Interfering with elytral chemistry delays but does not prevent mating in ladybird beetle, Cheilomenes sexmaculata (Fabricius)

The elytra of ladybird beetles serve not only as protective structures but also as key surfaces for chemical communication during reproduction. In this study, we investigated the role of elytral surface chemicals in mating behaviour of Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae) by experimentally manipulating chemical cues. Treatments included removal of surface chemicals, exchange of cuticular extracts, and coating of elytra with ink-based solvents that varied in persistence. Mating behaviour was assessed using two parameters: time to commence mating (TCM) and copulation duration (CD). Our results showed that persistent coatings caused the longest delays in mating initiation and the shortest copulation durations, suggesting strong interference with natural chemical signals. Temporary coatings also disrupted mating, though less severely, while solvent-washed and exchanged treatments produced moderate effects. Control groups, including handling and solvent-only treatments, did not differ significantly, confirming that the observed effects were due to chemical manipulations. Importantly, no treatment completely inhibited reproduction, highlighting the robustness of C. sexmaculata and the likely use of multiple sensory pathways in mate recognition. This work demonstrates that sexual recognition compounds on elytra plays a crucial role in mating communication but also reveals the adaptive resilience of C. sexmaculata when cues are disrupted. By showing that reproduction persists despite experimental interference, our study provides insight into the flexibility of insect communication systems and strengthens the case for C. sexmaculata as a reliable biological control agent under variable ecological and chemical conditions.