Nikola Vesović

Molecular Diversity of Compounds from Pygidial Gland Secretions of Cave-Dwelling Ground Beetles: The First Evidence

Three adult cave-dwelling ground beetle species were induced to discharge secretions of their pygidial glands into vials. Dichloromethane extraction was used to obtain the secretions. In total, 42 compounds were identified by GC/MS analysis. Pheggomisetes ninae contained 32 glandular compounds, Laemostenus (Pristonychus) punctatus 13, whereas Duvalius (Paraduvalius) milutini had nine compounds. Caproic, oleic, palmitic, and stearic acids were present in the samples of all analyzed species. Undecane was predominant in the extract of L. punctatus. Palmitic acid was the major component in the secretion of D. milutini. Finally, the most abundant compounds in P. ninae secretion were heptacosene and nonacosadienes. Herein, we present the first data on the identification of pygidial gland secretion components in both troglophilous and troglobite cave-dwelling ground beetles. Some compounds are reported for the first time in the secretions of ground beetles and other higher or lower taxa. The adaptation to underground life has not led to a reduction or changes in the chemical defense mechanism in the analyzed troglophilous and troglobitic Platyninae and Trechinae taxa.

Antimicrobial activity of the pygidial gland secretion of the troglophilic ground beetle Laemostenus (Pristonychus) punctatus (Dejean, 1828) (Insecta: Coleoptera: Carabidae).

The antimicrobial activity of the pygidial gland secretion released by adult individuals of the troglophilic ground beetle Laemostenus (Pristonychus) punctatus (Dejean, 1828), applying microdilution method with the aim to detect minimal inhibitory concentration, minimal bactericidal concentration and minimal fungicidal concentration, has been investigated. In addition, morphology of the pygidial glands is observed. We have tested 16 laboratory and clinical strains of human pathogens - eight bacterial both gram-positive and gram-negative species and eight fungal species. The pygidial secretion samples have showed antimicrobial properties against all strains of treated bacteria and fungi. Micrococcus flavus proved to be more resistant compared with other bacterial strains. More significant antimicrobial properties of the secretion are observed against Escherichia coli, which proved to be the most sensitive bacteria. Aspergillus fumigatus proved to be the most resistant, while Penicillium ochrochloron and Penicillium verrucosum var. cyclopium the most sensitive micromycetes. Commercial antibiotics Streptomycin and Ampicillin and antimycotics Ketoconazole and Bifonazole, applied as positive controls, showed higher antibacterial properties for all bacterial and fungal strains, except for P. ochrochloron, which proved to be more resistant on Ketoconazole compared with the pygidial gland secretion of L. (P.) punctatus. Apart from the role in ecological aspects, the antimicrobial properties of the tested secretion possibly might have medical significance in the future.

Antifungal activity of the pygidial gland secretion of Laemostenus punctatus (Coleoptera: Carabidae) against cave-dwelling micromycetes

The antifungal potential of the pygidial gland secretion of the troglophilic ground beetle Laemostenus punctatus from a cave in Southeastern Serbia against cave-dwelling micromycetes, isolated from the same habitat, has been investigated. Eleven collected samples were analyzed and 32 isolates of cave-dwelling fungi were documented. A total of 14 fungal species were identified as members of the genera Aspergillus, Penicillium, Alternaria, Cladosporium, Rhizopus, Trichoderma, Arthrinium, Aureobasidium, Epicoccum, Talaromyces, and Fusarium. Five isolates were selected for testing the antifungal activity of the pygidial gland secretion: Talaromyces duclauxi, Aspergillus brunneouniseriatus, Penicillium sp., Rhizopus stolonifer, and Trichoderma viride. The microdilution method has been applied to detect minimal inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs). The most sensitive isolate was Penicillium sp., while the other isolates demonstrated a high level of resistance to the tested agent. L. punctatus has developed a special mechanism of producing specific compounds that act synergistically within the secretion mixture, which are responsible for the antifungal action against pathogens from the cave. The results open opportunities for further research in the field of ground beetle defense against pathogens, which could have an important application in human medicine, in addition to the environmental impact, primarily.

