The Asian Tiger Mosquito, Aedes albopictus, is one of the most dangerous known invasive species (Scholte et al. 2007). They originated in Southeast Asia and have since spread worldwide to almost every continent where the climate is suitable (Rochlin et al. 2013). They are an arthropod and are one of the most abundant species within their phylum (Rochlin et al. 2013). Due to a multitude of traits, such as being able to survive in various climates, having drought-resistant eggs, and carrying various deadly diseases, the Asian Tiger Mosquito has a widespread invasive range and has a large effect within it. They hurt the human population by spreading deadly diseases and viruses and they outcompete and lower the abundance of other mosquitos which creates the need in implement control measures, such as using insecticides, source reduction, educating the public, and sterile insect technique.
The Asian Tiger Mosquito can be found on every continent besides Antarctica, where the climate is too harsh for the species to survive (Rochlin et al. 2013). In the United States specifically, there is a large population of the species in the Northeast and that number is going to increase as the climate changes and the environment allows for the species to spread throughout the country (Rochlin et al. 2013). Within the United States, as the climate warms, the range of the species will expand but that is not the same for Europe (Caminade et al. 2012). As climate changes in Europe, the range of the species won’t necessarily expand, the range will most likely move north. The species will start having a hard time being invasive in southern Europe and an easier time becoming invasive in northern Europe (Caminade et al. 2012). The reason for this change is due to the increase in warmer temperatures, the species will become more suitable in northern habitats (Caminade et al. 2012). Since the species can integrate into unique regions with varied climates, they become successful because they do not have preexisting predators (Caminade et al. 2012). Without predators the species flourish and spread their larvae throughout the region and as climates change, they start to spread to more and more environments without resistance (Rochlin et al. 2013).
After finding evidence of the species becoming introduced in Germany and then tracked over Europe, it was found that vehicle transportation, such as ground transportation and the trade of goods, is a main way that the species can move to northern Europe (Kampen et al. 2013). Aside from tracking and catching the Asian Tiger Mosquito in their process of integrating into new environments, finding the presence of the species larvae is another way to find regions in which the species resides. Within Italy and Switzerland, scientists have found evidence of the species larvae spread throughout the countries by using ovitraps (Suter et al. 2015). The reason that larvae is being found is because the Asian Tiger Mosquito has drought-resistant eggs (Caminade et al. 2012). This means that they are able to lay eggs pretty much anywhere because the eggs do not lose much water. With not having restriction to where they lay eggs, the species is able to spread their eggs by laying them on trains or other modes of transportation (Caminade et al. 2012). This allows the eggs to spread to other regions and when international trade increased, so did the spread of the Asian Tiger Mosquito (Caminade et al. 2012). While the species continues to spread worldwide, they bring with them various deadly diseases.
The trait that makes the Asian Tiger Mosquito one of the most dangerous invasive species is that they are a main vector for diseases such as dengue and chikungunya (Rochlin et al. 2013). Since the Asian Tiger Mosquito is such a successful vector for these diseases, it is a main reason that the species is so successful in its invasions. When these diseases are not common in areas where the species is invasive, it creates human health risks (Rochlin et al. 2013). The effect on the human population can vary but in regions where the Asian Tiger Mosquito recently invaded, the effects are harsher because those diseases are new to the region so there are no preexisting preventative measures (Goubert et al. 2016). The Asian Tiger Mosquito has been the catalyst of dengue outbreaks, one specific case is in Italy in 2007 (Labbe et al. 2010). Various other outbreaks have occurred due to Asian Tiger Mosquitos such as in La Reunion in 1977-1978 and in 2004 and in Hawaii in 2001-2002 (Medlock et al. 2012). More severe than dengue, chikungunya can affect the human population with more life-threatening cases caused by harsher fevers and more debilitating symptoms. Chikungunya outbreaks in La Reunion Island in 2005-2007 and in France in 2010 have all occurred thanks to the vector ability of the Asian Tiger Mosquito (Medlock et al. 2012). Also, it has been found that chikungunya carried by the Asian Tiger Mosquito, can mutate which can make the disease more deadly and catastrophic (Goubert et al. 2016). Aside from the known diseases, the Asian Tiger Mosquito has been found to have the ability to spread other viruses, such as the Zika virus, which has led to the more recent Zika outbreaks (Goubert et al. 2016). Another virus that the Asian Tiger Mosquito has been found to spread is Dirofilaria. It is a disease that is mostly spread to dogs but has also been found to have an effect is humans (Medlock et al. 2012). Human health is one of the entities most effected by the Asian Tiger Mosquito and it is due to the diseases the mosquitos carry with them. Aside from effecting the human population within its invasive range, the Asian Tiger Mosquito outcompetes and lowers the abundance of other mosquitos.
