Knowledge for a sustainable world

It has been announced by the Royal Entomological Society that one of NRI's entomologists Dr Stephen Torr and his co-authors from Canada and Zimbabwe have won an award for the best paper published in the Society's journal Medical and Veterinary Entomology in the last two years. Their paper, entitled 'Application of DNA markers to identify the individual specific hosts of tsetse feeding on cattle,' reported the use of DNA fingerprinting to identify which animals within a herd are preferred by tsetse flies.

The research showed that tsetse prefer to feed on older and larger cattle. When given the choice of a young calf or an old ox, for example, every one of the tsetse chose to feed on the ox. It seems that this preference reflects the fact that older cattle are easier and safer for the tsetse to feed on because they are much less likely than younger ones to swipe at the irritation and thus dislodge or even kill the feeding tsetse.


Photograph by Dr. Steve Mihok

The results from this study, combined with findings from related DFID-funded research, have important implications for the control of tsetse-borne trypanosomiasis, a major disease of livestock and humans in Africa. One way to control this disease is to treat cattle with insecticide, which kills tsetse that land on the treated animals. The finding that older cattle are bitten more often than others suggests that insecticide may only need to be applied to these animals. As a result, fewer cattle would need to be treated, which reduces both the cost and the environmental impact. Additionally, if the young cattle are not treated, they will be bitten by ticks that would otherwise be killed by the insecticide: this allows them to develop natural immunity to tick-borne diseases.

The award-winning paper was published in 2001. More recently, Steve Torr and colleagues have used the same DNA fingerprinting technique to study the feeding behaviour of stable flies and malarial mosquitoes in Zimbabwe and Ethiopia.