The Effect of Landcover on Anopheles Population Dynamics in Ann Township, Rakhine State, Myanmar

Abstract

Over the past several decades, developing countries such as Myanmar have increased industrialization and use of natural resources resulting in dramatic geographical, ecological and climatological changes. The effects of these human-driven landcover changes on the population densities, distribution, and ecology of mosquitoes, the most important disease-carrying insect in humans, are anticipated but largely undocumented in many resource-limited countries. In this study the effects of landcover variability on the abundance s of Anopheles, the vector responsible for transmitting malaria parasites from one human to the next, were assessed. Mosquitoes were systematically collected at randomized locations across specified landcovers throughout participating villages in Ann Township, Rakhine State, Myanmar, where malaria is highly endemic. This study was part of a longitudinal multiyear study, and data collected in the first six months were included in this study. Of trapped mosquitoes, Anopheles mosquitoes were identified morphologically, and speciated using molecular and genomic methods. The number of Anopheles per trap was determined across specified landcovers. Over six months, the number of Anopheles per trap was highest in the built structures (mean 13 Anopheles/trap; 95% confidence interval (CI) (12.15-13.96)/trap) than any other landcovers where the mean (95% CI) Anopheles/trap ranged from 0 to 1.61 (1.24-2.05). Anopheles species, determined via sequencing of the ITS2 gene, showed the three most prevalent species were An. maculatus, An. pallidus, and An. varuna. The species considered to be most dominant vectors in the region were absent from our study. The study findings raise questions about potentially changing species dominance over time, due to environmental changes, or the accuracy of a traditional wisdom. Research is ongoing in the region, and compiling data in the next few years will help fill this important knowledge gap.