Search Results (128)

Stag beetles are saproxylic insects, essential for decomposing rotten wood and maintaining the carbon cycle. Their gut bacteria contribute significantly to nutrient digestion and energy acquisition, making them crucial for understanding host-microbe interactions. Despite the fungivorous behavior of stag beetle larvae, research on how diet influences gut bacterial diversity remains scarce. Therefore, this study was conducted to compare the diversity and metabolic functions of gut bacteria in Dorcus hopei larvae fed on fungus (Pleurotus geesteranus) and rotten wood diets using high-throughput sequencing technology. Significant differences (p < 0.05) were observed in gut bacterial community composition between two diets, highlighting diet as a key factor shaping bacterial diversity. Additionally, gut bacterial communities varied across larval developmental stages (p < 0.05), indicating the influence of host age. Dominant bacterial phyla included Firmicutes, Bacteroidetes, and Proteobacteria. Bacteroidetes were more abundant in rotten-wood-fed larvae (7.61%) than fungus-fed larvae (0.15%), while Proteobacteria were more abundant in fungus-fed larvae. Functional analysis revealed that rotten-wood-fed larvae were primarily related to carbohydrate and amino acid metabolism, whereas fungus-fed larvae exhibited enhanced membrane transport function. This study enhances the understanding of gut bacterial diversity and functions in stag beetles, providing a theoretical foundation for their conservation and sustainable utilization. Full article

Bacterial symbionts play an important role in insect survival by contributing to key metabolic and defensive functions. While stingless bees are known to harbor diverse microbial communities, their core bacterial symbionts remain poorly characterized. In this study, we analyzed the gut microbiota of sixteen stingless bee species collected from different regions of Mexico using 16S rRNA gene sequencing on the Illumina^® MiSeq™ platform. Our results revealed that Proteobacteria, Firmicutes, and Actinobacteria are the most abundant bacterial phyla across species. Among the dominant genera, lactic acid bacteria, such as Lactobacillus spp., Bifidobacterium, and Fructobacillus spp., were the most prevalent. These bacteria are responsible for developing biochemical functions in metabolic processes like lactic fermentation and the biotransformation of complex organic compounds into molecules that are more easily assimilated by bees. This study offers a novel perspective on the diversity and predicted composition of gut microbiota in Mexican stingless bees. By highlighting differences in microbial communities among species with different feeding habits, our results emphasize the importance of preserving microbial biodiversity in these pollinators. Full article

Insects are often associated with diverse microorganisms that enhance their metabolism and nutrient assimilation. These microorganisms, residing in the insect’s gut, play a crucial role in breaking down complex molecules into simpler compounds essential for the host’s growth. This study investigates the diversity and functional potential of symbiotic bacteria in the gut of Arsenura armida (Lepidoptera: Saturniidae) larvae, an edible insect from southeastern Mexico, using culture-dependent and metagenomic approaches. Bacterial strains were isolated from different gut sections (foregut, midgut, and hindgut) and cultured on general-purpose media. Isolates were identified through 16S rRNA gene sequencing and genomic fingerprinting. Metagenomics revealed the bacterial community structure and diversity, along with their functional potential. A total of 96 bacterial strains were isolated, predominantly Gram-negative bacilli. Rapidly growing colonies exhibited enzymatic activity, cellulose degradation, and sugar production. Phylogenetic analysis identified eight genera, including Acinetobacter, Bacillus, Enterobacter, Pseudomonas, and others, with significant cellulose-degrading capabilities. Metagenomics confirmed Bacillota as the most abundant phylum. These complementary methods revealed abundant symbiotic bacteria with key metabolic roles in A. armida, offering promising biotechnological applications in enzymatic bioconversion and cellulose degradation. Full article

