HOST PREFERENCES OF TRIATOMA-SORDIDA

Triatoma sordida is a widespread vector of Trypanosoma cruzi, living i n 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 allowe d 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 3 0.2 mg, respectively. In the second experiment, groups of nymphs were exposed to a single host (guinea-pig or pigeon) at two different densi ties (10 and 30 bugs/host). Whatever the density of the bugs, a much l arger proportion of the bugs offered feeds on the guinea-pig tool; blo odmeals than of those offered the pigeon (55% v. 9%), and the bugs whi ch fed on the mammal again generally took larger bloodmeals (mean weig ht = 50.9 mg) than the few which fed on the bird (mean weight = 12.8 m g; 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 guin ea-pig. Triatoma sordida therefore does not appear to have a marked pr eference for avian blood; it is probably a generalist species that can invade a variety of habitats to exploit the range of available verteb rate hosts.