Work

Comparative pathogenicity of Photorhabdus entomopathogens against a stored grain pest, Tenebrio molitor and secondary metabolite profiles

Year: 2025

Type: article

Abstract: Photorhabdus (Entomopathogenic bacteria; EPB) is the symbiont of entomopathogenic nematodes (EPNs) in the genus Heterorhabditis . EPB are virulent and kill host insects. This study aimed to explain the virulence of Photorhabdus against a stored grain pest, Tenebrio molitor (Coleoptera: Tenebrionidae). The Photorhabdus strains were Photorhabdus temperata subsp. temperata ANU101 (‘Ptt’), P. luminescens subsp. thracensis (‘Pl thra’), P. luminescens 193 (‘Pl 193’), and P. luminescens subsp. laumondii (‘Pl laum’). Glycerine stock of these strains was cultured in tryptic soy broth and different dose (0, 10 1 ,10 2 ,10 3 ,10 4 ,10 5, and 10 6 CFU/larva) were injected into the hemocoel of fifth instar larvae to observe their pathogenicity against T. molitor . Among these, ‘Ptt’ showed the highest pathogenicity (LD 50 : 484.56 CFU/larva and LT 50 : 14.01 h) but ‘Pl laum’ showed the lowest pathogenicity (LD50: 1604.53 CFU/larva and LT50: 20.33 h) against T, molitor . GC-MS analysis of the organic extracts predicted the maximum number (166) of metabolites from ‘Ptt’ while the lowest number (111) of metabolites from ‘Pl laum’. However, eight metabolites were common in all Photorhabdus strains and from these, two metabolites, namely o-Cyanobenzoic acid (CBA) and Indole (IND), were synthesized and checked for their insecticidal activity. Mortality bioassays showed that both metabolites had toxicity against the third instar larvae of T. molitor , but CBA was more toxic (LC 50 : 17.45 ppm) than IND (LC 50 : 647.08 ppm). This study first reported the comparative study among four Photorhabdus strains for metabolite profiles, pathogenicity and toxicity against the stored product pest, T. molitor .

Source: Journal of Stored Products Research

DOI: 10.1016/j.jspr.2025.102870

Author: Md. Mahi Imam Mollah

Institutions: Gyeongkuk National University, Patuakhali Science and Technology University

Language: English

Topic: Entomopathogenic Microorganisms in Pest Control

Subfield: Insect Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: hybrid

Estimated APC paid: $4,190