Egg Diapause and Water Absorption in the False Melon Beetle, Atrachya menetriesi FALDERMANN(Coleoptera : Chrysomelidae)

Abstract

The relation between the egg diapause and water absorption was investigated in Atrachya menetriesi. The egg absorbed water in the post-diapause stage but not in the pre-diapause stage. When the non-diapuase and diapause-terminated eggs were kept wet, they absorbed water at a constant rate and their weight increased by about 80% just before hatching. If the diapausing egg was kept wet, it absorbed water very slowly, but the embryo remained in the definite diapause stage and further develpment was not discernible. On the other hand, if the non-diapause egg was not in contact with water from the time of oviposition, the embryo ceased to develop at a stage more advanced than the diapause stage and survived for a certain period. If water was not accessible to the diapause-terminated egg, the embryo was able to resume growth but did no develop beyond the spiracle-formation stage.It seems therefore unlikely that the egg diapause is caused by water deficiency.