Abstract: Predation functional responses are usually examined at the population level. However, one population is usually composed of more than one genotype such as mtCOI haplotypes. Genotypes within a population may differ in phenotypic traits. To date, little is known of predation ecology of genotypes in predacious insects. We compared two dominant mtCOI haplotypes of the harlequin ladybird Harmonia axyridis, Haplotype-I and Haplotype-II, for their functional response to aphid prey Megoura japonica. To fit Holling functional response models and estimate predation parameters derived from the model, the predation rates were calculated for both larvae (from 2^nd to 4^th instars) and adults (males and females) of those two haplotypes in response to varying prey densities. Our results showed that the two haplotypes were equivalent in the functional response, following the Holling-II model. However, they differed in some of predation parameters. Compared to Haplotype-II, Haplotype-I male adults had a higher attack (capture) rate, its 3^rd and 4^th instar larvae and female adults had a shorter prey-handling time, and its larvae and adults exhibited a higher search coefficient. These results suggest that Haplotype-I beetles may be more efficient than Haplotype-II ones in predation of aphids. This finding provides evidence for the successful colonization and strong dispersal of Haplotype-I in non-native North American and European ranges by H. axyridis. Furthermore, our study is informative to understanding of predator genotype-prey interaction ecology.

Key words: mtCOI haplotype, predation behavior, invasion biology, biological control, Coccinellidae