Author: F. Shahina and G. Mehreen
Publishing Date: 2015
Volume 33 Issue 1
In this study seven entomopathogenic nematode Steinernema isolates were examined using genetic analysis by ITS rDNA and 12S mtDNA. Phylogenetic analysis of these isolates was inferred by using four different methods i.e., Maximum Evolution (ME), Maximum Likelihood (ML), Maximum Parsimony (MP) and Neighbor Joining (NJ) based on the two makers. Sequence composition and phylogenetic analyses of these isolates showed closeness with Steinernema abbasi. On the basis of ITS rDNA region these seven Pakistani isolates were compared with seven worldwide isolates of S. abbasi and species of bicornutum group. While one isolate PAK.S.S.15 (JN599140) was analyzed using 12S mtDNA with other known species. In all four trees, isolate PAK.S.S.15 form monophyletic group with S. abbasi (AY944002). In laboratory experiment, biological life cycle of three isolates of S. abbasi PAK.P.S.9 (EF469773), PAK.S.S.15 (JN571086) and PAK.S.S.16 (JN571096) and one other isolate of Heterorhabditis indica PAK.S.H.56 (GU130179) were applied against fungus growing termite Microtermes mycophagus (D.). The study were also influenced by mortality; days to death, infection cycle length and reproductive potential. Highest mortality 100% was obtained on PAK.S.S.16 @ 75 IJs/cm2 . The strains PAK.S.S.16 and PAK.P.S.9 showed shortest 1.21 and 1.2 days to death in termites, while the isolate PAK.P.S.9 showed the shortest infection cycle length (4.65). Moreover, the strain PAK.S.S.16 showed highest rate of reproductive potential (830) than other three strains. The study was influenced by mortality; days to death, infection cycle length and reproductive potential. To elaborate biological life cycle, the results were presented using dendrogram of the association groups hierarchical cluster analysis.
Keywords: Entomopathogenic nematode, phylogenetic analysis, ITS rDNA, 12S rDNA gene and