Highly Reduced Complementary Genomes of Dual Bacterial Symbionts in the Mulberry Psyllid Anomoneura mori.

The genomes of obligately host-restricted bacteria suffer from accumulating mildly deleterious mutations, resulting in marked size reductions. Psyllids (Hemiptera) are phloem sap-sucking insects with a specialized organ called the bacteriome, which typically harbors two vertically transmitted bacterial symbionts: the primary symbiont "Candidatus Carsonella ruddii" (Gammaproteobacteria) and a secondary symbiont that is phylogenetically diverse among psyllid lineages. The genomes of several Carsonella lineages were revealed to be markedly reduced (158-174| |kb), AT-rich (14.0-17.9% GC), and structurally conserved with similar gene inventories devoted to synthesizing essential amino acids that are scarce in the phloem sap. However, limited genomic information is currently available on secondary symbionts. Therefore, the present study investigated the genomes of the bacteriome-associated dual symbionts, Secondary_AM (Gammaproteobacteria) and Carsonella_AM, in the mulberry psyllid Anomoneura mori (Psyllidae). The results obtained revealed that the Secondary_AM genome is as small and AT-rich (229,822 bp, 17.3% GC) as those of Carsonella lineages, including Carsonella_AM (169,120 bp, 16.2% GC), implying that Secondary_AM is an evolutionarily ancient obligate mutualist, as is Carsonella. Phylogenomic ana-lyses showed that Secondary_AM is sister to "Candidatus Psyllophila symbiotica" of Cacopsylla spp. (Psyllidae), the genomes of which were recently reported (221-237| |kb, 17.3-18.6% GC). The Secondary_AM and Psyllophila genomes showed highly conserved synteny, sharing all genes for complementing the incomplete tryptophan biosynthetic pathway of Carsonella and those for synthesizing B vitamins. However, sulfur assimilation and carotenoid-synthesizing genes were only retained in Secondary_AM and Psyllophila, respectively, indicating ongoing gene silencing. Average nucleotide identity, gene ortholog similarity, genome-wide synteny, and substitution rates suggest that the Secondary_AM/Psyllophila genomes are more labile than Carsonella genomes.

Molecular identification of predation on the Dubas bug (Hemiptera: Tropiduchidae) in Oman date palms: density-dependent response to prey.

The date palm (Phoenix dactylifera L.) (Arecales: Arecaceae) is the most economically important crop in Oman with an annual production of >360,000 tons of fruit. The Dubas bug (Ommatissus lybicus de Bergevin) (Hemiptera: Tropiduchidae) is one of the major pests of date palms, causing up to a 50% reduction in fruit production. Across the course of 2 seasons, a variety of arthropod predators living in the date palm canopy were investigated for possible biological control of Dubas bugs, given the growing interest in nonchemical insect pest control in integrated pest management. We collected ~6,900 arthropod predators directly from date palm fronds from 60 Omani date palm plantations and tested them for Dubas bug predation using PCR-based molecular gut content analysis. We determined that ≥56 species of arthropod predators feed on the Dubas bug. We found that predatory mites, ants, and the entire predator community combined showed a positive correlation between predation detection frequency and increasing Dubas bug density. Additionally, there was a significant impact of season on gut content positives, with the spring season having a significantly higher percentage of predators testing positive for Dubas bug, suggesting this season could be the most successful time to target conservation biological control programs utilizing a diverse suite of predators.

Phylogeny and evolution of hemipteran insects based on expanded genomic and transcriptomic data.

