Molecular Characterization of Ladybird Predators (Coleoptera: Coccinellidae) of Aphid Pests (Homoptera:Aphididae) in North East India

Ladybird beetles are potential and promising biological control agents for the management of insect pests. These insects show variations in biological fitness in diverse habitats and subsequently in term of genotypes. We used cytochrome oxidase I (COI) gene sequences to study within-species genetic variation in four species of ladybird predators, viz. Coccinella transversalis (Fab.), Cheilomenes sexmaculata (Fab.), Micraspis discolor (Fab.) and Anisolemnia dilatata (Fab.) collected from different cultivated habitats of Tripura, North East India. Results of multiple sequence alignments of partial COI gene (553 bp) of mitochondrial origin showed 100% homology among different populations (within species) of three ladybird species. The molecular identity of M. discolor could not be established due to the absence of matching nucleotide sequence for this region of COI gene in the NCBI database. Three of the four populations of Micraspis species showed 100% homology in partial COI gene sequencing, but one representative population showed 52 nucleotide mutations, of which 1 mutation was found to result in the alteration of the codon from valine to isoleucine, and seemed to represent a different Micraspis species previously not known from NE India. This study shows that the three most common species of ladybird predators of aphid pests in NE India are fairly homogenous with respect to the COI gene, but species of Micraspis are genetically diverse and need further studies to address this issue.