Has insecticidal pressure influenced Spodoptera litura (Fabricius, 1775) population genetic structure and genetic diversity in India?

Spodoptera litura is a prominent polyphagous pest in India and many other countries, and it’s growing tolerance to abiotic and biotic stresses has posed a greater threat to Indian and world agriculture. A study to acquire knowledge of its genetic features would provide useful information for articulating efficient management strategies. To understand the impact of decades of insecticidal pressure on the genetic diversity of the Indian population of S. litura , we analyzed and compared the S. litura cytochrome c oxidase subunit I ( cox1 ) gene sequences belonging to 21 locations of 10 agro-climatic zones of India and the cox1 sequences of foreign populations of S. litura (retrieved from NCBI). Overall, a low genetic variability among the Indian and foreign populations was exhibited along with a low level of genetic fixation ( F ST = 0.0088). The population genetic structure studies revealed monophyly along with the presence of five rare haplotypes in the Indian subcontinent. The absence of significant genetic divergence revealed profound interrelations of S. litura populations leading to higher gene flow among the studied countries, which was consistent with the fact that S. litura has sufficient flight capacity for dispersal. Neutrality tests and mismatch distribution analyses indicated that S. litura has had a recent rapid expansion in the absence of any genetic bottleneck. The presence of rare haplotypes in distinct interior regions of India showed the absence of bottlenecks or founder effects in those locations. The findings of this population genetic analysis can aid in the formulation of effective control measures for this migratory pest.