在动物园喂食时间:用于蚊子

Zoological gardens are exceptional environments for the study of mosquito ecology and their feeding behavior. They can provide unique insights for the control of mosquito populations and the prevention of the diseases that they may transmit to zoo vertebrates and humans. A new research studied the blood-feeding ecology of mosquitoes in two zoos in the United Kingdom.

在研究蚊子传播病原体的能力(矢量容量)时,三个关键因素具有相当大的影响:血液喂养行为,蚊子种群密度和蚊子长寿。然而,了解蚊子的血液喂养行为具有三个主要挑战:

  • 血腥的蚊子很难抓住,因为它们通常不会被陷阱所吸引。
  • Mosquitoes can disperse long distances when looking for a blood-meal and after they have it.
  • Assessing feeding patterns is a problem of positive bias because mosquitoes provide information about what vertebrates they fed on but not on which ones they did not.

To overcome these challenges, we need to know more about the environment and potential hosts available, and to use techniques to target blood-fed mosquitoes.

一些蚊子可能更喜欢一种类型的主体(专家),其他人可以在许多不同的(一般)上喂食,这两种策略都可以在适当的情况下改变。这可以使它们“桥梁向量”用于不同脊椎动物种类的病原体。如果病原体可以在新的主机(主管主管)中重现并转移到更多的蚊子,则可以观察到扩增效果,而如果不是,则病原体将在社区中稀释。

Zoos bring together a great diversity of potential hosts, endemic and exotic, thus mosquitoes can transmit pathogens among species and vertebrate groups that usually would not happen in natural environments. Therefore, it is not surprising that in zoos mosquitoes have been found feeding on zoo vertebrates, free wild vertebrates and even humans. In some cases, this adaptability of mosquitoes has created serious health problems, like theoutbreak of West Nile virus in the Bronx Zoo/Wildlife Conservation Park. Likewise, mosquitoes can also threaten the health of zoo vertebrates as with the case of avian malaria, caused by疟原虫SPP。并主要通过Culex.SPP。蚊子,这是俘虏企鹅大众死亡率的主要原因。

我们与彻斯特动物园和火烈鸟土地合作,收集蚊子,分析了禽疟疾的传动风险,对他们的企鹅殖民地。作为这项研究的一部分(during 2017 and 2018 in Chester Zoo, and 2017 in Flamingo Land), we captured blood-fed mosquitoes and we decided to specifically look for blood-fed mosquitoes in a third sampling year (2019) at Chester Zoo.

How to catch blood-fed mosquitoes?

在前两年中,我们使用传统的蚊子陷阱用于寻找潜在蚊子(BG-Modquitaire)和妊娠蚊子(CDC-妊娠陷阱),以及第三年,我们将干冰添加为CO的来源2to the BG-Mosquitaire traps and incorporated resting boxes and aspirated the vegetation. Comparing these methods, we did not find differences in the proportions of blood-fed mosquitoes caught with the BG-Mosquitaire and Gravid traps, but the resting boxes and the aspiration got a higher proportion of them, although the total number of mosquitoes was higher with the traps.

a) BG-Mosquitaire trap upgraded with dry ice; b) CDC-Gravid trap; c) Aspiration of resting mosquitoes; d) Resting box. Pictures by Freya Townsend.

喂养活动

抽血区域的血液供给蚊子的分布并不平等;可以预期捕获更多蚊子的地区将具有更高的血液喂养比例,但情况并非总是如此,因此有些东西在动物园的某些部分中吸引蚊子喂养更多。同样,蚊子喂养的活动在本赛季不一样,夏季较高。通过广义的线性建模,我们发现温度与蚊虫喂养活性的增加有关,这是预期的,随着温度对蚊虫生理产生强烈影响。

血腥蚊子的比例

The mosquitoes’ menu: feeding choices

我们使用了一个条形码技术来分析蚊帐内的DNA,并将数据库中的序列匹配以识别脊椎动物宿主。从640枚血腥的蚊子中,我们陷入了总共抓住,我们发现了从159个蚊子的脊椎动物主持人。这些代表了74只鸟,71人和20个非人类哺乳动物。居民鸟类,如欧亚山羊(Corvus Monedula.)和theEurasian magpie (Pica pica), were a popular choice, although zoo birds such as theSchalow’s turaco (Tauraco schalowi)Humboldt penguin (Spheniscus humboldti)和zoo non-human mammals like theBactrian camel (Camelus bactrianus.)Eld’s deer (Rucervus eldii thamin)也在菜单中。

Culex.pipiens., our most abundant mosquito, prefers to feed on birds andCuliseta Annulata.(the second most common one) prefers mammals, which corresponds with their natural preferences. However, we found manyCX。pipiens.在人类上喂养,这是在此之前描述但不是这样的比例。

Blood-fed Culex pipiens

CX。pipiens.属于一个非常相似的蚊子的复杂形态;例如,SympaTricCX。Torrentium.看起来也是如此,可以通过解剖男性的生殖器来区分。进一步调查,我们使用PCR技术以精确度识别,并确认它们都是CX。pipiens.。同样,该物种具有两种生物型或形式,CX。pipiens.pipiens.CX。pipiens摩擦,第一个宁愿在人类上喂食鸟类和第二个。我们怀疑我们抓到了一些molestus,但情况并非如此。因此,似乎大量的访客(彻斯特动物园收到超过200万美元)可能会影响蚊子喂养模式。这代表了对人和动物园脊椎动物的潜在传输风险Culex.SPP。是野生鸟类托管的病毒的载体,如西尼罗河病毒(WNV),Sindbis virususutu病毒

此外,我们发现混合血液膳食,表明蚊子送入了两个主持人;在所有情况下,涉及一只鸟类,在包括人类的那些与欧亚喜鹊等人,这是一个经过验证的WNV自然水库。

在切斯特动物园的一些蚊子的最小行驶距离。橙色圈子:抽样区域;红色区域:动物展品;虚线:距离。

在喂散席后

了解动物园脊椎动物的位置我们可以估计动物展品之间蚊子之间的最小行驶距离以及它们被捕获的位置。在动物展览中,三分之一的蚊子在50米范围内捕获,其中一半在100米范围内,这表明捕获蚊子更接近他们的饲养源的机会。尽管如此,我们也发现蚊子喂养我们假设的家畜来自附近的住宅和农场,因此蚊子可能比我们观察到的最大值更远(367米)。

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