Gut microbes are important for saproxylophagous insects, but little is known about the specific types of microbes that we can grow in the lab and how their diet affects them. We characterized aerobic culturable microbes from the superworm Zophobas atratus larvae reared on a standard diet (SD) and a fungal-based diet (FD) using the selective plating and 16S rRNA sequencing of isolates. Five functional groups were cultured: amino acid autotrophs, enterobacteria, yeasts, cellulolytic bacteria, and molds. A quantitative assessment revealed distinct diet-dependent patterns: SD-fed larvae showed the dominance of enterobacteria and amino acid autotrophs, while FD-fed larvae exhibited a higher abundance of enterobacteria and yeasts. Mold populations remained minimal under both diets. A phylogenetic analysis of bacterial isolates showed four core bacterial phyla (Pseudomonadota, Actinobacteria, Bacillota, and Bacteroidota) with diet-sensitive genus-level variations. Pseudomonadota dominated both diets, but certain genera were associated with different diets: Micrococcus and Brucella in the SD versus Citrobacter and Pseudomonas in the FD. Shared genera (Klebsiella, Enterobacter, and Bacillus) may represent a core culturable community. These findings demonstrate the influence of diet on culturable gut microbes while highlighting the need for complementary molecular approaches to study unculturable taxa. The isolated strains provide resources for investigating microbial functions in insect nutrition. Full article

Harmless crop-associated insect communities are a fundamental part of the agroecosystem. Their potential as a reservoir of natural enemies of pests has encouraged their conservation through the development of low-impact pest management programs. The brown marmorated stink bug, Halyomorpha halys, represents a serious threat to Italian hazelnut production. Laboratory and field experiments confirmed the susceptibility of this pest to the disruption of the obligated symbiotic interaction with gut bacteria, paving the way for the development of the symbiont-targeted control strategy. Here we present the results of a three-year field assessment of symbiont-targeted control in a hazelnut orchard in northwestern Italy. The use of a biocomplex to disrupt symbiont acquisition by H. halys nymphs was compared to the use of lambda-cyhalothrin insecticide. The effects on the local entomofauna were assessed, as were the trend of H. halys population and the damage caused by stink bugs to harvested hazelnuts. The insecticide consistently reduced the insect diversity in the field, while the anti-symbiont biocomplex had no effect. However, the control of the H. halys population and the stink bug-induced damage to hazelnuts varied over the years in the field plot submitted to the symbiont-targeted approach. Our results indicate that the symbiont-targeted control does not interfere with local insect communities. Key aspects for improving the effectiveness of this tactic are discussed. Full article

In insect–microbe symbiosis, understanding the diversity of associated bacteria is crucial. DNA-dependent sequence methods are widely used to assess microbial diversity in insects, but they cannot distinguish between live and dead microbes. In contrast, RNA-dependent sequencing can identify alive bacterial communities, making them more suitable for evaluating alive microbiota diversity. However, its practical reliability in insect–microbe symbiosis remains poorly validated. This study investigated larval gut bacteria diversity of Delia antiqua, a major pest of Liliaceae crops, by employing both DNA- and RNA-dependent 16S rRNA amplicon sequencing. The reliability of both sequencing methods was evaluated by comparing the effects of synthetic communities (SynComs, constructed according to DNA- or RNA-dependent sequencing) and bacterial communities from wild larvae on axenic larvae. Results revealed significant differences in bacterial community between DNA- and RNA-dependent sequence samples. Compared to bacterial communities from wild larvae, the SynCom constructed based on RNA-dependent sequencing exhibited inhibition effects on D. antiqua larvae survival and body weight, while DNA-dependent SynCom did not, suggesting that DNA-dependent methods were superior for assessing symbiotic microbiota in D. antiqua. This work will provide insights into microbial diversity detection in D. antiqua and offer a framework for other insect–microbe studies. Full article

In this study, the migratory agricultural pest Spodoptera frugiperda was exposed to three periodic short-term heat stress regimes at 37 °C, 40 °C, and 43 °C (2 h daily), with a constant 26 °C control. We systematically evaluated the effects of periodic thermal stress on developmental traits across all life stages. Combined with 16S rRNA high-throughput sequencing, we analyzed the structural and functional characteristics of the gut bacterial community in adults under heat stress. The results demonstrated that 37 °C exposure accelerated egg-to-adult development, whereas 43 °C markedly extended it. Additionally, 43 °C heat stress suppressed pupation and eclosion rates. Increasing stress temperatures were negatively correlated with pupal weight and body size in both sexes. Notably, 43 °C heat stress caused complete loss of hatching ability in offspring eggs, thereby rendering population reproduction unattainable. 16S rRNA sequencing revealed that Proteobacteria (>90%) dominated the gut bacterial community at the phylum level across all treatments. Under 43 °C heat stress, although female and male adults exhibited an increase in specific bacterial species within their gut bacteria, Alpha diversity analysis revealed no significant differences in the diversity (Shannon index) and richness (Chao index) of gut bacterial communities between sexes under temperature treatments. PICRUSt2 functional prediction indicated that metabolic pathways, biosynthesis of secondary metabolites, and microbial metabolism in diverse environments constituted the dominant functions of gut bacteria in both sexes, while heat stress exerted minimal effects on the functional profiles of gut bacteria in S. frugiperda. These findings not only provide a theoretical basis for predicting summer population dynamics and formulating ecological control strategies for S. frugiperda but also offer critical insights into the adaptive interactions between this pest and its gut bacterial community under heat stress. The results lay a foundation for further exploring the interactions between insect environmental adaptability and bacterial symbiosis. Full article

