Daily Rhythms of Sex Pheromone Emission and Courtship Behaviour in the Neotropical Brown Stink Bug Euschistus Heros

Understanding the chemical and behavioural ecology of the Neotropical brown stink bug, Euschistus heros (Hemiptera: Pentatomidae), is essential for developing effective integrated pest management (IPM) strategies in South American soybean production. This study investigated the courtship behaviour and diel periodicity of sex pheromone emission. Courtship behaviour and pheromone emission over a 24‐h cycle were characterised using laboratory‐reared (LR) males and females. In addition, comparisons between LR and first‐generation field‐collected (FC) males were conducted during the peak emission window. Courtship was categorised into distinct sequential stages, and pheromone emissions were quantified using dynamic headspace collection and analysed using generalised linear mixed models. LR males exhibited a pronounced emission peak between 12:00 and 18:00 h, with a model‐estimated mean total pheromone release of 520.39 ± 210.53 ng/ μL, significantly higher than at other time intervals. No significant differences in total emission or blend composition were detected between LR and FC males. Circadian analysis identified an acrophase at 16:44 h. Courtship followed a consistent sequence, including male antennal contact, female posterior orientation and inclination, male rotation (~180°) with aedeagus exposure, and copulation initiation. This study provides the first detailed characterisation of the diel pattern of sex pheromone emission and a comprehensive ethogram of E. heros short‐range courtship. These findings advance our understanding of reproductive behaviour and pheromone‐mediated communication, providing temporal guidance for optimising pheromone‐based monitoring and behavioural manipulation strategies in IPM programs.