Deorphanization of the odorant receptor CsepOR1 identifies a biphasic behavioral modulator in Coccinella septempunctata (Coleoptera: Coccinellidae).

Abstract

BACKGROUND The seven-spot ladybird beetle, Coccinella septempunctata, is a key predatory natural enemy widely deployed for biological control of agricultural pests. Olfaction is crucial for prey location and searching, yet the molecular mechanisms of chemoreception in this species remain largely unknown. RESULTS Antennal transcriptome analysis identified a repertoire of 24 odorant receptors (ORs), of which CsepOR1 exhibited the highest expression level in the antennae. Quantitative real-time polymerase chain reaction (qPCR) analysis confirmed that CsepOR1 is predominantly expressed in female antennae. Heterologous expression of CsepOR1 in Drosophila T1 neurons, combined with single sensillum recordings, revealed narrow tuning to butyl salicylate among 362 tested odorants. Y-tube olfactometer assays demonstrated that butyl salicylate acts as a strong attractant for female C. septempunctata at low doses (10 μg) but becomes repellent at higher doses (100 μg). Predation assays further showed that 10 μg of butyl salicylate significantly enhances predation efficiency in female ladybirds, whereas higher doses inhibit it. CONCLUSION These results represent the first deorphanization of a key odorant receptor in C. septempunctata and identify butyl salicylate as a dose-dependent behavioral modulator with strong potential for applications in conservation biological control. © 2026 Society of Chemical Industry.