Application of DNA markers to identify the individual-specific hosts of tsetse feeding on cattle

Primer sets for five different ungulate loci were used to obtain individual microsatellite DNA profiles for 29 Mashona cattle from a herd in Zimbabwe. There were 3-13 alleles for each locus and, using the entire suite of five loci, each animal within the herd, including closely related individuals, could be unequivocally distinguished. Wild-caught Glossina pallidipes Auste n (Diptera: Glossinidae) were fed on specific cattle and the bloodmeal was profiled 0.5-72 h after feeding. The individual specific sources of the blo odmeals, including mixed meals produced by allowing tsetse to feed on two d ifferent cattle, were reliably identified up to 24 h after feeding. The tec hnique was used in field studies of host selection by G. pallidipes and G. morsitans morsitans Westwood (Diptera, Glossinidae) attracted to pairs of c attle. When the pair comprised an adult and a calf, 100% of meals were from the adult. For some pairs of adult cattle, tsetse were biased significantl y towards feeding on one animal, whereas for other pairs there was no such bias. In general, feeding was greater on the animal known to have a lower r ate of host defensive behaviour. Results suggest that relatively slight dif ferences in the inherent defensive behaviour of cattle produce large differ ences in host-specific feeding rates when the hosts are adjacent. For flies attracted to pairs of cattle, <2% contained blood from both hosts. The DNA profiling technique will be useful in studying the epidemiology of vector- borne diseases of livestock.