Chemical secretion and morpho-histology of the pygidial glands in two Palaearctic predatory ground beetle species: Carabus ( Tomocarabus ) convexus and C . ( Procrustes ) coriaceus (Coleoptera: Carabidae)

ABSTRACT Although all ground beetles have pygidial glands homologous in structure and function, there are many differences among species, often significant, in terms of chemical composition of the secretion and morphology of the gland components. In this paper, two predatory ground beetle species of the genus Carabus, namely C. (Tomocarabus) convexus and C. (Procrustes) coriaceus, were subjected to chemical, morphological and histological study of their pygidial glands and the glands’ secretions. Altogether, three carboxylic acids were isolated, and the pygidial gland reservoir and other glandular parts are morphologically described in the study. We also tested whether there exist differences in chemical content of the secretion obtained by upsetting the beetles in a traditional way and that obtained directly from intact reservoirs. Detailed data on morphology of the pygidial glands of both species are presented, as well as updated information about the chemical components of the glandular secretions. Apart from tiglic and methacrylic acids, which are typical for Carabus pygidial secretions, we also found benzoic acid as a minor component of the secretion in both species. In addition, a chemotaxonomic overview of Carabus taxa is given in the paper.

The pygidial gland secretion of the forest caterpillar hunter, Calosoma (Calosoma) sycophanta: the antimicrobial properties against human pathogens

Recently, various insect secretions have been tested as possible antimicrobial agents. In beetles, these secretions are essentially products of various exocrine glands, of which particular emphasis is on pygidial glands that are common for the suborder Adephaga. The antimicrobial potential of the pygidial gland secretion isolated from the adults of Calosoma sycophanta against human pathogens has been tested and compared with the potential of other carabid species, particularly within the tribe Carabini. The antimicrobial assay includes a microdilution method which was applied in order to determine the minimal inhibitory, minimal fungicidal and minimal bactericidal concentrations. It has been tested the effect of the secretion against eight strains of fungal and eight strains of bacterial species. The secretion sample of the tested carabid species has shown statistically significant antifungal effect against all strains of treated micromycetes, the highest in comparison with previously tested carabids (Carabus spp., Laemostenus punctatus and Abax parallelepipedus). Aspergillus versicolor proved to be the most sensitive micromycete, while the remaining seven fungal strains have shown the same level of sensibility. In comparison with commercial mycotics ketoconazole and bifonazole, applied as positive controls, the tested secretion showed much higher antifungal activity for all fungal strains. Antibacterial effect has been manifested only against one bacterial strain (Escherichia coli), contrary to other previously studied carabid species. These observations might have a significant impact on the ecological domain and possible purpose in biomedical studies and applications in the future. Additionally, morpho-histology of the pygidial glands of C. sycophanta is investigated and discussed.

First report of aphaenopsoid trechines (Coleoptera: Carabidae: Trechini) from Serbia, with descriptions of new taxa

The trechine ground beetle taxa, Velesaphaenops gen. n., Velesaphaenops tarensis sp. n., and Acheroniotes lethensis sp. n., are described and diagnosed. The new taxa differ clearly from their closest relatives in a number of external characters and the shape of the genitalia. They probably belong to phyletic lineages of Pliocene age (the age of the palaeokarst of Kamena Gora and Mt. Tara). The new taxa are endemic to western and southwestern Serbia. Keys to the aphaenopsoid trechine genera in Serbia and to species of the genus Acheroniotes Lohaj Lakota, 2010 are appended.

Seven new taxa of Leptodirini (Coleoptera: Leiodidae: Cholevinae) from the Balkan Peninsula

Seven new troglobitic leiodid beetle taxa (six new species and one new subspecies) from several caves and pits in the Balkan Peninsula (Bosnia and Herzegovina and Serbia) are described and diagnosed. Three new species belong to the genus Adelopidius Apfelbeck, 1907, two-to the genus Pholeuonopsis Apfelbeck, 1901, one-to the genus Leonhardia Reitter, 1901, while a new subspecies belongs to the genus Apholeuonus Reitter, 1889. All important morphological characteristics of the new taxa have been mentioned and imaged, including the aspects of the male and female genitalia. The new leiodid taxa are properly distinguished from their relatives and are endemics of the Dinaric mountain chain. A key to Adelopidius taxa is added.

