Greater Wax Moth Galleria Mellonella Research Articles

Immunomodulation and Protective Effects of Cordyceps militaris Extract Against Candida albicans Infection in Galleria mellonella Larvae

Cordyceps militaris-derived formulations are currently used for multiple purposes because of their medical properties, especially immune system modulation. This study analyzes the inhibitory effects of C. militaris aqueous extract on Candida albicans infections and the immune response in larvae of the greater wax moth Galleria mellonella (Lepidoptera: Pyralidae). Larvae exhibited melanization within 1 h of being infected with C. albicans inoculum at a concentration of 106 cells/larvae, and died within 24 h from a lethal dose. Aqueous extract of C. militaris proved to be nontoxic at concentrations of 0.25 and 0.125 mg/larvae, and had the greatest ability to prolong the survival of larvae infected with a sublethal dose of C. albicans at a concentration of 105 cells/larvae. Moreover, the number of hemocytes in the hemolymph of G. mellonella increased after infection with C. albicans and treatment with the aqueous extract of C. militaris at 1, 24, and 48 h by 1.21 × 107, 1.23 × 107, and 1.4 × 107 cells/100 µL, respectively. The highest number of hemocytes was recorded after treatment of infected G. mellonella with the extract for 48 h. Transcriptional upregulation of the immune system was observed in certain antimicrobial peptides (AMPs), showing that the relative expression of galiomicin, gallerimycin, and lysozyme genes were upregulated as early as 1 h after infection. Therefore, we conclude that C. militaris aqueous extract can modulate the immune system of G. mellonella and protect against infection from C. albicans.

Structural characterization and bioactivity profiling of the fungal peptaibiotic tolypin reveal protective effects against influenza viruses.

In a bioprospection for new antivirals, we tested nonribosomally biosynthesized polypeptide antibiotics in MDCK II cells for their actions on influenza A and B viruses (IAV/IBV). Only tolypin, a mixture of closely related 16-residue peptaibiotics from the fungus Tolypocladium inflatum IE 1897, showed promising activity. It was selected for further investigation and structural characterization byultrahigh performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HR-MS/MS) and ultrahigh performance liquid chromatography coupled to in-source collision-induced dissociation tandem mass spectrometry (UHPLC-isCID-HR-MS/MS), revealing 12 partially co-eluting individual peptides that were fully sequenced. Since tolypin-related efrapeptins are potent inhibitors of F1/Fo-ATPase, we screened tolypin for its toxicity against MDCK II cells and larvae of the greater wax moth Galleria mellonella. We found that a nontoxic concentration of tolypin (1 µg/mL) reduced the titer of two IBV strains by 4-5 log values, and that of an H3N2 strain by 1-2 log values, but the H1N1pdm strain was not affected. The higher concentrations of tolypin were cytostatic to MDCK II cells, shifted their metabolism from oxidative phosphorylation to glycolysis, and induced paralysis in G. mellonella, supporting the inhibition of F1/Fo-ATPase as the mode of action. Our results lay the foundations for future work to investigate the interplay between viral replication and cellular energy metabolism, as well as the development of drugs that target host factors.

Transcriptional responses of detoxification genes to coumaphos in a nontarget species, Galleria mellonella (greater wax moth) (Lepidoptera: Pyralidae), in the beehive environment

