Mutations and Differential Transcription of Mating-Type and Pheromone Receptor Genes in Hirsutella sinensis and the Natural Cordyceps sinensis Insect-Fungi Complex.

Sexual reproduction in ascomycetes is controlled by the mating-type (MAT) locus. (Pseudo)homothallic reproduction has been hypothesized on the basis of genetic data from Hirsutella sinensis (Genotype #1 of Ophiocordyceps sinensis). However, the differential occurrence and differential transcription of mating-type genes in the MAT1-1 and MAT1-2 idiomorphs were found in the genome and transcriptome assemblies of H. sinensis, and the introns of the MAT1-2-1 transcript were alternatively spliced with an unspliced intron I that contains stop codons. These findings reveal that O. sinensis reproduction is controlled at the genetic, transcriptional, and coupled transcriptional-translational levels. This study revealed that mutant mating proteins could potentially have various secondary structures. Differential occurrence and transcription of the a-/α-pheromone receptor genes were also found in H. sinensis. The data were inconsistent with self-fertilization under (pseudo)homothallism but suggest the self-sterility of H. sinensis and the requirement of mating partners to achieve O. sinensis sexual outcrossing under heterothallism or hybridization. Although consistent occurrence and transcription of the mating-type genes of both the MAT1-1 and MAT1-2 idiomorphs have been reported in natural and cultivated Cordyceps sinensis insect-fungi complexes, the mutant MAT1-1-1 and α-pheromone receptor transcripts in natural C. sinensis result in N-terminal or middle-truncated proteins with significantly altered overall hydrophobicity and secondary structures of the proteins, suggesting heterogeneous fungal source(s) of the proteins and hybridization reproduction because of the co-occurrence of multiple genomically independent genotypes of O. sinensis and >90 fungal species in natural C. sinensis.

SsCyp86 modulates sporisorium scitamineum mating/filamentation and pathogenicity through regulating fatty acid metabolism.

BACKGROUND: Fatty acid metabolism constitutes a significant and intricate biochemical process within microorganisms. Cytochrome P450 (CYP450) enzymes are found in most organisms and occupy a pivotal position in the metabolism of fatty acids. However, the role of CYP450 enzyme mediated fatty acid metabolism in the pathogenicity of pathogenic fungi remains unclear. METHODS: In this study, a CYP450 enzyme-encoding gene, SsCYP86, was identified in the sugarcane smut fungus Sporisorium scitamineum and its functions were characterized using a target gene homologous recombination strategy and metabonomics. RESULTS: We found that the expression of SsCYP86 was induced by or sugarcane wax or under the condition of mating/filamentation. Sexual reproduction assay demonstrated that the SsCYP86 deletion mutant was defective in mating/filamentation and significantly reduced its pathogenicity. Further fatty acid metabolomic analysis unravelled the levels of fatty acid metabolites were reduced in the SsCYP86 deletion mutant. Exogenous addition of fatty acid metabolites cis-11-eicosenoic acid (C20:1N9), pentadecanoic acid (C15:0), and linolenic acid (C18:3N3) partially restored the mating/filamentation ability of the SsCYP86 deletion mutant and restored the transcriptional level of the SsPRF1, a pheromone response transcription factor that is typically down-regulated in the absence of SsCYP86. Moreover, the constitutive expression of SsPRF1 in the SsCYP86 deletion mutant restored its mating/filamentation. CONCLUSION: Our results indicated that SsCyp86 modulates the SsPRF1 transcription by fatty acid metabolism, and thereby regulate the sexual reproduction of S. scitamineum. These findings provide insights into how CYPs regulate sexual reproduction in S. scitamineum.

Identification of Aggregation Pheromone as an Attractant for Odontothrips loti, A Serious Thrips Pest on Alfalfa.

