Studies on the Alpine Form of the European Pine Sawfly, Neodiprion sertifer GEOFFROY (Hym. : Diprionidae) in the Central Japanese Alps : I. The Life Cycle and the Mortality Process of Egg and Larval Stages

Abstract

The life cycle and mortality process of the alpine form of the European pine sawfly Neodiprion sertifer was studied from the egg to prepupal stage during 1983-1985 at Senjojiki, Mt. Kiso-Komagatake, in the Central Japanese Alps (ca. 2, 600 m). The alpine form had a 2-year life cycle, overwintering in the egg stage in the first year and in the prepupal stage in the second year. Mortality factors were assessed quantitatively for the egg and larval stages, and partial life tables and surviorship curves were formulated for each year. The major mortality factor during the egg stage was the death of the embryo which was, however, extremely low in relation to overall mortality. High larval mortality was seen in the younger stadia (especially in the 1st stadium), due main to weather conditions such as high precipitation and strong winds during the rainy season.