TEMPERATURE-DEPENDENT OVARIAN DEVELOPMENT IN COCCINELLA-SEPTEMPUNCTATA (COLEOPTERA, COCCINELLIDAE)

A linear relationship was observed between ovarian developmental rate in Coccinella septempunctata L. and five constant temperatures (14-30 degrees C). The estimated lower temperature threshold for follicle dev elopment was 13 degrees C. Development of follicles to maturity (egg c horionation) required 833 degree-hours (degrees H > 13 degrees C). A f ive-stage rating system to describe ovarian development in C. septempu nctata was based on the length of the terminal follicle, number and sh ape of developing follicles in each ovariole, and presence of yellow c olor in the terminal oocyte. In 60-70% of females at each temperature, follicle development in relation to female age (time) followed a sigm oidal pattern. This sigmoidal curve had three phases, a previtellogeni c or lag phase, a vitellogenic development phase characterized by rapi d increase in follicle length, and a postvitellogenic or chorionizatio n phase characterized by a constant follicle length. An equation to pr edict either the proportion of gravid females on the basis of degree-h our accumulations, or the degree-hour accumulations on the basis of pr oportion of gravid females, was developed.