Odontothrips loti (Haliday) (Thysanoptera: Thripidae) is one of the most serious pests on alfalfa, causing direct damage by feeding and indirect damage by transmitting plant viruses. This damage causes significant loss in alfalfa production. Semiochemicals offer opportunities to develop new approaches to thrips management. In this study, behavioral responses of female and male adults of O. loti to headspace volatiles from live female and male conspecifics were tested in a Y-tube olfactometer. The results showed that both male and female adults of O. loti were attracted to the odors released by conspecific males but not those released by females. Headspace volatiles released by female and male adults were collected using headspace solid-phase microextraction (HS-SPME). The active compound in the volatiles was identified by gas chromatography-mass spectrometry (GC-MS). The analysis showed that there was one major compound, (R)-lavandulyl (R)-2-methylbutanoate. The attractive activity of the synthetic aggregation pheromone compound was tested under laboratory and field conditions. In an olfactometer, both male and female adults showed significant preference for synthetic (R)-lavandulyl (R)-2-methylbutanoate at certain doses. Lures with synthetic (R)-lavandulyl (R)-2-methylbutanoate significantly increased the trap catches of sticky white traps at doses of 40-80 µg in the field. This study confirmed the production of aggregation pheromone by O. loti male adults and identified its active compound as (R)-lavandulyl (R)-2-methylbutanoate, providing a basis for population monitoring and mass trapping of this pest.

A conserved pheromone receptor in the American and the Asian palm weevils is also activated by host plant volatiles.

The evolution of chemosensory receptors is key for the adaptation of animals to their environment. Recent knowledge acquired on the tri-dimensional structure of insect odorant receptors makes it possible to study the link between modifications in the receptor structure and evolution of response spectra in more depth. We investigated this question in palm weevils, several species of which are well-known invasive pests of ornamental or cultivated palm trees worldwide. These insects use aggregation pheromones to gather on their host plants for feeding and reproduction. An odorant receptor detecting the aggregation pheromone components was characterised in the Asian palm weevil Rhynchophorus ferrugineus. This study compared the response spectra of this receptor, RferOR1, and its ortholog in the American palm weevil R. palmarum, RpalOR1. Sequences of these two receptors exhibit more than 70 amino acid differences, but modelling of their 3D structures revealed that their putative binding pockets differ by only three amino acids, suggesting possible tuning conservation. Further functional characterization of RpalOR1 confirmed this hypothesis, as RpalOR1 and RferOR1 exhibited highly similar responses to coleopteran aggregation pheromones and chemically related molecules. Notably, we showed that R. ferrugineus pheromone compounds strongly activated RpalOR1, but we did not evidence any response to the R. palmarum pheromone compound rhynchophorol. Moreover, we discovered that several host plant volatiles also activated both pheromone receptors, although with lower sensitivity. This study not only reveals evolutionary conservation of odorant receptor tuning across the two palm weevil species, but also questions the specificity of pheromone detection usually observed in insects.

Innate and learned components of egg recognition in the ant Camponotus floridanus.

Insect societies discriminate against foreigners to avoid exploitation. In ants, helper workers only accept individuals with the familiar chemical cues of their colony. Similarly, unfamiliar eggs may get rejected at their first appearance in the nest. We investigated egg acceptance mechanisms by introducing different types of foreign eggs into worker groups of the ant Camponotus floridanus. Workers from established colonies familiar with queen-laid eggs always accepted eggs from highly fecund queens, but worker-laid eggs only after exposure for several weeks. Workers naive to eggs only rejected worker-laid eggs once they had prior exposure to eggs laid by highly fecund queens, suggesting that prior exposure to such eggs is necessary for discrimination. The general acceptance of eggs from highly fecund queens, irrespective of previous worker egg exposure, suggests an innate response to the queen pheromone these eggs carry. Workers learned to accept queen-laid eggs from different species, indicating high flexibility in learning egg-recognition cues. In incipient colonies with queen-laid eggs that carry a weak queen pheromone, worker-laid eggs were more likely to get accepted than queen-laid eggs from a different species, suggesting that the similarity of egg-recognition cues between the two types of C. floridanus eggs increases acceptance.

Functional Characterization of Peripheral Neurons and a Receptor Recognizing Sex Pheromones in Hyphantria cunea (Erebidae).

