The influence of each parent and geographic origin on larval diapause in the blow fly, Calliphora vicina

Abstract

The blow fly, Calliphora vicina R.-D. (Diptera: Calliphoridae), displays a larval diapause in response to short daylengths experienced by the adult female. The range of daylengths inducing diapause varies among geographic populations of fly and differences are genetic in origin, being maintained under laboratory conditions. The critical daylength for a southern, English strain is 14.5 hours of light and for a northern, Finnish strain is 16 hours. Crosses between these strains revealed that diapause incidence was produced entirely by maternal induction and was not influenced by the male. Diapause duration, in contrast, was affected by both parents; larvae with mothers of the northern strain and southern fathers entered diapause at the same rate as the pure bred northern larvae but emerged from it much more quickly. Thus diapause duration is a characteristic of the larvae themselves, influenced by the genetic background of both parents.