Euplatypus parallelus is an invasive ambrosia beetle causing severe economic damage to rubber plantations across tropical southern China. However, an integrated trapping system combining effective attractants and optimised deployment remains lacking. In a field programme in Danzhou, Hainan, China, we screened seven volatile compounds across eight concentrations in 75

Euplatypus parallelus, a major pest of rubber trees, has inflicted severe damage on the natural rubber industry in Hainan Province. Odorant binding proteins (OBPs) play a crucial role in insect host plant location and serve as potential targets for attractant development. However, the interactions between E. parallelus OBPs and host plant volatiles and pheromones remain largely unexplored. In this study, we identified and characterized EparOBP6 as an antennal binding protein II (ABPII), a protein subfamily typically involved in the detection of host plant volatiles and pheromones. Fluorescence competitive binding assays showed that EparOBP6 binds strongly to several rubber tree volatiles, notably (+)-longifolene, β-ionone, cinnamyl acetate, and α-copaene. Molecular docking revealed eight key amino acid residues critical for ligand binding interactions. Electroantennography (EAG) and Y-tube olfactometer assays confirmed that β-ionone and cinnamyl acetate elicited significant electrophysiological and behavioral responses in both male and female beetles, whereas 1-naphthaldehyde primarily attracted males. RNA interference experiments demonstrated that silencing EparOBP6 in males significantly reduced their attraction to β-ionone and cinnamyl acetate, confirming the essential role of EparOBP6 in detecting these compounds. Field trapping experiments validated these laboratory findings, showing that traps baited with β-ionone and 1-naphthaldehyde captured significantly more male beetles compared to the control. These findings offer the first comprehensive insights into the olfactory mechanisms of E. parallelus, highlighting the essential role of EparOBP6 in mediating specific host-seeking behavior. This study provides a foundation for developing semiochemical-based pest management strategies for effective monitoring and control of this pest.

Euplatypus parallelus is a polyphagous pest capable of harming multiple plant species. Adult beetles invade tree trunks by boring holes, which negatively impacts the trees’ growth and may result in tree death. E. parallelus depends on plant volatiles to identify and locate appropriate hosts for feeding or reproduction, with its olfactory system playing a vital role in volatile detection. In this work, we applied transcriptomics, phylogenetic analysis, and expression analysis to investigate four chemosensory membrane protein gene families that play a role in olfaction in E. parallelus. Based on the annotation analysis, 41 odorant receptors (ORs), 12 gustatory receptors (GRs), 14 ionotropic receptors (IRs), and 4 sensory neuron membrane proteins (SNMPs) were identified in the head. We used differential gene expression (DGE) and fragments per kilobase per million (FPKM) values to compare the transcription levels of chemosensory membrane protein gene families between males and females. The data indicate that the chemosensory membrane protein gene families in E. parallelus exhibit different expression levels in male and female heads, with some genes showing significant differences and displaying sex-biased expression. These results offer a basis for future exploration of the functions of chemosensory membrane protein gene families in E. parallelus and offer a theoretical framework for designing innovative eco-friendly control technologies.

Tirathaba rufivena Walker (Lepidoptera: Pyralidae) is a major pest of palm plants, causing severe yield losses in areca nut cultivation in Hainan, China. The adult stage is critical for reproduction, exhibiting pronounced sexual dimorphism in physiology, behavior, and reproductive anatomy. However, genomic and transcriptomic studies on T. rufivena remain limited. This study aimed to increase our understanding of the molecular characteristics of T. rufivena and elucidate the molecular basis of sexual dimorphism using PacBio SMRT and Illumina sequencing. A total of 19.8 GB of clean data was generated, yielding 34,387 non-redundant full-length non-chimeric (FLNC) reads. Simple sequence repeats (SSRs) were characterized, with mononucleotide repeats being the most abundant. Coding sequence prediction identified 27,738 open reading frames (ORFs), including 23,137 complete ORFs, while 8,427 lncRNAs and 1,462 transcription factors were annotated. Differential expression analysis identified 6,147 differentially expressed genes (DEGs) between adult females and males. Female-biased genes were enriched in reproductive and translational functions, including "rRNA processing" and "ribosome biogenesis," reflecting the biological demands of oocyte development and embryogenesis. In contrast, malebiased genes were associated with energy metabolism pathways, including the "tricarboxylic acid cycle" and "oxidative phosphorylation," supporting their energetically intensive roles in courtship and pheromone synthesis. These findings provide valuable insights into the molecular mechanisms of sexual dimorphism, reproduction and sex-specific behaviors in T. rufivena, offering a foundation for future research and highlighting potential targets for sustainable pest management.

