188 International Journal of Entomology Research www.entomologyjournals.com ISSN: 2455-4758 Received: 24-07-2021, Accepted: 10-08-2021, Published: 25-08-2021 Volume 6, Issue 4, 2021, Page No. 188-192 Genetic polymorphism in the field populations of Pectinophora gossypiella (Saunders) by using RAPD-PCR R V Kalaimathi 1 , R Umamaheswari 2 , S Krishnamoorthy 3* 1 Assistant Professor, Department of Zoology, Arulmigu Palaniandavar Arts and Culture College, Palani, Tamil Nadu, India 2 Assistant Professor, Department of Zoology, Arulmigu Palaniandavar Arts College For Women, Palani, Chinnakalayamputhur, Tamil Nadu, India 3 Research Scholar, Department of Zoology, Vivekananda College, Tiruvedakam West, Madurai, Tamil Nadu, India Abstract The populations of Pectinophora gossypiella obtained from different locations in Tamil Nadu were analyzed by RAPD-PCR. A total of twenty 10-mer oligonucleiotide primers (RAPD Kit A1 to Kit A20) were tested for their ability to provide suitable banding pattern for eight different populations of P. gossypiella. Of the primer set tested, RAPD KitA3, A9, A15, A18 and A20 yielded clear, consistent and discrete banding patterns for the populations of P. gossypiella. Dendrogram and similarity index were constructed based on the RAPD profiles generated by Kit A3, A9 and A15 primer using UPGMA. The three primers amplified a total of 115 scorable bands in the molecular weight range of approximately 267bp to 1352bp. The number of amplification products obtained was specific to each primer and ranged from thirty (Kit A9) to forty five (Kit A15). The UPGMA based dendrogram of all the primers grouped the populations of P. gossypiella in two clusters. The similarity coefficients values were ranged from 0.03 to 0.86, indicating that no two populations were 100% similar. The similarity matrix of all the primers indicated that most of the populations exhibited <50% similarity coefficient. Keywords: cotton pest, pink bollworm, Pectinophora gossypiella, RAPD-PCR, genetic polymorphism Introduction The pink bollworm, Pectinophora gossypiella (Lepidoptera: Insecta) is the most important cotton pest in the world (Dennehy et al., 2004) [7] . It is found in almost every cotton producing country and has caused lot of damage to the cotton bolls. The bollworm adult or moth lays its eggs on cotton bolls. The eggs hatch into larvae and eat the cottonseeds, damage and discolor the fiber. The pink bollworm, Pectinophora gossypiella (Saunders), was described by W.W. Saunders in 1843 as Depressaria gossypiella from specimens found to be damaging cotton in India in 1842 (Ingram, 1994) [10] . The insect has been taxonomically designated under several other generic names, and the complete synonymy was reported by Common (1958) [6] . The origin of pink bollworm remains unknown but the diversity of parasite species found in Pakistan (Cheema et al., 1980) appears to support an Indo- Pakistan origin (Ingram, 1994) [10] . It has also been suggested that its origin occurred in the area of the eastern Indian Ocean bordered on the east by northwestern Australia and on the west by the various islands of Indonesia-Malaysia (Common, 1958) [6] . In India a research team comprised of scientist from the Central Institute of Cotton Research (CICR, Nagpur), the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT) at Patancheru, Andra Pradesh studied various geographical strains of major cotton pests, which are as follows: the cotton bollworm (Helicoverpa armigera), tobacco catterpiller (Spodoptera litura), white fly (Bemisia tabaci), pink bollworm (Pectinophora gossypiella) and spotted bollworm (Earias vittella). The damage caused by these five major cotton pests were calculated as 20 to 80% (Kranthi et al., 2005). The pink bollworm, Pectinophora gossypiella is considered to be the most destructive pests of cotton bolls. It is worldwide in distribution and cotton is considered to be the preferred host for the insect. The pest can affect cotton seed and lint yield as quality and quantity (Temerak, 2003). Different kinds of molecular markers can reveal different levels of genetic variation, making population genetics studies possible on a wide range of geographical scales. DNA markers are especially effective tools in making inferences about movement between insect populations, because they present selectively neutral characters (Black et al., 2001). Randomly amplified polymorphic DNA (RAPD) (Welsh and McClelland, 1990; Williams et al., 1990) [23, 24] is a polymerase chain reaction (PCR) technique that allows detection of many polymorphisms within the genomic DNA in a short time. RAPD markers are generated by the amplification of random DNA segments with single primers of arbitrary nucleotide sequence. Polymorphisms most of which are inherited as dominant traits, are detected as the presence (or) absence of amplification products from a single locus (Williams et al., 1990) [24] . This technique has been used for many systematic and population genetic studies. RAPD-PCR requires very small amount of DNA and can be used with very small insects (Black et al., 1992) [3] . The RAPD technique (Williams et al., 1990) [24] has been widely used to elucidate the geographical origin of and gene flow among insect populations (Ayres et al., 2003) [2] . The properly performed RAPD analysis is a useful and reliable tool for studying the ecology and genetic structuring of populations (Armstrong and Wratten, 1996; Vaughn and