S. litura . Through morphological characterization of colonies, hyphae, and conidia, combined with molecular identification based on the ITS region and β-tubulin gene (TUB), the isolate was identified as Aspergillus ochraceus . Phenotypic traits were analyzed using the BIOLOG Phenotype MicroArray (PM) system to establish foundational biological and pathological data. A total of 950 distinct growth conditions were assessed across PM plates 1–10. The results revealed that the pathogen could metabolize 80.85% of the tested carbon sources, 97.26% of nitrogen sources, 91.43% of sulfur sources, and 88.14% of phosphorus sources. Carbohydrates were the most efficiently utilized carbon substrates, while various amino acids served as preferred nitrogen sources. The strain accessed 92 distinct nitrogen metabolic pathways. It demonstrated broad osmotic adaptability, growing in media containing up to 6% potassium chloride, 20% ethylene glycol, 5% urea, and 12% sodium lactate. Active metabolism was observed across a wide pH range (3.5–10), with optimal growth at approximately pH 6.0. The pathogen exhibited strong decarboxylase activity but lacked deaminase activity when exposed to various amino acids. To our knowledge, this is the first report documenting ovicidal activity in A. ochraceus , filling a critical gap in microbial biocontrol and offering a model for next-generation, egg-targeting pest management strategies.