The greater wax moth Galleria mellonella is a cosmopolitan pest of hives of the western honey bee Apis mellifera, where it remains exposed to varroicides applied by beekeepers in past decades as pest management chemicals for control of Varroa destructor, a devastating ectoparasite of bees. The prolonged presence of coumaphos residues, an organophosphate varroicide, in beeswax may be responsible for current levels of tolerance exhibited by G. mellonella, a non-target species that infests beehives. In this study, a field-collected strain of waxworms exhibited a higher LC50 value for coumaphos than that of a laboratory strain that had not been continuously exposed to coumaphos residues at field concentrations. Despite its higher tolerance for coumaphos, the field strain experienced growth inhibition at ecologically relevant concentration of coumaphos. Moreover, at low environmental concentrations that did not alter growth, detoxification gene expression levels were substantially altered. RNA-Seq analysis revealed 1181 and 658 differentially expressed genes in fat body and midgut, respectively, with 378 and 186 of those genes upregulated. This large-scale upregulation encompassed 21 genes encoding cytochrome P450 monooxygenases (CYPs), 13 encoding UDP-glycosyltransferases (UGTs), 5 encoding glutathione-S-transferases (GSTs), 2 encoding carboxylesterases (COEs), and 2 encoding ABC transporters (ABCs) in either tissue. Expression analysis of 13 selected candidate detoxification genes by RT-qPCR was consistent with their expression from RNA-Seq data. In sum, our results indicate that long-lasting pesticide residues in beeswax from past Varroa mite management may continue to act as selective agents on detoxification systems of hive residents other than the initial target species and that multiple resistance mechanisms to these chemicals may coexist within the beehive fauna.

Effect of Co-Diet Supplementation on Biodegradation of Polyethylene by Galleria mellonella L. (Lepidoptera: Pyralidae).

Pollution coming from plastic polymers, particularly polyethylene (PE), poses a serious threat to both humans and animals. The biodegradation of plastics facilitated by insects is a crucial and eco-friendly approach that can be employed to combat this global concern. Recently, the larvae of the greater wax moth Galleria mellonella (L.) have been recognized as avid 'plastivores'. The current study was aimed at evaluating the feeding efficiency of G. mellonella larvae on PEs of various densities with a co-diet supplementation of wheat germ + honey and beeswax. The results reveal that maximum PE consumption (9.98 ± 1.25 mg) was recorded in the case of 1.0 mm thick PE after a 24 h interval; however, the same scenario also achieved the greatest reduction in larval weight (27.79 ± 2.02 mg). A significant reduction in PE mass (5.87 ± 1.44 mg) was also observed in 1.0 mm PE when fed beeswax; however, the larvae experienced minimal weight loss (9.59 ± 3.81 mg). The larvae exhibited a higher PE consumption in 1.0 mm PE, indicating that the lower the density of PE, the greater the consumed area. Moreover, the biodegradation levels were notably higher within the 24 h interval. In conclusion, these findings suggest that the density of PEs and the supplementation of the co-diet have an impact on PE biodegradation. Additionally, the utilization of G. mellonella for the biodegradation of PE proves effective when combined with beeswax, resulting in minimal weight loss of the larvae. Our findings offer initial insights into how Galleria mellonella larvae biodegrade polyethylene (PE) of four different densities, along with co-diet supplementation. This approach helps us evaluate how varying densities affect degradation rates and provides a better understanding of the larvae's capabilities. Additionally, our observations at three specific time intervals (24, 48, and 72 h) allow us to identify the time required for achieving degradation rates. Through examining these time points, our method offers valuable insights into the initial phases of plastic consumption and biodegradation.

Transcriptome analysis and functional study of phospholipase A2 in Galleria mellonella larvae lipid metabolism in response to envenomation by an ectoparasitoid, Iseropus kuwanae.

There is abundant evidence that parasitoids manipulate their hosts by envenomation to support the development and survival of their progeny before oviposition. However, the specific mechanism underlying host nutritional manipulation remains largely unclear. To gain a more comprehensive insight into the effects induced by the gregarious ectoparasitoid Iseropus kuwanae (Hymenoptera: Ichneumonidae) on the greater wax moth Galleria mellonella (Lepidoptera: Pyralidae) larvae, we sequenced the transcriptome of both non-envenomed and envenomed G. mellonella larvae, specifically targeting genes related to lipid metabolism. The present study revealed that 202 differentially expressed genes (DEGs) were identified and 9 DEGs were involved in lipid metabolism. The expression levels of these 9 DEGs relied on envenomation and the duration post-envenomation. Further, envenomation by I. kuwanae induced an increase in triglyceride (TG) level in the hemolymph of G. mellonella larvae. Furthermore, silencing GmPLA2 in G. mellonella larvae 24h post-envenomation significantly decreased the content of 4 unsaturated fatty acids and TG levels in the hemolymph. The content of linoleic acid and α-linoleic acid were significantly decreased and the content of oleic acid was significantly increased by exogenous supplement of arachidonic acid. Meanwhile, the reduction in host lipid levels impairs the growth and development of wasp offspring. The present study provides valuable knowledge about the molecular mechanism of the nutritional interaction between parasitoids and their hosts and sheds light on the coevolution between parasitoids and host insects.

