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Zhao B, Yan Y, Cao D, Xia Y. Germinating rice seeds shape rhizospheric bacteria via releasing benzaldehyde. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 210:108632. [PMID: 38657546 DOI: 10.1016/j.plaphy.2024.108632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/23/2024] [Accepted: 04/14/2024] [Indexed: 04/26/2024]
Abstract
Plants are not passively exposed to microbes during their life cycles, but rather shape the microbiome in their own way. However, little information is available about when and how plants recruit their microbes in the life cycles. We scrutinized the recruitment of soil microbes by rice (Oryza sativa) at the seed germination stage. Bacteria of Enterobacteria and Weeksellaceae were the most preferentially recruited by the germinating seeds, despite of many other bacteria in the soil. The seedlings that recruited Enterobacteria and Weeksellaceae bacteria notably outperformed those without these microbes in leaf length (by 54.21%), root length (by 188.11%) and biomass (by 88.65%). Further, we detected benzaldehyde, a plant-specific volatile metabolite, in the exudates of germinating seeds. Addition of benzaldehyde to the soil resulted in enrichment of Enterobacteria bacteria, suggesting that seed-released benzaldehyde could be a cue to recruit beneficial bacteria. Taken together, our results demonstrated that plants could recruit beneficial bacteria from the soil at the very early life stage of seed germination via releasing specific metabolites.
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Affiliation(s)
- Bixi Zhao
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Yuxi Yan
- School of Environment, Harbin Institute of Technology, Harbin, 150001, China; School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Dechang Cao
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, 650201, China.
| | - Yu Xia
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
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Mutua BK, Dubois T, Akutse KS, Muli B, Karanja EN, Mutyambai DM. Electrophysiological and Behavioral Responses of Cabbage Aphid (Brevicoryne brassicae) to Rosemary (Rosmarinus officinalis) Volatiles, a Potential push Plant for Vegetable push-pull Cropping System. J Chem Ecol 2024:10.1007/s10886-024-01485-y. [PMID: 38470529 DOI: 10.1007/s10886-024-01485-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/23/2024] [Accepted: 03/03/2024] [Indexed: 03/14/2024]
Abstract
The cabbage aphid (Brevicoryne brassicae) is a major pest of kale (Brassica oleraceae var. acephala), an important vegetable that is grown worldwide due to its high nutritional and economic value. Brevicoryne brassicae poses a great challenge to B. oleraceae var. acephala production, causing significant direct and indirect yield losses. Farmers overly rely on synthetic insecticides to manage the pest with limited success owing to its high reproductive behavior and development of resistance. This necessitates a search for sustainable alternatives to mitigate these challenges. This study assessed behavioral responses of B. brassicae to odors from rosemary (Rosmarinus officinalis) and B. oleraceae var. acephala headspace volatiles in a Perspex four-arm olfactometer. We identified and quantified volatiles emitted by each of the two plants and those eliciting antennal response using coupled gas chromatography-mass spectrometry (GC-MS) and GC-electroantennograhic detection(GC-EAD), respectively. Our findings revealed that B. brassicae spent more time in the arms of the olfactometer that contained B. oleraceae var. acephala volatiles compared to the arm that held R. officinalis volatiles. Additionally, B. brassicae spent more time in the olfactometer arms with B. oleracea var. acephala compared to the arms holding B. oleracea var. acephala and R. officinalis enclosed together and clean air. GC-MS analysis revealed diverse and higher quantities of volatile compounds in R. officinalis compared to B. oleraceae var. acephala. GC-EAD analysis showed that antennae of B. brassicae detected Linalool, α-Terpineol, Verbenone, Geraniol, Camphor, and Borneol from the volatiles of R. officinalis, and Sabinene, γ-Terpinene, and β-Caryophyllene from B. oleraceae var. acephala volatiles. Our findings demonstrate the potential of R. officinalis as a repellent plant against B. brassicae and could be utilized as a 'push' plant in an intercropping strategy against this pest.