BACKGROUND: Hemiptera is the fifth species-rich order of insects and the most species-rich order of hemimetabolous insects, including numerous insect species that are of agricultural or medical significance. Despite much effort and recent advance in inferring the Hemiptera phylogeny, some high-level relationships among superfamilies remain controversial. RESULTS: We sequenced the genomes of 64 hemipteran species from 15 superfamilies and the transcriptomes of two additional scale insect species, integrating them with existing genomic and transcriptomic data to conduct a comprehensive phylogenetic analysis of Hemiptera. Our datasets comprise an average of 1625 nuclear loci of 315 species across 27 superfamilies of Hemiptera. Our analyses supported Cicadoidea and Cercopoidea as sister groups, with Membracoidea typically positioned as the sister to Cicadoidea + Cercopoidea. In most analyses, Aleyrodoidea was recovered as the sister group of all other Sternorrhyncha. A sister-group relationship was supported between Coccoidea and Aphidoidea + Phylloxeroidea. These relationships were further supported by four-cluster likelihood mapping analyses across diverse datasets. Our ancestral state reconstruction indicates phytophagy as the primary feeding strategy for Hemiptera as a whole. However, predation likely represents an ancestral state for Heteroptera, with several phytophagous lineages having evolved from predatory ancestors. Certain lineages, like Lygaeoidea, have undergone a reversal transition from phytophagy to predation. Our divergence time estimation placed the diversification of hemipterans to be between 60 and 150 million years ago. CONCLUSIONS: By expanding phylogenomic taxon sampling, we clarified the superfamily relationships within the infraorder Cicadomorpha. Our phylogenetic analyses supported the sister-group relationship between the superfamilies Cicadoidea and Cercopoidea, and the superfamily Membracoidea as the sister to Cicadoidea + Cercopoidea. Our divergence time estimation supported the close association of hemipteran diversification with the evolutionary success and adaptive radiation of angiosperms during the Cretaceous period.

ACL1-ROC4/5 complex reveals a common mechanism in rice response to brown planthopper infestation and drought.

Brown planthopper (BPH) is the most destructive insect pest of rice. Drought is the most detrimental environmental stress. BPH infestation causes adaxial leaf-rolling and bulliform cells (BCs) shrinkage similar to drought. The BC-related abaxially curled leaf1 (ACL1) gene negatively regulates BPH resistance and drought tolerance, with decreased cuticular wax in the gain-of-function mutant ACL1-D. ACL1 shows an epidermis-specific expression. The TurboID system and multiple biochemical assays reveal that ACL1 interacts with the epidermal-characteristic rice outermost cell-specific (ROC) proteins. ROC4 and ROC5 positively regulate BPH resistance and drought tolerance through modulating cuticular wax and BCs, respectively. Overexpression of ROC4 and ROC5 both rescue ACL1-D mutant in various related phenotypes. ACL1 competes with ROC4/ROC5 in homo-dimer and hetero-dimer formation, and interacts with the repressive TOPLESS-related proteins. Altogether, we illustrate that ACL1-ROC4/5 complexes synergistically mediate drought tolerance and BPH resistance through regulating cuticular wax content and BC development in rice, a mechanism that might facilitate BPH-resistant breeding.

Adaptation of feeding behaviors on two Brassica species by colonizing and noncolonizing Bemisia tabaci (Hemiptera: Aleyrodidae) NW whiteflies.

Bemisia tabaci New World (NW) (Gennadius) (Hemiptera: Aleyrodidae), a whitefly in the B. tabaci species complex, is polyphagous on many plant species. Yet, it has been displaced, albeit not entirely, by other whitefly species. Potential causes could include issues with adaptation, feeding, and the colonization of new-hosts; however, insights that would help clarify these possibilities are lacking. Here, we sought to address these gaps by performing electropenetrography (EPG) recordings of NW whiteflies, designated "Napus" and "Rapa," reared on 2 colony hosts, Brassica napus and B. rapa, respectively. Analysis of 17 probing and pathway (pw) phase-related EPG variables revealed that the whiteflies exhibited unique probing behaviors on their respective colony hosts, with some deterrence being encountered on B. rapa. Upon switching to B. rapa and B. napus, the probing patterns of Napus and Rapa whiteflies, respectively, adapted quickly to these new-hosts to resemble that of whiteflies feeding on their colony hosts. Results for 3 of the EPG variables suggested that B. rapa's deterrence against Napus whitefly was significant prior to the phloem phase. This also suggested that adaptation by Rapa whitefly improved its pw probing on B. rapa. Based on analysis of 24 phloem phase-related EPG variables, Napus and Rapa whiteflies performed equally well once they entered phloem phase and exhibited comparable phloem acceptability on both the colony- and new-hosts. These findings demonstrate that NW whiteflies reared on a colony host are highly adaptable to feeding on a new host despite encountering some deterrence during the nonphloem phases in B. rapa plant.