Hyphantria cunea (Lepidoptera: Erebidae) is difficult and costly to control as a quarantine pest found globally. Sex pheromone trapping is an effective measure for its population monitoring and control; however, the peripheral neural mechanism of sex pheromone recognition in H. cunea remains unclear. An electrophysiological analysis showed that both male and female moths of H. cunea responded to four components of sex pheromones and the responses of male moths were stronger than those of the female moths. We identified three types of trichoid sensilla (ST) responsive to sex pheromones using the single sensillum recording technique. Each type was involved in recognizing 9R, 10S-epoxy-1, Z3, Z6-heneicosatriene (1, Z3, Z6-9S, 10R-epoxy-21Hy). Four peripheral neurons involved in the olfactory encoding of sex pheromones were identified. Four candidate pheromone receptor (PR) genes, HcunPR1a, HcunPR1b, HcunPR3, and HcunPR4, were screened by transcriptome sequencing. All of them were highly expressed in the antennae of males, except for HcunPR4, which was highly expressed in the antennae of females. Functional identification showed that HcunPR1a responded to sex pheromone. Other HcunPRs were not functionally identified. In summary, neurons involved in sex pheromone recognition of H. cunea were located in the ST, and HcunPR1a recognized secondary pheromone components 1, Z3, Z6-9S, 10R-epoxy-21Hy. Interestingly, PRs that recognize the main components of the sex pheromone may be located in an unknown branch of the olfactory receptor and merit further study. Our findings provide a better understanding of the peripheral neural coding mechanism of type II sex pheromones, and HcunPR1a may provide a target for the subsequent development of highly effective and specific biopesticides for H. cunea.

Determinants of maturation of the Staphylococcus aureus autoinducing peptide.

The accessory gene regulatory (Agr) system is required for virulence factor gene expression and pathogenesis of Staphylococcus aureus. The Agr system is activated in response to the accumulation of a cyclic autoinducing peptide (AIP), which is matured and secreted by the bacterium. The precursor of AIP, AgrD, consists of the AIP flanked by an N-terminal [Formula: see text]-helical Leader and a charged C-terminal tail. AgrD is matured to AIP by the action of two proteases, AgrB and MroQ. AgrB cleaves the C-terminal tail and promotes the formation of a thiolactone ring, whereas MroQ cleaves the N-terminal Leader in a manner that depends on the four-amino acid linker immediately following a conserved IG helix breaker motif. However, the attributes of AgrD that dictate the sequence of events in peptide maturation are not fully defined. Here, we used engineered AgrD peptide intermediates to ascertain the sufficiency of MroQ for N-terminal peptide cleavage, peptide export, and generation of mature AIP. We found that MroQ promotes the removal of the N-terminal Leader peptide from both linear and cyclic peptide intermediates, while peptide cyclization remained essential for signaling. The expression of the Leader peptide in isolation was sufficient for MroQ-dependent cleavage proximal to the four-amino-acid linker. In addition, active site mutations within AgrB destabilized full-length AgrD and thiolactone-containing intermediates and prevented the release of the Leader peptide. Altogether, our data support a tandem peptide maturation event involving both MroQ and AgrB that appears to couple protease activity and export of bioactive AIP.IMPORTANCEThe accessory gene regulatory (Agr) system is important for S. aureus pathogenesis. Activation of the Agr system requires recognition of a cyclic peptide pheromone, which must be fully matured to exert its biological activity. The complete events in cyclic peptide maturation and export from the bacterial cell remain to be fully defined. We and others recently discovered that the membrane peptidase MroQ is required for pheromone maturation. This study builds off the identification of MroQ and considers the attributes of the pheromone pro-peptide that are required for MroQ-mediated processing as well as uncovers features important for peptide stability and export. Overall, the findings in this study have implications for understanding bacterial pheromone maturation and virulence.

Functional Characterization of Odorant Receptors for Sex Pheromone (Z)-11-Hexadecenol in Orthaga achatina.

Pheromone receptor (PR)-mediated transduction of sex pheromones to electrophysiological signals is the basis for sex pheromone communication. Orthaga achatina, a serious pest of the camphor tree, uses a mixture of four components (Z11-16:OAc, Z11-16:OH, Z11-16:Ald, and Z3,Z6,Z9,Z12,Z15-23:H) as its sex pheromone. In this study, we identified five PR genes (OachPR1-5) by phylogenetic analysis. Further RT-PCR and qPCR experiments showed that PR1-3 were specifically expressed in male antennae, while PR4 was significantly female-biased in expression. Functional characterization using the XOE-TEVC assay demonstrated that PR1 and PR3 both responded strongly to Z11-16:OH, while PR1 and PR3 had a weak response to Z3,Z6,Z9,Z12,Z15-23:H and Z11-16:Ald, respectively. Finally, two key amino acid residues (N78 and R331) were confirmed to be essential for binding of PR3 with Z11-16:OH by molecular docking and site-directed mutagenesis. This study helps understand the sex pheromone recognition molecular mechanism of O. achatina.

