Age distributions and reproductive status of declining and stationary populations of Glossina pallidipes Austen (Diptera: Glossinidae) in Zimbabwe

Abstract

AbstractAge structures and reproductive anomalies of two field populations of Glossina pallidipes Austen in Zimbabwe were compared. One population was treated with insecticide sprayed on odour-baited targets, while the other was left undisturbed. Both populations were sampled with F3 prism-type traps. Capture probabilities were higher for females in early stages of pregnancy than for those in later stages. Per-capita mortality rates were estimated from age distributions which had been corrected for rate of increase. The mortality rate steadily increased over time in the insecticide-treated area but remained roughly constant in the undisturbed area. Estimates of mortality had wide confidence intervals, and the mortality model is critically reviewed. No evidence was seen in the treated population for an increased incidence of abortion or other reproductive anomalies, or for a decrease in insemination rate.