Abstract
Arrest of oogenesis in Aldrichina grahami (Aldrich) was induced by long days (16L : 8D) at 20℃ and the follicle remained undeveloped in the previtellogenic stage. Ovarian development takes place under short days (11L : 13D) at 20℃ and oviposition occurs 6 days after the adult emergence. Ecdysteroid content in the whole body was measured from adult emergence to day 6 after emergence and the maximum value of ecdysteroid (l,400pg) was detected in the non-diapausing female on day 4, when the uptake of yolk protein by the oocytes began. Lipid content of the ovary and the fat body were compared between females reared under short and long days. The main fatty acids were palmitic, palmitoleic, oleic and linoleic acid. Especially, the content of palmitoleic acid increased from 15 to 40%in the ovary and 23 to 41% in the fat body of the non-diapausing female within 6 days. The high content of palmitoleic acid which has a melting point of ±0.5℃, is assumed to enable A. grahami to undergo alternation of generations at the low environmental temperatures of the winter in Japan.
