The effects of climate change and globalization on mosquito vectors: evidence from Jeju Island, South Korea on the potential for Asian tiger mosquito (Aedes albopictus) influxes and survival from Vietnam rather than Japan

Abstract

Background: Climate change affects the survival and transmission of arthropod vectors as well as the development rates of vector-borne pathogens. Increased international travel is also an important factor in the spread of vector-borne diseases (VBDs) such as dengue, West Nile, yellow fever, chikungunya, and malaria. Dengue is the most important vector-borne viral disease. An estimated 2.5 billion people are at risk of infection in the world and there are approximately 50 million dengue infections and an estimated 500,000 individuals are hospitalized with dengue haemorrhagic fever annually. The Asian tiger mosquito (Aedes albopictus) is one of the vectors of dengue virus, and populations already exist on Jeju Island, South Korea. Currently, colder winter temperatures kill off Asian tiger mosquito populations and there is no evidence of the mosquitos being vectors for the dengue virus in this location. However, dengue virus-bearing mosquito vectors can inflow to Jeju Island from endemic area such as Vietnam by increased international travel, and this mosquito vector's survival during colder winter months will likely occur due to the effects of climate change.

Methods and results: In this section, we show the geographical distribution of medically important mosquito vectors such as Ae. albopictus, a vector of both dengue and chikungunya viruses; Culex pipiens, a vector of West Nile virus; and Anopheles sinensis, a vector of Plasmodium vivax, within Jeju Island, South Korea. We found a significant association between the mean temperature, amount of precipitation, and density of mosquitoes. The phylogenetic analyses show that an Ae. albopictus, collected in southern area of Jeju Island, was identical to specimens found in Ho Chi Minh, Vietnam, and not Nagasaki, Japan.

Conclusion: Our results suggest that mosquito vectors or virus-bearing vectors can transmit from epidemic regions of Southeast Asia to Jeju Island and can survive during colder winter months. Therefore, Jeju Island is no longer safe from vector borne diseases (VBDs) due to the effects of globalization and climate change, and we should immediately monitor regional climate change to identify newly emerging VBDs.

Figure 1. Mosquitoes sampling sites on Jeju Island.

Figure 2. Total abundance of females of Ae. albopictus.

Total abundance of females of Ae. albopictus at the sampling sites on Jeju Island (A) and monthly abundances of females of Ae. albopictus to the northern and southern areas of Jeju Island (B).

Figure 3. Total abundance of females of Cx. pipiens.

Total abundance of females of Cx. pipiens at the sampling sites on Jeju Island (A) and monthly abundances of females of Cx. pipiens to the northern and southern areas of Jeju Island (B).

Figure 4. Total abundance of females of An. sinensis

Total abundance of females of An. sinensis at the sampling sites on Jeju Island (A) and monthly abundances of females of An. sinensis to the northern and southern areas of Jeju Island (B).

Figure 5. Phylogenetic tree constructed based on the partial atypical OBP (A), ND5 (B), and COI (C).

The tree was constructed using the neighbor-joining method in MEGA4. YW (Youngwol), collected in the Southwest of the Korean Peninsula, GC (Gimcheon), collected in Southeast of the Korean Peninsula, YD (Yeongdo), collected in the south of the Korean Peninsula, Ho Chi Minh Vietnam, Singapore, Nagasaki Japan, AlbOBP67 USA, and French isolates are in bold. Each sample was identified as year-month-collection site. The OBP and ND5 sequences of 10-11-Bomok, which was collected in November 2010, and in a forest area of Seogwipo-city, were the same as those in the collect of Ho Chi Minh Vietnam.

Figure 6. OBP's nucleotide and amino acid sequences.

Alignment of OBP's nucleotide sequences (A) and OBP's amino acid sequences (B) about AlbOBP67 USA, Ho Chi Minh Vietnam, Nagasaki Japan, Singapore, 10-06-Bomok, 11-09-Youngwol (YW), 11-09-Yeongdo (YD), 10-09-Bomok, and 10-11-Bomok isolates.

Figure 7. Mean temperature and trend of seasonal temperature of Jeju Isalnd.

Mean temperature and trend of seasonal temperature of Jeju-city (A and B), Seogwipo-city (C and D), were recorded from 1970 to 2011.