Artificial lighting affects the predation performance of the predatory bug Orius insidiosus (Say) against the Western flower thrips Frankliniella occidentalis (Pergande)

Protected crops, such as greenhouses and indoor farming environments, using light-emitting diodes (LEDs) enable the modulation of the light spectrum, intensity, and photoperiod for agronomic purposes. This creates dynamic artificial light conditions for insects and arachnids, including predators used in biological control. Despite increasing interest, the effects of LEDs on predator behavior and control performance remain poorly understood. In the laboratory, we examined the locomotion and predation behaviors of the generalist predator Orius insidiosus against the pest Frankliniella occidentalis under various light spectra and intensities. We tested narrowband blue, green, and red spectra, three ratios of red and blue light, and a spectrum combining all three colors across a gradient of light intensity in microcosms. Orius insidiosus was active and successfully attacked prey under all lighting conditions, with 70% of individuals engaging in predation during the observation period. The light spectrum significantly influenced all recorded behaviors, while light intensity had negligible effects. Narrowband spectra led to the highest attack probabilities, but the mixed blue-red spectrum with a higher proportion of red light yielded the highest prey capture rates. The spectrum with all three colors showed intermediate capture success. These trends were consistent regarding capture probability in more complex environments with cucumber plants, where thrips were exposed to 24-hour artificial light sequences before and during predator releases. However, thrips survival rates remained similar across all lighting treatments. Our results demonstrated that while lighting treatments affect predator behavior, Orius insidiosus retains its ability to capture prey under various light conditions. This paves the way for developing lighting strategies that balance plant productivity with effective biological control in protected crop environments.