CRISPR/Cas9-mediated ebony knockout causes melanin pigmentation and prevents moth Eclosion in Ectropis grisescens.

Ectropis grisescens (Lepidoptera: Geometridae) is a destructive tea pest in China. Mimesis, characterized by changing body color, is an important trait of E. grisescens larvae. Hence, identifying melanin pathway-related genes may contribute to developing new pest control strategies. In the present study, we cloned Egebony, a gene potentially involved in melanin pigmentation in E. grisescens, and subsequently conducted CRISPR/Cas9-mediated targeted mutagenesis of Egebony to analyze its role in pigmentation and development. At the larvae, prepupae, and pupae stages, Egebony-knockout individuals exhibited darker pigmentation than the wild-type. However, Egebony knockout did not impact the colors of sclerotized appendants, including ocelli, setae, and claws. While mutant pupae could successfully develop into moths, they were unable to emerge from the puparium. Notably, embryo hatchability and larval survival of mutants remained normal. Further investigation indicated that mutant pupae exhibited significantly stronger shearing force than the wild-type, with the pigmented layer of mutant pupae appearing darker and thicker. Collectively, these results suggest that the loss of Egebony might increase the rigidity of the puparium and prevent moth eclosion. This study provides new insights into understanding the function and diversification of ebony in insect development and identifies a lethal gene that can be manipulated for developing effective pest control strategies.

Olfactory Gene Families in Scopula subpunctaria and Candidates for Type-II Sex Pheromone Detection.

Scopula subpunctaria, an abundant pest in tea gardens, produce type-II sex pheromone components, which are critical for its communicative and reproductive abilities; however, genes encoding the proteins involved in the detection of type-II sex pheromone components have rarely been documented in moths. In the present study, we sequenced the transcriptomes of the male and female S. subpunctaria antennae. A total of 150 candidate olfaction genes, comprising 58 odorant receptors (SsubORs), 26 ionotropic receptors (SsubIRs), 24 chemosensory proteins (SsubCSPs), 40 odorant-binding proteins (SsubOBPs), and 2 sensory neuron membrane proteins (SsubSNMPs) were identified in S. subpunctaria. Phylogenetic analysis, qPCR, and mRNA abundance analysis results suggested that SsubOR46 may be the Orco (non-traditional odorant receptor, a subfamily of ORs) of S. subpunctaria. SsubOR9, SsubOR53, and SsubOR55 belonged to the pheromone receptor (PR) clades which have a higher expression in male antennae. Interestingly, SsubOR44 was uniquely expressed in the antennae, with a higher expression in males than in females. SsubOBP25, SsubOBP27, and SsubOBP28 were clustered into the moth pheromone-binding protein (PBP) sub-family, and they were uniquely expressed in the antennae, with a higher expression in males than in females. SsubOBP19, a member of the GOBP2 group, was the most abundant OBP in the antennae. These findings indicate that these olfactory genes, comprising five candidate PRs, three candidate PBPs, and one candidate GOBP2, may be involved in type II sex pheromone detection. As well as these genes, most of the remaining SsubORs, and all of the SsubIRs, showed a considerably higher expression in the female antennae than in the male antennae. Many of these, including SsubOR40, SsubOR42, SsubOR43, and SsubIR26, were more abundant in female antennae. These olfactory and ionotropic receptors may be related to the detection of host plant volatiles. The results of this present study provide a basis for exploring the olfaction mechanisms in S. subpunctaria, with a focus on the genes involved in type II sex pheromones. The evolutionary analyses in our study provide new insights into the differentiation and evolution of lepidopteran PRs.

Identification of cytochrome P450, odorant-binding protein, and chemosensory protein genes involved in Type II sex pheromone biosynthesis and transportation in the tea pest, Scopula subpunctaria.

