The flight activity of 15 species of mosquitoes, between them representing different geographical distributions from equatorial to Arctic and show all the characteristics of day-active, early-crepuscular, late-crepuscular, and night-active patterns, is presented and analyzed.

In Section 1, use of a double plotting method, the photoperiodogram, reveals how the apparently precise timing of activity responds to variation in the LD ratio. The occurrence of activity peaks at unexpected times, often apparently contradicting the inhibitory effect of light or dark, led to the development of the multi-clock concept.

In Section 2 how this concept arose is fully illustrated and the suggestion made that the apparently simple daily pattern of unimodal or bimodal activity is the end product of complex interactions between endogenous clocks, and the exogenous effects of the LD cycle. A consideration of the latest advances in molecular studies has been added (Feb. 1999).

A set of Appendices provides details of the known geographic ranges of each of the species, together with the sources of the populations studied in the experiments, and the raw results of the experiments in the form of mean activity over several consecutive days and nights.

BRIAN TAYLOR

1998, revised and enhanced February 1999, species images and reproductions of original papers added January 2001

©1999, 2001, 2010 , 2013- Brian Taylor CBiol FSB FRES
11, Grazingfield, Wilford, Nottingham, NG11 7FN, U.K.