RpedOBP1 plays key roles in aggregation pheromones reception of the Riptortus pedestris.

Riptortus pedestris (Hemiptera: Alydidae) is a notable soybean pest, with diapause and non-diapause individuals showing different sensitivities to aggregation pheromones. This study aimed to investigate how R. pedestris detects aggregation pheromones through electroantennogram (EAG) and behavioral experiments, transcriptome sequencing and qRT-PCR, as well as competitive fluorescence-binding assay. Results indicated that diapausing females and males of R. pedestris exhibited a heightened EAG response and were more attracted to the aggregation pheromone components compared to their non-diapause counterparts. Transcriptome sequencing and qRT-PCR analyses revealed significantly higher expression of RpedOBP1 in the antennae of diapause females and males compared to non-diapausing R. pedestris. The competitive fluorescence-binding assay demonstrated that RpedOBP1 displayed the strongest binding affinity to E2HE2H, suggesting its crucial role in recognizing the aggregation pheromone. These findings have the potential to inform the development of integrated pest management strategies utilizing behavioral approaches for bean bug control.

ß-Caryophyllene wrapped by nanoliposomes efficiently increases the control effect on Bemisia tabaci MED.

Bemisia tabaci poses a severe threat to plants, and the control of B. tabaci mainly relies on pesticides, which causes more and more rapidly increasing resistance. ß-Caryophyllene is a promising ingredient for agricultural pest control, but its feature of poor water solubility need to be improved in practical applications. Nanotechnology can enhance the effectiveness and dispersion of volatile organic compounds (VOCs). In this study, a nanoliposome carrier was constructed by ethanol injection and ultrasonic dispersion method, and ß-caryophyllene was wrapped inside it, thus solving the defect of poor solubility of ß-caryophyllene. The size of the ß-caryophyllene nanoliposomes (C-BT-NPs) was around 200 nm, with the absolute value of the zeta potential exceeding 30 mV and a PDI below 0.5. The stability was also maintained over a 14-d storage period. C-BT-NPs showed effective insecticidal activity against B. tabaci, with an LC50 of 1.51 g/L, outperforming thiamethoxam and offering efficient agricultural pest control. Furthermore, C-BT-NPs had minimal short-term impact on the growth of tomato plants, indicating that they are safety on plants. Therefore, the VOCs using nanoliposome preparation technology show promise in reducing reliance on conventional pesticides and present new approaches to managing agricultural pests.

Harnessing Lecanicillium attenuatum: A novel strategy for combatting Nilaparvata lugens in rice fields.

Nilaparvata lugens is a notorious rice pest causing significant annual yield and economic losses. The use of entomopathogenic fungi offers a promising and eco-friendly approach to sustainable pest management programs. However, research in this area is currently limited to a few specific types of insects and other arthropods. This study aimed to analyze the biocontrol potential of Lecanicillium attenuatum against N. lugens. Bioassays showed that L. attenuatum 3166 induced >80% mortality in N. lugens following 7 d exposure. Greenhouse and field investigations demonstrated that L. attenuatum 3166 application leads to a substantial reduction in N. lugens populations. Under greenhouse conditions, fluorescence was detected in GFP-labeled L. attenuatum 3166 hyphae enveloping the bodies of N. lugens. In field trials, L. attenuatum 3166 treatment exhibited a control efficacy of up to 68.94% at 14 d post-application, which was comparable to that of the commercial entomopathogenic fungal agent. Genomic sequencing of L. attenuatum 3166 revealed a comprehensive array of genes implicated in its infestation and lethality. Further, the transcriptome sequencing analysis highlighted the elevated expression levels of genes encoding proteases, chitinases, cutinases, and phospholipases. Our findings highlight the potential of L. attenuatum 3166 as an effective biological control agent against N. lugens.

