Current status of Glossina population ecology

Abstract

BACKGROUND: Vector control remains the most visible method for large scale control of trypanosomiasis; there is a lack of suitable prophylactic drugs and vaccines against trypanosomiases and chemotherapeutic agents remain too expensive and dangerous for most people in endemic areas. Glossina populations are the target units and therefore an in-depth understanding of their ecology is a pre-requisite to the development of effective control measures. SAMPLING METHODS: Refers to methods of catching tsetse flies in the field. Earlier Researchers utilized walking parties to catch flies or standing catch with hand nets. Studies in the 1970s highlighted the shortcomings of these methods. A variety of traps has since been developed for diverse species. POPULATION DYNAMICS: Refers to changes in population abundance over time. Three processes (dispersal, natality, mortality) are involved in determining population levels. Geographic structure is the distribution and abundance within and among populations. Based on direct observations, mark-recapture protocols or radio-tracking, earlier view was that Glossina dispersal was random. Currently, the best available description is a diffusion process; flies at the margins of the distributional range begin the process, which gradually moves inwards. Calculation of growth rates is easier for small closed Glossina populations. There is a consensus among tsetse ecologists that both density-dependent and density-independent factors are important in the regulation of tsetse numbers. POPULATION GENETICS: It encompasses two distinct but related components: demographic and genetic distribution of genetic variation and the result of migration, selection mutation, genetic drift and related factors: New molecular genetics techniques have allowed insights into many fields. CONCLUSION: There have been significant advances in Glossina ecology over the past 3 decades. These have been possible because of the availability of comprehensive data from long-term field studies and the introduction of new molecular genetics techniques that have allowed insights into many fields. Glossina population genetics and manipulation of prokaryotic symbiont species may provide avenues for management innovations to confront the intractable problem of trypanosomiasis in Africa.