Repellent and Attractant Effect of the Nettle Plant Urtica dioica on the Larvae of the Greater Wax Moth Galleria mellonella L. (Lepidoptera: Pyralidae)

Repellent and Attractant Effect of the Nettle Plant Urtica dioica on the Larvae of the Greater Wax Moth Galleria mellonella L. (Lepidoptera: Pyralidae)

Protease S of entomopathogenic bacterium Photorhabdus laumondii: expression, purification and effect on greater wax moth Galleria mellonella.

Protease S (PrtS) from Photorhabdus laumondii belongs to the group of protealysin-like proteases (PLPs), which are understudied factors thought to play a role in the interaction of bacteria with other organisms. Since P. laumondii is an insect pathogen and a nematode symbiont, the analysis of the biological functions of PLPs using the PrtS model provides novel data on diverse types of interactions between bacteria and hosts. Recombinant PrtS was produced in Escherichia coli. Efficient inhibition of PrtS activity by photorin, a recently discovered emfourin-like protein inhibitor from P. laumondii, was demonstrated. The Galleria mellonella was utilized to examine the insect toxicity of PrtS and the impact of PrtS on hemolymph proteins in vitro. The insect toxicity of PrtS is reduced compared to protease homologues from non-pathogenic bacteria and is likely not essential for the infection process. However, using proteomic analysis, potential PrtS targets have been identified in the hemolymph. The spectrum of identified proteins indicates that the function of PrtS is to modulate the insect immune response. Further studies of PLPs' biological role in the PrtS and P. laumondii model must clarify the details of PrtS interaction with the insect immune system during bacterial infection.

Effect of the Biostimulants of Microbiological Origin on the Entomopathogenic and Plant Parasitic Nematodes from Miscanthus × Giganteus Plantations

Abstract This study aimed to evaluate the effect of biostimulants derived from Streptomyces avermitilis metabolites on entomopathogenic nematodes: Steinernema carpocapsae, Steinernema feltiae, and Heterorhabditis bacteriophora, obtained from the soil of several Miscanthus × giganteus plantations in 2020–2023. The nematodes were isolated, identified, and cultured using live insects (the greater wax moth Galleria mellonella). Three preparations containing biostimulants – Charkor, Stimpo, and Regoplant, were tested for compatibility with entomopathogenic and plant parasitic nematodes. Their effect on nematode survival was evaluated using the Petri dish test. The study showed that the effect of biostimulants on the survival of nematodes depended on the concentration of aversectin contained in the evaluated preparations. Stimpo and Regoplant had an adverse effect on plant parasitic nematodes. The highest G. mellonella mortality was observed at the higher dose of Charkor (0.4%), and the lowest at the lower dose of Regoplant (1.22%). The study showed that the virulence of the nematodes decreased after 48 hours of incubation in Regoplant and Stimpo solutions containing aversectin. The degree of interaction between nematodes depended on the nematode species, trophic preferences, and the concentration of active ingredients in the preparations. This conclusion is crucial for the selection of appropriate types of entomopathogenic nematodes and the application rate of plant parasitic nematodes in the assessment of their short- and long-term spread, persistence, and recycling in field conditions.

Insect immunity - adaptive mechanisms and survival strategies

Host-pathogen interactions play an important role in understanding the dynamics of the insect immune system. The analysis of environmental modulators, both biotic and abiotic, directs our attention to the impact of the surroundings on the effectiveness of immunological responses. This knowledge is essential for the comprehensive understanding of insect’s immune reaction after infection with a pathogen. This article discusses the role of the immune system in insect, with a special emphasis on greater wax moth Galleria mellonella and highlights its adaptive capabilities. The processes are not only extremely interesting area of scientific research but also indicate potential practical applications in the context of plan protection, pest population control and medicine.

