Abstract：
The common bed bug Cimex lectularius (Linnaeus 1758) is an ectoparasite that feeds preferably on human blood, being considered an important public health issue. Blood-feeding is a challenging process for hematophagous organisms, and one of the inherent risks with this kind of diet is the liberation of high doses of free heme after the digestion of hemoglobin. In order to deal with this potent cytotoxic agent, such organisms have acquired different defense mechanisms. Here, we use UV-visible spectrophotometry and infrared spectroscopy to show that C. lectularius crystalizes free heme to form the much less dangerous compound, hemozoin. According to our results, the peak of formation of hemozoin in the intestinal contents occurred 4-5 days after the blood meal, primarily in the posterior midgut. The quantification of the rate of conversion of heme to hemozoin revealed that at the end of digestion all the heme was in the form of hemozoin. Inhibition of the synthesis of hemozoin using the anti-malarial drug quinine led to an increase in both catalase activity in the intestinal epithelium and the mortality of the bed bugs, indicating that the insects were unable to cope with the oxidative stress generated by the overload of free heme. The data presented here show for the first time how C. lectularius deals with free heme, and how the process of formation of hemozoin is essential for the survival of these insects. Since resistance to insecticides is a common feature among field populations of bed bugs, there is an urgent need to develop alternative control methods. Thus, targeting the synthesis of hemozoin emerges as a possible novel strategy to fight bed bugs.
摘要：
常见的臭虫Cimexlectularius（Linnaeus1758）是一种外寄生虫，最好以人类血液为食，被认为是一个重要的公共卫生问题。血液摄食对吸血生物来说是一个具有挑战性的过程，这种饮食的固有风险之一是血红蛋白消化后释放高剂量的游离血红素。为了处理这种有效的细胞毒性剂，这些生物获得了不同的防御机制。这里,我们使用紫外-可见分光光度法和红外光谱显示C.疟原虫色素.根据我们的结果,肠道内容物中疟原虫色素的形成高峰出现在血餐后4-5天，主要在后中肠。血红素向疟原虫色素的转化率的定量表明，在消化结束时，所有血红素都以疟原虫色素的形式存在。使用抗疟疾药奎宁抑制疟原虫色素的合成导致肠上皮中过氧化氢酶活性和臭虫死亡率的增加，表明昆虫无法应对游离血红素超负荷产生的氧化应激。这里提供的数据首次显示了C.lectularius如何处理游离血红素，以及疟原虫色素的形成过程对这些昆虫的生存至关重要。由于对杀虫剂的抗性是臭虫田间种群的共同特征，迫切需要开发替代控制方法。因此，靶向疟原虫色素的合成成为对抗臭虫的一种可能的新策略。