Chemosensory protein 22 in Riptortus pedestris is involved in the recognition of three soybean volatiles.

Riptortus pedestris (Hemiptera: Alydidae), a common agricultural pest, is the major causative agent of "soybean staygreen." However, the interactions between chemosensory proteins (CSPs) in R. pedestris and host plant volatiles have yet to be comprehensively studied. In this study, we performed real-time fluorescence quantitative polymerase chain reaction (PCR) to analyze the antennal expression of RpedCSP22 and subsequently analyzed the interactions between 21 soybean volatiles, five aggregation pheromones, and RpedCSP22 protein in vitro using a protein expression system, molecular docking, site-directed mutagenesis, and fluorescence competitive binding experiments. The RpedCSP22 protein showed binding affinity to three soybean volatiles (benzaldehyde, 4-ethylbenzaldehyde, and 1-octene-3-ol), with optimal binding observed under neutral pH conditions, and lost binding ability after site-directed mutagenesis. In subsequent RNA interference (RNAi) studies, gene silencing was more than 90 %, and in silenced insects, electroantennographic responses were reduced by more than 75 % compared to non-silenced insects. Moreover, Y-tube olfactory behavioral assessments revealed that the attraction of R. pedestris to the three soybean volatiles was significantly attenuated. These findings suggest that RpedCSP22 plays an important role in the recognition of host plant volatiles by R. pedestris andprovides a theoretical basis for the development of novel inhibitors targeting pest behavior.

Current status of molecular rice breeding for durable and broad-spectrum resistance to major diseases and insect pests.

In the past century, there have been great achievements in identifying resistance (R) genes and quantitative trait loci (QTLs) as well as revealing the corresponding molecular mechanisms for resistance in rice to major diseases and insect pests. The introgression of R genes to develop resistant rice cultivars has become the most effective and eco-friendly method to control pathogens/insects at present. However, little attention has been paid to durable and broad-spectrum resistance, which determines the real applicability of R genes. Here, we summarize all the R genes and QTLs conferring durable and broad-spectrum resistance in rice to fungal blast, bacterial leaf blight (BLB), and the brown planthopper (BPH) in molecular breeding. We discuss the molecular mechanisms and feasible methods of improving durable and broad-spectrum resistance to blast, BLB, and BPH. We will particularly focus on pyramiding multiple R genes or QTLs as the most useful method to improve durability and broaden the disease/insect spectrum in practical breeding regardless of its uncertainty. We believe that this review provides useful information for scientists and breeders in rice breeding for multiple stress resistance in the future.

CYP4CE1 Metabolized Nitenpyram through Two Types of Oxidation Reaction, Hydroxylation, and N-Demethylation.

Nitenpyram, taking the place of imidacloprid, is a widely used neonicotinoid insecticide to control Nilaparvata lugens in Asia. Two P450s, CYP4CE1 and CYP6ER1, are key factors in the metabolic resistance against nitenpyram and imidacloprid. In this study, we found that CYP4CE1 expression was strongly associated with nitenpyram resistance in 8 field-collected populations, whereas CYP6ER1 expression correlated with imidacloprid resistance. Hence, we focused on nitenpyram metabolism by CYP4CE1, due to that imidacloprid metabolism by CYP6ER1 has intensively investigated. Mass spectrometry analysis revealed that recombinant CYP4CE1 metabolized nitenpyram into three products, N-desmethyl nitenpyram, hydroxy-nitenpyram, and N-desmethyl hydroxy-nitenpyram, with a preference for hydroxylation. In contrast, CYP6ER1 metabolized nitenpyram into a single product, N-desmethyl nitenpyram. These results provide new insights into the specific catalytic mechanisms of P450 enzymes in neonicotinoid metabolism and underscore the importance of different catalytic reactions in neonicotinoid insecticide resistance.

