Elucidation of lipopeptide biosurfactants responsible for the larvicidal activity of Bacillus velezensis PHP1601 towards Lucilia cuprina larvae

Lipopeptide biosurfactant compounds derived from cultures of Bacillus velezensis PHP1601 (Bacillales: Bacillaceae) show antagonism towards the larval stage of Lucilia cuprina (Diptera: Calliphoridae), a blowfly pest of agricultural significance. A study was undertaken to characterise and elucidate t...

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Bibliographic Details
Published inBiocontrol science and technology Vol. 33; no. 8; pp. 772 - 787
Main Authors Ramesar, Danvir Rajesh, Hunter, Charles Haig
Format Journal Article
LanguageEnglish
Published Abingdon Taylor & Francis 03.08.2023
Taylor & Francis Ltd
Subjects
Bacillus velezensis
Bioassays
Biological control
Biosurfactants
Cadavers
Discoloration
Larvae
lipopeptide biosurfactants
Lipopeptides
Lucilia cuprina
microbial pesticides
Pest control
Surfactants
Surfactin
Thin layer chromatography
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Summary:Lipopeptide biosurfactant compounds derived from cultures of Bacillus velezensis PHP1601 (Bacillales: Bacillaceae) show antagonism towards the larval stage of Lucilia cuprina (Diptera: Calliphoridae), a blowfly pest of agricultural significance. A study was undertaken to characterise and elucidate the lipopeptide biosurfactant compounds contributing to this effect. Lipopeptide extracts were obtained from cultures grown in Landy medium by acid precipitation and methanol extraction. Thin layer chromatography and UPLC ESI-TOF MS were used to partially purify and characterise the lipopeptides present in the extract. Lipopeptide fractions contained homologues of surfactin (C13-C17), fengycin (C14-C17) and iturin (C14-C17). Each lipopeptide fraction (20 µg g −1 ) displayed larvicidal activity against second-instar L. cuprina larvae, with a highly polar surfactin fraction (Rf: 0.90) being the most effective. The potency of surfactin was confirmed with bioassays incorporating a surfactin standard whereby a LT 50 of 179.97 h and LC 50 of 9.87 µg g −1 was determined. Interestingly, larvae cadavers recovered from the bioassays displayed significant physiological discolouration and stunting; this was attributed to the biosurfactant nature of the lipopeptide compounds. These findings corroborate the role of lipopeptide compounds, specifically surfactin, in the fly biocontrol mechanism of PHP1601 and constitute the first report of these compounds being insecticidal towards blowfly larvae.
ISSN:0958-3157
1360-0478
DOI:10.1080/09583157.2023.2231180