Sex pheromone-based pest management technology has been widely used to monitor and control insect pests in the agricultural, forestry, and public health sectors. Scopula subpunctaria is a widespread tea pest in China with Type II sex pheromone components. However, limited information is available on the biosynthesis and transportation of Type II sex pheromone components. In this study, we constructed an S. subpunctaria sex pheromone gland (PG) transcriptome and obtained 85,246 transcripts. Cytochrome P450 monooxygenases (CYPs) thought to epoxidize dienes and trienes to epoxides in the PG and odorant-binding proteins (OBPs) and chemosensory genes (CSPs) thought to be responsible for the binding and transportation of sex pheromone components. In present study, a total of 79 CYPs, 29 OBPs and 17 CSPs were identified. We found that SsubCYP341A and SsubCYP341B_ortholog1 belonged to the CYP341 family and were more highly expressed in the PG than in the female body. Of these, SsubCYP341A was the seventh-most PG-enriched CYP in the PG transcriptome. Two CYP4 members, CYP340BD_ortholog2 and CYP4G, were the top two most PG-enriched CYPs. Tissue expression and phylogenetic tree analysis showed that SsubOBP25, 27, and 28 belonged to the moth pheromone-binding protein family; they were distinctly expressed in the antennae and were more abundant in male antennae than in female antennae. SsubCSP16 was distributed into the same clade as CSPs from other moths that showed high binding affinities to sex pheromone components. It indicated that all the above-mentioned genes could be involved in sex pheromone biosynthesis or transportation. Our study provides large-scale PG sequence information that can be used to identify potential targets for the biological control of S. subpunctaria by disrupting its sex pheromone biosynthesis and transportation pathways.

Molecular identification of differential expression genes associated with sex pheromone biosynthesis in Spodoptera exigua.

Species-specific sex pheromone is biosynthesized and released in most female moths as a chemical cue in mating communication. However, information on genes involved in this pathway is limited. The beet armyworm, Spodoptera exigua, is a cosmopolitan agricultural pest that causes severe economic losses to many crops. In China, the female sex pheromones in sex pheromone glands (PGs) of S. exigua have been measured which comprises (Z,E)-9,12-tetradecadienyl acetate, (Z)-9-tetradecen-l-ol, (Z)-9-tetradecenyl acetate, and (Z,E)-9,12-tetradecadien-1-ol in a ratio of 47:18:18:17. Fifty-nine putative genes related to sex pheromone biosynthesis were identified in the present study by sequencing and analyzing the sex pheromone gland (PG) transcriptome of S. exigua. Expression profiles revealed that two desaturase (SexiDes5 and SexiDes11) and three fatty acyl reductase (SexiFAR2, 3, and 9) genes had PG-specific expression, and phylogenetic analysis demonstrated that they clustered with genes known to be involved in pheromone synthesis in other moth species. Our results provide crucial background information that could facilitate the elucidation of sex pheromone biosynthesis pathway of S. exigua as well as other Spodoptera species and help identify potential targets for disrupting sexual communication in S. exigua for developing novel environment-friendly pesticides.

Expression Analysis and Binding Assays in the Chemosensory Protein Gene Family Indicate Multiple Roles in Helicoverpa armigera.

Chemosensory proteins (CSPs) have been proposed to capture and transport hydrophobic chemicals to receptors on sensory neurons. We identified and cloned 24 CSP genes to better understand the physiological function of CSPs in Helicoverpa armigera. Quantitative real-time polymerase chain reaction assays indicate that CSP genes are ubiquitously expressed in adult H. armigera tissues. Broad expression patterns in adult tissues suggest that CSPs are involved in a diverse range of cellular processes, including chemosensation as well as other functions not related to chemosensation. The H. armigera CSPs that were highly transcribed in sensory organs or pheromone glands (HarmCSPs 6, 9, 18, 19), were recombinantly expressed in bacteria to explore their function. Fluorescent competitive binding assays were used to measure the binding affinities of these CSPs against 85 plant volatiles and 4 pheromone components. HarmCSP6 displays high binding affinity for pheromone components, whereas the other three proteins do not show affinities for any of the compounds tested. HarmCSP6 is expressed in numerous cells located in or close to long sensilla trichodea on the antennae of both males and females. These results suggest that HarmCSP6 may be involved in transporting female sex pheromones in H. armigera.

Odorant-binding proteins display high affinities for behavioral attractants and repellents in the natural predator Chrysopa pallens.

