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Using models to estimate mortality in immature tsetse flies

Overview

A good understanding of the population dynamics of trypanosomes and their tsetse vectors is important in the formulation of cost-effective methods for disease and vector control. Good estimates of mortality are fundamental to an understanding of population dynamics, but such estimates, for wild populations, have been surprisingly difficult to obtain for tsetse.

This group will develop a modeling approach to the estimation of mortality among early developmental stages of tsetse flies (Glossina spp).

Things to consider

• This project uses extremely detailed, long-term data on tsetse fly populations to understand factors influencing fly development, mortality, and catch probabilities.

• This group is recommended for:
  • Interested in vector-borne diseases
  • Interested in population dynamics, and its modeling, particularly as it concerns insects
  • Interested in fitting models to published data
  • Interested in the effect of climate, and changes therein, on insect population dynamics.
  • Track A or B participants
• This group will have the opportunity to engage in any of the following:
  • Analyze data provided for the project
  • Develop dynamical models that can be used to fit these data
  • Use the outputs of fitted models to estimate numbers of tsetse pupae and, thereby, mortality rates among them
  • If desired: use agent-based models to fit mark-recapture data to parameterize population-level models

Background

An extensive mark-release-recapture exercise was carried out in the early 1980s using two species of tsetse on an island in Lake Kariba Zimbabwe. The exercise provided excellent estimates of population parameters pertaining to mature adult tsetse of both sexes of both species. That data have not, however, been used to provide good estimates of mortality in immature flies – that is to say pupae and adults that have just emerged, and have not yet fed, and are thus not yet available for capture and marking. The present project will attempt to rectify this situation.

More detailed background is provided in the project proposal, available from the project repository.

Resources

• Data and additional resources are available from the project’s repository on GitHub.

References

• Ackley S.F., Fengchen Liu & Hargrove J.W. (2015) A dynamical modelling technique for estimating adult female mortality from ovarian dissection data for the tsetse fly G. pallidipes Austen sampled in Zimbabwe (in preparation).
• Ferreira R-C (2014) An individual-based model of tsetse fly populations dynamics: modelling an extensive mark-release-recapture experiment. MSc Thesis. University of Stellenbosch. 55pp.
• Hargrove, J. W. (2001) Mark-recapture and Moran curve estimates of the survival probabilities of an island population of tsetse flies Glossina morsitans morsitans (Diptera: Glossinidae). Bulletin of Entomological Research 91, 25-36.
• Hargrove JW, Ackley SF (2015) Mortality estimates from ovarian age distributions of the tsetse fly Glossina pallidipes Austen sampled in Zimbabwe suggest the need for new analytical approaches. Bulletin of Entomological Research 105, 294-304.
• Hargrove, J.W. & Williams, B.G. (1998) Optimized simulation as an aid to modelling, with an application to the study of a population of tsetse flies, Glossina morsitans morsitans Westwood (Diptera: Glossinidae). Bulletin of Entomological Research, 88, 425-435.
• Phelps, R. J. & Clarke, G.P.Y. (1974) Seasonal elimination of some size classes in males of Glossina morsitans morsitans Westwood. (Diptera, Glossinidae). Bulletin of Entomological Research, 64, 313-324.
• Rogers, D. J. & Randolph, S. E. (1984). A review of density-dependent processes in tsetse populations. Insect Science and its Application, 5, 397-402.
• Vale, G.A. (2015) Modelling changes in the population of Glossina morsitans morsitans Westwood. (Diptera, Glossinidae) on Antelope Island (in preparation)