Xyleborus affinis, one of the most important pests of rubber trees, has caused severe damage to the natural rubber industry in Hainan province. The ability to detect host plants through a sensitive and specific olfactory system is crucial for Xyleborus affinis. Odorant binding proteins (OBPs) are believed to bind and carry hydrophobic active compounds from the environment to the surface of olfactory receptor neurons. To investigate the potential functional role of the highly expressed XaffOBP9 in binding with semiochemicals, we cloned and analyzed the cDNA sequence of XaffOBP9. The results showed that XaffOBP9 contains a 411bp open reading frame that encodes 136 amino acids. Then XaffOBP9 was expressed in Escherichia coli. The binding affinity of the recombinant OBP to 15 different ligands (14 host plant volatiles and 1 aggregation pheromone) was then examined using a fluorescence competitive binding approach. The results demonstrated that XaffOBP9 exhibited broad binding capabilities and strong affinities for 14 ligands. The structure of XaffOBP9 and its interactions with fourteen ligands were further analyzed by modeling and molecular docking, respectively. Based on the docking result, we found hydrophobic interactions are important between XaffOBP9 to these ligands and three amino acid residues (L71, Y106, and L114) were highly overlapped and contributed to the interaction with ligands. Mutation functional assays confirmed that the mutant L114A showed significantly reduced binding capacity to these ligands. This study suggested that XaffOBP9 may be involved in the chemoreception of semiochemicals and that it is helpful for the integrated management of X. affinis.

Tirathaba rufivena Walker, a major insect pest of Areca catechu L., has severely threatened areca nut cultivation in Hainan, China. To improve our understanding of the communication mechanism in host plant seeking and mate-finding for T. rufivena, we described and further characterized the external morphology and internal sensilla structures using scanning electron microscopy and transmission electron microscopy in this study. The antennal morphology was similar between males and females, and there was no significant difference in length between the two sexes. In total, nine sensilla types were identified: sensilla trichodea (Str), sensilla chaetica (Sch), sensilla basiconica (Sba), sensilla auricillica (Sau), sensilla coeloconica (Sco), sensilla styloconica (Sst), Böhm sensilla (Bs), uniporous peg sensilla (Ups) and sensilla squamiformia (Ssq). Sexual dimorphism mainly occurs in variation in the length of Sba, Sch, Sco1 and Bs, and the abundance of Sba, Sau1 and Sau2. The Sba had larger size and numbers on female antennae than that on males, suggesting that these sensilla might have important roles in locating host plants. Both Sau1 and Sau2 were significantly more abundant in females and were probably associated with the detection of mates and host plant for oviposition. These data were important for ongoing studies on host plant seeking and mate-finding behavior in T. rufivena and provided a theoretical foundation to further studies of semiochemical control for this pest.

Odorant-binding proteins (OBPs) play a key role in the olfactory system and are essential for mating and oviposition host selection. Tirathaba rufivena, a serious lepidopterous insect pest of the palm area in recent years, has threatened cultivations of Areca catechu in Hainan. Female-biased odorant-binding protein 4 of T. rufivena (TrufOBP4) expression was hypothesized to participate in the process of oviposition host recognition and localization. In this study, we cloned and analyzed the cDNA sequence of TrufOBP4. The predicted mature protein TrufOBP4 is a small, soluble, secretory protein and belongs to a classic OBP subfamily. Fluorescence binding assay results showed that TrufOBP4 had high binding abilities with the host plant volatiles, octyl methoxycinnamate, dibutyl phthalate, myristic acid and palmitic acid. These four components tend to dock in the same binding pocket based on the molecular docking result. The interactions and contributions of key amino acid residues were also characterized. This research provides evidence that TrufOBP4 might participate in the chemoreception of volatile compounds from inflorescences of A. catechu and can contribute to the integrated management of T. rufivena.