Omics approaches to unravel insecticide resistance mechanism in Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae).

Bemisia tabaci (Gennadius) whitefly (BtWf) is an invasive pest that has already spread worldwide and caused major crop losses. Numerous strategies have been implemented to control their infestation, including the use of insecticides. However, prolonged insecticide exposures have evolved BtWf to resist these chemicals. Such resistance mechanism is known to be regulated at the molecular level and systems biology omics approaches could shed some light on understanding this regulation wholistically. In this review, we discuss the use of various omics techniques (genomics, transcriptomics, proteomics, and metabolomics) to unravel the mechanism of insecticide resistance in BtWf. We summarize key genes, enzymes, and metabolic regulation that are associated with the resistance mechanism and review their impact on BtWf resistance. Evidently, key enzymes involved in the detoxification system such as cytochrome P450 (CYP), glutathione S-transferases (GST), carboxylesterases (COE), UDP-glucuronosyltransferases (UGT), and ATP binding cassette transporters (ABC) family played key roles in the resistance. These genes/proteins can then serve as the foundation for other targeted techniques, such as gene silencing techniques using RNA interference and CRISPR. In the future, such techniques will be useful to knock down detoxifying genes and crucial neutralizing enzymes involved in the resistance mechanism, which could lead to solutions for coping against BtWf infestation.

Nanoparticle LDH enhances RNAi efficiency of dsRNA in piercing-sucking pests by promoting dsRNA stability and transport in plants.

Piercing-sucking pests are the most notorious group of pests for global agriculture. RNAi-mediated crop protection by foliar application is a promising approach in field trials. However, the effect of this approach on piercing-sucking pests is far from satisfactory due to the limited uptake and transport of double strand RNA (dsRNA) in plants. Therefore, there is an urgent need for more feasible and biocompatible dsRNA delivery approaches to better control piercing-sucking pests. Here, we report that foliar application of layered double hydroxide (LDH)-loaded dsRNA can effectively disrupt Panonychus citri at multiple developmental stages. MgAl-LDH-dsRNA targeting Chitinase (Chit) gene significantly promoted the RNAi efficiency and then increased the mortality of P. citri nymphs by enhancing dsRNA stability in gut, promoting the adhesion of dsRNA onto leaf surface, facilitating dsRNA internalization into leaf cells, and delivering dsRNA from the stem to the leaf via the vascular system of pomelo plants. Finally, this delivery pathway based on other metal elements such as iron (MgFe-LDH) was also found to significantly improve the protection against P. citri and the nymphs or larvae of Diaphorina citri and Aphis gossypii, two other important piercing-sucking hemipeteran pests, indicating the universality of nanoparticles LDH in promoting the RNAi efficiency and mortality of piercing-sucking pests. Collectively, this study provides insights into the synergistic mechanism for nano-dsRNA systemic translocation in plants, and proposes a potential eco-friendly control strategy for piercing-sucking pests.

Rich diversity of RNA viruses in the biological control agent, Orius laevigatus.

Orius laevigatus (Hemiptera, Anthocoridae) is a generalist predator extensively used for the biocontrol of diverse agricultural pests. Previous studies on O. laevigatus have focused on the improvement of insect genetic traits, but little is known about its association with microbes, especially viruses that may influence its production and efficacy. More than 280 RNA viruses have been described in other Hemiptera insects, in line with the continuous discovery of insect-specific viruses (ISVs) boosted by next-generation sequencing. In this study, we characterized the repertoire of RNA viruses associated with O. laevigatus. Its virome comprises 27 RNA viruses, classified within fourteen viral families, of which twenty-three viruses are specific to O. laevigatus and four are likely associated with fungal microbiota. The analysis of viral abundance in five O. laevigatus populations confirmed the presence of simultaneous viral infections and highlighted the ubiquitous presence and high abundance of one solinvivirus and three totiviruses. Moreover, we identified 24 non-retroviral endogenous viral elements (nrEVEs) in the genome of O. laevigatus, suggesting a long-term relationship between the host and its virome. Although no symptoms were described in the insect populations under study, the high diversity of viral species and the high abundance of certain RNA viruses identified indicate that RNA viruses may be significant for the applicability and efficacy of O. laevigatus in biocontrol programs.