Phenotypic and genotypic characterization of Campylobacter coli isolates from the Vietnamese poultry production network; a pilot study

IntroductionChanging farming practices and the associated increase in the use of antibiotics are amongst the main drivers shaping the global increase of Campylobacter infections. The effects farming practices have on Campylobacter species, need to be studied at the global scale, particularly in emerging middle-income countries, where the demand for low-cost poultry meat is rising. While Campylobacter jejuni causes the majority of poultry associated diarrhoea, Campylobacter coli causes a significant amount of disease but are relatively understudied. In this study we characterised seven C. coli strains isolated from chicken faeces and chicken meat in Thai Nguyen province, Vietnam.MethodsWhole Genome Sequencing and phenotypic assays (growth, motility, antimicrobial resistance testing, virulence assay) were performed to reveal the genetic relatedness and pathophysiological characteristics of the isolates. ResultsAll isolates were resistant to ciprofloxacin and nalidixic acid but susceptible to phenicols. Three were resistant to macrolides azithromycin and erythromycin. Six isolates were classified as multi-drug resistant. All isolates had similar growth rates in laboratory culture media, while five were hyper-motile. Lethality towards a tractable host-model system, larvae of the greater wax moth Galleria mellonella, often used to determine Campylobacter virulence, was demonstrated for the first time for C. coli. DiscussionMultilocus sequence typing data identified five ST’s all within the C. coli ST-828 clonal complex and were previously reported in North American (ST-829), European (ST-1586), and Asia (ST-5511) from patients suffering from gastroenteritis, emphasising the global spread of these strains. This work highlights the importance of further research into this understudied global threat.

Immunophenotyping of hemocytes from infected Galleria mellonella larvae as an innovative tool for immune profiling, infection studies and drug screening

In recent years, there has been a considerable increasing interest in the use of the greater wax moth Galleria mellonella as an animal model. In vivo pharmacological tests, concerning the efficacy and the toxicity of novel compounds are typically performed in mammalian models. However, the use of the latter is costly, laborious and requires ethical approval. In this context, G. mellonella larvae can be considered a valid option due to their greater ease of use and the absence of ethical rules. Furthermore, it has been demonstrated that the immune system of these invertebrates has similarity with the one of mammals, thus guaranteeing the reliability of this in vivo model, mainly in the microbiological field. To better develop the full potential of this model, we present a novel approach to characterize the hemocyte population from G. mellonella larvae and to highlight the immuno modulation upon infection and treatments. Our approach is based on the detection in isolated hemocytes from G. mellonella hemolymph of cell membrane markers typically expressed by human immune cells upon inflammation and infection, for instance CD14, CD44, CD80, CD163 and CD200. This method highlights the analogies between G. mellonella larvae and humans. Furthermore, we provide an innovative tool to perform pre-clinical evaluations of the efficacy of antimicrobial compounds in vivo to further proceed with clinical trials and support drug discovery campaigns.

Genomics, transcriptomics, and peptidomics of the greater wax moth Galleria mellonella neuropeptides and their expression in response to lead stress.

Neuropeptides are crucial in regulation of a rich variety of developmental, physiological, and behavioral functions throughout the life cycle of insects. Using an integrated approach of multiomics, we identified neuropeptide precursors in the greater wax moth Galleria mellonella, which is a harmful pest of honeybee hives with a worldwide distribution. Here, a total of 63 and 67 neuropeptide precursors were predicted and annotated in the G. mellonella genome and transcriptome, in which 40 neuropeptide precursors were confirmed in the G. mellonella peptidome. Interestingly, we identified 12 neuropeptide precursor genes present in G. mellonella but absent in honeybees, which may be potential novel pesticide target sites. Honeybee hives were contaminated with heavy metals such as lead, enabling its bioaccumulation in G. mellonella bodies through the food chain, we performed transcriptome sequencing to analyze the effects of Pb stress on the mRNA expression level of G. mellonella neuropeptide precursors. After treatment by Pb, the expression of neuropeptide F1 was found to be significantly downregulated, implying that this neuropeptide might be associated with responding to the heavy metal stress in G. mellonella. This study comprehensively identified neuropeptide precursors in G. mellonella, and discussed the effects of heavy metals on insect neuropeptides, with the example of G. mellonella. The results are valuable for future elucidation of how neuropeptides regulate physiological functions in G. mellonella and contribute to our understanding of the insect's environmental plasticity and identify potential new biomarkers to assess heavy metal toxicity in insects.

