Galleria mellonella: The Versatile Host for Drug Discovery, In Vivo Toxicity Testing and Characterising Host-Pathogen Interactions

Larvae of the greater wax moth, Galleria mellonella, are a convenient in vivo model for assessing the activity and toxicity of antimicrobial agents and for studying the immune response to pathogens and provide results similar to those from mammals. G. mellonella larvae are now widely used in academia and industry and their use can assist in the identification and evaluation of novel antimicrobial agents. Galleria larvae are inexpensive to purchase and house, easy to inoculate, generate results within 24–48 h and their use is not restricted by legal or ethical considerations. This review will highlight how Galleria larvae can be used to assess the efficacy of novel antimicrobial therapies (photodynamic therapy, phage therapy, metal-based drugs, triazole-amino acid hybrids) and for determining the in vivo toxicity of compounds (e.g., food preservatives, ionic liquids) and/or solvents (polysorbate 80). In addition, the disease development processes are associated with a variety of pathogens (e.g., Staphylococcus aureus, Listeria monocytogenes, Aspergillus fumigatus, Madurella mycotomatis) in mammals are also present in Galleria larvae thus providing a simple in vivo model for characterising disease progression. The use of Galleria larvae offers many advantages and can lead to an acceleration in the development of novel antimicrobials and may be a prerequisite to mammalian testing.

Evaluation Efficacy and Persistence of Some Volatile Plant Oils on Immature Stages of Galleria mellonella (L.)

The Experiment was carried out to measure the effect of four natural plant oils (namely: Cinnamonium zeylanicum L., Syzygium aromatic L., Citrus aurantium amara, and Lavandula spica) on controlling the greater wax moth and their ability to persist. The methodology included collecting and rearing the greater wax moth under laboratory conditions to be able to isolate the target tested stages. The immature stages (eggs and larvae) of the experiment moth were exposed to fumes of tested oils (50 µl/500 ml) to calculate hatchability and mortality percentage. The results were clear that fumes of C. zeylanicum and S. aromatic were caused 100% unhatching eggs after zero time as the same recorded by comparable compound (paradix) and able to persist their effect at the closed and limited zone for 60 days. On another side, C. zeylanicum and S. aromat were affected on last larval instars and emerged adults. The accumulative effect was appeared in the case of treatment by C. zeylanicum which was caused sterility to emerged adults and reduced eggs deposition to zero. The data indicated that some natural product compounds could be used as an alternative way of control insect pests.

First report of entomopathogenic nematode Steinernema surkhetense and its pathogenic potential to larvae of the Greater Wax Moth (Galleria mellonella L.) in Vietnam

Background Entomopathogenic nematodes (EPNs) are evidently a useful nematode group for the biocontrol of insect pests. It is well known that efficacy of different EPN strains, even belonging to the same species, can be significantly varied in different localities. Therefore, exploring EPNs and testing their efficacy in various ecological regions is of crucial importance to find out more efficient EPN strains. On the other hand, this practice is also needed to enhance the knowledge on diversity and distribution model of EPNs over the world. Results In this study, a species belonging to the genus Steinernema, S. surkhetense, has been characterized for the first time in Vietnam based on morphological and molecular characterizations. Morphological characterizations of infective juveniles, the first and second-generation adults, and molecular characterization of D2-D3 expansion segment of 28S rRNA region were given. Molecular phylogeny of the genus Steinernema was also provided. In addition, the study showed that the lethal efficacy of this local strain to larvae of Galleria mellonella L. was relatively higher than other reported EPN strains in Vietnam. Conclusions The Vietnamese EPN population found in this study was determined to be conspecific with S. surkhetense, revealed its new distribution in Vietnam. Besides, detailed morphological and molecular characterizations of it was provided with small variations compared to other populations in the world, and its relatively high lethal efficacy on larvae of G. mellonella implied that this strain can be potentially a useful strain for biological control of insect pests.