Exposure to Sublethal Concentrations of Dinotefuran Induces Apoptosis in the Gut of Diaphorina citri Adults via Activating the Mitochondrial Apoptotic Pathway.

Diaphorina citri is a serious citrus pest. Dinotefuran is highly insecticidal against D. citri. To analyze the sublethal effects of dinotefuran on D. citri adults, an indoor toxicity test was performed, which revealed that the lethal concentration 50 (LC50) values were 4.23 and 0.50 µg/mL for 24 and 48 h treatments, respectively. RNA-Seq led to the identification of 71 and 231 differentially expressed genes (DEGs) after dinotefuran treatments with LC20 and LC50 doses, respectively. Many of the DEGs are significantly enriched in the apoptosis pathway. Dinotefuran-induced apoptosis in the gut cells was confirmed through independent assays of 4',6-diamidino-2-phenylindole (DAPI) and TdT-mediated dUTP nick end labeling (TUNEL) staining. Increased levels of reactive oxygen species (ROS) and a loss of mitochondrial membrane potential were observed. Four caspase genes were identified, and dinotefuran treatments resulted in increased mRNA levels of DcCasp1 and DcCasp3a. These findings shed light on the sublethal effects of dinotefuran on D. citri.

Insect-transmitted plant virus balances its vertical transmission through regulating Rab1-mediated receptor localization.

Rice stripe virus (RSV) establishes infection in the ovaries of its vector insect, Laodelphax striatellus. We demonstrate that RSV infection delays ovarian maturation by inhibiting membrane localization of the vitellogenin receptor (VgR), thereby reducing the vitellogenin (Vg) accumulation essential for egg development. We identify the host protein L. striatellus Rab1 protein (LsRab1), which directly interacts with RSV nucleocapsid protein (NP) within nurse cells. LsRab1 is required for VgR surface localization and ovarian Vg accumulation. RSV inhibits LsRab1 function through two mechanisms: NP binding LsRab1 prevents GTP binding, and NP binding LsRab1-GTP complexes stimulates GTP hydrolysis, forming an inactive LsRab1 form. Through this dual inhibition, RSV infection prevents LsRab1 from facilitating VgR trafficking to the cell membrane, leading to inefficient Vg uptake. The Vg-VgR pathway is present in most oviparous animals, and the mechanisms detailed here provide insights into the vertical transmission of other insect-transmitted viruses of medical and agricultural importance.

'Candidatus Liberibacter brunswickensis' colonization has no effect to the early development of Solanum melongena.

This study is the first to investigate the presence and movement of the novel Liberibacter species 'Candidatus Liberibacter brunswickensis' (CLbr) in eggplant, Solanum melongena. The psyllid, Acizzia solanicola can transmit CLbr to eggplant and CLbr can be acquired by CLbr-negative A. solanicola individuals from CLbr-positive eggplants. In planta, CLbr can replicate, move and persist. Investigation into the early development of eggplants showed that CLbr titres had increased at the inoculation site at 14 days post inoculation access period (DPIAP). CLbr had become systemic in the majority of plants tested by 28 DPIAP. The highest bacterial titres were recorded at 35 DPIAP in all samples of the inoculated leaf, the roots, stems and the midrib and petiole samples of the newest leaf (the top leaf). This finding strongly suggests that CLbr movement in planta follows the source to sink relationship as previously described for 'Ca. Liberibacter asiaticus' (CLas) and 'Ca. Liberibacter solanacearum' (CLso). No symptoms consistent with Liberibacter-associated diseases were noted for plants colonised by CLbr during this study, consistent with the hypothesis that CLbr does not cause disease of eggplant during the early stages of host colonisation. In addition, no significant differences in biomass were found between eggplant colonised with CLbr, compared to those that were exposed to CLbr-negative A. solanicola, and to control plants.

