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Mortality estimates from ovarian age distributions of the tsetse fly Glossina pallidipes Austen sampled in Zimbabwe suggest the need for new analytical approaches

  • J.W. Hargrove (a1) and S.F. Ackley (a2)

Mortality estimates are central to understanding tsetse fly population dynamics, but are difficult to acquire from wild populations. They can be obtained from age distribution data but, with limited data, it is unclear whether the assumptions required to make the estimates are satisfied and, if not, how violations affect the estimates. We evaluate the assumptions required for existing mortality estimation techniques using long-term longitudinal ovarian dissection data from 144,106 female tsetse, Glossina pallidipes Austen, captured in Zimbabwe between 1988 and 1999. At the end of the hot-dry season each year, mean ovarian ages peaked, and maximum-likelihood mortality estimates declined to low levels, contrary to mark-recapture estimates, suggesting violations of the assumptions underlying the estimation technique. We demonstrate that age distributions are seldom stable for G. pallidipes at our study site, and hypothesize that this is a consequence of a disproportionate increase in the mortality of pupae and young adults at the hottest times of the year. Assumptions of age-independent mortality and capture probability are also violated, the latter bias varying with capture method and with pregnancy and nutritional status. As a consequence, mortality estimates obtained from ovarian dissection data are unreliable. To overcome these problems we suggest simulating female tsetse populations, using dynamical modelling techniques that make no assumptions about the stability of the age distribution.

