Discrepancies between estimates of tsetse fly populations using mark-recapture and removal trapping techniques.
A population of Glossina morsitans Westw. and G. pallidipes Aust. in Zimbabwe that was studied by R. J. Phelps & G. A. Vale [see RAE/B 67, 1901] was modelled on the basis of a first-order kinetic system. Rate coefficients for recruitment, loss and trapping were estimated from published data using non-linear regression techniques. The model explained 92-98% of the variance in catches of all mature flies. A similar model explained 92% of the variance for teneral females of G. pallidipes. Estimates of the mature tsetse population obtained from this model were one-third to one-twelfth of those obtained using mark-recapture techniques, and the estimate of daily emergence of teneral females of G. pallidipes was one-twenty-eighth of the previous estimate. The discrepancies may be partially due to more extensive population movements into and out of the sampling area than had been supposed and/or to differences in behaviour of the marked and unmarked populations.