Chrysopa pallens is an important natural predator of various pests in many different cropping systems. Understanding the sophisticated olfactory system of insect antennae is crucial for studying the physiological bases of olfaction and could also help enhance the effectiveness of C. pallens in biological control. However, functional studies of the olfactory genes in C. pallens are still lacking. In this study, we cloned five odorant-binding protein (OBP) genes from C. pallens (CpalOBPs). Quantitative RT-PCR results indicated that the five CpalOBPs had different tissue expression profiles. Ligand-binding assays showed that farnesol, farnesene, cis-3-hexenyl hexanoate, geranylacetone, beta-ionone, octyl aldehyde, decanal, nerolidol (Ki<20 µM), and especially 2-pentadecanone (Ki=1.19 µM) and 2-hexyl-1-decanol (Ki=0.37 µM) strongly bound to CpalOBP2. CpalOBP15 exhibited high binding affinities for beta-ionone, 2-tridecanone, trans-nerolidol, and dodecyl aldehyde. Behavioral trials using the 14 compounds exhibiting high binding affinities for the CpalOBPs revealed that nine were able to elicit significant behavioral responses from C. pallens. Among them, farnesene and its corresponding alcohol, farnesol, elicited remarkable repellent behavioral responses from C. pallens. Our study provides several compounds that could be selected to develop slow-release agents that attract/repel C. pallens and to improve the search for strategies to eliminate insect pests.

An antenna-biased carboxylesterase is specifically active to plant volatiles in Spodoptera exigua.

Odorant-degrading enzymes (ODEs) in sensillar lymph are proposed to play important roles in the maintenance of the sensitivity of the olfactory sensilla, by timely degrading the odorants that have already fulfilled the activation of the odorant receptor (OR). Here we reported the cloning and characterization of an ODE gene (SexiCXE10) from the polyphagous insect pest Spodoptera exigua. SexiCXE10 is a carboxylesterase (CXE) gene, encoding a protein with 538 amino acid residues, and bearing typical characteristics of Carboxyl/cholinesterase (CCE, EC 3.1.1.1.) gene family. Tissue-temporal expression pattern by qPCR revealed that the SexiCXE10 mRNA was highly antenna biased, and maintained at high level throughout the adult stage. Further fluorescence in situ hybridization demonstrated that SexiCXE10 mRNA signal was detected under sensilla basiconica and short and long sensilla trichodea. Finally, enzymatic study using purified recombinant enzyme showed that SexiCXE10 had high activity specifically for ester plant volatiles with 7-10 carbon atoms, while no activity was found with S. exigua sex pheromone components and plant volatiles with more carbon atoms. In addition, SexiCXE10 displayed lower activity at acidic pH (pH 5.0), while higher activity was found at neutral and alkaline conditions (pH 6.5-9.0). Our results suggest that SexiCXE10 may play an important role in the degradation of the host plant volatiles, and thus contributes to the high sensitivity of the olfactory system in S. exigua. Meanwhile, the CXE would be a potential target for developing behavioral antagonists and pesticides against S. exigua.

Two esterases from the genus Spodoptera degrade sex pheromones and plant volatiles.

In moths, high temporal sensitivity in perception of sex pheromones and host plant volatiles suggests the existence of mechanisms acting to maintain antennal sensitivity. The antennal enzymes have been long hypothesized to play a central role in the mechanisms, by rapid metabolism of the odorants soon after the fulfillment of the sensillum receptor activation. In the present study, two putative homologous esterases, SexiCXE13 and SlituCXE13, were cloned by RT-PCR and RACE procedures from Spodoptera exigua and Spodoptera litura, respectively. The phylogenetic tree assigned the two genes into the same group with two previously identified male antennal-specific pheromone-degrading enzymes. SexiCXE13 and SlituCXE13 were expressed in High Five cells, and the enzymatic characteristics and substrate specificity were investigated using the purified recombinant enzymes. Both esterases showed high activity to a variety of acetate substrates, including the sex pheromones, their analogs, and some common plant odorants. Our study, for the first time, provides direct biochemical and molecular evidence that the ubiquitously expressed enzyme has the ability to degrade sex pheromones and plant volatiles, and thus this adds new knowledge to the mechanism underlying the sensitivity of moth olfaction.

Functional characterization of an antennal esterase from the noctuid moth, Spodoptera exigua.

