Let’s talk about the Asian tiger mosquito!

Heinrich Damm - CC BY-SA 3.0
Heinrich DammCC BY-SA 3.0

Imagine the busy streets of Bangkok during the winter. The streets are similar to that of Times Square in NYC, but with more motorcycles and open sewage systems. You might imagine a lot of standing water, which are the breeding grounds for mosquitoes. That was my experience of Bangkok in the 6th grade. I stayed in an apartment in the city with my family and I would have mosquito bites all over my body at the end of each day. At the time I didn’t realize that mosquitoes have the potential to transmit diseases, but once I started taking more biology courses in High school I realized that the tropics have prime real-estate for mosquito growth and that trip to Thailand really piqued my interest in biology and diseases.

James Gathany/CDC - Public Domain
James Gathany/CDC Public Domain

With the outbreak of Zika primarily in the Americas in April 2015 in Brazil, there have been concern over whether the United States can harbor such a debilitating vector of Zika virus.  You might have heard of the Aedes aegypti, but this is the Asian tiger mosquito. You may also see it presented in the scientific literature as Aedes albopictus. It has the prefix of Aedes, and you might be thinking that they’re related to the aegypti, and you are right! They are of the same genus in the binomial nomenclature. In a piece written by the Morning Call, they have ruled out Aedes aegypti as a possible endemic mosquito to transmit Zika in the Lehigh Valley. But is Pennsylvania off the hook?

 

 

Dennis Punyodyana - [2016]
Dennis Punyodyana – [2016]

 

 

 

 

 

 

albopictus
Dennis Punyodyana [2016]

 

 

 

 

 

 

In a recent article published in the past month, the Morning call notes that “We do need to pay attention to the Asian tiger mosquito… it has evolved the ability to survive our winters.”The fact that it is capable of adapting to the winter ties into what the character Dr. Ian Malcolm in Jurassic park states “Life breaks free, it expands to new territories and crashes through barriers, painfully, maybe even dangerously” You might be asking what brought these mosquito over and many government and educational websites have been citing that the Asian tiger mosquito entered the U.S. from shipments from northern Asia in the mid-1980s and is capable of surviving in a broad array of climates.

© Brady et al. - Open Access article
© Brady et al. – Open Access article

Published in 2014, the journal Parasite Vectors explains the constraints that Global temperature has on Aedes aegypti and Ae. Albopictus. Temperature was related to the transmission potential of dengue fever. Their discussion section of their paper states that the Ae. albopictus has adapted its immature stages to local environments to allow it to persist long in winters in Europe and the USA. The paper also mentions that Ae. albopictus eggs can undergo long period of diapause that allow populations to persist in temperate environments, like Pennsylvania, that are unsuitable for adult survival. Diapause refers to the animal dormancy which an animal undergoes in response to adverse environmental conditions. Now that we have looked at potential ways that mosquitos transmit diseases, it’s important to look at how it is able to be controlled.

But, considering its potential to migrate, does the Asian Tiger mosquito have the potential to to spread to the U.S.?  Only the females require a blood meal to develop eggs. It is also capable of transmitting pathogens such as Yellow fever virus, Dengue fever, and Chikungunya fever.  A brief summary of those mosquito borne diseases can be found here. Looking in the scope of the Zika outbreaks, we know that viruses cannot survive within mosquitos as a host. Rather, they have coevolved with these mosquitos and avert being destroyed by a mosquito’s immune system. Viruses and other pathogens can go through the tract of the mosquito and find a way to advert the mosquito immune system. The black arrows represent the direction that the virus might travel through the mosquito tract. In the process of following that tract, the pathogen can make its way off its projected path instead of being destroyed by the mosquito immune system.

It is also capable of transmitting pathogens such as Yellow fever virus, Dengue fever, and Chikungunya fever.  A brief summary of those mosquito borne diseases can be found here. Looking in the scope of the Zika outbreaks, we know that viruses cannot survive within mosquitoes as a host. Rather, they have co evolved with these mosquitos and avert being destroyed by a mosquito’s immune system. Viruses and other pathogens can go through the tract of the mosquito and find a way to advert the mosquito immune system. The black arrows represent the direction that the virus might travel through the mosquito tract. In the process of following that tract, the virus can make its way off its projected path instead of being destroyed by the mosquito immune system.

In terms of mosquito control in addition to other methods, there are special compounds very specific to ONLY insect reproduction and their life cycle. They are called juvenile hormone analogs and are of relatively low toxicity to humans. There are efforts to place these in water supplies across the globe to prevent these mosquitos from reproducing. Its chemical name is called Methprene. It affects the lifecycle of the mosquito by preventing it from having this vital time in its reproduction cycle. It is the time in which the steroid hormone ecdysone is released in a small amount in the absence of juvenile hormone. The way the analog works is by never giving that mosquito larvae the chance to have that commitment peak by having the always the juvenile hormone present.

With all that in consideration, should we ignore the Asian tiger mosquito? No. The Asian Tiger mosquito has many unique characteristics different from that of Aedes agypti. It shoudl definately be studied but also worried about. Mosquitos shouldn’t ruin your day if you get bitten many times like I have. You should take your misfortunes and use them as a way to get inspired to get curious and get informed. Sometimes new experiences are good even if they make you uncomfortable like traveling in a tropical place. It shouldn’t deter you from flying abroad!

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