Genetic modules for α-factor pheromone controlled growth regulation of Saccharomyces cerevisiae.

Saccharomyces cerevisiae is a commonly used microorganism in the biotechnological industry. For the industrial heterologous production of compounds, it is of great advantage to work with growth-controllable yeast strains. In our work, we utilized the natural pheromone system of S. cerevisiae and generated a set of different strains possessing an α-pheromone controllable growth behavior. Naturally, the α-factor pheromone is involved in communication between haploid S. cerevisiae cells. Perception of the pheromone initiates several cellular changes, enabling the cells to prepare for an upcoming mating event. We exploited this natural pheromone response system and developed two different plasmid-based modules, in which the target genes, MET15 and FAR1, are under control of the α-factor sensitive FIG1 promoter for a controlled expression in S. cerevisiae. Whereas expression of MET15 led to a growth induction, FAR1 expression inhibited growth. The utilization of low copy number or high copy number plasmids for target gene expression and different concentrations of α-factor allow a finely adjustable control of yeast growth rate.

A comparative study between integrative practices and preappointement gabapentin on serum cortisol in cats.

Clinical appointment generates stress in feline patients, influencing the frequency of veterinary care with the species. The purpose of this study was to assess serum cortisol in cats submitted to oral gabapentin and integrative practices during clinical care. Twenty cats were evaluated in three clinical appointments, one week apart. All cats were submitted to treatments: placebo (PL), gabapentin (GA), and integrative practices (IP) (music therapy, pheromone therapy, and chromotherapy). GA and PL were administered by the owners 90 min before transportation to the veterinary teaching hospital, and IP were applied 30 min before clinical care. Cats were physically examined at all timepoints, and blood samples were collected for cortisol measurement. Serum cortisol levels ranged from 0.49 µg/dL to 17.99 µg/dL. Mean cortisol concentrations when cats received PL (7.6 µg/dL) were higher than when cats received GA (4.9 µg/dL) and IP (4.1 µg/dL). There was a statistical difference in cortisol levels when cats receiving PL and GA were compared (p = 0.03) and between PL and IP (p = 0.005). The study showed that feline serum cortisol levels were lower when cats received the treatments to IP (integrative practices) and GA (gabapentin), demonstrating that these are applicable methods for reducing stress of feline patients in clinical evaluation.

Functional characterization of sex pheromone receptors PflaOR29 and PflaOR44 involved in the chemoreception of a diurnal moth, Phauda flammans (Walker) (Lepidoptera: Phaudidae).

Recognition of sex pheromones released by heterosexual moths via sex pheromone receptors is key for establishing mating connections in moths. The day-flying moth Phauda flammans is an oligophagous pest in southern cities of China and Southeast Asian countries. Our previous study reported that male P. flammans can be attracted to two sex pheromone compounds [Z-9-hexadecenal and (Z, Z, Z)-9,12,15-octadecadienal] released by females in the field; however, the mechanism of olfactory recognition is not clear. In this study, two sex pheromone receptor genes (PflaOR29 and PflaOR44) were cloned. Among the different tissues, both PflaOR29 and PflaOR44 were highly expressed in the antennae of mated male adults. At different developmental stages, the expression levels of PflaOR29 and PflaOR44 were significantly greater in mated male adults than other stages. The fluorescence signals of PflaOR29 and PflaOR44 were mostly distributed on the dorsal side of the antennae, with a large number of trichoid sensilla. The results of the gene function of PflaOR29 and PflaOR44 based on a Drosophila empty neuron heterologous expression system indicated that PflaOR29 strongly responded to (Z, Z, Z)-9,12,15-octadecadienal but not to Z-9-hexadecenal, whereas PflaOR44 did not respond to the two sex pheromones. Our findings clarify the sex pheromone receptor gene corresponding to (Z, Z, Z)-9,12,15-octadecatrienal. These results provide essential information for analyzing the mechanism of sexual communication in diurnal moths and for identifying target genes for the development of efficient attractants.

Identification and Functional Analysis of Odorant Binding Proteins in Apriona germari (Hope).