Odorant-degrading esterases (ODEs) act in the fast deactivation of ester pheromone components and plant volatiles in insects. However, only few ODEs have been characterised to date. In this study, six full-length putative ODE genes (designated SexiCXE4, 5, 17, 18, 20, and 31) were cloned from the male antennae of Spodoptera exigua. The deduced amino acid sequences possessed typical characteristics of a carboxylesterase (CXE) and shared high identities with reported insect CXEs. The tissue and temporal expression patterns were investigated by quantitative real time PCR. Although all six SexiCXEs are expressed in antennae of both sexes, SexiCXE4, 17 and 20 are antennae-enriched; while SexiCXE5 and SexiCXE18 are dominantly expressed in wings, and SexiCXE31 is mainly expressed in proboscises, heads and legs. With the highly biased expression in antennae and proboscises, SexiCXE4 was selected for further functional assay. The recombinant SexiCXE4 were expressed in High-five cells and purified by a Ni(2+) affinity column. SexiCXE4 has much higher enzyme activity against plant volatiles (Z)-3-hexenyl acetate and hexyl acetate than to the sex pheromone components, suggesting that it may function mostly in the degradation of the plant volatiles.

Comparative transcriptomics reveals the conservation and divergence of reproductive genes across three sympatric Tomicus bark beetles.

Three tree-killing bark beetles belonging to the genus Tomicus, Tomicus yunnanensis, Tomicus brevipilosus and Tomicus minor (Coleoptera; Curculionidae, Scolytinae), are serious wood-borers with larvae feeding on the phloem tissues of Pinus yunnanensis. The three Tomicus beetles, in some cases, coexist in a same habitat, providing a best system for exploring the conservation and divergence of reproductive genes. Here, we applied comparative transcriptomics and molecular biology approaches to characterize reproductive-related genes in three sympatric Tomicus species. Illumina sequencing of female and male reproductive systems and residual bodies generated a large number of clean reads, representing 185,920,232 sequences in T. yunnanensis, 169,153,404 in T. brevipilosus and 178,493,176 in T. minor that were assembled into 32,802, 56,912 and 33,670 unigenes, respectively. The majority of the genes had detectable expression in reproductive tissues (FPKM >1), particularly those genes in T. brevipilosus accounting for 76.61 % of the total genes. From the transcriptomes, totally 838 genes encoding 463 detoxification enzymes, 339 chemosensory membrane proteins and 36 ionotropic glutamate receptors (iGluRs) were identified, including 622 reproductive tissue-expressed genes. Of these, members of carboxylesterases (COEs), ionotropic receptors (IRs), sensory neuron membrane proteins (SNMPs) and iGluRs were highly conserved in gene numbers and sequence identities across three Tomicus species. Further, expression profiling analyses revealed a number of genes expressed in reproductive tissues and the diverse expression characteristics in these beetles. The results provide evidence for the conservation and differences of reproductive genes among three sympatric closely related beetles, helping understand their different reproductive strategies and the maximization of the reproductive success.

Mating and post-copulation behavior in the tea leafhopper, Empoasca onukii (Hemiptera: Cicadellidae).

The tea leafhopper, Empoasca onukii, relies on substrate-borne vibrations for sexual communication and is mainly controlled with chemical pesticides, which poses risks to the environment and food safety. Based on previous studies, we conducted a series of behavioral assays by simultaneous observation of vibration signals and movement to investigate the mating and post-copulation behavior of tea leafhoppers. During mating, the activity of E. onukii was restricted to dawn and dusk and concentrated on the sixth or seventh mature leaf below the tea bud. By comparing the time spent in locating females among different males, the timely reply of females was the key factor affecting mating success. Empoasca onukii females mated only once in their lives, while males could mate multiple times. Male rivalry behavior involved two distinct strategies. The rivals could send disruptive pulses to overlap the male calling signals, locate the courting males, and drive them away after contact. Some rivals could emit mating disruption signals (MDSs) to interrupt the ongoing identification duet and establish their own mating communication. Both identification and location duets could be interrupted by playback of MDSs, which is essential to create effective synthetic signals to disrupt mating communication of E. onukii. Our study clarified the spatial and temporal distribution of E. onukii in mating and the function of MDSs, which will be essential to develop future vibrational mating disruption techniques for E. onukii and its energy-efficient application in the field.

Molecular characterization, expression patterns, and ligand-binding properties of two odorant-binding protein genes from Orthaga achatina (Butler) (Lepidoptera: Pyralidae).

