| Abstract: | Larval ontogeny of the scarab Mecynorhina polyphemus was monitored throughout all instars, and larvae were weighed at 7-day intervals. Durations of the prepupal, pupal and postpupal stages were recorded. Larvae increase their body masses over 300 times during ontogeny. Male imagines are larger than females, and this is primarily a function of faster growth rates during instar III, resulting in significantly heavier larvae at the end of this instar. The durations of the three instars are not significantly different in males and females, but the duration of the prepupal and postpupal phases is significantly longer in males. There is a strong correlation in both sexes between maximal larval mass and the mass of the imago, but larval mass–imago mass scales with significantly different slopes in males and females. Male larvae must allocate increasingly more resources into production of cephalic horns with increments in larval mass, requiring differently proportioned pupal chambers. |