DEVELOPMENT OF A PLANT FOR THE INTRODUCTION OF ENERGY-SAVING LIGHT TECHNOLOGY FOR GROWING GREATER WAX MOTH IN AN INDUSTRIAL SCALE

The larvae of the greater wax moth (Galleria mellonella L.) are not only a serious pest of bee colonies, but also a valuable raw material for the production of biologically active substances widely used in pharmaceuticals, cosmetology, food industry, animal feed, as well as a source of high-quality protein. We have developed an energy-saving installation for industrial insect cultivation, consisting of two modules: the first for butterflies (adults), the second for larvae, pupae and eggs. To implement energy-saving light technology, experiments with a large wax moth were carried out in the laboratory of Udmurt Federal Research Center of the Ural Branch of the Russian Academy of Sciences. The experiments were repeated 4 times. There were 20 specimens of G. mellonella in each experiment. The air temperature was maintained at 28° C, air humidity 50%. The influence of the duration and wavelength of radiation (400 nm, 491 nm, 546 nm and 577 nm) on the number of adults that moved to the module for butterflies and on the mass of laid eggs was studied. The radiation of 400 nm turned out to be the most effective, since 45% of butterflies moved to it and the mass of laid eggs was 32%, which is significantly higher than that of the radiation of 491, 546 and 577 nm. The duration of the radiation was 10 minutes, 30 minutes and 60 min. With an experiment duration of 60 min. 45% of the large wax moth is transferred to the butterfly module, with an experiment duration of 30 minutes. - 44%, and with an experiment duration of 10 minutes, 43% of the large wax moth moved. Therefore, it is recommended to maintain the operating time of LEDs with a wavelength of 400 nm for 30 minutes. The aim of the research is to develop an installation for the implementation of energy-saving light technology for the cultivation of larvae of the greater wax moth (Galleria mellonella L.) on an industrial scale

The Effects of Nosema apis and Nosema ceranae Infection on Survival and Phenoloxidase Gene Expression in Galleria mellonella (Lepidoptera: Galleriidae) Compared to Apismellifera

The study aims to prove the possibility of colonization of N. apis and N. ceranae to the intestine of the greater wax moth, detect the differences of greater wax moth based on the presence of Nosema species and examine the effect of Nosema species on the phenoloxidase level of greater wax moth compared with honeybees. Each group was fed on the 1st day of the experiment with its appropriate diet containing 106 Nosema spores per insect. Each group was checked daily, and dead insects were counted. Furthermore, changes in the level of expression of the phenoloxidase-related gene after Nosema spp. treatment on the 6th, 9th and 12th days, which was detected by Q-PCR, and the mRNA level of phenoloxidase gene were measured in all experiment groups with the CFX Connect Real-Time PCR Detection System. This study shows that Apis mellifera L. has a 66.7% mortality rate in mixed Nosema infections, a 50% mortality rate in N. ceranae infection, a 40% mortality rate in N. apis infection, while there is no death in G. mellonella. A significant difference was found in the mixed Nosema infection group compared to the single Nosema infection groups by means of A. mellifera and G. mellonella (Duncan, p < 0.05). G. mellonella histopathology also shows that Nosema spores multiply in the epithelial cells of greater wax moth without causing any death. The increase in the mRNA level of Phenoloxidase gene in A. mellifera was detected (Kruskal–Wallis, p < 0.05), while the mRNA level of the Phenoloxidase gene did not change in G. mellonella (Kruskal–Wallis, p > 0.05). These findings prove that the Nosema species can colonize into the greater wax moth, which contributes to the dissemination of these Nosema species between beehives.

Biodegradation of Polystyrene by Tenebrio molitor, Galleria mellonella, and Zophobas atratus Larvae and Comparison of Their Degradation Effects

Plastic waste pollution and its difficult degradation process have aroused widespread concern. Research has demonstrated that the larvae of Tenebrio molitor (yellow mealworm), Galleria mellonella (greater wax moth), and Zophobas atratus (superworm) possess a biodegradation ability for polystyrene (PS) within the gut microbiota of these organisms. In this study, the difference in PS degradation and the changes of the gut microbiota were compared before and after feeding PS. The results showed that superworm had the strongest PS consumption capacity and the highest survival rate during the 30 d experiment period. They all could degrade PS to different degrees. Superworm showed the highest ability to degrade PS into low-molecular-weight substances, while yellow mealworm depolymerized PS strongly by destroying the benzene ring. The changes of the intestinal microbiome caused by feeding PS showed that after ingesting PS, there was a decrease in community diversity in superworm and yellow mealworm, but an increase in greater wax moth. Meanwhile, Enterococcus and Enterobacteriaceae, found in all three species’ larvae upon 20 d of PS feeding, might play an important role in PS degradation. The results will provide more accurate PS degradation comparative data of the three species’ larvae and theoretical guidance for further research on the efficient PS biodegradations.