Population admixture can enhance establishment success of the introduced biological control agent Cryptolaemus montrouzieri.

BACKGROUND: Introduced biological control agents have opportunities of population admixture through multiple introductions in the field. However, the importance of population admixture for their establishment success often remains unclear. Previous studies based on genetic markers have suggested a history of population admixture in the predatory ladybird Cryptolaemus montrouzieri Mulsant in China. RESULTS: We tested whether population admixture may lead to fitness changes under laboratory conditions. We first found no mating barrier or strong bias between two parental populations, despite their differences in genetics and phenotypes. Then, our experimental evidence supported the hypothesis that admixed populations have a higher potential of establishment success, due to their superior reproductive ability, and hunger and cold tolerance inherited from one of the parental populations. CONCLUSIONS: We suggest that population admixture can be a breeding method to improve the performance of biological control agents, particularly when used in a classical biological control approach, but that consequences for potential invasiveness need to be considered.

Episodic positive selection at mitochondrial genome in an introduced biological control agent.

Artificial introduction in classical biological control provides a unique opportunity to understand mitochondrial evolution driving adaptation to novel environments. We studied mitochondrial genomes of a world-wide introduced agent, Cryptolaemus montrouzieri. We detected positive selection in complex I genes (ND5 and ND4) against a background of widespread negative selection. We further detected significant signals in neutrality tests within 11 populations at ND5 gene, indicating a recent selective sweep/positive selection. Our results imply that these candidate mutations may contribute local adaptation of exotic biological control agents and these provide new insights into the improvement of classical biological control programs.