Genetic relatedness among Helicoverpa armigera (Hübner) occurring on different host plants as revealed by random amplified polymorphic DNA markers

The genetic relatedness among Helicoverpa armigera (Hübner) occurring on different host plants prevailing in South India was studied using PCR-RAPD. Genomic DNA was isolated individually from five larvae collected from each of 10 different host plants (except in okra). PCR-RAPD analysis was carried out using a set of 20 random primers which had produced repeatable banding patterns from a original set of 60 primers. A set of 155 amplicon levels were available for analysis, of which 154 were polymorphic. An average of 7.75 bands per primer was recorded. Similarity coefficients based on the frequency of band sharing among host strains varied from 0.25 in cotton and sunflower to 0.72 in groundnut. Clustering analysis on the basis of the PCR-RAPD-generating band sharing indicated that most of the individuals occurring on niger, safflower, green gram, abutilon and lagasca clustered together, indicating greater genetic similarity among themselves, than those occurring on other crops. Furthermore, the pattern of genetic variation in the individuals collected from niger, safflower, green gram, groundnut, abutilon and lagasca was seem to be largely host-dependent.