Coxiella co-opts the Glutathione Peroxidase 4 to protect the host cell from oxidative stress–induced cell death

The causative agent of human Q fever, Coxiella burnetii, is highly adapted to infect alveolar macrophages by inhibiting a range of host responses to infection. Despite the clinical and biological importance of this pathogen, the challenges related to genetic manipulation of both C. burnetii and macrophages have limited our knowledge of the mechanisms by which C. burnetii subverts macrophages functions. Here, we used the related bacterium Legionella pneumophila to perform a comprehensive screen of C. burnetii effectors that interfere with innate immune responses and host death using the greater wax moth Galleria mellonella and mouse bone marrow-derived macrophages. We identified MceF (Mitochondrial Coxiella effector protein F), a C. burnetii effector protein that localizes to mitochondria and contributes to host cell survival. MceF was shown to enhance mitochondrial function, delay membrane damage, and decrease mitochondrial ROS production induced by rotenone. Mechanistically, MceF recruits the host antioxidant protein Glutathione Peroxidase 4 (GPX4) to the mitochondria. The protective functions of MceF were absent in primary macrophages lacking GPX4, while overexpression of MceF in human cells protected against oxidative stress-induced cell death. C. burnetii lacking MceF was replication competent in mammalian cells but induced higher mortality in G. mellonella, indicating that MceF modulates the host response to infection. This study reveals an important C. burnetii strategy to subvert macrophage cell death and host immunity and demonstrates that modulation of the host antioxidant system is a viable strategy to promote the success of intracellular bacteria.

Efficiency of the Iraqi Isolates of Beauveria Bassiana & Metarhizium Anisopliae in Controlling the Greater Wax Moth Galleria Mellonella L.

The current study was conducted in the laboratories of the Plant Protection Department/College of Agriculture and Forestry/University of Mosul during the year 2019-2020. The aim of this study was to evaluate the efficiency of the Iraqi isolate of the biological control fungi Beauveria bassian and Metarhizium anisopliaeas chemical pesticides alternatives in controlling different stages of the greater wax moth Galleria mellonella. The results of the biological effect of the fungi Beauveria bassiana and Metarhizium anisopliae on the greater wax moth life stages showed that the cumulative mortality of eggs increased gradually with increasing concentration used. However, Beauveria bassiana was more efficient in achieving higher mortality rates than M. anisopliae in general. The highest cumulative mortality rate for eggs was at the highest concentration (7.5g/l) for both fungi. On the other hand, it was found that the highest mortality rate in wax moth larvae was inB. bassianacombined treatmentwhere spraying the larvae and the feed. The third and fourth larval instars were more sensitive than the sixth and seventh larval instars, which were not affected by the lower concentrations of the pesticide (2.5 and 5 g/L), regardless of pesticide type. The results also showed that the mortality rate in all phases increases with the increase in the post-treatment period. The results of the study indicated the superiority of B. bassiana in all treatments, concentrations and periods after treatment and led to the highest mortality rate compared with using M. anisopliae. The cumulative mortality rate in the greater wax moth was directly proportional to the increase in treatment methods and the increase in concentration and the time period after treatment.

