Acoustics related to the queen presence in honey bee (Apis mellifera ligustica L.) colonies

The presence of a fertile queen is essential for the stability and productivity of a honey bee colony. However, her status is generally assessed through visual hive inspections, which are invasive, time-consuming, and performed at non-continuous intervals. For this reason, within the framework of the so-called precision beekeeping, there is growing interest in remote monitoring systems. The analysis of hive acoustics represents a promising approach for detecting variations in colony state. In this study, the potential of acoustic analysis to discriminate against the presence or absence of the queen in colonies of Apis mellifera ligustica Spin. was evaluated. Audio recordings were collected inside the hive during two experimental summer and autumn trials. The queen bee absence was simulated by isolating them in the secondary queen-rearing compartment of a French-like breeding hive. The acoustic signal was analyzed using Short-Time Fourier Transform (STFT) and spectral peak tracking within three selected frequency bands (80-140 Hz, 200-270 Hz, and 380-455 Hz). The results show a consistent increase in peak frequency within the middle band (200-270 Hz) following queen isolation, with a shift of approximately 20 Hz observed in three out of four colonies. In contrast, the lower and higher frequency bands investigated did not show systematic differences between simulated queenright and queenless conditions. These findings suggest that monitoring the peak frequency in the middle band may provide useful information on colony/queen status and represent a promising basis for the development of lightweight acoustic tools for queen monitoring in precision beekeeping. The ongoing study involving a larger number of colonies is however necessary to confirm the robustness and generalizability of such acoustic indicator.