Heritability of male morph in the bulb mite, Rhizoglyphus robini (Astigmata, Acaridae).

In several species of Acaridae (Astigmata), heteromorphic males, possessing a sharply terminated third pair of legs which they use to mortally stab other males, coexist with scrambler males with unmodified legs. Previous research showed that in the bulb mite, Rhizoglyphus robini (Claparède), the male morph is heritable. In this study I used a different population and carried out selection in both downward and upward direction in order to change the proportion of morphs. Starting from the proportion of about 0.2 homeomorphs in the population, I obtained a significant response to 8-10 generations of selection in two repetitions. The response was asymmetrical (stronger in upward direction). Realised heritabilities were in the range of 0.3 (downward) and 0.8 (upward).