Sex-based differences in mobility and taxis of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) after exposure to benzoquinones

Tribolium castaneum emits an alarm pheromone, consisting of benzoquinones, which plays a role in defense as well as a stress response to overcrowding. The density of the T. castaneum is a biotic factor that can modulate how the beetles respond to stress and affect emissions of benzoquinones. Many studies related to density factors focus on the reaction of only mixed-sex adult T. castaneum, and do not investigate potential differences in behavioral responses between males and females. Thus, in our study, we assessed mobility of males or females in response to concentrations of synthetic benzoquinone alarm pheromone in the range of 0.05–3 beetle equivalents. Pupa of the T. castaneum were sexed then reared separately from one other. The mobility of individual adults was assessed using Ethovision coupled with video-tracking. Response was compared to a control containing the solvent (acetone) only. A follow-up study investigated mobility in response to headspace extracts collected from sexed beetles, which was also analyzed using gas chromatography coupled with mass spectrometry (GC-MS). This experiment is to compare if the male and female T. castaneum release the same amount of benzoquinones. We found sex-based differences in mobility after exposure to synthetic benzoquinones, which may have population-level ramifications. We also found differential expression of benzoquinones among males and females. This study contributes to our foundational knowledge on the chemical ecology of T. castaneum and provides guidance on how to interpret T. castaneum flight response.