Ferreira Raquel A, Lazzari Claudio R, Lorenzo Marcelo G, Pereira Marcos H
Laboratório de Triatomíneos e Epidemiologia da Doença de Chagas, Centro de Pesquisas René Rachou, Belo Horizonte, Brazil.
PLoS One. 2007 Sep 26;2(9):e932. doi: 10.1371/journal.pone.0000932.
It is known that some blood-sucking insects have the ability to reach vessels under the host skin with their mouthparts to feed blood from inside them. However, the process by which they locate these vessels remains largely unknown. Less than 5% of the skin is occupied by blood vessels and thus, it is not likely that insects rely on a "random search strategy", since it would increase the probability of being killed by their hosts. Indeed, heterogeneities along the skin surface might offer exploitable information for guiding insect's bites.
METHODOLOGY/PRINCIPAL FINDINGS: We tested whether the bug Rhodnius prolixus can evaluate temperature discontinuities along the body surface in order to locate vessels before piercing the host skin. When placed over a rabbit ear, the bug's first bites were mostly directed towards the main vessels. When insects were confronted to artificial linear heat sources presenting a temperature gradient against the background, most bites were directly addressed to the warmer linear source, notwithstanding the temperature of both, the source and the background. Finally, tests performed using uni- and bilaterally antennectomized insects revealed that the bilateral integration of thermal inputs from both antennae is necessary for precisely directing bites.
CONCLUSIONS/SIGNIFICANCE: R. prolixus may be able to exploit the temperature differences observed over the skin surface to locate blood vessles. Bugs bite the warmest targets regardless of the target/background temperatures, suggesting that they do not bite choosing a preferred temperature, but select temperature discontinuities along the skin. This strategy seems to be an efficient one for finding blood vessels within a wide temperature range, allowing finding them on different hosts, as well as on different areas of the host body. Our study also adds new insight about the use of antennal thermal inputs by blood sucking bugs.
已知一些吸血昆虫能够用口器抵达宿主皮肤下的血管并从其中吸血。然而，它们定位这些血管的过程在很大程度上仍不为人知。不到5%的皮肤被血管占据，因此昆虫不太可能依赖“随机搜索策略”，因为这会增加被宿主杀死的概率。实际上，皮肤表面的异质性可能为引导昆虫叮咬提供可利用的信息。
方法/主要发现：我们测试了吸血猎蝽是否能够评估体表的温度不连续性，以便在刺穿宿主皮肤之前定位血管。当把这种猎蝽放在兔耳上时，它最初的叮咬大多指向主要血管。当昆虫面对呈现出相对于背景温度梯度的人工线性热源时，尽管热源和背景的温度不同，但大多数叮咬都直接指向较温暖的线性热源。最后，对单侧和双侧切除触角的昆虫进行的测试表明，来自两只触角的热输入的双侧整合对于精确引导叮咬是必要的。
结论/意义：吸血猎蝽可能能够利用在皮肤表面观察到的温度差异来定位血管。昆虫叮咬最温暖的目标，而不管目标/背景温度如何，这表明它们不是选择一个偏好的温度进行叮咬，而是沿着皮肤选择温度不连续性。这种策略似乎是在很宽的温度范围内找到血管的一种有效方法，使得能够在不同宿主以及宿主身体的不同部位找到血管。我们的研究还为吸血昆虫对触角热输入的利用增添了新的见解。
