Controlling tsetse with targets

How many targets do I need?

To eliminate a population of tsetse, you need to kill at least 4% of the female population per day (Hargrove, 1988). The odour-baited targets that we use to control G. pallidipes kill about 1-2% of the population per day. So we need 2-4 targets per square kilometre; most successful operations against this species have used four targets per square kilometre (Vale et al., 1988).

Riverine species such as G. fuscipes are less responsive to host odours (Mwangelwa et al., 1988). Consequently, the unbaited targets used to control these species are less effective and so we need to use more of them; successful operations against these species have used densities of 10-50 targets per square kilometre. As their name suggests however, these species are confined largely to drainage lines. So while the density of targets might be higher, the area that needs to be treated is not generally as extensive as that needed to control savanna species of tsetse.

The more targets that you deploy, the quicker tsetse are killed. So you could choose to eliminate G. pallidipes from an area very quickly by deploying 10 rather than 4 targets per square kilometre. But of course this would cost more. Tsetse Plan shows you what would happen to a tsetse population with various levels of mortality so that you can choose a balance between cost and effect that suits your circumstances.

References
Hargrove, J.W. (1988) The limits to population growth. Medical and Veterinary Entomology, 2, 203-217.

Mwangelwa, M.I., Dransfield, R.D., Otieno, L.H. & Mbata, K.J. (1995). The responses of Glossina fuscipes fuscipes Newstead to odour attractants and traps. Journal of African Zoology 109, 23-30.

Vale, G.A., Lovemore, D.F., Flint, S. & Cockbill, G.F. (1988) Odour-baited targets to control tsetse flies, Glossina spp. (Diptera: Glossinidae) in Zimbabwe. Bulletin of Entomological Research, 78, 31-49.