It is postulated that insect pheromone-binding proteins (PBPs) are involved in sex pheromone reception, while the general odorant-binding proteins (GOBPs) are involved in reception of the general odorants including plant volatiles. However, this functional specificity is not completely conclusive. In the present study, full-length sequences of two new OBP genes were molecularly identified as OachPBP1 and OachGOBP2 from Orthaga achatina, an important pest of the camphor tree Cinnamomum camphora. Quantification of transcript levels by qRT-PCR showed that the two genes highly expressed in antennae, with OachPBP1 male-biased and OachGOBP2 similar between sexes. These expression patterns are consistent with the generally proposed functions of PBPs and GOBPs. With the recombinant proteins obtained by a bacterial expression system, the binding specificity of these proteins was further investigated and compared using the competitive binding assay. OachPBP1 exhibited high binding affinities with all three putative sex pheromones and 10 pheromone analogs, supporting its role in pheromone reception. On the other hand, in addition to binding with some plant volatiles, OachGOBP2 surprisingly displayed similar or even higher binding affinities with the sex pheromones than OachPBP1. Therefore, we propose that OachGOBP2 might play roles in reception of sex pheromone. Additionally, plant volatiles farnesol and farnesene showed high binding with both OachGOBP2 and OachPBP1, suggesting that these volatile chemicals have regulatory functions in the behavior of O. achatina.

Anatomical Comparison of Antennal Lobes in Two Sibling Ectropis Moths: Emphasis on the Macroglomerular Complex.

Ectropis obliqua and Ectropis grisescens are two sibling moth species of tea plantations in China. The male antennae of both species can detect shared and specific sex pheromone components. Thus, the primary olfactory center, i.e., the antennal lobe (AL), plays a vital role in distinguishing the sex pheromones. To provide evidence for the possible mechanism allowing this distinction, in this study, we compared the macroglomerular complex (MGC) of the AL between the males of the two species by immunostaining using presynaptic antibody and propidium iodide (PI) with antennal backfills, and confocal imaging and digital 3D-reconstruction. The results showed that MGC of both E. obliqua and E. grisescens contained five glomeruli at invariant positions between the species. However, the volumes of the anterior-lateral glomerulus (ALG) and posterior-ventral (PV) glomerulus differed between the species, possibly related to differences in sensing sex pheromone compounds and their ratios between E. obliqua and E. grisescens. Our results provide an important basis for the mechanism of mating isolation between these sibling moth species.

Two carboxylesterase genes in Plutella xylostella associated with sex pheromones and plant volatiles degradation.

BACKGROUND: Carboxyl/cholinesterases (CCEs) are thought to play a pivotal role in the degradation of sex pheromones and plant-derived odorants in insects, but their exact biochemistry and physiological functions remain unclear. RESULTS: In this study, two paralogous antennae-enriched CCEs from Plutella xylostella (PxylCCE16a and 16c) were identified and functionally characterized. High-purity protein preparations of active recombinant PxylCCE16a and 16c have been obtained from Sf9 insect cells by Ni2+ affinity purification. Our results revealed that the purified recombinant PxylCCE016c is able to degrade two sex pheromone components Z9-14:Ac and Z11-16:Ac at 27.64 ± 0.79% and 24.40 ± 3.07%, respectively, while PxylCCE016a presented relatively lower activity. Additionally, a similar difference in activity was measured in plant-derived odorants. Furthermore, both CCEs displayed obvious preferences for the two sex pheromone components, especially on Z11-16:Ac (Km values are in the range 7.82-45.06 µmol L-1 ) which much lower than plant odorants (Km values are in the range 1290-4030 µmol L-1 ). Furthermore, the activity of the two newly identified CCEs is pH-dependent. The activity at pH 6.5 is obviously higher than that at pH 5.0. Interestingly, only PxylCCE016c can be inhibited by a common esterase inhibitor triphenyl phosphate (TPP) with LC50 of 1570 ± 520 µmol L-1 . CONCLUSION: PxylCCE16c plays a more essential role in odorant degradation than PxylCCE16a. Moreover, the current study provides novel potential pesticide targets for the notorious moth Plutella xylostella. © 2021 Society of Chemical Industry.

Foliage Intensity is an Important Cue of Habitat Location for Empoasca onukii.

