Polarotactic Aggregation of the Migratory Locust Locusta migratoria migratorioides (Insecta: Orthoptera) Driven by Spectral-Polarization Vector Combinations

The migratory locust, Locusta migratoria migratorioides (Fairmaire et L.J. Reiche) (Insecta: Orthoptera) (syn. L. m. manilensis), exhibits polarization-sensitive (polarotactic) aggregation behavior that can be exploited for behavioral control. This study elucidates the effects of circumferential vector combination patterns generated by linearly polarized and polarization-detection violet (520 nm) + orange (610 nm) lighting systems on locust aggregation. Using standard, linearly polarized, and polarization-detection lighting devices, we quantified phototactic and polarotactic aggregation responses under controlled breeding-shed conditions to assess sensitivity differences. The results indicate that polarization characteristics are the primary determinants of differential sensitivity between polarotactic and phototactic aggregation, mediated by circumferential vector combination patterns. Light exposure duration significantly influenced aggregation responses; at 9.0 h, the polarization-detection device VI elicited the strongest polarotactic aggregation response, whereas device I induced the strongest phototactic aggregation response. Furthermore, the circumferential vector patterns produced by linearly polarized device III and polarization-detection device VI were most effective in inducing polarotaxis. These findings demonstrate that locust visual sensitivity is regulated by heterogeneous polarization properties of light and modulated by exposure duration. Leveraging the dependence of polarotactic sensitivity on specific vector combination patterns, particularly the optimal performance of device VI and the suboptimal effect of device III, at 9.0 h strategic deployment of such lighting systems can disrupt celestial polarization-based navigation. This provides a practical basis for locust behavioral control and contributes behavioral evidence on polarization-guided aggregation in locusts.