摘要: Mythimna separata is a notorious phytophagous pest which poses serious threats to cereal crops owing to the gluttony of the larvae. Because short neuropeptide F (sNPF) and its receptor sNPFR are involved in a diversity of physiological functions, especially in functions related to feeding in insects, it is a molecular target for pest control. Herein, an sNPF and 2 sNPFRs were identified and cloned from M. separata. Bioinformatics analysis revealed that the sNPF and its receptors had a highly conserved RLRFamide C-terminus and 7 transmembrane domains, respectively. The sNPF and its receptor genes were distributed across larval periods and tissues, but 2 receptors had distinct expression patterns. The starvation-induced assay elucidated that sNPF and sNPFR expression levels were downregulated under food deprivation and recovered with subsequent re-feeding. RNA interference knockdown of sNPF, sNPFR1, and sNPFR2 by injection of double-stranded RNA into larvae not only suppressed food consumption and increased body size and weight, but also led to decrease of glycogen and total lipid contents, and increase of trehalose compared with double-stranded green fluorescent protein injection. Furthermore, molecular docking was performed on the interaction mode between sNPFR protein and its ligand sNPF based on the 3-dimensional models constructed by AlphaFold; the results indicated that both receptors were presumably activated by the mature peptide sNPF-2. These results revealed that sNPF signaling played a considerably vital role in the feeding regulation of M. separata and represents a potential control target for this pest.

摘要: The lesser mealworm, Alphitobius diaperinus, is an invasive tenebrionid beetle and a vector of pathogens. Due to the emergence of insecticide resistance and consequent outbreaks that generate significant phytosanitary and energy costs for poultry farmers, it has become a major insect pest worldwide. To better understand the molecular mechanisms behind this resistance, we studied a strain of A. diaperinus from a poultry house in Brittany that was found to be highly resistant to the beta-cyfluthrin. The strain survived beta-cyfluthrin exposures corresponding to more than 100 times the recommended dose. We used a comparative de novo RNA-Seq approach to explore genes expression in resistant versus sensitive strains. Our de novo transcriptomic analyses showed that responses to beta-cyfluthrin likely involved a whole set of resistance mechanisms. Genes related to detoxification, metabolic resistance, cuticular hydrocarbon biosynthesis and proteolysis were found to be constitutively overexpressed in the resistant compared to the sensitive strain. Follow-up enzymatic assays confirmed that the resistant strain exhibited high basal activities for detoxification enzymes such as cytochrome P450 monooxygenase and glutathione-S-transferase. The in-depth analysis of differentially expressed genes suggests the involvement of complex regulation of signaling pathways. Detailed knowledge of these resistance mechanisms is essential for the establishment of effective pest control.

摘要: The brown planthopper (BPH, Nilaparvata lugens) is a notorious sap-sucking insect pest that damages rice (Oryza sativa) plants throughout Asia. During BPH feeding, saliva enters rice plant tissues, whereas during oviposition egg-associated secretions (EAS) are deposited in damaged plant tissue. Dynamic changes in rice to planthopper salivary effectors have been widely reported. However, the effects of EAS from planthopper on rice immunity remains largely unexplored. In this study, we found that both infestation of rice by gravid BPH female adults and treatment with the EAS elicited a strong and rapid accumulation of jasmonic acid (JA), JA-isoleucine, and hydrogen peroxide in rice. EAS enhanced plant defenses not only in rice but also in tobacco, and these impaired the performance of BPH on rice, as well as the performance of aphids and whiteflies on tobacco. High-throughput proteome sequencing of EAS led to 110 proteins being identified and 53 proteins with 2 or more unique peptides being detected. Some proteins from BPH EAS were also found in the salivary proteome from herbivores, suggesting potential evolutionary conservation of effector functions across feeding and oviposition; however, others were only identified in EAS, and these are likely specifically related to oviposition. These findings point to novel proteins affecting interactions between planthoppers and rice during oviposition, providing an additional source of information for effector studies.

摘要: Sex pheromones are considered to play critical roles in partner communication of most parasitic Hymenoptera. However, the identification of sex pheromone components remains limited to a few families of parasitoid wasps. In this study, we functionally characterized a candidate sex pheromone component in Microplitis mediator (Hymenoptera: Braconidae), a solitary parasitoid of Noctuidae insects. We found that the body surface extract from female wasps could significantly stimulate courtship behavior of males. Gas chromatography-electroantennographic detection (GC-EAD) analysis revealed that a candidate semiochemical from extract triggered significant electrophysiological response of antennae of males. By performing gas chromatography-mass spectrometer (GC-MS) measurement, GC-EAD active compound was identified as n-octyl acrylate, a candidate sex pheromone component in female M. mediator. In electroantennogram (EAG) tests, antennae of male wasps showed significantly higher electrophysiological responses to n-octyl acrylate than those of females. Y-tube olfactometer assays indicated that male wasps significantly chose n-octyl acrylate compared with the control. Furthermore, male wasps showed a remarkable preference for n-octyl acrylate in a simulated field condition behavioral trial; simultaneously, n-octyl acrylate standard could also trigger significant courtship behavior in males. We propose that n-octyl acrylate, as a candidate vital sex pheromone component, could be utilized to design behavioral regulators of M. mediator to implement the protection and utilization of natural enemies.

