Some principles of selecting natural material for rearing and the endogenous processes in laboratory strains of the blowfly Calliphora vicina R.-D. (Diptera, Calliphoridae)

Abstract

The ability to enter reproductive and larval diapauses should be taken into account when natural populations of the blowfly Calliphora vicina are selected for laboratory rearing. The reproductive diapause occurring at 20–25° in some females retards their maturation and decreases the reproductive activity of the laboratory strain. On the other hand, diapausing females conditioned by low temperature may be used for temporary conservation of the strain. However, keeping the diapausing larvae is the most reliable way of storage. The endogenous variation of the incidence of larval (from 0 to 100%) and reproductive (from 0 to 55%) diapauses was observed in successive generations of several laboratory strains developing under constant photoperiodic and temperature conditions. The significance of such endogenous processes for interpretation of experimental data is discussed. For over 20 years of laboratory breeding of C. vicina, cases of strain depression were observed, when the number of the egg rafts decreased and then oviposition ceased, abnormal puparia appeared, the flies hardly emerged, etc. Such depressed strains may be revived by changing the photoperiodic regime.