The impact of short-term feeding of three distinct diets containing insect meals on the intestinal microbiota of African catfish hybrid (Clarias gariepinus × Heterobranchus longifilis) juveniles was examined. The animals received experimental diets containing 30% insect meals derived from black soldier-fly larvae (BSL) (Hermetia illucens), yellow mealworm (Tenebrio molitor) or blue bottle-fly larvae (Calliphora vicina) for 18 days. The relative abundance of the Bacillaceae, the Planococcaceae and other bacteria significantly increased (p < 0.05) in the intestinal microbiota of the BSL group and also in the pooled group of the three catfish groups that received insect meals. Several strains of the Bacillales cultured from BSL feed had higher (p < 0.05) abundance in the intestinal microbiota of the BSL group compared to those of the control group. Among these Bacillales strains, a single fosB antibiotic resistance gene was identified. In the gut resistomes of both the BSL and the control catfish groups, the tetA(P), tetB(P) and lnu(C) antibiotic-resistance determinants were detected, while fosB was detected only in the BSL group. Overall, the study showed that a short-term shift to diets containing insect meals can induce significant (q < 0.05) changes in the gut microbiota of the African catfish without the development of reduced α-diversity and without the overgrowth of bacteria pathogenic to fish. Full article

Trehalose, a disaccharide consisting of two D-glucose molecules, is present in a variety of organisms, including bacteria, yeast, fungi, insects, and plants. In plants, it functions as a source of energy and carbon, and in yeast and plants, it serves as a signaling molecule, influencing metabolic pathways and growth regulation. Additionally, it plays a role in protecting proteins and cell membranes from stress-induced damage. This study aims to assess the optimal level of trehalose supplementation in the diets of layer hens aged 34 to 49 weeks, addressing the limited existing literature on its effects on productivity. Experimental diets, designed in accordance with nutritional recommendations, were formulated to contain six different levels of trehalose (0, 0.05, 0.10, 0.30, 0.60, and 1.00%). The study was conducted over five 21-day periods, during which various performance parameters were evaluated. The results indicated that trehalose supplementation at levels of 0.05%, 0.10%, and 0.30% led to increased feed intake (FI) compared to the 1.00% level (p < 0.05). Furthermore, the highest trehalose level (1.00%) significantly reduced the feed conversion ratio by egg mass (FCRem) compared to both the control group and the other supplementation levels; however, the feed conversion ratio by dry matter (FCRDz) remained consistent across all treatments. The levels of 0.05%, 0.10%, and 0.30% exhibited superior FCREm and FCRDz compared to the 1.00% level. Egg weight (EW) was higher in the trehalose-supplemented groups compared to the control group. Additionally, the 1.00% trehalose treatment was found to be the most effective in terms of relative weights of shells (RWS), and egg mass (EM) was higher at all trehalose levels compared to the control group. The antioxidant status, as measured by malondialdehyde (MDA) levels, indicated that supplementation with 0.30% and 0.60% trehalose had a protective effect against oxidative stress, although the 1.00% level resulted in increased MDA levels. Total weight (TW) was highest in the 0.30% treatment group, and bone strength (BS) improved in the groups supplemented with 0.10% and 1.00% trehalose. Other parameters, including lipid content (L), dry matter (DM), phosphorus (P), and calcium (Ca), did not show any significant differences among the treatment groups. In conclusion, supplementation with 1.00% trehalose enhances feed efficiency, egg weight, and quality, with minimal impact on lipid peroxidation, while potentially providing benefits for gut health and egg quality. Full article