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Bursell, E. & Glasgow, J.P. (1960) Further observations on lakeside and riverine communities of Glossina palpalis fuscipes Newstead. Bulletin of Entomological Research 51, 4756.
Carey, J.R. (2011) Biodemography of the Mediterranean fruit fly: aging, longevity and adaptation in the wild. Experimental Gerontology 46, 404411.
Carey, J.R., Papadopoulos, N.T., Papanastasiou, S., Diamantidis, A. and Nakas, C.T. (2012 a) Estimating changes in mean population age using the death distributions of live-captured medflies. Ecological Entomology 37, 359369.
Carey, J.R., Müller, H.G., Wang, J.L., Papadopoulos, N.T., Diamantidis, A. and Koulousis, N.A. (2012 b) Graphical and demographic synopsis of the captive cohort method for estimating population age structure in the wild. Experimental Gerontology 47, 787791.
Carey, J.R., Papadopoulos, N.T., Müller, H.G., Katsoyannos, B.I., Kouloussis, N.A., Wang, J.L., Wachter, K., Yu, W. and Liedo, P. (2008) Age structure changes and extraordinary lifespan in wild medfly populations. Aging Cell 7, 426437.
Challier, A. (1965) Amélioration de la méthode de détermination de l'âge physiologique des glossines. Études faites sur Glossina palpalis palpalis Vanderplank, 1949. Bulletin de la Société de Pathologie Exotique 58, 250259.
Curtis, C.F. & Jordan, A.M. (1968) Calculations on the productivity of Glossina austeni Newst. maintained on goats and on lop-eared rabbits. Bulletin of Entomological Research 59, 651658.
Dransfield, R.D., Brightwell, R., Kiilu, J., Chaudhury, M.F. & Adabie, D.A. (1989) Size and mortality rates of Glossina pallidipes in the semi-arid zone of southwestern Kenya. Medical and Veterinary Entomology 3, 8395.
Glasgow, P.A. (1961) Selection for size in tsetse flies. Journal of Animal Ecology 30, 8794.
Hargrove, J.W. (1990) Age-dependent changes in the probabilities of survival and capture of the tsetse fly Glossina morsitans morsitans Westwood. Insect Science and its Application 11, 323330.
Hargrove, J.W. (1991) Ovarian ages of tsetse flies (Diptera: Glossinidae) caught from mobile and stationary baits in the presence and absence of humans. Bulletin of Entomological Research 81, 4350.
Hargrove, J.W. (1993) Age-dependent sampling biases in tsetse flies (Glossina). Problems associated with estimating mortality from sample age distributions. pp. 549556. in Management of Insect Pests: Nuclear and Related Molecular and Genetic Techniques. Vienna, Austria, International Atomic Energy Agency.
Hargrove, J.W. (1999 a) Nutritional levels of female tsetse Glossina pallidipes from artificial refuges. Medical and Veterinary Entomology 13, 150164.
Hargrove, J.W. (1999 b) Lifetime changes in the nutritional characteristics of female tsetse flies Glossina pallidipes caught in odour-baited traps. Medical and Veterinary Entomology 13, 165176.
Hargrove, J.W. (1999 c) Reproductive abnormalities in field tsetse flies in Zimbabwe. Entomologia Experimentalis et Applicata 92, 8999.
Hargrove, J.W. (2001 a) The effect of temperature and saturation deficit on mortality in populations of male Glossina m. morsitans (Diptera: Glossinidae) in Zimbabwe and Tanzania. Bulletin of Entomological Research 91, 7986.
Hargrove, J.W. (2001 b) Factors affecting density-independent survival of an island population of tsetse flies in Zimbabwe. Entomologia Experimentalis et Applicata 100, 151164.
Hargrove, J.W. (2004) Tsetse population dynamics. pp 113137. in Maudlin, I., Holmes, P.H. & Miles, P.H. (Eds). The Trypanosomiases. Oxford, UK, CABI Publishing.
Hargrove, J.W. & Brady, J. (1992) Activity rhythms of tsetse flies (Glossina spp.) (Diptera: Glossinidae) at low and high temperatures in nature. Bulletin of Entomological Research 82, 321326.
Hargrove, J.W. & Langley, P.A. (1990) Sterilizing tsetse in the field: a successful field trial. Bulletin of Entomological Research 80, 397403.
Hargrove, J.W. & Langley, P.A. (1993) A field trial of pyriproxyfen-treated targets as an alternative method for controlling tsetse (Diptera: Glossinidae). Bulletin of Entomological Research 83, 361368.
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, 425435.
Hargrove, J.W., Holloway, M.T.P., Vale, G.A., Gough, A.J.E. & Hall, D.J. (1995) Catches of tsetse flies (Glossina spp.) (Diptera: Glossinidae) from traps baited with large doses of natural and synthetic host odour. Bulletin of Entomological Research 85, 215227.
Hargrove, J.W., Ouifki, R. & Ameh, J.E. (2011) A general model for mortality in adult tsetse (Glossina spp). Medical and Veterinary Entomology 25, 385394.
Jackson, C.H.N. (1941) The analysis of a tsetse fly population. Annals of Eugenics 10, 332369.
Jackson, C.H.N. (1944) The analysis of a tsetse fly population II. Annals of Eugenics 12, 176205.
Jackson, C.H.N. (1945) Comparative studies of the habitat requirements of tsetse fly species. Journal of Animal Ecology 14, 4651.
Jackson, C.H.N. (1948) Some further isolated generation of tsetse flies. Bulletin of Entomological Research 39, 441451.
Jarry, M., Gouteux, J.-P. & Khaladi, M. (1996) Are tsetse fly populations close to equilibrium? Acta Biotheoretica 44, 317–33.
Jarry, M., Gouteux, J.-P. & Khaladi, M. (1999) Estimation of age-dependent survival rates of female tsetse flies (Diptera: Glossinidae) from ovarian age distributions. Bulletin of Entomological Research 89, 515521.
Jolly, G.M. (1965) Explicit estimates from capture–recapture data with both death and immigration – stochastic model. Biometrika 52, 225247.
Jordan, A.M. & Curtis, C.F. (1968) Productivity of Glossina austeni Newst. maintained on lop-eared rabbits. Bulletin of Entomological Research 58, 399410.
Jordan, A.M. & Curtis, C.F. (1972) Productivity of Glossina morsitans Westwood maintained in the laboratory, with particular reference to the sterile – insect release method. Bulletin of the World Health Organisation 46, 3338.
Novoseltsev, V.N., Michalski, A.I., Novoseltseva, J.A., Yashin, A.I., Carey, J.R. and Ellis, A.M. (2012) An age-structured extension to the vectorial capacity model. PLoS ONE 7, e39479. doi:10.1371/journal.pone.0039479
Phelps, R.J. (1973) The effect of temperature on fat consumption during the puparial stages of Glossina morsitans morsitans Westw. (Dipt., Glossinidae) under laboratory conditions, and its implication in the field. Bulletin of Entomological Research 62, 423438.
Phelps, R.J. & Clarke, G.P.Y. (1974) Seasonal elimination of some size classes in males of Glossina morsitans morsitans Westw. (Diptera, Glossinidae). Bulletin of Entomological Research 64, 313324.
Rogers, D.J. (1988) A general model for the African trypanosomiases. Parasitology 97, 193212.
Rogers, D.J., Randolph, S.E. & Kuzoe, F.A.S. (1984) Local variation in the population dynamics of Glossina palpalis palpalis (Robineau-Desvoidy) (Diptera: Glossinidae). I. Natural population regulation. Bulletin of Entomological Research 74, 403423.
Saunders, D.S. (1960) The ovulation cycle in Glossina morsitans Westwood (Diptera: Muscidae) and a possible method of age determination for female tsetse flies by the examination of their ovaries. Transaction of the Royal Entomological Society London 112, 221238.
Saunders, D.S. (1962) Age determination for female tsetse flies and the age compositions of samples of Glossina pallidipes Aust., G. palpalis fuscipes Newst. and G. brevipalpis Newst. Bulletin of Entomological Research 53, 579595.
Seber, G.A.F. (1965) A note on the multiple recapture census. Biometrika 52, 249259.
Seber, G.A.F. (1982) The Estimation of Animal Abundance and Related Parameters. London, UK, Charles Griffin & Co. 654 pp.
Vale, G.A. (1971) Artificial refuges for tsetse flies (Glossina spp.). Bulletin of Entomological Research 61, 331350.
Vale, G.A. (1974) The responses of tsetse flies (Diptera: Glossinidae) to mobile and stationary baits. Bulletin of Entomological Research 64, 545588.
Van Sickle, J. & Phelps, R.J. (1988) Age distributions and reproductive status of declining and stationary populations of Glossina pallidipes Austen (Diptera: Glossinidae) in Zimbabwe. Bulletin of Entomological Research 78, 5161.
Williams, B., Dransfield, R. & Brightwell, R. (1990) Tsetse fly (Diptera: Glossinidae) population dynamics and the estimation of mortality rates from life-table data. Bulletin of Entomological Research 80, 479485.
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