Photothermal control of larval diapause in the blowfly, Calliphora vicina R.-D. (Diptera, Calliphoridae) from the Lofoten Islands (Northern Norway)

Abstract

Photothermal control of the rate of development and of larval diapause in the arctic population of Calliphora vicina from the Lofoten Islands (Northern Norway) was studied under the laboratory conditions. In the temperature range from 8 to 23°C, the rate of development of the studied population from egg to puparium can be well (r = 0.95) approximated by linear regression. The sum of effective temperatures was about 160 degree-days with the lower development threshold of 4.5 ± 0.6°C. The maternal photoperiodic response induced the larval diapause in a significant fraction of individuals only when larvae developed at temperatures of 4–10°C; relatively high proportion of diapausing larvae was recorded even in the progeny of females that were kept under long day conditions. The intensity of the larval diapause was very variable, which was manifested in the separation of diapausing larvae into two fractions differing in the time of pupariation during both spontaneous and induced reactivation.