From suboptimal prey to optimal performance: selective breeding improves Orius laevigatus performance on a low-cost mite diet

The mass production of the generalist predator Orius laevigatus currently relies on expensive factitious prey, such as Ephestia kuehniella eggs. While astigmatid mites offer a low-cost alternative, their use has been historically limited by a significant decline in predator fecundity and fitness. This study evaluates the success of a 15-generation selection program aimed at developed strains adapted to an astigmatid mite diet ( Acarus siro ). We compared two selected lines (MITE1–15 and MITE2-15) against a commercial population. Our results show that the MITE2–15 line overcame the reduced fecundity typically associated with alternative prey, reaching oviposition on A. siro comparable to E. kuehniella . Furthermore, this genetic gain in reproductive output was achieved without physiological trade-offs, as the selected lines maintained standard morphological size, improved developmental time, and exhibited high survival rates across multiple astigmatid species, including Suidasia medanensis and Carpoglyphus lactis . A significant population-diet interaction confirms that targeted selection leads to a synergistic adaptation superior to generalist stress-tolerance strategies. These findings represent an advance in the development of improved natural enemies, providing the biocontrol industry with a robust, cost-effective strategy to replace expensive factitious prey without compromising the quality or resilience of the mass-reared predators.