Climatic Factors and Mosquito Species in Rural and Urban Areas
at Kantharom District, Srisaket Province
Student: JirasukChai-Chana, Srisaket Province
School: KantharomSchool, Kantharom District, Srisaket Province, Thailand.
Scientists: KrisanadejJaroensutasinee, Mullica Jaroensutasinee, SiriwanWongkoon
School of Science, Walailak University, Nakhon Si ThammaratProvince, Thailand.
- The Public Health Department reported that the number of dengue Fever patients in Srisaketprovince was highest in the North Eastern Thailand(Public Health Department online 2009). There was hypothesized that the climatic factors of the air temperature, relative humidity and the amount of rainfall were the major affected factors on the increasing of the numbers and species of dengue fever mosquito larvae. These were also informed facts that during summer, especially in the April with very high temperature and very dry humidity, the number of dengue Fever mosquito larvae were very high. Those facts lead to the purpose of this study to compare the relationships of climatic factors and mosquito species between rural and urban areas in Kantharom district, Srisaket province were specified by GLOBE standardized protocol (http://www.globe.gov/). From May 2009 to October 2010, the air temperature, relative humidity and the amount of rainfall were collected from the Srisaketmeteorological department, the species and number of mosquito larvae, Aedesspp. (Aedesaegypti and Aedesalbopictus), Anopheles spp., and Culexspp.at each study site were identified by GLOBE-based IPST mosquito standardized Protocol (http://www.globe.gov). The relationships among climatic factors and the number of mosquito larvae were identified by House Index, Container Index and Breteau Index. It was found that at the urban area, there were 2 genus of mosquito larvae, Aedesspp. and Culexspp.were found. Within the Aedesspp., the Aedesaegypti and Aedesalbopictus were found. At the Rural area, the 3 genus of mosquito larvae, Aedesspp.,Culexspp. And Anopheles spp. were found. At both urban and rural areas, the Aedesalbopictuswere found most in July 2009, the Culexspp. were found most in October 2009. The number of mosquito larvae at both Urban and Rural areas decreased with time. The decreasing of the Aedesalbopictus to the least number at the urban area might be inferred to the more encouragement of taking good care of the environment to be more clean, not suitable for mosquitoes to lay eggs at the urban area.
- In 2009, the number of dengue fever patients was highest in the North Eastern Thailand. This research examined the effects of climatic factors (air temperature relative humidity and the amount of rainfall) on the number and species of mosquito larvae, at the more crowed and less clean at the urban area and at the less crowed and cleaner rural area in Kantharom District, Srisaket Province.
- Are there some differences between climatic factors and the number of mosquito larvae in urban and rural areas at Kantharom District, SrisaketProvince?
- Research Hypothesis
- If there are some differences in climatic factors in urban and rural areas, then this should cause some differences in the number of mosquito larvae between these two areas.
- Materials and Methods
- Data Collection
- We collected monthly mosquito larvae from 53 sites from urban and rural areas in Kantharom District, Srisaket Province using GLOBE Standardized Protocol (http://www.globe.gov/) during May 2009 to October 2010 and identified up to species level by using GLOBE-based IPST mosquito standardized Protocol (http://www.globe.gov/).
- Climatic factors (ie. air temperature, relative humidity, rainy days and the amount of rainfall) were obtained from the Srisaketmeteorological department over the same period.
- House, Container and BreteauIndices were calculated and the linear regression tests were used to find some association between climatic factors and the number of mosquito larvae.
- We feel very much appreciate for the very kind contribution of Mr.SatapisuchKraisri working with us as the teacher advisor and feel so grateful to the patient and valuable advices of Dr. KrisanadejJaroensuthasinee, Dr. Mullica Jaroensuthasinee, Miss SiriwanWongkul, Scientist advisors, School of Science, Walailak University. We also feel thankful to the GLOBE project, The Institute for the Promotion of Teaching Science and Technology for research funding supports and research advices.
- S.C. Tewari, V. Thenmozhi, C. R. Katholi, R. Manavalan, A. Munirathinam and A. Gajanana. (2004). Dengue vector prevalence and virus infection in a rural area in south India. Tropical Medicine and International Health 9(4): 499-507.
- S. Wongkoon, M. Jaroensuthasinee and K. Jaroensuthasinee. (2011). Climatic variability and dengue virus transmission in Chiang Rai, Thailand. Biomedica 27: 5-13.
- S. Thammapalo, V. Chongsuwiwatwong, D. McNeil and A. Geater. (2005).
- The climatic factors influencing the occurrence of dengue hemorrhagic fever in Thailand. Southeast Asian J Trop Med Public Health, 36 (1) , 191-196.
- P.-C. Wu, H.-R. Guo, S.-C. Lung, C.-Y. Lin, H.-J. Su. (2007). Weather as an effective predictor for occurrence of dengue fever in Taiwan. ActaTropica 103: 50–57.
Figure 1. number of a) Ae. aegupti, b) Ae. albopictus and c) Culexspp. found that at both urban () and at rural () areas in KantharomDistrict, Srisaket Province during May 2009 to October 2010.
Figure 2. a) House Index b) Container Index and c) Breteau Index mosquito larvae during May 2009 to October 2010.
Figure 3. Max/min temperature in Kantharom area during May 2009 to October 2010.
Figure 4. The amount of rainfall in Kantharom Area Srisaket Province during May 2009 to October 2010.
Figure 6. The number of dengue fever patients at urban ()and at rural ()areas during May 2009 to October 2010.
Figure 5. Max/min relative humidity in Kantharom area during May 2009 to October 2010.
Figure 7. a) The relationship of the number of rainy days and the number of Ae. aegyptilarvae.
- b) The relationship of the number of rainy days and the number of dengue incidences.
Conclusion and Discussion
Aedesspp. and Culexspp. were found in both rural and urban areas but Anopheles spp. only found at rural area. Aedesaegypti and Ae. albopictus were found most in July 2010, but Culexspp.was found most in October 2010 (Figure 1a-c). The number of Culex spp. was higher than Ae. aegyptiand Ae. albopictus(Figure 1 a-c). There was higher numbers of mosquito larvae in rural area than in urban area (Figure 1a-c). In addition, there was more Culex larvae found in the rural area (Figure 1a-c). This is not surprising because many studies Wongkoon et al. (2009, 2010, 2011), have been reported that rural areas have more suitable habitats for Culex spp.
As the number of rainy days increased, the number of Ae. aegyptiand the number of dengue incidences increased (Figure 7a,b). This strongly indicated that climatic factors (in this case, the number of rainy days) strongly influences the number of mosquito larvae. The increases in the number of mosquito larvae will increase the chance of dengue vectors to transmit the dengue virus at a higher rate. Moreover, during rainy days, people tend to stay inside their houses which may also increase the chance of being bitten by Ae. aegypti females. As we already know that Ae. aegyptitends to stay inside the house and lays their eggs in the indoor water containers.
The results indicated the seasonal effects. There were least mosquito larvae during summer season (April) and more during rainy season (July). Many studies (Tewari et al. 2004, Wongkoon et al. 2011, Thammapalo, et al. 2005) reported this finding. Tewari et al. (2004) reported that there was some correlation between the number of Aedesaegypti, climatic factors and the number of dengue fever patients in southern part of India. This might be due to the fact that during rainy season there are more suitable water containers available as breeding sites.