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Title: SEX SEPARATION OF TSETSE FLY PUPAE USING NEAR-INFRARED SPECTROSCOPY

Author
item Dowell, Floyd
item PARKER, A - FAO/IAEA, AUSTRIA
item BENEDICT, M - CDC & PREVENTION
item ROBINSON, A - FAO/IAEA, AUSTRIA
item BROCE, A - KANSAS STATE UNIV
item WIRTZ, R - CDC & PREVENTION

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2005
Publication Date: 6/1/2005
Citation: Dowell, F.E., Parker, A.G., Benedict, M.Q., Robinson, A.S., Broce, A.B., Wirtz, R.A. 2005. Sex separation of tsetse fly pupae using near-infrared spectroscopy. Bulletin of Entomological Research 95(3):249-257

Interpretive Summary: Implementation of the sterile insect technique (SIT) for tsetse (Glossina spp) requires that only sterile male insects be released; thus, at some stage of the fly production process, the females have to be removed. A further constraint in the use of SIT for tsetse is that the females are needed for colony production and hence, a non-destructive method of sex separation is required. In most tsetse SIT programs thus far, females have been separated from the released material by hand-sexing of chilled adults. Using near-infrared (NIR) spectroscopy, significant differences have been found between the spectra for the pupae of male and female G. pallidipes. Significantly, the differences appear to be maximized four to five days before emergence of the adults. We report that tsetse fly pupae up to 5 days before emergence can be sexed with accuracies that generally range from 80 to 100%. This system, when refined, will enable effective separation of male and female pupae to be carried out with emerged females being returned to the colony and males being irradiated and released. If separation can be achieved five days before emergence, this will also enable male pupae to be shipped to other destinations as required.

Technical Abstract: Tsetse flies are important vectors of African trypanosomes, which cause sleeping sickness in humans and nagana, a fatal disease, in livestock. About 300,000 human deaths are estimated to occur annually. Approximately three million cattle deaths occur annually, causing a direct annual loss of about $1.5 billion. Implementation of the sterile insect technique (SIT) for tsetse requires that only sterile male insects be released; thus, at some stage of the fly production process the females have to be removed. We examined the use of near-infrared spectroscopy technology to sex and sort the fly pupae. This technology was developed for measuring and sorting single grain kernels. Tsetse fly pupae up to 5 days before emergence can be sexed with accuracies that generally range from 80 to 100%. This system will enable effective separation of male and female pupae to be carried out with emerged females being returned to the colony and males being irradiated and released. This will significantly reduce the cost and efficiency of rearing tsetse flies for SIT programs.