Effects of the maternal social environment on the mating signals and mate preferences of adult offspring in Enchenopa treehoppers.

Much is known about how the maternal environment can shape offspring traits via intergenerational effects. It is less clear, however, whether such effects may reach adult offspring sexual traits, with potential consequences for sexual selection and speciation. Here, we report effects of adult female aggregation density on the mating signals and mate preferences of their offspring in an insect that communicates via plant-borne vibrational signals. We experimentally manipulated the density of aggregations experienced by egg-laying mothers, reared the offspring in standard densities, and tested for corresponding differences in their signals and preferences. We detected a strong effect in male signals, with sons of mothers that experienced low aggregation density signalling more. We also detected a weak effect on female mate preferences, with daughters of mothers that experienced low aggregation density being less selective. These adjustments may help males and females find mates and secure matings in low densities, if the conditions they encounter correspond to those their mothers experienced. Our results thus extend theory regarding adjustments to the social environment to the scale of intergenerational effects, with maternal social environments influencing the expression of the sexual traits of adult offspring.

Identification and expression profiles of olfactory-related genes in the antennal transcriptome of Graphosoma rubrolineatum (Hemiptera: Pentatomidae).

Graphosoma rubrolineatum (Hemiptera: Pentatomidae) is an important pest of vegetables and herbs (e.g., Umbelliferae and Cruciferae) in China, Siberia, Korea, and Japan. Insects are highly dependent on their olfactory system to detect odorants. However, no molecular-mediated olfactory genes in G. rubrolineatum have yet been identified. In this study, we first established the antennal transcriptome of G. rubrolineatum and identified 189 candidate olfactory genes, including 31 odorant-binding proteins (OBPs), 15 chemosensory proteins (CSPs), four sensory neuron membrane proteins (SNMPs),94 odorant receptors (ORs), 23 ionotropic receptors (IRs), and 22 gustatory receptors (GRs). Additionally, phylogenetic trees were constructed for olfactory genes between G. rubrolineatum and other hemipteran insects. We also detected the expression profiles of ten OBPs, five CSPs, two SNMPs, five ORs, four IRs, and four GRs by real-time quantitative PCR. The results revealed that most genes (GrubOBP1/11/31, GrubCSP3/8, GrubSNMP1a/1b, GrubOrco/OR9/11/13, GrubGR1/4/22, GrubIR25/75h/76b/GluR1) were highly expressed in the antennae, GrubOBP13/31 and GrubCSP4/11/12 were highly expressed in the legs, while GrubOBP20 and GrubGR19 were highly expressed in the wings. Our results will enrich the gene inventory of G. rubrolineatum and provide further insight into the molecular chemosensory mechanisms of G. rubrolineatum.

Born suckers: the cibarial pump of Philaenus spumarius scales across ontogeny to ensure functional equivalence.

A select group of hemipterans within the suborder Auchenorrhyncha are the only animals that feed exclusively on xylem sap - a nutritionally poor liquid that exists under negative pressure within a plant's xylem vessels. To consume it, xylem-feeding bugs have evolved enlarged cibarial pumps capable of generating enormous negative pressures. A previous study examining the allometry of this feeding model suggested that small xylem feeders pay relatively higher energetic costs while feeding, favouring the evolution of larger-bodied species. However, this interspecific analysis only considered adult xylem-feeding insects and neglected the considerable intraspecific change in size that occurs across the insect's development. Here, we examine the changes in cibarial pump morphology and function that occur during the development of Philaenus spumarius, the common meadow spittlebug. We show that the cibarial pump scales largely as expected from isometry and that the maximum negative pressure is mass independent, indicating that size has no effect on the xylem-feeding capacity of juvenile spittlebugs. We conclude that a first instar nymph with a body mass 2% of the adult can still feed at the >1 MPa tension present in a plant's xylem vessels without a substantial energetic disadvantage.