Crematogaster rogenhoferi (Hymenoptera: Formicidae), an omnivorous ant, is one of the dominant predatory natural enemies of a soft scale pest, Parasaissetia nigra Nietner (Homoptera: Coccidae), and can effectively control P. nigra populations in rubber forests. Olfaction plays a vital role in the process of predation. However, the information about the molecular mechanism of olfaction-evoked behaviour in C. rogenhoferi is limited. In this study, we conducted antennal transcriptome analysis to identify candidate olfactory genes. We obtained 53,892 unigenes, 16,185 of which were annotated. Based on annotations, we identified 49 unigenes related to chemoreception, including four odourant-binding proteins, three chemosensory proteins, 37 odourant receptors, two odourant ionotropic receptors and three sensory neuron membrane proteins. This is the first report on the molecular basis of the chemosensory system of C. rogenhoferi. The findings provide a basis for elucidating the molecular mechanisms of the olfactory-related behaviours of C. rogenhoferi, which would facilitate a better application of C. rogenhoferi as a biological control agent.

Euplatypus parallelus (Coleoptera: Curculionidae) is a neotropical ambrosia beetle that that is rapidly spreading around the world. It has been recorded from over 80 host trees and is implicated as a primary pest attacking rubber trees and rosewood. Here, we report the first country record and successful establishment of the species in Hainan, China. Currently, E. parallelus does not appear to act as a destructive forest pest in Hainan.

Assessing the potential effects of insect-resistant genetically engineered (GE) plants on collembolans is important because these common soil arthropods may be exposed to insecticidal proteins produced in GE plants by ingestion of plant residues, crop pollen, or root exudates. Laboratory studies were conducted to evaluate the potential effects of two Bacillus thuringiensis (Bt)-rice lines expressing Cry1C and Cry2A in pollen and leaves and of their non-Bt conventional isolines on the fitness of the collembolan Folsomia candida and on the activities of its antioxidant-related enzymes, superoxide dismutase and peroxidase, and of its detoxification-related enzymes, glutathione reductase and glutathione S-transferase. Survival, development, reproduction, and the intrinsic rate of increase (rm) were not significantly reduced when F. candida fed on the Bt rice pollen or leaf powder than on the non-Bt rice materials; these parameters, however, were significantly reduced when F. candida fed on non-Bt rice pollen or non-Bt leaf-based diets containing the protease inhibitor E-64 at 75 μg/g. The activities of the antioxidant-related and detoxification-related enzymes in F. candida were not significantly affected when F. candida fed on the Bt rice materials, but were significantly increased when F. candida fed on the non-Bt rice materials containing E-64. The results demonstrate that Cry1C and Cry2A are not toxic to F. candida, and also indicate the absence of unintended effects on the collembolan caused by any change in plant tissue nutritional composition due to foreign gene transformation.

The common soil arthropod Folsomia candida can survive well when fed only maize pollen and thus may be exposed to insecticidal proteins by ingesting insect-resistant genetically engineered maize pollen containing Bacillus thuringiensis (Bt) proteins when being released into the soil. Laboratory experiments were conducted to assess the potential effects of Cry1Ab/Cry2Aj-producing transgenic Bt maize (Shuangkang 12-5) pollen on F. candida fitness. Survival, development, and the reproduction were not significantly reduced when F. candida fed on Bt maize pollen rather than on non-Bt maize pollen, but these parameters were significantly reduced when E candida fed on non-Bt maize pollen containing the protease inhibitor E-64 at 75 mu g/g pollen. The intrinsic rate of increase (r(m)) was not significantly reduced when F. candida fed on Bt maize pollen but was significantly reduced when F. candida fed on non-Bt maize pollen containing E-64. The activities of antioxidant-related enzymes in F candida were not significantly affected when F candida fed on Bt maize pollen but were significantly increased when F. candida fed on non-Bt pollen containing E-64. The results demonstrate that consumption of Bt maize pollen containing Cry1Ab/Cry2Aj has no lethal or sublethal effects on F candida. (C) 2017 Elsevier Ltd. All rights reserved.

[Objective] To predict the occurrence of rubber borers by using meteorological and cold damage indices.[Method] The relationships between damage rate of rubber borers and cold damage of rubber in the past few years were analyzed.The regression model of various cold damage parameters of rubber tree and rubber borer population was simulated.[Result] The longer the low temperature duration and the lower the extremely low temperature,the heavier the cold damage rate and damage grade of rubber tree.[Conclusion] The regression models established in this study could be used in indirect monitoring of the occurrence of rubber borers in the field.