Bustamante Gomez Marinely, Gonçalves Diotaiuti Liléia, Gorla David E
Laboratório de Referência em Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou-FIOCRUZ Minas, Belo Horizonte, Brazil.
Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Córdoba, Argentina.
PLoS Negl Trop Dis. 2016 Mar 23;10(3):e0004561. doi: 10.1371/journal.pntd.0004561. eCollection 2016 Mar.
A number of studies published during the last 15 years showed the occurrence of insecticide resistance in Triatoma infestans populations. The different toxicological profiles and mechanisms of resistance to insecticides is due to a genetic base and environmental factors, being the insecticide selective pressure the best studied among the last factors. The studies on insecticide resistance on T. infestans did not consider the effect of environmental factors that may influence the distribution of resistance to pyrethroid insecticides. To fill this knowledge gap, the present study aims at studying the association between the spatial distribution of pyrethroid resistant populations of T. infestans and environmental variables.
METHODOLOGY/PRINCIPAL FINDINGS: A total of 24 articles reporting on studies that evaluated the susceptibility to pyrethroids of 222 field-collected T. infestans populations were compiled. The relationship between resistance occurrence (according to different criteria) with environmental variables was studied using a generalized linear model. The lethal dose that kills 50% of the evaluated population (LD50) showed a strong linear relationship with the corresponding resistance ratio (RR50). The statistical descriptive analysis of showed that the frequency distribution of the Log (LD50) is bimodal, suggesting the existence of two statistical groups. A significant model including 5 environmental variables shows the geographic distribution of high and low LD50 groups with a particular concentration of the highest LD50 populations over the region identified as the putative center of dispersion of T. infestans.
CONCLUSIONS/SIGNIFICANCE: The occurrence of these two groups concentrated over a particular region that coincides with the area where populations of the intermediate cytogenetic group were found might reflect the spatial heterogeneity of the genetic variability of T. infestans, that seems to be the cause of the insecticide resistance in the area, even on sylvatic populations of T. infestans, never before exposed to pyrethroid insecticides, representing natural and wild toxicological phenotypes. The strong linear relationship found between LD50 and RR50 suggest RR50 might not be the best indicator of insecticide resistance in triatomines.
过去15年发表的多项研究表明，侵扰锥蝽种群中出现了杀虫剂抗性。对杀虫剂的不同毒理学特征和抗性机制归因于遗传基础和环境因素，其中杀虫剂选择压力是这些因素中研究最多的。关于侵扰锥蝽对杀虫剂抗性的研究未考虑可能影响拟除虫菊酯类杀虫剂抗性分布的环境因素。为填补这一知识空白，本研究旨在探讨侵扰锥蝽拟除虫菊酯抗性种群的空间分布与环境变量之间的关联。
方法/主要发现：总共汇编了24篇报道对222个野外采集的侵扰锥蝽种群进行拟除虫菊酯敏感性评估研究的文章。使用广义线性模型研究了抗性发生情况（根据不同标准）与环境变量之间的关系。杀死50%评估种群的致死剂量（LD50）与相应的抗性比率（RR50）呈现出很强的线性关系。对数（LD50）的统计描述性分析表明其频率分布是双峰的，这表明存在两个统计组。一个包含5个环境变量的显著模型显示了高LD50组和低LD50组的地理分布，其中最高LD50种群特别集中在被确定为侵扰锥蝽假定扩散中心的区域。
结论/意义：这两组集中出现在一个特定区域，该区域与发现中间细胞遗传学组种群的区域重合，这可能反映了侵扰锥蝽遗传变异性的空间异质性，这似乎是该地区杀虫剂抗性的原因，即使在从未接触过拟除虫菊酯类杀虫剂的侵扰锥蝽野生种群中也是如此，代表了自然和野生的毒理学表型。LD50和RR50之间发现的强线性关系表明RR50可能不是锥蝽杀虫剂抗性的最佳指标。
