The natural hosts of larvae and nymphs of Amblyomma tigrinum Koch, 1844 (Acari: Ixodidae).

SANTIAGO NAVA, ATILIO J. MANGOLD, ALBERTO A. GUGLIELMONE

VETERINARY PARASITOLOGY

Año: 2006 vol. 140 p. 124 - 132

0304-4017

The hosts of larvae and nymphs of Amblyomma tigrinum, a tick whose adults feed on wild and domestic Canidae in SouthAmerica, are uncertain. A 17 months survey was carried out trapping wild vertebrates in north-western Co´rdoba, Argentina, toevaluate their parasitism with A. tigrinum subadults. Larvae and nymphs of this tick species were identified conventionally andby comparison of 16S rDNA sequences with GenBank deposited sequences. A total of 207 small and medium-sized rodents and182 birds were captured and examined for ticks. Most ticks on birds were from ground forest feeding birds (BB) with a minimalcontribution of birds feeding in open pastures. All ticks from rodents were obtained from representatives of the familiesCricetidae (SR) and Caviidae (MR). Percent of larvae infestation was higher (P < 0.01, Chi-square distribution) in BB (55.2%)and SR (46.4%) than in MR (17.4%) and the same trend was found for number of larvae on these hosts (test of Kruskal–Wallis).Caviidae (only representative Galea musteloides) rodents were extremely prone to be infested with nymphs of A. tigrinum(94.2%) followed by BB (50.6%) and SR (3.6%) (P < 0.01) and the same tendency was found for number of nymphs (P < 0.01).The index of aggregation for nymphs on MR was the lowest (0.409) followed by nymphs on BB (0.706) which may be aconsequence of higher and homogenous exposure of G. musteloides to host-seeking nymphs. Several BB are food source forboth larvae and nymphs of A. tigrinum while for rodents larvae were common only on SR (mainly on the Sigmodontinae Akodondolores and Graomys sp.) and nymphs feed almost exclusively on MR. Therefore, both birds and rodents are of importance forthe survival strategy of A. tigrinum subadults. The plasticity of A. tigrinum to colonize areas with different climates plus thecapacity of their subadults to feed on hosts widely distributed indicates that this tick has the potential to become a widespreadparasite but this does not seem to be the actual situation. Several proposals are presented to further understand its ecology.