This experiment investigated the role of the gut microbiota in the growth and development of Antheraea pernyi, isolated gut bacteria related to lignin degradation in oak trees, and preliminarily verified their lignin degradation ability, providing a new tool for the field of biodegradation. The changes in the structure of the gut microbial community of the oak silkworm Antheraea pernyi at different developmental stages were analyzed via high-throughput sequencing of the 16SrDNA genes of the gut microbiota of fifth-instar larvae. A series of biological analyses were conducted, including amplicon sequence variant (ASV), microbial community diversity, microbial community composition, species difference, and evolutionary analyses. Ralstonia, Achromobacter, Pseudomonas, Cupriavidus, Bacteroidetes, Enterococcus, and Bacillus were the dominant bacterial groups in the gut microbiota of the larvae, with Ralstonia comprising the highest proportion, thereby providing a reference basis for a deeper understanding of the functions of the gut microbiota in insect growth and development. In this study, we activated and identified the MYZ028 strain isolated from the fifth-instar larvae of Antheraea pernyi through molecular biology, and we determined that the strain belonged to Bacillus subtilis. In terms of performance, the strain exhibited a high lignin-degrading ability and could effectively degrade lignin in a short time and simple environment. Due to the complex and difficult nature of degrading the lignin structure, research on the degradation of lignin by composite strains can be explored in the field of biodegradation. Full article

The Aedes aegypti mosquito serves as a vector for several diseases, including dengue, Zika, chikungunya, and yellow fever. This species is well adapted to urban environments and poses a significant threat to public health. Some studies suggest that the gut bacteria of insect vectors may play a crucial role in developing resistance to insecticides. This study assessed the resistance of Ae. aegypti from Florencia, Caquetá, to temephos and deltamethrin and analyzed the diversity of gut bacteria in resistant larvae and adult females. Larvae exhibited resistance to temephos at a lethal concentration 50 (LC₅₀) of 0.034 µg/mL, while females showed resistance to deltamethrin at a discriminant concentration of 10 µg/mL. The bacterial load in the guts of deltamethrin-treated females (3.42 × 10⁶ CFU/mL) was significantly higher compared to temephos-treated larvae (9.4 × 10⁵ CFU/mL) and untreated females (8 × 10⁴ CFU/mL). A total of sixty-eight bacterial strains were isolated from the guts of both larval and resistant females Ae. aegypti, with 31 strains identified through 16S rRNA gene analysis and 11 confirmed by gyrB gene sequencing. In untreated females, Bacillus comprised 12.55% of the gut bacteria and was identified as an exclusive genus. In resistant larvae, Serratia was the most abundant and exclusive genus, accounting for 35.29%, while in resistant females, Cedecea was the predominant genus, representing 66.67%. These findings suggest that gut bacteria may influence the resistance of Ae. aegypti to temephos and deltamethrin. Furthermore, this research provides valuable information that can be considered for the design of local vector control strategies. The results highlight new research focused on the study of insecticide tolerance and degradation within the gut microbiota of insect vectors of arboviruses. Full article

Gampsocleis gratiosa Brunner von Wattenwyl, 1862, is a type of omnivorous chirping insect with a long history of artificial breeding. It has high economic value and is also an excellent orthopteran model organism. In this study, 12 types of culture media combined with 16S rRNA sequencing were employed to isolate 838 bacterial strains from the gut of G. gratiosa. After sequence comparison, a total of 98 species of bacteria were identified, belonging to 3 phyla, 5 classes, 11 orders, 20 families, and 45 genera. Firmicutes and Proteobacteria accounted for the majority (92.86%). At the order level, Enterobacteriaceae, Bacillales, and Lactobacillales predominated (79.59%). At the genus level, Klebsiella (11.22%) and Enterococcus (7.14%) predominated. This study also enumerated the strain morphological, physiological and biochemical properties of 98 species of bacteria, including colony morphology, Gram staining, bacterial motility test, temperature gradient growth, pH gradient growth, citrate utilization test, temperature oxidase test, contact enzyme test, methyl red test, V-P test, indole test, gelatin liquefaction test, nitrate reduction test, hydrogen sulfide test, starch hydrolysis test, cellulose decomposition test, esterase (corn oil) test and antibiotic susceptibility testing. Additionally, 16 antibiotics were utilized to test the bacterial susceptibility of the strains. This study explored the types and community structure of some culturable microorganisms in the intestinal tract of G. gratiosa and recorded their physiological characteristics. These data reflect the physiological functions of the intestinal microorganisms of G. gratiosa and provide support for subsequent research on the interaction mechanism between microorganisms and their hosts. Full article