For many herbivorous insects, vision is more important than olfaction in the prealighting stage of host habitat location. Tea leafhoppers, Empoasca onukii (Hemiptera, Cicadellidae), are serious pests that preferentially inhabit the tender leaves of tea plants across China. Here, we investigated whether tea leafhoppers could distinguish foliage colors associated with different leaf ages and use this visual cue to guide suitable habitat location from short distances. Similar to honeybees, the adult E. onukii has an apposition type of compound eye, and each ommatidium has eight retinular cells, in which three spectral types of photoreceptors are distributed, with peak sensitivities at 356 nm (ultraviolet), 435 nm (blue), and 542 nm (green). Both changes in spectral intensity and hue of reflectance light of the host foliage were correlated with varying leaf age, and the intensity linearly decreased with increasing leaf age. Behavioral responses also showed that adult E. onukii could discriminate between the simulated colors of host foliage at different leaf ages without olfactory stimuli and selected the bright colors that strongly corresponded to those of tender leaves. The results suggest that, compared with the spectral composition (hue), the intensity of light reflectance from leaves at different ages is more important for adult leafhoppers when discriminating host foliage and could guide them to tender leaves at the top of tea shoots.

Identification and Expression Profile of Olfactory Receptor Genes Based on Apriona germari (Hope) Antennal Transcriptome.

Insects' olfactory receptor plays a central role in detecting chemosensory information from the environment. Odorant receptors (ORs) and ionotropic receptors (IRs) are two types of olfactory receptors, and they are essential for the recognition of ligands at peripheral neurons. Apriona germari (Hope) (Coleoptera: Cerambycidae) is one of the most serious insect pests that cause damage to economic trees and landscaping trees, resulting in massive environmental damages and economic losses. Olfactory-based management strategy has been suggested as a promising strategy to control this wood-boring beetle. However, the olfactory perception mechanism in A. germari is now almost unknown. In the present study, RNA sequencing analysis was used to determine the transcriptomes of adult A. germari antennae. Among 36,834 unigenes derived from the antennal assembly, we identified 42 AgerORs and three AgerIRs. Based on the tissue expression pattern analysis, 27 AgerORs displayed a female-biased expression. Notably, AgerOR3, 5, 13, 33, and 40 showed a significant female-biased expression and were clustered with the pheromone receptors of Megacyllene caryae in the phylogenetic tree, suggesting that these AgerORs could be potential pheromone receptors for sensing male-produced sex pheromones in A. germari. The AgerIRs expression profile demonstrated that AgerIR2 had high expression levels in male labial palps, suggesting that this receptor may function to detect female-deposited trail-sex pheromone blend of A. germari. In addition, the phylogenetic tree showed that the Orco gene of five cerambycidae species was highly conservative. These results provide a foundation for further studies on the molecular mechanisms of olfactory chemoreception in A. germari apart from suggesting novel targets for the control of this pest in the future.

Geographical Distribution of Ectropis grisescens (Lepidoptera: Geometridae) and Ectropis obliqua in China and Description of an Efficient Identification Method.

Ectropis grisescens Warren 1894 (Lepidopotera: Geometridae) and Ectropis obliqua Prout 1915 (Lepidopotera: Geometridae) are the most destructive chewing pests in China's tea plantations. Ectropis grisescens sex pheromone lures and E. obliqua nucleopolyhedrosis virus (EoNPV) are two species-specific and effective bio-control technologies to control these pests. Because these two species are morphologically similar, tea growers are unable to discriminate them by visual inspection. Hence, determining whether to use E. grisescens sex pheromone lures or EoNPV is difficult without knowledge on the geographical distribution of these two Ectropis species in China. In this study, we developed an efficient identification method, which is considerably cheaper and faster than sequencing the cytochrome c oxidase I gene. Overall, 2,588 E. grisescens and E. obliqua samples, collected from 13 provinces and municipalities in China covering the major regions where these pests have been reported, were identified. All insect samples from southern Jiangsu Province were identified as E. obliqua. Both Ectropis species were mix-distributed at the Anhui-Zhejiang Province border areas, whereas E. grisescens was mostly collected from the other sampling sites. Thus, E. obliqua might be mainly distributed at the junction of Jiangsu, Anhui, and Zhejiang Provinces. In contrast, E. grisescens has a considerably wide distribution area and is the main lepidopteran pest in the tea plantations of China. Our results contribute to improve the management of E. grisescens and E. obliqua populations and provide new insights for further studies on these two species.

