Genetic improvement ofOrius laevigatusfor better fitness feeding on pollen

In many protected crops, augmentative biological control heavily relies on generalist predators, which continuous presence on the crop allows an early response to pest immigration and outbreaks. Persistence is possible by their ability to feed on alternative food, such as pollen, plant-provided or artificially supplemented. However, fitness is decreased when feeding on alternative foods, hindering performance. We present a new approach to face this challenge: genetic improvement for better fitness feeding on suboptimal food.Orius laevigatusis one of the main biological control agents used in greenhouse vegetable crops. A breeding process was carried out on the basis of a broad intraspecific variability exploration for 10-day fecundity feeding on pollen (14.2-37.9 eggs/female for 30 wild and commercial populations). Life history traits were finally compared between our two selected strains and three commercial, wild and acclimated-to-pollen unselected populations, both on rich (Ephestiaeggs) and suboptimal (dry honeybee pollen) diets. Selected lines showed considerably improved values for longevity (1.5-fold), early (1.3-fold) and lifetime fecundity (1.9-fold), nymphal survival (3.5-fold), intrinsic rate of natural increase (r(m)) (7.3-fold) and net reproductive rate (R-0) (6.7-fold) as compared to reference unselected strains when they were fed on pollen, although still lower than on the optimal diet. Selection feeding on plant material resulted in no trade-offs when feeding on the factitious prey. This improvement was due to genetic gain rather than to phenotypic plasticity to tolerate nutritious restriction. Finally, some potential contributions of these improved lines not only for augmentative biocontrol but also for artificial rearing are provided.

Automated summary

The study conducted genetic improvement on Orius laevigatus to enhance its fitness on suboptimal food, comparing the selected strains with unselected strains on rich and suboptimal diets. The selected lines showed significantly improved values for various traits, indicating that genetic gain played a critical role in enhancing their performance on suboptimal food. The improved lines have the potential for augmentative biocontrol and artificial rearing.