Debilitation of Galleria mellonella hemocytes using CytCo a cytolytic-like protein derived from the entomopathogen Conidiobolus obscurus

Cytolytic (Cyt)-like genes are present in both pathogenic bacteria and fungi. Bacterial Cyt proteins can destroy insect midgut epithelial cells after ingestion by hosts and some of them have been developed as biopesticides; however, few studies have investigated their functions in fungal pathogens. This study investigated the effects of a Cyt-like protein (CytCo) derived from Conidiobolus obscurus (Entomophthoromycotina) on the hemocytes of the greater wax moth Galleria mellonella larvae. The results showed a significant decline in hemocyte viability after treatment with CytCo in vivo or in vitro. The hemocyte density in the hemolymph was reduced by 65.2% and 50.2% after 12 h in vivo and 6 h in vitro treatments, respectively. Apoptosis/necrosis tests using fluorescence microscopy demonstrated that CytCo-treated hemocytes displayed apoptosis, and many of them also showed necrosis after 6 h in vitro treatment. Based on transcriptome analysis, several genes involved in the programmed cell death signaling pathway were upregulated in the CytCo-treated hemocytes. Meanwhile, the differentially expressed genes related to energy production, signal transduction, transcription regulation, and melanization were upregulated, demonstrating activated immune responses; those putatively related to hemocyte adhesion were downregulated, possibly in response to the reduction of hemocytes in hemolymph. In conclusion, CytCo as a virulence factor, could irreversibly incapacitate host hemocytes, playing an important role in debilitating insect immunity. This novel insecticidal protein holds a potential to develop biopesticide for controlling agroforestry pests.

Valuation The efficiency of Nanotechnology and biological activity of Nanoparticle for two plant extracts Ricinus communis and Neriun oleander against immature stages of Greater wax moth.Galleria mellonella (Lepidoptera: pyralidae)

The results of present study conducted on the Laboratory of advance entomology \ Department of biology \ Faculty of Education for Girls \ University of Kufa, during the years 2018-2019 for evaluating The efficiency of Nanotechnology and biological control and the effect of two plant extracts on the different immature stages of the greater wax moth Galleria mellonella (Lepidoptera: Pyrallidae). eggs, first and fourth larval instars. The cold aqueous extract of castor Ricinus communis and Nerium oleander leaves ,from which different concentrations ( 1,2,3 and 4) mg \ ml were prepared in the Laboratory. The experiments include the enhancement of these plant extracts of toxic nature with chemically prepared particles, silver nanoparticles, and conducting multiple experiments for the same instars of the insect, which was treated with aqueous plant extracts .The statistical results as well as the observation during different stages of the experiments were superior of these nanoextracts over plant extracts in the mortality of eggs and first and fourth latval instars. Experiments indicated that the mortality percentages when treated with aqueous leaves extract of castor were (76, 91, 96) % respectively while the same instars were treated with nano extract of castor was(83.3 ,92.3 ,98.6 )% respectivly . The leaves extract of N.oleander was (86.6%, 96.6%, 99.4%) compared with (93.3, 100, 100) % respectively of the nanoparticle of the eggs and larvae of the first and fourth phases at 4 mg / ml. It also proved that the first instar was the most sensitive to the extract of the fourth instar, where the highest mortality percentages was (96.6, 100) % compared with (86.6, 93.3)% respectively of the first and fourth larval instars when treated with and nano of N. oleander and R.communis respectively.

UV-induced mutagenesis of Beauveria bassiana (Hypocreales: Clavicipitaceae) yields two hypervirulent isolates with different transcriptomic profiles.

