Colour-associated mating success in a polymorphic Ladybird Beetle, Harmonia axyridis

1. Body size is often an important character in mating success, but has bee n only infrequently mentioned in regard to colour polymorphism. In this stu dy, mating success was investigated in a colour polymorphic Ladybird Beetle , Harmonia axyridis, with reference both to colour morph and to body size. 2. In the non-melanic males the mating individuals were significantly large r than solitary individuals, while in melanic males there was no significan t difference. 3. The mating pattern was close to random mating with respect to colour mor ph and there was no significant deviation. 4. The results suggest both body size and colour morph affect the male mati ng success and males of different body size obtain mating advantage accordi ng to the colour morph. Colour polymorphism in this species is controlled b y alleles on a single locus. Thus, the alleles on that locus significantly influence the effect of selection on the quantitative character.