Evolution in biocontrol strains: insight from the harlequin ladybird Harmonia axyridis

After being used as a biocontrol agent against aphids for decades without harmful consequences, the Asian harlequin ladybird Harmonia axyridis has suddenly become an invasive pest on a worldwide scale. We investigate the impact of captive breeding on several traits of this ladybird such as genetic diversity, fecundity, survival and pathogen resistance. We conducted an experiment in the laboratory to compare the fecundity and the susceptibility to the entomopathogenic fungus Beauveria bassiana of wild and biocontrol adults of H. axyridis. We compiled these new findings with already published data. Altogether, our findings suggest that mass rearing of biological control agents may strongly impact genetic diversity and life-history traits. We discuss how such changes may subsequently affect the fitness of biological control strains in natural environments.