Different artificial lighting spectra change the mating behavior of generalist predator Orius insidiosus (Say), and photoperiod extension promotes its development

In protected cropping systems such as greenhouses and indoor farming, augmentative biological control depends on release rates, establishment, and reproduction of natural enemies. Light-emitting diodes (LEDs) are widely used to enhance plant growth in these systems and are increasingly implemented in mass-rearing facilities for natural enemies. However, the impacts of LEDs on the life cycle of beneficial predators remain insufficiently explored. This study examined the mating behaviors and developmental performance of generalist predator Orius insidiosus under light spectra previously shown to support its predation of the pest thrips Frankliniella occidentalis . In laboratory experiments, predator pairs were exposed to artificial light sequences starting with a 12h base light condition simulating a cloudy winter day, supplemented by 8h photoperiod extensions (blue, blue-red, or blue-green-red spectra), and a control without extension. Mating occurred under all tested conditions, but blue light reduced mating probability, frequency, and duration. Photoperiod extension improved fecundity, fertility, and second-generation numbers of O. insidiosus adults, with blue light favoring egg laying and hatching but not metamorphosis into adults. The second-generation sex ratio was unaffected by light sequence, maintaining population viability with a balanced proportion of females. Our findings demonstrate that O. insidiosus can successfully mate, reproduce, and develop under artificial lighting and highlight the potential of modulating light spectrum to optimize both mass-rearing and establishment in protected crops.