Insecticidal effect and mechanism of Metarhizium anisopliae ZHKUJGZ1 against Solenopsis invicta (Hymenoptera: Formicidae)

The red imported fire ant (RIFA), Solenopsis invicta Buren, poses threats to biodiversity, public safety, agriculture, and the economy, especially as global trade expands its reach into China. To address this, researchers screened fungal isolates from soil in Dongguan City, Guangdong Province, aiming to develop a biopesticide against RIFA. Metarhizium anisopliae, known for its biocontrol potential, was identified as a candidate. This insect pathogenic fungus parasitizes Lepidoptera pest larvae and Hemiptera stinkbugs, causing green rigidity and repeated infestations. Microscopic, morphological, and molecular analyses were conducted on the fungal isolates, with ZHKUJGZ1, a strain of M. anisopliae, showing promise. Tests revealed that inoculating RIFA workers with 1 × 10⁷ cfu/mL of ZHKUJGZ1 resulted in an 83.33 ± 1.57 % mortality rate, with an LC50 of 8.36 × 10⁶ cfu/mL. Untargeted metabolomics suggested that ZHKUJGZ1 enhances insecticidal activity by disrupting the nervous system, signaling, digestive system, amino acid metabolism, and biosynthesis in RIFA. This study highlights the potential of using entomopathogenic fungi like M. anisopliae isolated from Dongguan as an effective strategy for controlling RIFA, offering a promising biocontrol option for agricultural pests.