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) can infest over 300 plant species and cause huge economic losses. Beauveria bassiana (Hypocreales: Clavicipitaceae) is one of the most widely used entomopathogenic fungi (EPF). Unfortunately, the efficacy of B. bassiana against S. frugiperda is quite low. Hypervirulent EPF isolates can be obtained by ultraviolet (UV)-irradiation. Here we report on the UV-induced mutagenesis and transcriptomic analysis of B. bassiana. The wild-type (WT) B. bassiana (ARSEF2860) was exposed to UV light to induce mutagenesis. Two mutants (named 6M and 8M) showed higher growth rates, conidial yields, and germination rates compared to the WT strain. The mutants showed higher levels of tolerance to osmotic, oxidative, and UV stresses. The mutants showed higher protease, chitinase, cellulose, and chitinase activities than WT. Both WT and mutants were compatible with the insecticides matrine, spinetoram, and chlorantraniliprole, but incompatible with emamectin benzoate. Insect bioassays showed that both mutants were more virulent against S. frugiperda and the greater wax moth Galleria mellonella. Transcriptomic profiles of the WT and mutants were determined by RNA-sequencing. The differentially expressed genes (DEGs) were identified. The gene set enrichment analysis (GSEA), protein-protein interaction (PPI) network, and hub gene analysis revealed virulence-related genes. Our data demonstrate that UV-irradiation is a very efficient and economical technique to improve the virulence and stress resistance of B. bassiana. Comparative transcriptomic profiles of the mutants provide insights into virulence genes. These results provide new ideas for improving the genetic engineering and field efficacy of EPF. © 2023 Society of Chemical Industry.

Low dose γ-radiation induced effects on wax moth (Galleria mellonella) larvae

Larvae of the greater wax moth Galleria mellonella are common pests of beehives and commercial apiaries, and in more applied settings, these insects act as alternative in vivo bioassays to rodents for studying microbial virulence, antibiotic development, and toxicology. In the current study, our aim was to assess the putative adverse effects of background gamma radiation levels on G. mellonella. To achieve this, we exposed larvae to low (0.014 mGy/h), medium (0.056 mGy/h), and high (1.33 mGy/h) doses of caesium-137 and measured larval pupation events, weight, faecal discharge, susceptibility to bacterial and fungal challenges, immune cell counts, activity, and viability (i.e., haemocyte encapsulation) and melanisation levels. The effects of low and medium levels of radiation were distinguishable from the highest dose rates used – the latter insects weighed the least and pupated earlier. In general, radiation exposure modulated cellular and humoral immunity over time, with larvae showing heightened encapsulation/melanisation levels at the higher dose rates but were more susceptible to bacterial (Photorhabdus luminescens) infection. There were few signs of radiation impacts after 7 days exposure, whereas marked changes were recorded between 14 and 28 days. Our data suggest that G. mellonella demonstrates plasticity at the whole organism and cellular levels when irradiated and offers insight into how such animals may cope in radiologically contaminated environments (e.g. Chornobyl Exclusion Zone).

Pseudomonas aeruginosa exotoxin A induces apoptosis in Galleria mellonella hemocytes

The cellular immune response of the greater wax moth Galleria mellonella to Pseudomonas aeruginosa exotoxin A was investigated for the first time. The insects were challenged with a sublethal dose of exoA, and then hemocyte parameters were assessed. The analysis showed a statistically significant decrease in the total hemocyte count (THC), which was associated with significant decreases in the number of granulocytes and plasmatocytes. In turn, no statistically significant changes were observed in the number of spherulocytes and oenocytoides. Fluorescent staining indicated that cells collected from the exoA-challenged larvae exhibited features characteristic for apoptotic and autophagic cell death, e.g. cytoplasm vacuolization and chromatin condensation. The flow cytometry analysis revealed a significant increase in the number of phosphatidylserine- and active caspase 3-positive hemocytes challenged with exoA, which proved apoptosis induction. Our results will help in understanding the role of exotoxin A during P. aeruginosa infections not only in insects but also in mammals, including humans.

Efficacy of gamma radiation on the greater wax moth <i>Galleria mellonella</i> L.

The effect of ionizing radiation from 50 to 450 Gy on the eggs and larvae 100 to 1500 Gy. on larvae of greater wax moth Galleria mellonella L. The results revealed that the egg hatchability reduced to 50% at 102.70 Gy. In the most radiation resistant eggs, 350 Gy resulted in no pupal formation while a dose of 250 Gy resulted in no adult formation. Within 51.53 hr, a dose of 500 Gy reduced the larval survival to 50%. With 148, 574 and 680 Gy, the proportion of larvae that matured into adults reduced to 50%, 10%, and 0%, respectively. A radiation dose between 300 and 400 Gy was found adequate for egg sterilization and larval mortality.