Host preferences of Triatoma sordida.

Triatoma sordida is a widespread vector of Trypanosoma cruzi, living in both sylvatic and domestic habitats. To see if Tri. sordida 'prefers' to feed from avian or mammalian hosts, two experiments were carried out. In the first experiment, in which fifth-instar nymphs were allowed free access to two unrestrained hosts, a guinea-pig and a pigeon, 98% of those feeding fed on the guinea-pig, and the mammalian bloodmeals were generally larger than the avian, with mean weights of 50.9 and 30.2 mg, respectively. In the second experiment, groups of nymphs were exposed to a single host (guinea-pig or pigeon) at two different densities (10 and 30 bugs/host). Whatever the density of the bugs, a much larger proportion of the bugs offered feeds on the guinea-pig took bloodmeals than of those offered the pigeon (55% v. 9%), and the bugs which fed on the mammal again generally took larger bloodmeals (mean weight = 50.9 mg) than the few which fed on the bird (mean weight = 12.8 mg; P < 0.0001). Bug density was found to have a greater effect on the size of the bloodmeals taken from pigeon than on those taken from guinea-pig. Triatoma sordida therefore does not appear to have a marked preference for avian blood; it is probably a generalist species that can invade a variety of habitats to exploit the range of available vertebrate hosts.