A new hypogean species of the genus Chaetomargoreicheia Magrini & Bulirsch, 2005 (Carabidae: Scaritinae: Clivinini) from Croatia

Chaetomargoreicheia Magrini Bulirsch, 2005 is a recently established genus of scaritine ground beetles (Bulirsch Guéorguiev, 2008) (treated by certain authors as a subgenus of the genus Reicheadella Reitter, 1913) (Magrini Bulirsch, 2005; Balkenohl, 2017) which currently contains two endogean species inhabiting the Balkan Peninsula: Chaetomargoreicheia zoufali (Reitter, 1913) and C. lakotai (Magrini Bulirsch, 2005) (Balkenohl, 2003, 2017; Magrini Bulirsch, 2005; Bulirsch Guéorguiev, 2008). The aforementioned species are montane and inhabit confined geographic areas (Jeannel, 1957; Magrini Bulirsch, 2005). C. zoufali was found only in the surroundings of the village of Ravno (collected beneath a deep layer of leaf-litter), Mt. Bjelasnica, near Trebinje, E Herzegovina (Bosnia and Herzegovina), while C. lakotai was found at the entrance of a cave nearby a road (collected under a huge stone), in Mt. Lovćen, near Kotor, S Montenegro (Reitter, 1913; Holdhaus, 1924; Jeannel, 1957; Magrini Bulirsch, 2005). Chaetomargoreicheia species represent quite rare, stenoendemic taxa, for each of the up-to-now known species only one specimen has been collected by hand so far (Reitter, 1913; Jeannel, 1957; Magrini Bulirsch, 2005). The fourth author of the current study investigated numerous underground and endogean high-altitude habitats in Dalmatia (Croatia) in the last few years. As a result of the exploration, he has recently collected a small sample of scaritine ground beetles from a cave in S Croatia. After thorough analysis of the sample, we have identified a new Chaetomargoreicheia species.

Inhibition of tumour and non-tumour cell proliferation by pygidial gland secretions of four ground beetle species (Coleoptera: Carabidae)

Inhibition of the proliferation of human tumour cells and porcine non-tumour cells by the pygidial gland secretion released by adults of four ground beetle species was observed in this study. The sulphorhodamine B (SRB) assay was applied to establish the percentages of inhibition of the net growth of four human tumour cell lines and porcine liver primary non-tumour cells. The secretions of all tested ground beetle species were shown to have an antiproliferative effect on the tested cell lines. Special emphasis is put on the secretion of Abax parallelepipedus, which showed the highest antitumour potential and weakest inhibition of non-tumour cell proliferation. The antitumour and antiproliferative potential of the pygidial gland secretions of ground beetles is here demonstrated for the first time. It is suggested that certain organic acids are responsible for the action. Further investigation needs to be conducted in order to better understand the mechanisms governing the observed cytotoxic and antitumour activity.

Increased motor activity of the beetle Laemostenus punctatus caused by a static magnetic field of 110 mT

The aim of this study was to investigate the effects of a static magnetic field on six behavioral parameters (travel distance, average speed while in motion, travel distance of the head, body rotations, time in movement, and immobility time) of the ground beetle Laemostenus (Pristonychus) punctatus (Dejean) (Coleoptera: Carabidae). Adults of this troglophilic and guanophilic beetle were randomly divided into two groups, the first exposed to a static magnetic field of 110 mT for 5 h, and the second a control group. Beetle behavior after these 5 h was monitored in an open‐field test for 12 min and analyzed using ANY‐maze software. Exposure to a static magnetic field of 110 mT increased motor activity (travel distance and average speed while in motion) in the first 4 min. After that there were no significant differences. We conclude that the applied static magnetic field affects motor activity of adult specimens of L. (P.) punctatus, and we discuss the mechanism, possibly through acting on the control centers responsible for orientation and movement.