Efficacy assessment of entomopathogenic nematodes native to Morocco against the white grubs Rhizotrogus obesus Lucas and Geotrogus olcesii Fairmaire (Coleoptera: Scarabaeidae). (May 2021)

• Record Type: Journal Article
• Authors: Benseddik, Youssef; Joutei, Abdelmalek Boutaleb; Laghfiri, Malaynine; Blenzar, Abdelali; Amiri, Said; Ezrari, Said; Saleh, Azzam; Mokrini, Fouad; Tahiri, Abdessalem; Dababat, Abdelfettah A.; Lahlali, Rachid
• Is Part Of: Crop protection. Volume 143(2021)
• Publication Date: 2021-05
• Subjects: Entomopathogenic nematodes -- Heterorhabditis -- Steinernema -- Rhizotrogus obesus Lucas -- Geotrogus olcesii Fairmaire -- White grubs -- Efficacy; Plants, Protection of -- Periodicals; 632.05
• DOI: 10.1016/j.cropro.2021.105534
• Languages: English
• ISSNs: 0261-2194

Abstract

Abstract: The white grubs Rhizotrogus obesus Lucas and Geotrogus olcesii Fairmaire (Coleoptera: Scarabaeidae) are two of the most problematic soil-dwelling pests of some annual crops in Morocco, where they may become a target for entomopathogenic nematodes (EPN). In this study, fourteen EPN strains reported from different fields in Morocco were investigated for their efficacy against both scarab species, under laboratory and greenhouse conditions. In laboratory experiments, seven strains of Heterorhabditis bacteriophora (HB-MOR2, HB-MOR6, HB-MOR1, HB-MOR5, HB-MOR7, HB-MOR4, and HB-MOR8) and one strain of Steinernema feltiae (SF-MOR10), provided remarkable efficacy against R. obesus (38–73% of mortalities). The EPN strains of Steinernema sp.2 (Sfg-MOR12), H. bacteriophora (HB-MOR4), Steinernema sp.1 (Sfg-MOR11), and H. bacteriophora (HB-MOR1) caused mortality rates ranging from 53 to 68% against G. olcesii . In greenhouse experiments where chlorpyrifos-ethyl was used as a positive control, larval mortality of R. obesus caused by both strains of H. bacteriophora, HB-MOR6 (81%) and HB-MOR2 (75%), was higher than that obtained by chlorpyrifos-ethyl (73%). The mortality rate in G. olcesii caused by Steinernema sp.2 (Sfg-MOR12) (77%) was the same as for chlorpyrifos-ethyl treatment (74%). Therefore, it can be concluded that EPN can constitute a promising biological alternative for the sustainable control of R. obesus and G. olcesii . Graphical abstract: Image 1 Highlights: The virulence of indigenous entomopathogenic nematodes was assessed against two white grub R . obesus and G . olcesii . EPN strains collected from Meknes-El Hajeb area were the most effective in controlling R. obesus and G. olcesii . Entomopathogenic nematodes induced mortalities rates of white grubs similar to that of chlorpyrifos-ethyl. EPN could be a reliable eco-friendly alternative to chemical control. The present study extends the host range of EPN in Morocco and worldwide.