Apriona germari (Hope) presents a significant threat as a dangerous wood-boring pest, inflicting substantial harm to forest trees. Investigating the olfactory sensory system of A. germari holds substantial theoretical promise for developing eco-friendly control strategies. To date, however, the olfactory perception mechanism in A. germari remains largely unknown. Therefore, we performed transcriptome sequencing of A. germari across four distinct body parts: antennae, foreleg tarsal segments, mouthparts (maxillary and labial palps), and abdomen terminals, pinpointing the odorant binding protein (OBP) genes and analyzing their expression. We found eight AgerOBPs (5, 19, 23, 25, 29, 59, 63, 70) highly expressed in the antennae. In our competitive binding experiments, AgerOBP23 showed strong binding abilities to the pheromone component fuscumol acetate, eight plant volatiles (farnesol, cis-3-hexenal, nerolidol, myristol acetate, cis-3-hexenyl benzoate, (-)-α-cedrene, 3-ethylacetophenone, and decane), and four insecticides (chlorpyrifos, phoxim, indoxacarb, and cypermethrin). However, AgerOBP29 and AgerOBP63 did not show prominent binding activities to these tested chemicals. Through homology modeling and molecular docking, we identified the key amino acid sites involved in the binding process of AgerOBP23 to these ligands, which shed light on the molecular interactions underlying its binding specificity. Our study suggests that AgerOBP23 may serve as a potential target for future investigations of AgerOBP ligand binding. This approach is consistent with the reverse chemical ecology principle, establishing the groundwork for future studies focusing on attractant or repellent development by exploring further the molecular interactions between OBP and various compounds.

Synergism of (E)-ß-farnesene and Its Analogue to Insecticides against the Green Peach Aphid Myzus persicae.

With high aphid-repellent activity but low stability, (E)-ß-farnesene (EßF), the major component of the aphid alarm pheromone, can be used as a synergist to insecticides. Some EßF analogues possess both good aphid-repellent activity and stability, but the synergistic effect and related mechanism are still unclear. Therefore, this study investigated the synergistic effect and underlying mechanism of the EßF and its analogue against the aphid Myzus persicae. The results indicated that EßF and the analogue showed significantly synergistic effects to different insecticides, with synergism ratios from 1.524 to 3.446. Mechanistic studies revealed that EßF and the analogue exhibited effective repellent activity, significantly upregulated target OBP genes by 161 to 731%, increased aphid mobility, and thereby enhanced contact with insecticides. This research suggests that the EßF analogue represents a novel synergist for insecticides, with the potential for further application in aphid control owing to its enhanced bioactivity and the possibility of reducing insecticide doses.

Dibutyl phthalate released by solitary female locusts mediates sexual communication at low density.

Sex pheromones play a crucial role in mate location and reproductive success. Insects face challenges in finding mates in low-density environments. The population dynamics of locusts vary greatly, ranging from solitary individuals to high-density swarms, leading to multiple-trait divergence between solitary and gregarious phases. However, differences in sexual communication between solitary and gregarious locusts have not been sufficiently explored. Herein, we found that solitary locusts but not gregarious ones heavily rely on a single compound, dibutyl phthalate (DBP), for sexual communication. DBP is abundantly released by solitary female locusts and elicits strong attraction of male solitary and gregarious locusts. Solitary adult males display much higher electrophysiological responses to DBP than adult females. Additionally, LmigOr13 was identified as the DBP-specific odorant receptor expressed in neurons housed in basiconic sensilla. Male LmigOr13-/- mutants generated by CRISPR/Cas9 have low electrophysiological responses and behavioral attraction to DBP in both laboratory and field cage experiments. Notably, the attractiveness of DBP to male locusts becomes more evident at lower population densities imposed by controlling the cage size. This finding sheds light on the utilization of a sex pheromone to promote reproductive success in extremely low-density conditions and provides important insights into alternative approaches for population monitoring of locusts.

Mating Disruption of a Flighted Spongy Moth, Lymantria Dispar Japonica (Motchulsky) in Japan.

