Nava S, Mangold A J, Guglielmone A A
Instituto Nacional de Tecnología Agropecuaria, Estación Experimental Agropecuaria Rafaela, CC 22, CP 2300 Rafaela, Santa Fe, Argentina.
Vet Parasitol. 2006 Aug 31;140(1-2):124-32. doi: 10.1016/j.vetpar.2006.03.009. Epub 2006 May 8.
The hosts of larvae and nymphs of Amblyomma tigrinum, a tick whose adults feed on wild and domestic Canidae in South America, are uncertain. A 17 months survey was carried out trapping wild vertebrates in north-western Córdoba, Argentina, to evaluate their parasitism with A. tigrinum subadults. Larvae and nymphs of this tick species were identified conventionally and by comparison of 16S rDNA sequences with GenBank deposited sequences. A total of 207 small and medium-sized rodents and 182 birds were captured and examined for ticks. Most ticks on birds were from ground forest feeding birds (BB) with a minimal contribution of birds feeding in open pastures. All ticks from rodents were obtained from representatives of the families Cricetidae (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 a consequence of higher and homogenous exposure of G. musteloides to host-seeking nymphs. Several BB are food source for both larvae and nymphs of A. tigrinum while for rodents larvae were common only on SR (mainly on the Sigmodontinae Akodon dolores and Graomys sp.) and nymphs feed almost exclusively on MR. Therefore, both birds and rodents are of importance for the survival strategy of A. tigrinum subadults. The plasticity of A. tigrinum to colonize areas with different climates plus the capacity of their subadults to feed on hosts widely distributed indicates that this tick has the potential to become a widespread parasite but this does not seem to be the actual situation. Several proposals are presented to further understand its ecology.
南美钝缘蜱的成虫以野生和家养犬科动物为食，但其幼虫和若虫的宿主尚不确定。在阿根廷科尔多瓦省西北部开展了一项为期17个月的调查，捕获野生脊椎动物，以评估它们被南美钝缘蜱未成熟个体寄生的情况。该蜱种的幼虫和若虫通过传统方法并通过将16S rDNA序列与GenBank中保存的序列进行比较来鉴定。共捕获并检查了207只中小型啮齿动物和182只鸟类是否有蜱虫。鸟类身上的大多数蜱虫来自地面森林觅食鸟类（BB），在开阔牧场觅食的鸟类贡献极小。啮齿动物身上的所有蜱虫均来自仓鼠科（SR）和豚鼠科（MR）的代表动物。BB（55.2%）和SR（46.4%）的幼虫感染率高于MR（17.4%）（P<0.01，卡方分布），这些宿主上的幼虫数量也呈现相同趋势（Kruskal-Wallis检验）。豚鼠科（仅代表物种鼬豚鼠）啮齿动物极易被南美钝缘蜱的若虫寄生（94.2%），其次是BB（50.6%）和SR（3.6%）（P<0.01），若虫数量也呈现相同趋势（P<0.01）。MR上若虫的聚集指数最低（0.409），其次是BB上的若虫（0.706），这可能是由于鼬豚鼠对寻找宿主的若虫有更高且均匀的暴露。几种BB是南美钝缘蜱幼虫和若虫的食物来源，而对于啮齿动物，幼虫仅常见于SR（主要是稻鼠属的多洛雷斯稻鼠和禾鼠属物种），若虫几乎只以MR为食。因此，鸟类和啮齿动物对南美钝缘蜱未成熟个体的生存策略都很重要。南美钝缘蜱在不同气候地区定殖的可塑性，加上其未成熟个体以广泛分布的宿主为食的能力，表明这种蜱有成为广泛寄生虫的潜力，但实际情况似乎并非如此。提出了几项建议以进一步了解其生态学。
