Lufenuron affects the fecundity of Panonychus citri by regulating the methyl farnesoate–ponasterone A network.

In insects, the juvenile hormone (JH) and 20‐hydroxyecdysone (20E) pathways jointly regulate fecundity, but only methyl farnesoate (MF) and ponasterone A exist in mites. Comparative transcriptomic analysis in <italic>Panonychus citri</italic> showed that <italic>E75B</italic> was significantly downregulated when exposed to lufenuron. Knockdown of <italic>E75B</italic> significantly affects the expression of vitellogenin (<italic>Vg</italic>), Fushi tarazu factor 1 (<italic>Ftz‐f1</italic>) and juvenile hormone acid <italic>O</italic>‐methyltransferase (<italic>JHAMT</italic>), reducing fecundity in mites. The knockdown of <italic>Ftz‐f1</italic> produced a more significant effect than the knockdown of <italic>E75B</italic>, indicating that the ponasterone A pathway positively regulates fecundity in <italic>P. citri</italic>. After the knockdown of <italic>JHAMT</italic>, the expression levels of both <italic>Vg</italic> and <italic>Ftz‐f1</italic> and fecundity were significantly increased, along with the inhibition of <italic>Kr‐h1</italic>, suggesting that <italic>JHAMT</italic> was negatively correlated with fecundity in the regulatory network. Knockdown of <italic>Kr‐h1</italic> inhibited the expression of <italic>Vg</italic> and <italic>Ftz‐f1</italic> and fecundity, and whether the drop in fecundity is caused by <italic>Kr‐h1</italic> or <italic>Ftz‐f1</italic> is unclear. Subsequent feeding with MF induced <italic>Kr‐h1</italic> and <italic>Vg</italic> expression, whereas no significant effects were observed for <italic>JHAMT</italic> and <italic>Ftz‐f1</italic>. Therefore, the MF pathway stimulates fecundity independently. RNA interference (RNAi) showed that <italic>JHAMT</italic> and <italic>Ftz‐f1</italic> inhibited each other, resulting in opposite effects of MF and ponasterone A pathways on steady‐state fecundity when either factor changed. Meanwhile, <italic>JHAMT</italic> knockdown led to increased fecundity, indicating that the stimulating effect of the ponasterone A pathway was greater than the inhibiting effect of the MF pathway, and demonstrating the dominant role of the ponasterone A pathway. Therefore, the interaction between <italic>JHAMT</italic> and <italic>Ftz‐f1</italic> may be closely associated with the maintenance of MF–ponasterone A regulatory network homeostasis and is involved in the reduction of fecundity in <italic>P. citri</italic> induced by exposure to lufenuron. [ABSTRACT FROM AUTHOR]