In order to study the range of flight and feeding activity of
The number of vivax malaria, which was once regarded as eradicated from this country in late 1970s, has rapidly increased every year since 1993 in the northern part of Gyeonggi-do, Republic of Korea (
Understanding the dispersal patterns of vector mosquitoes in nature is essential to evaluating the risk of malaria transmission to human, implementing surveillance, and developing abatement strategies. It is known that malaria transmission is closely related to the population density and the flight range of the vector mosquitoes (
Despite many studies worldwide concerning the flight range of various species, the only study done in Korea has been with
In this study, we measured the flight range and patterns of
This study was conducted from 7th to 28th September 1998 in Paju city, where there had recently been re-emergence of malaria. The study area is located near the demilitarized zone (DMZ) between South Korea and North Korea. The study area covers rice paddy fields and roads among which small villages was scattered toward south-west (SW) and north-northwest (NNW). Many mountains are located on north-northeast (NNE), and Imjin- and Han-River are located to the north-west (NW). During the study period, the livestock census of the dispersal area were 1,647 cows and 9,483 pigs in Paju city, 1,915 cows and 12,697 pigs in Munsan-eup, 5,533 cows and 9,896 pigs in Beobwon-eup, and 668 cows and 7,110 pigs in Wollong-myeon. Many rice paddy fields and small villages were located within 1 km around the center of dispersal (
All weather conditions were obtained from Monthly Report of National Institute of Weather, and rainfall, wind speed and wind direction were recorded continuously at the release site.
We collected unfed females of
In order to recapture the marked females of
All light traps were set up outside of the cattle sheds and were operated from 18:00 to 06:00 for 21 successive nights after release. All captured mosquitoes were transported to our laboratory and
The period of dispersal experiment was from early to middle of September, and the climate of high temperature and humidity was influenced by high atmospheric pressure of North Pacific. The temperature was around upper 20℃ during this time, which was 1-3℃ higher than the annual average, but the number of rainy days and amount of rainfall were lower than usual. Although the wind blew openly toward southeast, wind condition of dispersal areas was not regular. The average velocity of the wind was 3 m/sec (
One hundred ninety four female mosquitoes were sorted according to the distance from the release site. 72 female mosquitoes (37.1%) were recaptured within 1 km from the release site, 57 mosquitoes (29.4%) in 1-3 km, 41 mosquitoes (21.1%) in 3-6 km, 20 mosquitoes (10.3%) in 6-9 km, and 4 mosquitoes (2.1%) in 9-12 km. Total 170 female mosquitoes (87.6%) out of 194 marked mosquitoes were recaptured within 6 km. It was therefore concluded that the main area of activity was within 6 km. 45 female mosquitoes (23.2%) were recaptured on the next day after releasing. one mosquito was captured in light trap which was set at 12 km from the release site. Until 20 days after the beginning of release, the released mosquitoes were captured, indicating that
To estimate the longest flight range, we had 2 light traps installed at 16 km and 20 km from the release sites (No. 14 and 15 of
Of the 12,773 released females of
In NNE direction, 8,975 female mosquitoes of
In SW direction, 19,809 female mosquitoes of
According to their recapture rate, the main direction of flight of
To clarify the origin, first we should elucidate the characteristics of Anopheline mosquitoes activity, because we have the buffering region called DMZ between North and South Korea, which are separated by 4 km. Therefore in order to study the flight range of female
We recaptured 194 marked female mosquitoes, showing 1.52% of the recapture rate. There have been some differences of the recapture rates depending on the aim of dispersal experiment, the species of mosquitoes and configuration of dispersal area. Reisen et al. (
Generally, movement of mosquito from one habitat to another is classified as being either active dispersal or passive dispersal. Active dispersal includes finding a resting place after bloodsucking, finding and mating place for fertilization, finding food such as nectar in the case of male mosquito, finding blood sources such as human or animals, and finding place for laying eggs in the case of female mosquito. On the other hand, passive dispersal is the movement of mosquito by ship, plane, train or wind. In the case of active dispersal, distances are different according to the species of mosquitoes.
Also, the number of livestock such as cows and pigs are higher in this area, and they influenced the movement of mosquitoes. It seemed that
Since 170 female mosquitoes (87.6%) out of 194 marked mosquitoes were captured within 6 km from the release point, this flight radius represents the main activity area.
This work was supported by a grant of
Map of the northern part of Gyeonggi-do, Korea showing the placement of black light traps used for the mark-release-recapture studies during 1999. White circle: release point; black circle: light trap point; quadrangle: distance from release site (km): demilitarized zone, DMZ.
Temperature and relative humidity for experimental period in the northern part of Gyeonggi-do, Korea, from 7th to 28th September, 1998.
