Effect of land use and land cover modification on distribution of anopheline larval habitats in Meghalaya, India.

BACKGROUND & OBJECTIVES: The Meghalaya region had been considered free of malaria, but recently malaria cases in the foothills and valley areas raised concern that malaria transmission at high elevations may be increasing. This increase is associated with land use and land cover (LULC) changes. This LULC directly modifies larval habitats and affect the anopheline larval distribution patterns.

METHODS: In this survey, effects of LULC changes on the distribution of anopheline larval habitats in Meghalaya over a three year period (April 2008 to March 2011) was observed. Mosquito density and diversity of neighbouring four villages located along natural swamps (less disturbed) were compared with 16 villages located near disturbed area (cultivated area, urban area, pastures land area and national highway area).

RESULTS: The association between LULC type and occurrence of anopheline larvae was statistically significant. The distribution of anopheline positive habitats varied significantly between seasons. The mean density of Anopheles was significantly higher in urban area in all the seasons, but higher in farm land and pasture land areas only in rainy and post-rainy seasons. The six most common species collected were Anopheles maculatus (19.2%), An. vagus (13.7%), An. annularis (9.1%), An. philippinensis (8.1%), An. barbirostris (5.1%) and An. minimus (4.6%). LULC changes occurred mainly in valleys and National Highway Development Programme Phase III site. Overall, open forest area, farm land area and national highway development project phase area were observed to increase by 2.9, 1.7, and 2.1% respectively.

INTERPRETATION AND CONCLUSION: Our results indicate that LULC changes in the study area were favourable to Anopheles larval development, increasing the risk of the spread of malaria vector habitats and malaria transmission to non-malarious regions of Meghalaya.