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Octanoic Acid—An Insecticidal Metabolite of Conidiobolus coronatus (Entomopthorales) That Affects Two Majors Antifungal Protection Systems in Galleria mellonella (Lepidoptera): Cuticular Lipids and Hemocytes

Authors :
Agata Kaczmarek
Anna Katarzyna Wrońska
Michalina Kazek
Mieczysława Irena Boguś
Source :
International Journal of Molecular Sciences, Vol 23, Iss 9, p 5204 (2022)
Publication Year :
2022
Publisher :
MDPI AG, 2022.

Abstract

The food flavour additive octanoic acid (C8:0) is also a metabolite of the entomopathogenic fungus Conidiobolus coronatus, which efficiently infects and rapidly kills Galleria mellonella. GC-MS analysis confirmed the presence of C8:0 in insecticidal fraction FR3 extracted from C. coronatus filtrate. Topical administration of C8:0 had a dose-dependent effect on survival rates of larvae but not on pupation or adult eclosion times of the survivors. Topically applied C8:0 was more toxic to adults than larvae (LD100 for adults 18.33 ± 2.49 vs. 33.56 ± 2.57 µg/mg of body mass for larvae). The administration of C8:0 on the cuticle of larvae and adults, in amounts corresponding to their LD50 and LD100 doses, had a considerable impact on the two main defense systems engaged in protecting against pathogens, causing serious changes in the developmental-stage-specific profiles of free fatty acids (FFAs) covering the cuticle of larvae and adults and damaging larval hemocytes. In vitro cultures of G. mellonella hemocytes, either directly treated with C8:0 or taken from C8:0 treated larvae, revealed deformation of hemocytes, disordered networking, late apoptosis, and necrosis, as well as caspase 1–9 activation and elevation of 8-OHdG level. C8:0 was also confirmed to have a cytotoxic effect on the SF-9 insect cell line, as determined by WST-1 and LDH tests.

Details

Language :
English
ISSN :
14220067 and 16616596
Volume :
23
Issue :
9
Database :
Directory of Open Access Journals
Journal :
International Journal of Molecular Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.3968f8a56d274da0a7a2bba11667f45c
Document Type :
article
Full Text :
https://doi.org/10.3390/ijms23095204