Molecular characterisation and phylogeographic patterns of Maruca vitrata, on black gram in rainfed and SAT regions of Andhra Pradesh

Molecular and phylogeographic patterns of M. vitrata in Andhra Pradesh

Abstract

The legume spotted pod borer, Maruca vitrata Fabricius, is a significant pest of leguminous crops in tropical and subtropical regions, particularly in Andhra Pradesh, India. This study was conducted during Rabi 2023-2024 at the Department of Entomology, Sri Krishnadevaraya College of Horticultural Sciences, Ananthapuram, to investigate the genetic variability and phylogeographic patterns of M. vitrata populations across Rainfed and Semi-Arid Tropical (SAT) regions of Andhra Pradesh, providing insights into how environmental conditions influence pest adaptation. A total of 10 larvae were collected from key black gram growing areas in Rainfed (Nellore, Vijayawada, Guntur, Bapatla & Tirupathi) and SAT (Kadapa, Anantapur & Prakasam) regions. DNA was isolated and the mitochondrial cytochrome-c oxidase subunit I (mtCOI) gene was amplified and sequenced, yielding an average sequence length of 700 bp. Phylogenetic analysis revealed distinct genetic clustering, with SAT populations exhibiting greater genetic divergence, forming separate clades from those in Rainfed regions. This divergence is indicative of adaptation to the harsher climatic conditions of SAT regions. Sequence alignment revealed unique haplotypes in SAT samples, contrasting with a more conserved genetic sequence in Rainfed populations. The unique genetic makeup of SAT populations suggests they may respond differently to control measures, such as insecticides or biocontrol agents, compared to their counterparts in Rainfed regions. Moreover, the high genetic diversity observed in SAT regions raises concerns about the potential for developing insecticide resistance. This study provides critical insights into the evolutionary dynamics of M. vitrata, on black gram crop in Andhra Pradesh.