Assessment of Gene Pool Similarity Among Indian Isolates of Steinernema spp. Using RAPD-PCR

Species of entomopathogenic nematodes belonging to the genus Steinernema have great potential for biological control of insect pests and identifying Indian isolates will be highly useful and practical for Indian agriculture. Fourteen populations of Steinernema spp. and one isolate of S. glaseri were compared for the genetic relatedness by random amplified polymorphic DNA (RAPD) markers. Six decamer oligonucleotide primers were used to generate random amplified polymorphic DNA fragments from 15 populations. The primers generated 136 fragments, ranging from 300 to 3000 base pairs in size. The similarity index varied from 0.08 to 0.85. RAPD analysis used as a first screen to identify genetic similarity/variation among 15 populations that included one identified species and 14 undetermined isolates indicated a wide range of similarity index among the populations from different states probably due to the types of crops grown and variation in climate and other factors. The observed genetic variation also indicate the potential and rich source of different strains and species of Steinernema spp. suitable for the management of regional insect pests specific to various crops in different regions.