Genetic diversity of the zigzag ladybird beetle, Cheilomenes sexmaculata (F.) (Coleoptera: Coccinellidae) with its distribution in India and implications for biological control

Biological control is considered the backbone of any integrated pest management programme. Exploring native ranges to identify new biological control agents is technically challenging and time-consuming; however, incorporating biogeographical insights into the selection process enhances the likelihood of success in biological control efforts. The zigzag beetle, Cheilomenes sexmaculata (F.), the most important and abundant of all ladybird beetles, feeds on a diverse range of prey. To study the population structure of C. sexmaculata, individuals were collected from five different zones, consisting of 25 subpopulations (subsets from their respective main zones) that uniformly represented India. We identified 109,585 contigs, 304,784 SNPs, and 46,583 INDELs, among which 5 INDELs and 9 SSRs were polymorphic. We observed high genetic diversity parameters for populations collected from the West Zone in all SNPs, SSRs, and INDELs markers. However, gene flow (N_m) was restricted, and F_ST was high in the South Zone and East Population (F_ST=0.45) populations, while the populations from the Central, North and West zones recorded zero F_ST. The structure and dendrogram construction analysis revealed individuals from Coorg and Mudigere of the South Zone and Barapani of the East Zone populations formed separate clusters. Mantel correlation revealed genetic distances decreased with the increasing geographical distance SNPs (R_xy= - 0.184 and P = 0.07); INDELs (R_xy= - 0.204 and P = 0.05) and SSRs (R_xy= - 0.339 and P = 0.06) indicated moderate genetic differentiation in the South and East zones populations due to geographic barriers, genetic drift and local environmental conditions. Populations in the North, West, and Central zones showed high gene flow, likely due to modern domestication and human activities. Additionally, the findings indicated that the populations from the West, North, and Central zones are better strains due to their high genetic fitness, so these populations can be used for classical and augmentative biological control.