摘要: Juvenile hormone (JH) acts in the regulation of caste differentiation between queens and workers (i.e., with or without reproductive capacity) during vitellin synthesis and oogenesis in social insects. However, the regulatory mechanisms have not yet been elucidated. Here, we identified a highly expressed microRNA (miRNA), miR-1175-3p, in the red imported fire ant, Solenopsis invicta. We found that miR-1175-3p is prominently present in the fat bodies and ovaries of workers. Furthermore, miR-1175-3p interacts with its target gene, broad-complex core (Br-C), in the fat bodies. By utilizing miR-1175-3p agomir, we successfully suppressed the expression of the Br-C protein in queens, resulting in reduced vitellogenin expression, fewer eggs, and poorly developed ovaries. Conversely, decreasing miR-1175-3p levels led to the increased expression of Br-C and vitellogenin in workers, triggering the re-development of the ovaries. Moreover, when queens were fed with JH, the expression of miR-1175-3p decreased, whereas the expression of vitellogenin-2 and vitellogenin-3 increased. Notably, the suppression of fertility in queens caused by treatment with agomir miR-1175-3p was completely rescued by the increased vitellogenin expression induced by being fed with JH. These results suggest the critical role of miR-1175-3p in JH-regulated reproduction, shedding light on the molecular mechanism underlying miRNA-mediated fecundity in social insects and providing a novel strategy for managing S. invicta.

摘要: Anisopteromalus calandrae (Howard) shows great promise as an ectoparasitoid for controlling various coleopteran pests in warehouses. However, for a large-scale release, it is crucial to establish an ample supply of A. calandrae while carefully maintaining their quality and effectiveness. Appropriate cold storage techniques are the key to achieving these goals. Previous studies on cold storage have focused on specific developmental stages and explored cold storage conditions that can be applied only to those stages. Herein, we examined the development, survival and reproductive capacity of A. calandrae at different temperatures (13, 16, and 19 degrees C) and storage durations (30, 60, and 90 d) and evaluated the fitness of the offspring. A. calandrae completed its egg-to-larva development and pupated at 16 degrees C, but its development was arrested at an early pupal stage. Even after 90 d of cold storage at 16 degrees C, the survival rate of A. calandrae remained high at 77%, with no significant impact on reproductive capacity. Furthermore, cold storage showed no negative effect on the F1 generation. In contrast, eggs stored at 13 degrees C failed to hatch, whereas those stored at 19 degrees C developed. Adults emerged after > 60 d. This indicates that storage at 19 degrees C is only suitable for short durations. Our findings highlight the developmental pattern of A. calandrae at 16 degrees C, indicating that the parasitic wasp can be stored for a long time at this temperature across all stages of development before pupation, substantially facilitating its mass reproduction and industrial production.

摘要: Aedes albopictus is an important vector of arboviruses and prefers small containers of stagnant water as oviposition sites. One of the mechanisms mosquitoes use to search for suitable oviposition sites is relying on odor cues from prospective sites and their surroundings. The genetic and molecular bases of this behavior are not known for Ae. albopictus. Oviposition site-searching behavior can be separated into 2 stages: container location and water detection. We applied a glue compound to the antennae and the maxillary palps of adult females to mask their ability to detect molecules that may guide them to preferred oviposition sites. Treatment of the antennae significantly reduces the location index (P < 0.001), indicating a decreased ability to find oviposition sites, whereas no significant difference was observed in mosquitoes with maxillary palps treated with the same glue compound (P > 0.05). The detection time, measured as the duration from contact with the water surface to the deposition of the first egg, was extended in mosquitoes with treated antennae or maxillary palps, supporting the conclusion that olfaction is involved in the detection of oviposition site. Transcriptomic analysis identified differentially expressed olfactory-related genes, including obp67, obp56d-like, obp19d-like and obp67-like. RNA interference (RNAi)-mediated knockdown of obp67 and obp56d-like significantly affected the location index and detection time, respectively. Cas9/guide RNA-mediated knockout of obp56d-like resulted in a prolonged detection time, compared with the wild type (P < 0.05). These findings help to elucidate aspects of the olfactory mechanisms involved in Ae. albopictus oviposition site selection, and provide a basis for the development of mosquito surveillance and control strategies.