Of the many continents that the Asian Tiger Mosquito has invaded, the southern part of the United States, Florida in particular, has seen an increase in the population (Lounibos et al. 2001). A reason for that increase is that the species has been out competing similar species that are both invasive and native but have resided in the region before the Asian Tiger Mosquito (Lounibos et al. 2001). One of those species, Aedes aegypti, has seen a tremendous decline in abundance within Florida and that is the direct result of the Asian Tiger Mosquito integrating into their environment (Lounibos et al. 2001). This is not the only case, another example is with the Eastern Treehole Mosquito, Aedes triseriatus, which is native to Florida and resides in tires, cemetery vases, and treeholes (Lounibos et al. 2001). Similar to the Eastern Treehole Mosquito, the Asian Tiger Mosquito likes to reside in the same shelters, which as a result has lowered the amount of Eastern Treehole Mosquitos that reside in both used tires and cemetery vases. Even though the Asian Tiger Mosquito does not initially reduce the population of the Eastern Treehole Mosquitos that reside in treeholes, they over crowd the species making it hard for the species to flourish and survive (Lounibos et al. 2001). By the Asian Tiger Mosquito overcrowding the Eastern Treehole Mosquito within treeholes, they have reduced the number of pupae produced by the Eastern Treehole Mosquito over time. While the number of pupae was reduced, the Asian Tiger Mosquito was able to develop a larger presence within those same treeholes which overtime could result in the Asian Tiger Mosquito taking over the Eastern Treehole Mosquito within its native habitats (Lounibos et al. 2001). While the Asian Tiger Mosquito continues to spread its invasive range with its successful traits, they continue to spread deadly diseases and outcompete other mosquito species which results in a variety of control measures being implemented.
Due to the fact that the Asian Tiger Mosquito is one of the most abundant mosquito species and one of the most dangerous, control measures are being put in place in order to stop the spread of the species and prevent further disasters (Scholte et al. 2007). Various different kinds of insecticides are being used in order to kill the species and prevent the species from growing in population and becoming even more invasive (Medlock et al. 2012). Methoprene and diflubenzuron are both types of insecticides that can be used on both adult mosquitos and mosquito larvae (Medlock et al. 2012). Although both of these insecticides are proven to be effective, trying to apply them to the mosquitos is a challenge in itself due to the varying range of shelters the Asian Tiger Mosquito can reside in (Medlock et al. 2012). Another type of insecticide is pyrethrin and it can be used to spray indoor living spaces in order to prevent the mosquitos from breeding within a person’s home (Medlock et al. 2012). Relating back to La Reunion in which outbreaks of dengue and chikungunya were caused by the Asian Tiger Mosquito, there was evidence found in which the mosquitos showed resistance to such insecticide as pyrethrin. They found a gene with a resistance allele which prevented pyrethrin from being effective against the Asian Tiger Mosquito (Medlock et al. 2012). Even though there have not been many cases in which the Asian Tiger Mosquito was resistant to insecticides, it is still a possibility and a reason they are so successful in invasions. Also, since the Asian Tiger Mosquito has drought-resistant eggs and have the ability to lay their eggs outside or on top of water, monomolecular films could be used. They stop the larvae from being on the surface of water which ends up killing the eggs (Medlock et al. 2012). Even though the monomolecular films are effective for the mosquito’s eggs, they are not as effective for adult mosquitos. Another measure that is being used against the spread of the Asian Tiger Mosquito larvae is the reduction of sources in which the eggs can survive (Medlock et al. 2012). This technique is overly challenging though, since the mosquito can lay eggs on a diverse group of surfaces, it is near impossible to reduce all of them. It has been shown that even though there are various techniques in order to limit the spread of the Asian Tiger Mosquito, there are just as many issues with those techniques. That is why informing the public about health risks and trying to create new techniques are the next preventative steps.
