Detection of activity cycles of tsetse from capture–recapture data

Activity cycles of female tsetse ( Glossina palpalis palpalis Robineau‐Desvoidy) in the field are contrasted with those of males, using mark‐release‐recapture data from continuous biconical trap samples over a period of 80 days in two villages in Ivory Coast. Variability in recapture rates was examined using the techniques of autocorrelation and spectral analysis. In order to do this a two‐dimensional diffusion model incorporating both mortality and emigration was first fitted to corrected recapture rate data to produce a trend line, deviations from which were subjected to the analysis. The autocorrelations for the data for males suggest considerable variability in activity, presumably associated with feeding, around a mean period of about 4 days in one village and seven in the other. Data for females show a strong regular periodicity of about 9–10 days, reflecting the pregnancy cycle, and shorter, more variable periodicities probably corresponding to feeding.