Abstract
Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis have demonstrated great potential as useful bio-control agents in the management of certain important soil-inhabiting insect pests of agricultural crops. In a survey of nematodes associated with organic honeybush cultivation, soil samples were obtained from nine organic honeybush plots, which are located in the Bredasdorp area of the Western Cape province of South Africa. The EPNs were isolated from soil by baiting with larvae of Galleria mellonella (greater wax moth) and identified by the amplification of the internal transcribed spacer region using the primer set TW81 and AB28. EPNs were abundant in the honeybush orchards, accounting for about 50% of the sampled fields and five EPN species were identified including Heterorhabditis bacteriophora, Heterorhabditis safricana, Steinernema khoisanae,. Steinernema nguyeni, Oscheius sp. and an unknown EPN, therefore suggesting a substantial diversity of EPNs in the sampled fields. A 100% mortality of infected G. mellonella larvae was recorded within 48 h of exposure to the nematodes. However, although these EPNs have been previously reported in South Africa, it is the first time they are found in such diversity on a conservative tillage management system in organic honeybush cultivation.
Highlights
Entomopathogenic nematodes (EPNs) are useful biocontrol agents or ‘bio-predators’ that have been successfully used in the management of various soil-inhabiting insect pests worldwide (Nguyen & Smart, 1996; Bhat et al, 2020)
EPNs belonging to the genera Heterorhabditis, Steinernema and Oscheius were isolated from organic honeybush farms and identified using molecular tools
Some of the EPNs that were isolated from organic honeybush orchards in the current study, include those that have been demonstrated as useful biocontrol agents with proven potential against serious agricultural pests such as T. absoluta, C. pomonella and fruit fly species, Ceratitis capitata, and C. rosa (Malan & Manrakhan, 2009; De Waal et al, 2011; Ndereyimana et al, 2019)
Summary
Entomopathogenic nematodes (EPNs) are useful biocontrol agents or ‘bio-predators’ that have been successfully used in the management of various soil-inhabiting insect pests worldwide (Nguyen & Smart, 1996; Bhat et al, 2020). The EPNs belonging to the genera Steinernema and Heterorhabditis have been frequently reported as having great potentials for the biological control of insect pests of economic importance worldwide (Kaya & Gaugler, 1993; Lacey & Georgis, 2012; Gozel & Gozel, 2016; Bhat et al, 2020) The relevance of these nematodes as biocontrol agents in South Africa is being demonstrated by the extent of research activities that were dedicated to the identification and reporting of new local species (Malan et al, 2006, 2008, 2011, 2014; Malan & Ferreira, 2017; Abate et al, 2018; Ramakuwela et al, 2018; Lephoto & Gray, 2019a; Lulamba & Serepa-Dlamini, 2020). Attention is being focused on the development of commercial and industrial-scale production of the EPNs (Van Zyl & Malan, 2014; Kagimu & Malan, 2019; Dunn et al, 2020)
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