Comparison of life-history traits of the two male morphs of the bulb mite,Rhizoglyphus robini

Two basic male morphs occur in several species of the family Acaridae: hete romorphic fighters, possessing a thickened and sharply terminated third pai r of legs, and homeomorphic males with unmodified legs. We compared major l ife-history traits of the two morphs in the bulb mite, Rhizoglyphus robini. We found no significant differences in development time or virility, but h omeomorphic males lived 23% longer than heteromorphs. We discuss the possib ility that the trade-off between longevity and adaptation for fighting main tains genetic variation for the male morph in the studied species.