Abstract: 【Aim】Anopheles stephensi  is a major urban human malaria vector in South-East Asia contributing about twelve percent of malaria cases in India. The gene flow in An. stephensi belonging to the areas under Enhanced Malaria Control Project (EMCP) and non-EMCP of north-eastern regions of Madhya Pradesh (central India) was studied as initially there was a decline in malaria cases in EMCP areas due to various malaria control strategies but malaria appeared to be back-track with malaria cases increasing readily, indicating that the overall malaria risk remained stable. 【Methods】 The An. stephensi mosquitoes collected from four different areas under EMCP and non-EMCP from north eastern Madhya Pradesh (central India) were genotyped using 7 microsatellite loci for analysis of various population parameters. 【Results】 The markers were found to be highly polymorphic in all the populations. Not much genetic diversity was found between the two regions. Higher genetic differentiation was observed in eastern populations under EMCP (F_ST= 0.0485, R_ST=0.1112) than northern populations under non-EMCP (F_ST=0.020, R_ST=0.0145) and high gene flow (12.90, 6.16, 5.06 and 2.38) was observed between EMCP and non-EMCP areas. The higher sensitivity of R_ST than F_ST indicated that the differentiation was probably caused by the mutation but not due to genetic drift. 【Conclusion】 The study revealed substantially high gene flow within and between EMCP and non-EMCP areas. The high gene flow combined with development of insecticide resistance seems to be a potent reason for increase in malaria cases in EMCP as well as non-EMCP areas.

Key words: Anopheles stephensi, microsatellite markers, gene flow, genetic differentiation, genetic drift, malaria