Identification and pathogenicity of four fungi against egg development in migratory locust, Locusta migratoria

Background: The migratory locust, Locusta migratoria, is one of the most notorious agricultural pests, but current control strategy via biological agents has focused on the nymphal and adult stages, limiting the establishment of a comprehensive management system covering the entire locust development stages.

Results: In this study, we isolated four fungi with distinct culture characteristics from the unhatched locust eggs. Through morphological and molecular biological identification, these fungi were identified as Actinomucor elegans W-1, Mucor circinelloides G-1, Fusarium solani W-1, and Aspergillus fumigatus GG-1. Koch's postulates provided the sufficiency of their Infection capacity against locust eggs. Infection assays indicated that all four fungi exhibited high pathogenicity toward early-stage locust eggs, suppressing egg development even at low concentrations (10³ spores mL^-1). M. circinelloides G-1 exhibited the strongest inhibitory effect. Moreover, in comparison with the well-established locust biocontrol fungus Metarhizium acridum, these four fungi showed significantly weaker pathogenicity against nymphs, demonstrating egg-stage specificity. Furthermore, the four isolates showed production advantages over M. acridum. A. elegans W-1, and M. circinelloides G-1 exhibited optimal growth at 25 and 30 °C, and A. fumigatus GG-1 demonstrated a broader thermotolerance, high spore production, and good adaptability to different culture media, indicating the potential in industrial production.

Conclusions: The discovery of these four pathogenic fungi suppressing locust egg development provides supplements for life-stage management of locust plagues. © 2026 Society of Chemical Industry.