Molecular Characterization and Phylogenetic Analysis of Samia ricini and Samia canningi Populations from Assam, India Using Mitochondrial Cytochrome c Oxidase Subunit I Gene Sequences
Nimiksha Devi *
Department of Sericulture, Assam Agricultural University, Jorhat-13, Assam, India.
Sourav Singh
Department of Sericulture and Entomology, Assam Agricultural University, Jorhat-13, Assam, India.
Roshmi Borah Dutta
Department of Sericulture and Entomology, Assam Agricultural University, Jorhat-13, Assam, India.
Anjumoni Devee
Department of Sericulture and Entomology, Assam Agricultural University, Jorhat-13, Assam, India.
Mahima Begum
Department of Sericulture and Agricultural Statistics, Assam Agricultural University, Jorhat-785013, Assam, India.
Monimala Saikia
Department of Sericulture and Agricultural Statistics, Assam Agricultural University, Jorhat-785013, Assam, India.
Supahi Mahanta
Department of Sericulture and Agricultural Statistics, Assam Agricultural University, Jorhat-785013, Assam, India.
*Author to whom correspondence should be addressed.
Abstract
Background: Molecular comparison of eri silkworm populations from Assam may assist species identification and assessment of their relationships with reference populations.
Aims: To characterise Samia ricini (Donovan) and the related species Samia canningi (Hutton) (Lepidoptera: Saturniidae) from different agroclimatic zones of Assam using the mitochondrial cytochrome c oxidase subunit I (COX1) gene, and to determine their phylogenetic relationships with isolates from other regions.
Study Design: Laboratory-based molecular characterisation study.
Place and Duration of Study: Department of Sericulture and Biocontrol Laboratory, Department of Entomology, Assam Agricultural University, Jorhat, Assam, India, during 2023–24 and 2024–25.
Methodology: Genomic DNA was extracted from adult moths reared from seed cocoons of S. ricini (Titabor, Udalguri, Nagaon and Kamrup) and S. canningi (Mariani). A partial COX1 fragment was amplified by polymerase chain reaction (PCR) using the universal primers LCO1490 and HCO2198 and sequenced. Sequences were compared with reference sequences in GenBank, and phylogenetic trees were constructed by the neighbour-joining method in MEGA 11.
Results: COX1 was amplified in all samples. The S. canningi isolate from Mariani showed 100% sequence identity with a Nagaland isolate (MT385729.1) and 93.01–96.81% similarity with isolates from Japan, Taiwan, China, Malaysia and Indonesia. The S. ricini isolates from Titabor, Udalguri, Nagaon and Kamrup showed 95.67–100% similarity with isolates from India and other countries. All Assam isolates clustered within their respective species groups.
Conclusion: The COX1 gene is a reliable marker for species authentication and phylogenetic assessment of eri silkworms, and the Assam S. ricini populations are closely related to those reported from other parts of India and abroad.
Keywords: Samia ricini, Samia canningi, cytochrome c oxidase subunit I, DNA barcoding, phylogeny, eri silkworm