miR-571 manipulating termite immune response to fungus and showing potential for green management of Copotermes formosanus (Blattodea: Isoptera).

Termites are not merely social insects; they are also globally important insect pests. MicroRNAs (miRNAs) are potential molecular targets for the biological control of termites. However, their role in termite resistance to pathogens, particularly their impact on termite social immune behaviour, remains unclear. In this study, we identified 50 differentially expressed miRNAs in Coptotermes formosanus, a globally economically important termite pest, in response to Metarhizium anisopliae infection. Injecting miR-571 agomir, one of significantly upregulated miRNAs, significantly increased termite mortality without or with M. anisopliae infection (compared to that with M. anisopliae infection alone). Meanwhile, termites infected with M. anisopliae exhibited a significant reduction in the avoidance, trophallaxis, and grooming behaviors. Subsequently, we identified POP5 as a target gene of miR-571 and found that miR-571-POP5 inhibits the termite immune response to M. anisopliae by inhibiting the expression of downstream genes, trypsin-like serine protease and serine protease. Finally, we confirmed that the ingestion of miR-571 agomir also increased the mortality of M. anisopliae-infected termites. Our findings enhance knowledge regarding miRNA role in insect social immunity, pathogen manipulation mechanisms, and optimizing pathogen effectiveness through insect miRNAs. This offers new molecular targets for the biological control of termites.