Male morph determination in Rhizoglyphus echinopus (Acaridae)

In Rhizoglyphus echinopus (Fumouze and Robin) two male morphs occur: hetero morphs, with a thickened and sharply terminated third pair of legs that ser ve as a weapon in intrasexual conflicts, and homeomorphs, with unmodified l egs. This study investigated the system of male morph determination. No sig nificant heritability of male morph was found, but cues emanating from a de nse colony were found to suppress the production of heteromorphs. Developme ntal plasticity was retained throughout the protonymphal stage. Diet did no t influence morph expression, but lowered temperature decreased the proport ion of heteromorphs emerging.