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Elita Chikwati Senior Agriculture Reporter
THE Zambezi Valley is still infested with tsetse fly although there has been changes in population levels due to different micro-climatic conditions, Government has said.

This follows a research carried out by the Division of Tsetse Control Services and its associates that indicated there was a reduction in tsetse populations in the Zambezi Valley due to the 1,5 degrees Celsius rise in temperature.

Division of Tsetse Control Services director Mr William Shereni last week said tsetse catches had been exceptionally high this year compared to the low numbers recorded at the same time last year.

“These fluctuations from very low to very high levels in the two consecutive years clearly demonstrate how tsetse fly populations are sensitive to changing micro-climatic conditions,” he said.

“There is need for more research to fully understand key drivers for the dynamic changes in tsetse populations in the Zambezi Valley.”

Mr Shereni said high veld areas in Zimbabwe were too cool to support tsetse populations.

“However, rising temperatures are expected to make such areas more suitable for the flies, although tsetse populations can become established in new areas only if suitable woodland is present and adequate numbers of wildlife or domestic host animals are valuable.

“The recent upsurge in sleeping sickness cases in the Makuti area where the disease was not prevalent in the past may suggest that the fly has started to invade cooler areas above the Zambezi escarpment, exposing people and livestock to the risk of contracting trypanosomiasis.”

Mr Shereni said research showed that most areas in Zimbabwe would become ecologically suitable for tsetse flies if there was a degree Celsius rise in temperature due to global warming.

He said the division had developed and tested methods of tsetse control that were suitably cheap, simple and safe to apply in settled areas, including the use of insecticide-treated cattle and artificial baits.

“Theoretical models have been produced to indicate how best these control measures can be applied in and near settled areas,” he said.

Tsetse flies affect food production, natural-resource utilisation and the pattern of human settlement throughout much of sub-Saharan Africa.

The pest can cause sleeping sickness in human beings, and nagana in cattle.

The reduction of tsetse fly infestations has the potential of boosting tourism activities and improving the  economy.

Zimbabwe also control tsetse flies through anti-tsetse ground spraying operations based on the application of residual deposits of pyrethroid, which are applied to tsetse resting and refuge sites such as trees.

The pesticide is applied during the hot and dry season, which coincides with the time when tsetse population levels are high.

Tsetse differ from other insects in that they drop larvae, which dig an inch into the soil and stay in pupal form before they emerge as a fly, a month or so later.

The pesticide kills the emerging flies on contact.

According to the Division of Tsetse Control Services, the country is now using insecticide treated and odour baited targets that are deployed at the density of four per square kilometre.

This provides a barrier by blocking tsetse flies from re-invading previously cleared areas.