Diversity of entomopathogenic nematodes and their symbiotic bacteria in south African plantations and indigenous forests

Abstract

The occurrence and diversity of entomopathogenic nematodes (EPN) and their symbiotic bacteria was evaluated in commercial forestry plantations (Eucalyptus spp., Pinus spp. and Acacia mearnsii) and indigenous forests in South Africa. EPN were most prevalent in A. mearnsii plantations, accounting for 60.7% of the isolates, while indigenous forests, plantations of Pinus spp. and Eucalyptus spp. accounted for 35.7, 3.6 and 0% of the isolates, respectively. DNA sequences of the internal transcribed spacer (ITS) and D2-D3 28S rDNA regions were used to identify the nematode species. Four Steinernema spp. were identified, including S. citrae, S. sacchari, two undescribed species, as well as Heterorhabditis bacteriophora and H. baujardi. Heterorhabditis baujardi is reported from South Africa for the first time. Analysis of 16S rRNA of the bacteria confirmed the presence of at least three Xenorhabdus species from Steinernema isolates and two subspecies of Photorhabdus luminescens from Heterorhabditis species.