Genetic diversity and phylogenetic analysis of Aphis craccivora in the Vidarbha region of Maharashtra based on the mitochondrial COI gene

Abstract

Genetic characterisation of pest populations is critical for designing effective and sustainable management strategies, particularly in agroecosystems under intense insecticide selection. This study investigates the genetic diversity and population structure of the cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae), across six major cowpea-growing districts of the Vidarbha region, Maharashtra, India. A 658-bp fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene was amplified, sequenced, and subjected to BLAST analysis, multiple sequence alignment, and pairwise genetic distance estimation. All samples were unequivocally identified as A. craccivora, with nucleotide identities ranging from 93.7% to 100% relative to reference sequences in GenBank. Pairwise genetic distances were low, varying from 0.008 (between Nagpur and Amravati) to 0.143 (between Akola and Bhandara), indicating minimal intraspecific divergence. Phylogenetic reconstruction using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) revealed no distinct geographic clustering, suggesting high gene flow among populations. These findings support the hypothesis that A. craccivora in the Vidarbha region constitutes a genetically homogeneous metapopulation, likely facilitated by its parthenogenetic reproduction and high dispersal capacity. The observed genetic uniformity implies that region-wide pest management interventions, including insecticide rotation and deployment of resistant cultivars, may be uniformly efficacious. Nevertheless, continuous molecular surveillance is warranted to monitor for emerging resistance-associated genetic variants in this adaptive pest.