摘要: Bumblebees are important pollinators for many natural and agricultural systems in temperate regions. Interspecific and intraspecific variation in floral resource preferences have been proposed to influence bumblebee community structure. In particular, sexual dimorphism is a major source of intraspecific niche variation. Although interspecific resource partitioning is well studied, few studies have explored the intraspecific dynamics between workers and males. Here, we report a study on a total of 11 528 workers and 2220 males of 14 bumblebee species recorded over 5 years in the Hengduan Mountains of Southwest China. We first compared the potential for interspecific and intraspecific competition between workers and males using visitation records and resource partitioning indices (overlap index). We then evaluated the influence of nectar traits on flower preference, including nectar volume and the levels of hexose, sucrose and 10 essential amino acids (EAAs). We found that the niche overlap between intraspecific workers and males was higher than that between different species, and temporal overlap alone did not strongly determine diet overlap. Males of most species preferred flowers with high levels of EAAs and hexose, whereas workers of some species preferred flowers with high nectar volume and sucrose levels. This study suggests that there is floral resource partitioning among bumblebee species, and between workers and males, which may play a key role in alleviating interspecific and intraspecific competition. These findings also provide a useful guide for which kinds of plants might be most valuable for bumblebees, especially the understudied males, in this biodiversity hotspot. We demonstrated that the competition between intraspecific workers and males was potentially more intense than that observed in interspecific dynamics. However, floral resource partitioning between workers and males should result from their nutritional preferences. We found that males preferred flowers with high essential amino acids and hexose, whereas workers preferred flowers with high nectar volume and sucrose, suggesting that partitioning between workers and males might help to alleviate interspecific and intraspecific competition. image

摘要: Harvester ants are one of the most extensively studied groups of ants, especially the group foraging ants, Messor barbarus (Linnaeus, 1767), which construct long-lasting trunk trails. Limited laboratory investigations have delved into head-on encounters along foraging trails involving workers moving in opposing directions, with fewer corresponding studies conducted in the natural environment. To address this gap, we devised an in-field experimental design to induce lane segregation on the foraging trunk trail of M. barbarus. Using an image-based tracking method, we analyzed the foraging behavior of this species to assess the costs associated with head-on encounters and to figure out the natural coexistence of outgoing and returning workers on a bidirectional route. Our results consistently reveal heightened straightness and speed in unidirectional test lanes, accompanied by an elevated foraging rate compared to bidirectional lanes. This suggests a potential impact of head-on collisions on foraging behavior, especially on foraging efficiency. Additionally, Kinematic analysis revealed distinct movement patterns between outbound and inbound flows, particularly low speed and sinuous trajectories of inbounding unladen workers. The study of encounter rates in two traffic systems hints at the plausible utilization of individual memory by workers within trails, underscoring the pivotal role of encounters in information exchange and load transfer. To address the question of why outgoing and returning workers of the harvester ants, M. barbarus, do not segregate on a one-way route, we employed a novel methodology involving an asymmetrical ramp (depicted in the middle-left section of the Graphical Abstract Image). This ramp acts as a behavioral check valve, compelling workers to move within unidirectional traffic lanes.In the central portion of the graphical abstract image (A), it is evident that workers traversing the test lane (unidirectional) exhibited higher speeds compared to the control lane (bidirectional). On the middle-right of the graphical abstract image (B), workers demonstrated straighter trajectories in contrast to the control lane (bidirectional).Furthermore, outbound lane workers displayed a more direct trajectory with increased speed compared to those in the inbound lane. In the latter scenario, laden workers exhibited both higher speed and a superior straightness index.These findings, coupled with the monitoring of foraging rate and encounter rate, indicate that, overall, ants exhibit a propensity to meet during foraging, facilitating information exchange and load transfer. This tendency appears to be driven by the need for interaction rather than being a consequence of bidirectional traffic, suggesting a potential utilization of individual memory by workers within trails. image

摘要: N-6-methyladenosine (m(6)A) is the most prevalent modification in cellular RNA which orchestrates diverse physiological and pathological processes during stress response. However, the differential m(6)A modifications that cope with herbivore stress in resistant and susceptible crop varieties remain unclear. Here, we found that rice stem borer (RSB) larvae grew better on indica rice (e.g., MH63, IR64, Nanjing 11) than on japonica rice varieties (e.g., Nipponbare, Zhonghua 11, Xiushui 11). Then, transcriptome-wide m(6)A profiling of representative resistant (Nipponbare) and susceptible (MH63) rice varieties were performed using a nanopore direct RNA sequencing approach, to reveal variety-specific m(6)A modifications against RSB. Upon RSB infestation, m(6)A methylation occurred in actively expressed genes in Nipponbare and MH63, but the number of methylation sites decreased across rice chromosomes. Integrative analysis showed that m(6)A methylation levels were closely associated with transcriptional regulation. Genes involved in herbivorous resistance related to mitogen-activated protein kinase, jasmonic acid (JA), and terpenoid biosynthesis pathways, as well as JA-mediated trypsin protease inhibitors, were heavily methylated by m(6)A, and their expression was more pronounced in RSB-infested Nipponbare than in RSB-infested MH63, which may have contributed to RSB resistance in Nipponbare. Therefore, dynamics of m(6)A modifications act as the main regulatory strategy for expression of genes involved in plant-insect interactions, which is attributed to differential responses of resistant and susceptible rice varieties to RSB infestation. These findings could contribute to developing molecular breeding strategies for controlling herbivorous pests.