Mating disruption of a flighted spongy moth, Lymantria dispar japonica (Motchulsky)(Lepidoptera: Lymantridae), with a synthetic version of its sex pheromone, (+)-disparlure ([7R,8S] -cis-7,8-epoxy-2- methyloctadecane), was tested in the forests in Japan. Pheromone trap catches and the percentage mating of tethered females were measured in the pheromone-treated and untreated control forests. The attraction of male moths to pheromone traps placed at a height of 1.5 m was significantly disrupted when the pheromone dispensers were placed at 1.5 m height, but many moths were captured in control plots. Mating of tethered females placed at 1.5 m was inhibited entirely, while 44% of females were mated in an untreated control forest. We report the first trial of mating disruption against a flighted spongy moth, and these results suggest that mating disruption with the synthetic sex pheromone appears promising for reducing damage caused by L. dispar japonica.

Lure specificity, phenology, and damage caused by Epiphyas moths (Lepidoptera: Tortricidae) in Western Australian apple orchards.

Multiple Epiphyas species inhabit southwestern Western Australia, including Light Brown Apple Moth (LBAM) Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), a globally significant, polyphagous pest. This study evaluated the efficacy and specificity of lures designed for 3 Epiphyas species: E. postvittana, Epiphyas pulla (Turner), and the undescribed Epiphyas sp. (1) (Common). Additionally, the study sought to determine the presence and distribution of Epiphyas species in 3 significant apple-growing localities. Trapping, together with partial sequencing of the mitochondrial COI gene, found LBAM to be restricted to the Perth Hills and E. pulla, to apple orchards near Manjimup and Pemberton. This geographic disjunction remains unexplained. Epiphyas sp. (1) was not recorded despite using a specifically designed lure. The E. pulla and LBAM traps demonstrated superior efficacy in capturing their target species, while the catch in Epiphyas sp. (1) traps did not significantly differ between the 2. Both E. pulla and LBAM exhibited peak abundance from late spring to the end of summer (October-February), with variations in timing and peak catch of male moths across species, locations, and years. Surveys conducted in April during the harvest period (February-May), when moth traps caught an average of 1-1.8 moths/trap/week, found no Epiphyas larvae or damage on 140,400 mature apples or on 26,000 leaves. While E. pulla and LBAM traps effectively monitor their target moths, genetic identification of trap catch would be necessary if they co-occurred. Encouragingly, the results indicate that both species become relatively rare as harvest season approaches, and neither inflicts significant damage to mature apples under existing management.

Lipid Metabolism in Insect Vectors of Diseases.

According to the World Health Organization vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually. Vectors are organisms that are able to transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are hematophagous insects, which ingest the pathogen from an infected host during a blood meal, and later transmit it into a new host. Malaria, dengue, African trypanosomiasis, yellow fever, leishmaniasis, Chagas disease, and many others are examples of diseases transmitted by insects.Both the diet and the infection with pathogens trigger changes in many metabolic pathways, including lipid metabolism, compared to other insects. Blood contains mostly proteins and is very poor in lipids and carbohydrates. Thus, hematophagous insects attempt to efficiently digest and absorb diet lipids and also rely on a large de novo lipid biosynthesis based on utilization of proteins and carbohydrates as carbon source. Blood meal triggers essential physiological processes as molting, excretion, and oogenesis; therefore, lipid metabolism and utilization of lipid storage should be finely synchronized and regulated regarding that, in order to provide the necessary energy source for these events. Also, pathogens have evolved mechanisms to hijack essential lipids from the insect host by interfering in the biosynthesis, catabolism, and transport of lipids, which pose challenges to reproduction, survival, fitness, and other insect traits.In this chapter, we have tried to collect and highlight the current knowledge and recent discoveries on the metabolism of lipids in insect vectors of diseases related to the hematophagous diet and pathogen infection.

Pheromone cCF10 inhibits the antibiotic persistence of Enterococcus faecalis by modulating energy metabolism.