[Jasmonates: From induced plant anti-herbivore defensive reaction to growth-defense tradeoffs]. / èŒ‰èŽ‰é ¸ç±»åŒ–åˆç‰©:从植物的诱导抗虫防御反应到生长-防御权衡.

Jasmonates (JAs), which can exogenously induce anti-herbivore defensive reaction in plants, are important in the field of plant physiology and plant protection. We summarized the ecological effects of exogenous JAs applied on 40 species of plants on various herbivores (such as Lepidoptera and Hemipteran) and their natural enemies in the past 20 years. We systematically genera-lized the research status about the direct and indirect antiherbivore defense induced by JAs, induced systemic defense, induction methods, induced performance in field, and the application status of JAs. Moreover, combining with the latest literatures, we reviewed the effects of JAs on plant growth-defense trade-offs from the cross-talk between phytohormone signaling pathways, and the regulation of nodes in the JA signaling pathway. Finally, we proposed the future directions and key aspects of the research on the plant anti-herbivore defense induced by exogenous JAs, which would promote the development of the related research and the application of JAs in field.

Design of an Attractant for Empoasca onukii (Hemiptera: Cicadellidae) Based on the Volatile Components of Fresh Tea Leaves.

The tea leafhopper, Empoasca onukii Matsuda, is a serious pest of the tea plant. E. onukii prefers to inhabit vigorously growing tender tea leaves. The host selection of E. onukii adults may be associated with plant volatile compounds (VOCs). We sought to identify potentially attractive VOCs from tea leaves at three different ages and test the behavioral responses of E. onukii adults to synthetic VOC blends in the laboratory and field to aid in developing an E. onukii adult attractant. In darkness, the fresh or mature tea leaves of less than 1-mo old could attract more leafhoppers than the mature branches (MB) that had many older leaves (leaf age >1 mo). Volatile analysis showed that the VOC composition of the fresh leaves was the same as that of the mature leaves, but linalool and indole were not at detectable levels in VOCs from the MB. Moreover, the mass ratio differed for each common volatile in the three types of tea leaves. When under competition with volatiles from the MB, the leafhoppers showed no significant tropism to each single volatile but could be attracted by the synthetic volatile blend imitating the fresh leaves. With the removal of some volatile components, the effective synthetic volatile blend was mixed with (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, and linalool at a mass ratio of 0.6:23:12.6. These three volatiles may be the key components for the host selection of E. onukii adults and could be used as an attractant in tea gardens.

Distinct binding affinities of odorant-binding proteins from the natural predator Chrysoperla sinica suggest different strategies to hunt prey.

Chrysoperla sinica is an important natural predator of many notorious agricultural pests. Understanding its olfactory mechanism can help enhance the effectiveness of C. sinica in biological control. In the present study, we investigated the tissue expression patterns of 12 odorant-binding protein (OBP) genes from C. sinica (CsinOBPs). The results of quantitative real-time polymerase chain reaction (qPCR) showed that CsinOBP1, CsinOBP2, CsinOBP3, CsinOBP4, CsinOBP6, CsinOBP7, CsinOBP9, CsinOBP10, and CsinOBP12 were predominantly expressed in the antennae of both sexes, indicating their roles in olfaction. Additionally, the qPCR analysis revealed that the 12 CsinOBP genes had distinct expression patterns, while the motif-pattern investigation suggested that the OBPs had different ligands. The ligand-binding assay showed that CsinOBP1 and CsinOBP10 had broader binding spectra than did the other OBPs. Thus, CsinOBP1 was able to bind not only plant volatiles (such as farnesol, cis-3-hexenyl hexanoate, geranylacetone, ß-ionone, 2-tridecanone, and trans-nerolidol) but also the aphid alarm pheromone (E)-ß-farnesene. On the other hand, CsinOBP2 and CsinOBP6 exhibited relatively narrow binding spectra, only binding ethyl benzoate. The study also identified several compounds that can potentially be used to develop slow-release agents attracting C. sinica and to improve search strategies for insect pest control.