Kagoshima University Research Center for the Pacific Islands Occasional Papers No.39, 111-114, 2003
Section 3, Report 5. The Progress Report of the 2000 and 2001 Survey of the Research Project“Social Homeostasis of Small Islands in an Island-zone”

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A SURVEY OF THE MOSQUITO FAUNA IN ULITHI ATHOL, YAP STATE,FEDERATED STATES OF MICRONESIANODA Shinichi1) and John GILMATAM2)

Abstract
Surveys of larval mosquitoes were carried out in four Islands of Ulithi Athol, Mogmog, Falalop
Asor, and Fassarai, in October 2001. Larval mosquitoes were collected at 56 habitats which are composed of coconut shells, cans, plastic vessels, metal vessels, a ceramic vessel, a plastic bucket, a shell,a tuckerbox, plastic water barrels, metal water barrels and a concrete water tank. Only two mosquito
species, Aedes (Stegomya) hensilli and Culex (Culex) quiquefasciatus, were collected at various artificial habitats of four islands.
Keywords: mosquito fauna, Aedes hensilli, Ulithi Athol, Federated States of Micronesia

Introduction
The most important group of biting insect is the mosquitoes. Their biting is a considerable
nuisance in many parts of the world. More importantly, mosquitoes are carriers of a number ofdiseases, mostly in the tropics, causing illness and death on a large scale. Dengue fever is causedby several closely related viruses, called dengue types 1, 2, 3 and 4. The disease is transmitted
from person to person mainly by Aedes aegypti, but Aedes albopictus can also act as a vector.
Two forms of the disease occur: dengue fever and dengue haemorrhagic fever. The disease isprevalent in the tropics and subtropics, particularly in Southeast Asia. The World HealthOrganization estimates that 2000 million people are at risk. Each year there are millions of infections and thousands of deaths. Recently, a dengue fever/dengue haemorrghagic fever outbreak in
Yap State caused by dengue-4 virus was confirmed serologically and by virus isolation fromserum samples. And entomologic investigations implicated the native mosquito species, Aedes
hensilli as a previously unrecognized epidemic vector of dengue viruses (S AVAGE et al. 1998).
We report here the fauna and breeding sites of mosquitoes in Ulithi Atoll, Yap State, Federated
States of Micronesia.

Materials and Methods
Surveys of larval mosquitoes were carried out in four Islands of Ulithi Athol, Mogmog,Falalop, Asor, and Fassarai, on October 2001. Larval mosquitoes were collected at 56 habitats
which are composed of coconut shells, cans, plastic vessels, metal vessels, a ceramic vessel, aplastic bucket, a shell, a tuckerbox, plastic water barrels, metal water barrels and a concretewater tank. Collected larvae were preserved in 70% ethanol for the identification.

1)
2)

Kagoshima University Research Center for the Pacific Islands. Kagoshima 890-8580, Japan.
Department of Health Services, Yap State Government, P. O. Box 148, Colonia, Yap 96943, FSM.

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NODA Shinichi and John GILM ATAM

Results and Discussion
Table 1 presents the result of the mosquito collection. Only two mosquito species, Aedes(Stegomya) hensilli and Culex (Culex) quiquefasciatus, were collected at various artificial habitats of four islands. Four hundred seventy-three larvae of Ae. hensilli were collected from 51
habitats: coconut shells, cans, plastic vessels, metal vessels, a plastic bucket, a shell, a tuckerbox,
plastic water barrels, and metal water barrels (Fig. 1). One hundred eighty-five Cx.
quiquefasciatus were collected from 9 habitats; a ceramic vessel, a plastic vessel, a metal vessel,
a tuckerbox, plastic water barrels, metal water barrels and a concrete water tank (Fig. 1).
Aedes larvae are container-breeders which thrive in both clean and organically rich water inboth natural and artificial containers. On four islands, larvae of Ae. hensilli were collected fromvarious sizes of artificial container. There are few natural habitats of mosquito larvae on the fourislands. Mosquito larvae were not collected from the taro patch on Mogmog Island. Entomologic
investigations implicated Ae. hensilli as a vector of dengue viruses (S AVAGE et al. 1998). For theprevention of dengue fever outbreak, the container management to reduce the sources of breeding habitats is one of the best approaches. If the containers are consider to be useless or nonessential, removal and destruction is desirable. If the population considers the containers to beuseful or essential, the strategy employed will be the prevention of Aedes breeding in containers
rather than the destruction or removal of the containers. These programmes should be conductedconcurrently with health education programmes and communications to encourage community
participation in the planning, execution and evaluation of container-management programmes(e.g. regular household sanitation or clean-up campaigns) (WHO 1997).

References
SAVAGE, H. M., C. L. FRITZ, D. RUTSTEIN, A. Y OLWA, V. V ORNDAM, and D. J. G ULBLER. 1998.
Epidemic of Dengue-4 Virus in Yap State, Federated States of Micronesia, and Implicationof Aedes hensilli as an Epidemic Vector. Am. J. Trop. Med. Hyg. 59: 519–524.
WHO. 1997. Dengue Haemorrhagic Fever: Diagnosis, Treatment, Prevention and Control. 84
pp. Geneva: World Health Organization.

A SURVEY OF THE MOSQUITO FAUNA IN ULITHI ATHOL, YAP STATE, FEDERATED STATES OF MICRONESIA 113

Table 1. Number of mosquitoes collected in islands of Urithi Athol
IslandMogmog

Larval Habitat
A. h.
coconut shell1
coconut shell3
coconut shell5
coconut shell9
coconut shell
17
can4
plastic vessel
1plastic vessel
1
ceramic vessel
metal vessel
32
plastic water barrel
9
metal water barrel
2
metal water barrel
6
metal water barrel
8
Falalopcoconut shell3
coconut shell13
coconut shell
15
coconut shell
16
coconut shell
31
plastic vessel
1plastic vessel
2
metal vessel
metal vessel
plastic water barrel
5
metal water barrel
1
Asorcoconut shell1
coconut shell1
coconut shell2
coconut shell2
coconut shell5
coconut shell
15
coconut shell21
coconut shell
41
plastic vessel
1plastic vessel
1
metal vessel
2tuckerbox
3
metal water barrel
1
metal water barrel
Fassaraicoconut shell1
coconut shell
5coconut shell8
coconut shell
9coconut shell
10coconut shell
19
coconut shell
62
can
1can
6can23shell
9plastic vessel
1plastic vessel
20
plastic bucket
15
plastic water barrel
1
metal water barrel
2
concrete water tankA. h.: Aedes (Stegomya) hensilli
C. q.: Culex (Culex) quinquefasciatus

C. q.

3
7

1130
34
32

48
1

19

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NODA Shinichi and John GILM ATAM

Fig. 1. Larval habitats in Ulithi Athol; (a) coconut shell, (b) can, (c) plastic vessel,(d) plastic water barrel, (e) metal water barrel, (f) concrete water tank.