Characterisation of Anopheles species composition and genetic diversity in Meghalaya, northeast India, using molecular identification tools

<p>Malaria in India is declining, in part due to the use of long-lasting insecticide-treated nets (LLINs) and vector control. Historically, the north-eastern region of India has contributed ~10%-12% of the nation's malaria burden. The important mosquito vectors in northeast India have long been considered to be <em>Anopheles baimaii</em> and <em>An. minimus</em>, both associated with forest habitats. Local deforestation and increased rice cultivation, along with widespread LLIN use, may be changing vector species composition. Understanding if and how vector species composition is changing is critical to successful malaria control. In Meghalaya state, malaria is now at a low level of endemicity with occasional seasonal outbreaks. In a biodiverse setting like Meghalaya, where >24 Anopheles mosquito species have been recorded, accurate morphological identification of all species is logistically challenging. To accurately determine <em>Anopheles</em> species richness in the West Khasi Hills (WKH) and West Jaintia Hills (WJH) districts, adult and larval mosquitoes were collected and identified using molecular methods of allele-specific PCR and cytochrome oxidase I DNA barcoding. In 14 villages across both districts, we identified high species richness, 19 species in total. Molecular findings indicated that <em>An. minimus</em> and <em>An. baimaii</em> were rare, while four other species (<em>An. maculatus</em>, <em>An. pseudowillmori,</em> <em>An. jeyporiensis</em> and <em>An. nitidus</em>) were abundant. <em>Anopheles maculatus</em> was highly prevalent in WKH (39% of light trap collections) and <em>An. pseudowillmori</em> in WJH (45%). Larvae of these four species were found in rice fields, suggesting that land cover change is influencing species composition change. Our results suggest that rice fields might be contributing to the observed abundance of <em>An. maculatus</em> and <em>An. pseudowillmori,</em> which could be playing a role in malaria transmission, either independently due to their high abundance, or in combination with <em>An. baimaii</em> and/or <em>An. minimus</em>.</p>