Informing people about the health risks associated with the Asian Tiger Mosquito is the first step but it does not stop there. Just by informing people about risks the species can cause is a good way to prevent contact between humans and the mosquitos, but more must be done (Medlock et al. 2012). People need to be informed about the habitats in which the species can reside in which can allow people to avoid those areas such as trash cans and water storage containers (Medlock et al. 2012). Also, people should be informed about areas where the mosquitos can lay eggs around a person’s home in order for people to prevent the species from spreading and increasing its population size. By knowing about the risks the mosquitos can cause, the areas where the mosquitos can live and lay eggs, and how to prevent areas around a person’s home from becoming a potential breeding site, people can start to decrease the spread of the Asian Tiger Mosquito and lower its abundance (Medlock et al. 2012). Even though informing the public about associated risks of the mosquito is a good control method, scientists are still trying to find and create new ways to eliminate the species.
Sterile insect technique is one of the new methods that has been under development in the fight against the Asian Tiger Mosquito (Medlock et al. 2012). There are many ways to go about this technique, but one example is that they produced a male mosquito with a gene that limits wing production. When the mosquito then mates with females they create offspring that cannot use their wings and fly, which entails that the offspring will not survive for long (Medlock et al. 2012). Then the mosquito with the genetic mutation would get introduced into a population which would overtime reduce the population of the mosquito in that area (Medlock et al. 2012). There have not been many studies in which the sterile insect technique has been used in a large wild mosquito population, but scientists are so far happy with the results they are seeing and hope to establish this technique as a successful new approach in the fight against the Asian Tiger Mosquito (Medlock et al. 2012). Since the species is so successful in its invasion and one of the most abundant mosquito species, multiple methods should be put in place in order to control the mosquito.
All in all, the Asian Tiger Mosquito is successfully invasive on almost every continent due to its unique traits such as having a wide climate tolerance, having drought-resistant eggs, and carrying various deadly diseases. Those traits then lead to the species having a large effect within its invasive range by hurting the human population by spreading diseases and by outcompeting and lowering the abundance of other mosquito species which leads to control measures like insecticides, source reduction, educating the public, and sterile insect technique being put in place. The Asian Tiger Mosquito is a unique invasive species owing to the fact that they effect human and other organism populations more severely than they effect the habitats they invade.
Works Cited
Caminade, C., J. M. Medlock, E. Ducheyne, K. M. McIntyre, S. Leach, M. Baylis, A. P. Morse. 2012. Suitability of European climate for the Asian tiger mosquito Aedes albopictus: recent trends and future scenarios. Journal of the Royal Society Interface 9(75): 2708-2717.
Goubert, C., G. Minard, C. Vieira, M. Boulesteix. 2016. Population genetics of the Asian tiger mosquito Aedes albopictus, an invasive vector of human diseases. Heredity 117:125-134.
Kampen, H., M. Kronefeld, D. Zielke, D. Werner. 2013. Further specimens of the Asian tiger mosquito Aedes albopictus (Diptera, Culicidae) trapped in southwest Germany. Parasitology Research 112: 905-907.
Labbe, G. M., D. D. Nimmo, L. Alphey. 2010. piggybac- and PhiC31-mediated genetic transformation of the Asian tiger mosquito, Aedes albopictus (Skuse). PLoS Neglected Tropical Diseases 4(8): e788.
Lounibos, L. P., G. F. O’Meara, R. L. Escher, N. Nishimura, M. Cutwa, T. Nelson, R. E. Campos, S. A. Juliano. 2001. Testing predictions of displacement of native Aedes by the invasive Asian tiger mosquito Aedes albopictus in Florida, USA. Biological Invasions 3: 151-166.
Medlock, J. M., K. M. Hansford, F. Schaffner, V. Versteirt, G. Hendrickx, H. Zeller, W. Van Bortel. 2012. A review of the invasive mosquitoes in Europe: ecology, public health risks, and control options. Vector-Borne and Zoonotic Diseases 12(6): 435-447.
Rochlin, I., D. V. Ninivaggi, M. L. Hutchinson, A. Farajollahi. 2013. Climate change and range expansion of the Asian tiger mosquito (Aedes albopictus) in Northeastern USA: implications for public health practitioners. PLoS One 8(4): e60874.
Scholte, E. J., E. Dijkstra, H. Ruijs, F. Jacobs, W. Takken, A. Hofhuis, C. Reusken, M. Koopmans, A. de Boer. 2007. The Asian tiger mosquito (Aedes albopictus) in the Netherlands: should we worry? Proceedings of the Netherlands Entomological Society Meeting 18: 131-136.
Suter, T., E. Flacio, B. F. Farina, L. Engeler, M. Tonolla, P. Muller. 2015. First report of the invasive mosquito species Aedes koreicus in the Swiss-Italian border region. Parasites and Vectors 8(402).