Underlying sperm precedence pattern in the millipede <em>Centrobolus inscriptus </em>(Attems, 1928) (Diplopoda, Pachybolidae)

Abstract

Three scenarios exist for sperm precedence; first-male, last-male and no order effect. I replicated the H3+ radiolabel technique to show sperm precedence patterns in the arthropod Centrobolus inscriptus (Attems, 1928). Male and female morphometric parameters illustrated a clear sexual dimorphism. Disintegration rates (d.p.m.) from immediate dissections of once-mated females were higher than females dissected after 24 hours (L (0) » L (24)). A significant difference between mean d.p.m. values occurred in double mating (L-UL vs. UL- L). D.p.m. values were higher when second mating followed immediately after the first (UL-L (O) >UL-L (24) and L-UL (0) » L-UL (24)). D.p.m. from L mating were significantly lower than those of UL-L mating but not then L-UL double mating. There was a reduction of up to 57% in favour of the second male over 24 hours in C. inscriptus.