Histaminergic regulation of phototactic divergence between two forms of Callosobruchus maculatus via the HisCl2 receptor

BACKGROUND: Callosobruchus maculatus, a global storage pest, exhibits two distinct forms: flight form and normal form. The phototactic divergence critically influences their survival, reproduction, and dispersal. Here, we elucidate the molecular mechanisms underlying this phototactic divergence. RESULTS: In this study, we initially found significantly elevated levels of histamine, a monoamine neurotransmitter, in the heads of the flight form via liquid chromatography-mass spectrometry. We subsequently investigated the effects of histidine decarboxylase, histamine, and its receptor on the phototaxis of two forms using a combination of the RNA interference method, electroretinograms and phototaxis behavior approaches. Our results showed that histamine modulates phototactic divergence in two forms of C. maculatus through the Hiscl2 receptor. CONCLUSION: This study demonstrates that histamine binding to the Hiscl2 receptor mediates phototactic divergence between two forms of C. maculatus. These findings reveal a novel histaminergic mechanism underlying behavioral divergence and suggest potential molecular targets for pest management. © 2026 Society of Chemical Industry.