Department of Preventive Veterinary Medicine and Animal Health, Faculty of Veterinary Medicine, University of São Paulo, Av. Prof. Orlando Marques de Paiva 87, São Paulo, SP, Brazil.
Exp Appl Acarol. 2011 May;54(1):41-9. doi: 10.1007/s10493-011-9428-6. Epub 2011 Feb 1.
The present study evaluated the reproductive compatibility of the crosses between adult ticks of the following three geographically different populations of Amblyomma cajennense: State of São Paulo (SP), southeastern Brazil; State of Rondônia (RO), northern Brazil; and Colombia (CO). In addition, crosses between A. cajennense ticks from Argentina (AR) and SP ticks were also performed. The Argentinean population (AR) was compatible with SP because their crosses resulted in high % egg hatching (mean values ranging from 71.5 to 93.5%), similarly to all homologous (intrapopulational) crosses. In contrast, the tick populations SP, RO, and CO were shown to be incompatible with each other, since their heterologous (interpopulational) crosses always resulted in very low % egg hatching (range: 0-5%). The F(1) larval offspring derived from some of these females that yielded 5% egg hatching were reared until the F(1) adult stage. In all cases, only adult females molted from engorged nymphs. These F(1) females were likely to be a product of thelytokous parthenogenesis of the SP, RO, and CO females that were used in the heterologous crosses. Reproductive incompatibility is not expected to occur between different populations of a single species. Thus, our results suggest that the taxon A. cajennense might be represented by a complex of different species, whereas SP and AR ticks might represent a single species. Further populational genetic studies, coupled with extensive morphological analyses, are needed to clarify and determine a possible complex of valid species that might have been classified under the taxon A. cajennense.
本研究评估了来自巴西东南部圣保拉州（SP）、巴西北部朗多尼亚州（RO）和哥伦比亚（CO）三个地理上不同地区的成年硬蜱之间的杂交的生殖相容性。此外，还进行了来自阿根廷（AR）和 SP 的硬蜱之间的杂交。阿根廷种群（AR）与 SP 相容，因为它们的杂交产生了高百分比的卵孵化（平均值范围为 71.5%至 93.5%），与所有同源（种内）杂交相同。相比之下，SP、RO 和 CO 的蜱种群彼此不相容，因为它们的异源（种间）杂交总是导致非常低的卵孵化率（范围：0-5%）。从这些产卵率为 5%的雌性中获得的一些 F1 幼虫被饲养到 F1 成虫阶段。在所有情况下，只有雌虫从饱血的若虫中蜕皮。这些 F1 雌性可能是 SP、RO 和 CO 雌性进行异源杂交时进行孤雌生殖的产物。不同种群之间不应发生生殖不相容。因此，我们的结果表明，A. cajennense 分类单元可能代表不同物种的复合体，而 SP 和 AR 蜱可能代表一个单一的物种。需要进一步的种群遗传研究，结合广泛的形态分析，以澄清和确定可能被归类为 A. cajennense 分类单元的有效物种复合体。