Insects often rely on symbiotic bacteria and fungi for various physiological processes, developmental stages, and defenses against parasites and diseases. Despite their significance, the associations between bacterial and fungal symbionts in Apis mellifera are not well studied, particularly in the Philippines. In this study, we collected A. mellifera from two different sites in the Municipality of Bacnotan, La Union, Philippines. A gut microbiome analysis was conducted using next-generation sequencing with the Illumina MiSeq platform. Bacterial and fungal community compositions were assessed using 16S rRNA and ITS gene sequences, respectively. Our findings confirm that adult worker bees of A. mellifera from the two locations possess distinct but comparably proportioned bacterial and fungal microbiomes. Key bacterial symbionts, including Lactobacillus, Bombilactobacillus, Bifidobacterium, Gilliamella, Snodgrassella, and Frischella, were identified. The fungal community was dominated by the yeasts Zygosaccharomyces and Priceomyces. Using the ENZYME nomenclature database and PICRUSt2 software version 2.5.2, a predicted functional enzyme analysis revealed the presence of β-glucosidase, catalase, glucose-6-phosphate dehydrogenase, glutathione transferase, and superoxide dismutase, which are involved in host defense, carbohydrate metabolism, and energy support. Additionally, we identified notable bacterial enzymes, including acetyl-CoA carboxylase and AMPs nucleosidase. Interestingly, the key bee symbionts were observed to have a negative correlation with other microbiota. These results provide a detailed characterization of the gut microbiota associated with A. mellifera in the Philippines and lay a foundation for further metagenomic studies of microbiomes in native or indigenous bee species in the region. Full article

The evolution of phytophagous insects has resulted in the development of feeding specializations that are unique to this group. The majority of current research on insect palatability has concentrated on aspects of ecology and biology, with relatively little attention paid to the role of insect gut symbiotic bacteria. Symbiont bacteria have a close relationship with their insect hosts and perform a range of functions. This research aimed to investigate the relationship between insect host plant range and gut symbiotic bacteria. A synthesis of the extant literature on the intestinal commensal bacteria of monophagous, oligophagous, and polyphagous tephritids revealed no evidence of a positive correlation between the plant host range and the diversity of larval intestinal microbial species. The gut symbionts of same species were observed to exhibit discrepancies between different literature sources, which were attributed to variations in multiple environmental factors. However, following beta diversity analysis, monophagy demonstrated the lowest level of variation in intestinal commensal bacteria, while polyphagous tephritids exhibited the greatest variation in intestinal commensal bacteria community variation. In light of these findings, this study proposes the hypothesis that exclusive or closely related plant hosts provide monophagy and oligophagy with a stable core colony over long evolutionary periods. The core flora is closely associated with host adaptations in monophagous and oligophagous tephritids, including nutritional and detoxification functions. This is in contrast to polyphagy, whose dominant colony varies in different environments. Our hypothesis requires further refinement of the data on the gut commensal bacteria of monophagy and oligophagy as the number of species and samples is currently limited. Full article

The ongoing interplay among plants, insects, and bacteria underscores the intricate balance of defense mechanisms in ecosystems. Regurgitant bacteria directly/indirectly impact plant immune responses, but the underlying mechanism is unclear. Here, we focus on the interaction between regurgitant bacteria, diamondback moth (DBM), and plant. Six culturable bacteria were isolated from DBM gut regurgitant, including three Enterobacter strains (RB1-3), Micrococcus sp. (RB4), Staphylococcus haemolyticus (RB5), and Bacillus cereus (RB6). These RB strains suppressed genes related to jasmonic acid and glucosinolate signaling pathways but had little effect on salicylic acid signaling pathway genes in Arabidopsis thaliana wounds. RB1 and RB5 inhibited DBM development on A. thaliana but not on an artificial diet. RB1 and RB5 significantly suppressed GOX genes and proteins in DBMs. However, the Pxgox2 insect mutant strain inoculated with RB1 or RB5 did not significantly affect DBM feeding on A. thaliana compared to the wild type. Six RB have been functionally identified, with RB1 and RB5 negatively regulating GOX-mediated host adaptability. The deliberate addition of RB1 and RB5 can negatively affect DBM herbivory and fitness. Our study provides a molecular basis for the further application of RB for insect pest management by modulating insect–plant interactions. Full article