Spectral- and Temperature-Dependent Phototaxis of Bemisia tabaci and Its Predator Serangium japonicum: Implications for Predator-Aware Selective LED-Based Trapping

LED-based trapping may improve whitefly management, but light conditions that attract pests may also affect beneficial predators. This study evaluated how wavelength, irradiance, and temperature influence the phototactic behavior of Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) and its predator Serangium japonicum (Coleoptera: Coccinellidae). Adults were tested in Y-tube assays across multiple wavelength–irradiance combinations at 25 ± 1 °C, followed by temperature-dependent experiments at 20, 25, 30, and 35 °C under selected settings. B. tabaci MEAM1 consistently showed strong positive phototaxis. At irradiances of 100, 200, 400, 600, and 800 µW cm−2, positive phototaxis was highest under 480 nm light, whereas at 1000 µW cm−2, it was highest under 520 nm light. For S. japonicum, negative phototaxis was highest under 440 nm at 200 µW cm−2 and under 400 nm at 600, 800, and 1000 µW cm−2, and this avoidance weakened as temperature increased. Under a strict predator-safe criterion, 400 nm at 600 µW cm−2 was the best coordinated setting at 20–30 °C, whereas 440 nm at 600 µW cm−2 was the best strict predator-safe setting at 35 °C. These results indicate that selective LED trapping should be deployed as a temperature-aware strategy rather than as a single fixed setting. The findings provide a basis for improving the compatibility of physical and biological control in B. tabaci management.