The predominant direction of movement of marked female
Correlation between female
Dispersal range of recaptures of marked females of
Day after release | No. of |
Total | ||||
---|---|---|---|---|---|---|
1 km | 1-3 km | 3-6 km | 6-9 km | 9-12 km | ||
1 | 7 | 9 | 8 | 5 | 1 | 30 |
2 | 9 | 1 | 4 | 0 | 1 | 15 |
3 | 14 | 17 | 0 | 1 | 0 | 32 |
4 | 2 | 6 | 3 | 3 | 0 | 14 |
5 | 24 | 8 | 4 | 2 | 1 | 39 |
6 | 4 | 1 | 7 | 2 | 0 | 14 |
7 | 2 | 4 | 4 | 0 | 0 | 10 |
8 | 5 | 0 | 0 | 0 | 1 | 6 |
9 | 0 | 1 | 5 | 0 | 0 | 6 |
10 | 1 | 4 | 2 | 1 | 0 | 8 |
11 | 2 | 3 | 0 | 2 | 0 | 7 |
12 | 0 | 0 | 0 | 0 | 0 | 0 |
13 | 0 | 0 | 0 | 2 | 0 | 2 |
14 | 0 | 1 | 4 | 1 | 0 | 6 |
15 | 1 | 2 | 0 | 0 | 0 | 3 |
16 | 0 | 0 | 0 | 0 | 0 | 0 |
17 | 0 | 0 | 0 | 0 | 0 | 0 |
18 | 0 | 0 | 0 | 0 | 0 | 0 |
19 | 0 | 0 | 0 | 0 | 0 | 0 |
20 | 1 | 0 | 0 | 1 | 0 | 2 |
21 | 0 | 0 | 0 | 0 | 0 | 0 |
Total (%) | 72 (37.1) | 57 (29.4) | 41 (21.1) | 20 (10.3) | 4 (2.1) | 194 (100.0) |
Result of dispersal direction of recaptured
Direction | No. collected by light trap | Recovery rate (%) |
No. recaptured (Direction/194) (%) | Recaptured rate (%) |
---|---|---|---|---|
NNW |
27,208 | 0.42 | 114 (58.8) | 0.89 |
NNE |
8,975 | 0.43 | 39 (20.1) | 0.31 |
SW |
19,809 | 0.21 | 41 (21.1) | 0.32 |
Total | 55,992 | 0.35 | 194 (100.0) | 1.52 |
NNW: north-northwest toward; NNE: north-northeast; SW: south-west.
No. of recaptured/No. of total collected ×100.
No. of recaptured/No. of total released ×100.
Comparison of recapture rates of female
Distance (km) | No. of |
No. of marked mosquitoes recaptured |
Recovery rates (%) |
||
---|---|---|---|---|---|
Yellow (%) (6,439) |
Orange (%) (6,334) |
Total (%) (12,773) | |||
1 | 4,772 | 34 (0.53) | 9 (0.14) | 43 (0.34) | 0.90 |
3 | 5,208 | 18 (0.28) | 8 (0.13) | 26 (0.20) | 0.50 |
6 | 5,863 | 6 (0.09) | 20 (0.30) | 26 (0.20) | 0.44 |
9 | 10,410 | 7 (0.11) | 11 (0.17) | 18 (0.14) | 0.17 |
12 | 955 | 1 (0.02) | 0 (0.0) | 1 (0.01) | 0.10 |
Total | 27,208 | 66 | 48 | 114 | 0.42 |
Recapture rate (%) |
1.03 | 0.76 | 0.89 |
No. of
No. of
No. of recaptured/No. of total collected ×100.
No. of recaptured/No. of total released ×100.
Comparison of recapture rates of female
Distance (km) | No. of |
No. of marked mosquitoes recaptured |
Recovery rates (%) |
||
---|---|---|---|---|---|
Yellow (%) (6,439) |
Orange (%) (6,334) |
Total (%) (12,773) | |||
1 | 1,746 | 9 (0.14) | 3 (0.05) | 12 (0.09) | 0.69 |
3 | 4,053 | 4 (0.06) | 5 (0.09) | 9 (0.07) | 0.22 |
6 | 1,085 | 3 (0.05) | 10 (0.16) | 13 (0.10) | 1.20. |
9 | 1,640 | 0 (0.00) | 2 (0.03) | 2 (0.02) | 0.12 |
12 | 451 | 1 (0.02) | 2 (0.03) | 3 (0.02) | 0.67 |
Total | 8,975 | 17 | 22 | 39 | 0.43 |
Recapture rate (%) |
0.26 | 0.35 | 0.31 |
No. of
No. of
No. of recaptured/No. of total collected ×100.
No. of recaptured/No. of total released ×100.
Comparison of recapture rates of female
Distance (km) | No. of |
No. of marked mosquitoes recaptured |
Recovery rates (%) |
||
---|---|---|---|---|---|
Yellow (%) (6,439) |
Orange (%) (6,334) |
Total (%) (12,773) | |||
1 | 5,689 | 7 (0.11) | 10 (0.16) | 17 (0.13) | 0.30 |
6 | 12,855 | 8 (0.12) | 14 (0.22) | 22 (0.17) | 0.17 |
9 | 1,265 | 0 (0.00) | 2 (0.03) | 2 (0.02) | 0.16 |
Total | 19,809 | 15 | 26 | 41 | 0.21 |
Recapture rate (%) |
0.23 | 0.41 | 0.32 |
No. of
No. of
No. of recaptured/No. of total collected ×100.
No. of recaptured/No. of total released ×100.
Weather condition and the number of female
Parameter | Direction |
|||
---|---|---|---|---|
NNW |
NNE |
SW |
||
Weather | Rainfall (mm) | 123 | 115.4 | 177.9 |
Wind direction | ENE |
ENE | NNW | |
Wind speed (m/s) | 1.6 | 1.3 | 1.8 | |
No. of large animal reared | 2,954 | 2,585 | 643 | |
No. of total females captured | 27,208 | 8,975 | 19,809 | |
No. of positive recaptured (%) | 114 (58.8) | 39 (20.1) | 41 (21.1) |
NNW = north-northwest.
NNE = north-northeast.
SW = south-west.
ENE = east-northeast.