Intestinal symbiotic bacteria have played an important role in the digestion, immunity detoxification, mating, and reproduction of insects during long-term coevolution. The oriental fruit moth, Grapholita molesta, is an important fruit tree pest worldwide. However, the composition of the G. molesta microbial community, especially of the gut microbiome, remains unclear. To explore the differences of gut microbiota of G. molesta when reared on different host plants, we determined the gut bacterial structure when G. molesta was transferred from an artificial diet to different host plants (apples, peaches, nectarines, crisp pears, plums, peach shoots) by amplicon sequencing technology. The results showed that Proteobacteria and Firmicutes are dominant in the gut microbiota of G. molesta. Plum-feeding G. molesta had the highest richness and diversity of gut microbiota, while apple-feeding G. molesta had the lowest. PCoA and PERMANOVA analysis revealed that there were significant differences in the gut microbiota structure of G. molesta on different diets. PICRUSt2 analysis indicated that most of the functional prediction pathways were concentrated in metabolic and cellular processes. Our results confirmed that gut bacterial communities of G. molesta can be influenced by host diets and may play an important role in host adaptation.

Spodoptera frugiperda is a highly polyphagous and invasive agricultural pest that can harm more than 300 plants and cause huge economic losses to crops. Symbiotic bacteria play an important role in the host biology and ecology of herbivores, and have a wide range of effects on host growth and adaptation. In this study, high-throughput sequencing technology was used to investigate the effects of different hosts (corn, wild oat, oilseed rape, pepper, and artificial diet) on gut microbial community structure and diversity. Corn is one of the most favored plants of S. frugiperda. We compared the gut microbiota on corn with and without a seed coating agent. The results showed that Firmicutes and Bacteroidetes dominated the gut microbial community. The microbial abundance on oilseed rape was the highest, the microbial diversity on wild oat was the lowest, and the microbial diversity on corn without a seed coating agent was significantly higher than that with such an agent. PCoA analysis showed that there were significant differences in the gut microbial community among different hosts. PICRUSt analysis showed that most of the functional prediction categories were related to metabolic and cellular processes. The results showed that the gut microbial community of S. frugiperda was affected not only by the host species, but also by different host treatments, which played an important role in host adaptation. It is important to deepen our understanding of the symbiotic relationships between invasive organisms and microorganisms. The study of the adaptability of host insects contributes to the development of more effective and environmentally friendly pest management strategies.

Sitophilus zeamais is one of the most destructive pests of stored grains. Both adults and larvae penetrate and consume the grains, thereby diminishing the grain quality and nutritional value. We determined the chemical composition of Angelica archangelica essential oil, its fumigation toxicity against S. zeamais, and its effects on the activities of detoxification enzymes in the insects. RNA-seq was performed to analyze the impact of the essential oil on the transcriptional level of S. zeamais, and qRT-PCR was conducted to validate the differentially expressed genes. Chemical analysis identified 35 components in essential oil, including δ-3-Carene (24.26%), Limonene (19.81%), and α-Pinene (14.96%). A significant positive correlation was observed between the fumigation activity of the essential oil and the applied dose. The median lethal concentrations (LC₅₀) values were 164.38, 132.62, and 90.35 mg/L air at 24, 48, and 72 h, respectively. Fumigation significantly inhibited the activities of the three detoxification enzymes. RNA-seq revealed a total of 3718 significantly differentially expressed genes (DEGs). qRT-PCR confirmed that the expression patterns of the DEGs were consistent with the RNA-seq data. This study comprehensively evaluates the control efficacy of A. archangelica essential oil against S. zeamais and provides data support for developing novel, eco-friendly, plant-based pesticides.

Schizaphis graminum is the most important pest of wheat, and its feeding harm not only affects photosynthesis but also causes diseases, posing a serious threat to wheat production. We measured the contact killing and fumigation activities, population changes, enzyme activities, and nanoemulsion physicochemical property of Eupatorium fortune essential oil (EFEO) and pyrethrin against S. graminum and its natural enemy (Harmonia axyridis). Toxic effects of EFEO and pyrethrin increased with increasing concentration. After 24 h of contact killing, the LD₅₀ of S. graminum were 9.23 and 0.02 μg/head, respectively. Harmonia axyridis were 36.71 and 0.07 μg/head. The fumigation of EFEO LD₅₀ on S. graminum was 9.779 mg/L (y = 2.88x − 2.852). EFEO contains 28 chemical components, including l-Caryophyllene, Lily aldehyde, α-Terpineol, and Cineole. EFEO LD₅₀ significantly reduced the adult longevity, nymph production, and nymph production duration of the F0 S. graminum, while there were no significant differences in various parameters of offspring. The activity of acetylcholinesterase, glutathione-S-transferase, and carboxylesterase is significantly affected. The population decline rate of EFEO nanoemulsion is significantly higher than that of EFEO. This research aims to clarify the toxic effect of EFEO on S. graminum, providing a scientific basis for developing new plant essential oil preparations and nano preparations.

Background: Propolis is a composite substance that Apis mellifera worker bees produce from plant resins they collect and blend with their own secretions. The antennae detect signals from nectar, pollen, and propolis sources during the foraging process, thereby regulating foraging behavior. However, the relationship between resin collection behavior and olfaction in worker bees from different colonies remains unclear. We compared the antennal morphology and RNA-seq profiles of foragers from high propolis-producing and ordinary colonies of A. mellifera worker bees, comprehensively characterized three gene families (OBPs, CSPs, and ORs), and validated expression patterns by qRT-PCR. Results: We found that the total length of both the left and right antennae, as well as the lengths of flagellomeres FL7 and FL10, were significantly shorter in high-yield colonies than in ordinary colonies. We analyzed the FPKM heatmaps, chromosomal locations, and conserved domains of six CSPs, 19 OBPs, and 34 ORs, and performed phylogenetic analyses with Apis cerana , Chouioia cunea , Nasonia vitripennis , and Bombus . qRT-PCR expression levels of these 58 genes were consistent with the RNA-seq expression patterns. We report for the first time the differences in antennal morphology and RNA-seq results between colonies with differential propolis yield, as well as differences in gene expression of these three gene families between the two colony types. Conclusions: Results not only provide a molecular basis for further research into how worker bee antennae function in honeybee colonies, but also offer new perspectives on the molecular mechanisms underlying the interaction between worker bee behavioral differentiation and the olfactory system.