Selection for larger body size in Orius laevigatus: Intraspecific variability and effects on reproductive parameters

Abstract Different characters of natural enemies can affect their performance in biological control programs. Among them, body size may play a significant role, as has been associated with increased fitness. No specific studies on body size have been carried out in any Orius species, important predators widely used in biological control. Therefore, the aim of this work was to study the variation in body size in wild and commercial populations of O. laevigatus, and artificially select a strain with larger body size. The parameters of the life table of populations showing different body sizes was investigated. We found a significant variability in body size among wild populations of O. laevigatus, with commercial populations within the natural range. From this variation we started a selective breeding programme for larger body size, successfully obtaining a strain with a significant larger body size. Our selected strain showed higher fecundity when provided a nutritionally superior food (Ephestia kuehniella eggs), and increased fecundity and longevity when fed a nutritionally inferior food (honey bee pollen). Despite a slightly slower development time, the overall reproductive potential was similar or superior to that of the commercial and unselected populations. We hypothesize that the enhanced characteristics of the selected large strain are based on a superior ability to exploit nutritional resources, conferring stronger resilience under stresses (low food quality or quantity) typically found in agricultural ecosystems, improving its performance as biological control agent.