Introduction: Bacterial resistance presents a major challenge to both the ecological environment and human well-being, with persistence playing a key role. Multiple studies were recently undertaken to examine the factors influencing the formation of persisters and the underlying process, with a primary focus on Gram-negative bacteria and Staphylococcus aureus (Gram-positive bacteria). Enterococcus faecalis (E. faecalis) is capable of causing a variety of infectious diseases, but there have been few studies of E. faecalis persisters. Previous studies have shown that the sex pheromone cCF10 secreted by E. faecalis induces conjugative plasmid transfer. However, whether the pheromone cCF10 regulates the persistence of E. faecalis has not been investigated. Methods: As a result, we investigated the effect and potential molecular mechanism of pheromone cCF10 in regulating the formation of persisters in E. faecalis OG1RF using a persistent bacteria model. Results and discussion: The metabolically active E. faecalis OG1RF reached a persistence state and temporarily tolerated lethal antibiotic concentrations after 8 h of levofloxacin hydrochloride (20 mg/mL) exposure, exhibiting a persistence rate of 0.109 %. During the growth of E. faecalis OG1RF, biofilm formation was a critical factor contributing to antibiotic persistence, whereas 10 ng/mL cCF10 blocked persister cell formation. Notably, cCF10 mediated the antibiotic persistence of E. faecalis OG1RF via regulating metabolic activity rather than suppressing biofilm formation. The addition of cCF10 stimulated the Opp system and entered bacterial cells, inhibiting (p)ppGpp accumulation, thus maintaining the metabolically active state of bacteria and reducing persister cell generation. These findings offer valuable insights into the formation, as well as the control mechanism of E. faecalis persisters.

SNMP1 is critical for sensitive detection of the desert locust aromatic courtship inhibition pheromone phenylacetonitrile.

BACKGROUND: Accurate detection of pheromones is crucial for chemical communication and reproduction in insects. In holometabolous flies and moths, the sensory neuron membrane protein 1 (SNMP1) is essential for detecting long-chain aliphatic pheromones by olfactory neurons. However, its function in hemimetabolous insects and its role for detecting pheromones of a different chemical nature remain elusive. Therefore, we investigated the relevance of SNMP1 for pheromone detection in a hemimetabolous insect pest of considerable economic importance, the desert locust Schistocerca gregaria, which moreover employs the aromatic pheromone phenylacetonitrile (PAN) to govern reproductive behaviors. RESULTS: Employing CRISPR/Cas-mediated gene editing, a mutant locust line lacking functional SNMP1 was established. In electroantennography experiments and single sensillum recordings, we found significantly decreased electrical responses to PAN in SNMP1-deficient (SNMP1-/-) locusts. Moreover, calcium imaging in the antennal lobe of the brain revealed a substantially reduced activation of projection neurons in SNMP1-/- individuals upon exposure to PAN, indicating that the diminished antennal responsiveness to PAN in mutants affects pheromone-evoked neuronal activity in the brain. Furthermore, in behavioral experiments, PAN-induced effects on pairing and mate choice were altered in SNMP1-/- locusts. CONCLUSIONS: Our findings emphasize the importance of SNMP1 for chemical communication in a hemimetabolous insect pest. Moreover, they show that SNMP1 plays a crucial role in pheromone detection that goes beyond long-chain aliphatic substances and includes aromatic compounds controlling reproductive behaviors.

Identification of Attractants from Three Host Plants and How to Improve Attractiveness of Plant Volatiles for Monochamus saltuarius.

As a new vector insect of pine wood nematodes in China, the Monochamus saltuarius (Coleoptera: Cerambycidae) vectors pine wilt nematodes into healthy pine trees through feeding and oviposition, resulting in huge economic losses to forestry. A promising control strategy is to develop safe and efficient attractants. This study aims to screen for the key active volatiles of Pinus koraiensis (Pinales: Pinaceae), Pinus tabuliformis (Pinales: Pinaceae), and Picea asperata (Pinales: Pinaceae) that can attract M. saltuarius, and to study the synergistic attraction of the main attractant plant volatiles with ethanol and insect aggregation pheromones. The preference of M. saltuarius for three hosts is P. koraiensis > P. tabuliformis > Picea asperata. We detected 18 organic volatiles from three host plants. Through EAG assays and indoor Y-tube behavioral experiments, 3-carene, (-)-camphor, ß-pinene, α-phellandrene, terpinolene, α-pinene, D-limonene, and myrcene were screened to have attractive effects on M. saltuarius. We found that 3-carene, ß-pinene, and α-pinene are the most attractive kairomones in field experiments, which may play a crucial role in the host localization of M. saltuarius. Ethanol has a synergistic effect on the attractant activity of 3-carene and ß-pinene, and the synergistic effect on ß-pinene is the best. The mixture of ethanol, 2-undecyloxy-1-ethanol, and ipsdienol can significantly enhance the attraction effect of ß-pinene on M. saltuarius. These new findings provide a theoretical basis for the development of attractants for adult M. saltuarius and contribute to the green control of M. saltuarius.