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Affiliation(s)
- Bretor Katuku Mutua
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
- Department of Agricultural Sciences, South Eastern Kenya University, P.O Box 170-90200, Kitui, Kenya
| | - Thomas Dubois
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
| | - Komivi Senyo Akutse
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, 2520, South Africa
| | - Benjamin Muli
- Department of Agricultural Sciences, South Eastern Kenya University, P.O Box 170-90200, Kitui, Kenya
| | - Edward Nderitu Karanja
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya
| | - Daniel Munyao Mutyambai
- International Centre of Insect Physiology and Ecology, P. O. Box 30772-00100, Nairobi, Kenya.
- Department of Life Sciences, South Eastern, Kenya University, P.O Box 170-90200, Kitui, Kenya.
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Giri AP, Short BD, Piñero JC. Male and Female Tortricid Moth Response to Non-Pheromonal Semiochemicals. INSECTS 2023; 14:884. [PMID: 37999083 PMCID: PMC10671916 DOI: 10.3390/insects14110884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/14/2023] [Accepted: 11/14/2023] [Indexed: 11/25/2023]
Abstract
In eastern North America, apple orchards are often attacked by several species of tortricid moths (Lepidoptera), including Cydia pomonella, Grapholita molesta, Argyrotaenia velutinana, and Pandemis limitata. Sex pheromones are routinely used to monitor male moth populations. Adding plant volatiles to monitoring traps could increase the capture of moths of both sexes and improve the effectiveness of mating disruption systems. This study sought to quantify the attraction of adults of four tortricid moth species to five olfactory treatments, namely (1) Pherocon® CM L2-P, (2) Pherocon Megalure CM 4K Dual® (=Megalure), (3) Megalure + benzaldehyde, (4) TRE 2266 (linalool oxide + (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT)), and (5) TRE 2267 (linalool oxide + DMNT + benzaldehyde), in non-mating disrupted commercial apple orchards in Massachusetts. The commercial lure Megalure was attractive to both sexes of G. molesta and C. pomonella. The addition of benzaldehyde to TRE 2266 or to Megalure significantly increased the capture of male G. molesta during the mid and late season of 2021. Only when benzaldehyde was added to TRE 2266 did the latter lure attract P. limitata in 2020 and 2021. The greatest number of tortricid moths (all four species combined) was captured by TRE 2267. This finding highlights the opportunity to enhance the attractiveness of a commercial lure through the addition of benzaldehyde, an aromatic compound, to Megalure. The potential of these additional volatiles to detect moths in a mating-disrupted orchard and/or remove female moths as a component of a management system is discussed.
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Affiliation(s)
- Ajay P. Giri
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA;
| | | | - Jaime C. Piñero
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA;
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Zhao J, Zheng R, Li X, Lyu Z, Ma L, Song C, Qie X, Yan X, Hao C. Electrophysiological and Behavioral Responses of Plodia interpunctella (Hübner) Females to Aldehyde Volatiles from Dried Fruits. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023. [PMID: 37921278 DOI: 10.1021/acs.jafc.3c04530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Plodia interpunctella (Lepidoptera: Pyraloidea) is a notorious pest of stored grain globally. The dried fruits (Ziziphus jujuba, Malus pumila, and Fragaria ananassa) can strongly attract P. interpunctella. However, specific volatile compounds responsible for such effects have not been identified. Volatiles were analyzed by using headspace solid-phase microextraction (HS-SPME) and chromatography-mass spectrometry (GCMS) techniques. Five aldehyde compounds were selected for electroantennogram (EAG), single sensillum recording (SSR), and behavioral response assays. The three chemicals that elicited the strongest EAG responses to mated females at 100 μg/μL include hexanal (1.13 mV), heptanal (0.92 mV), and octanal (0.73 mV). In SSR experiments, the basiconic sensilla of the antennae responded to these aldehyde compounds. The results of behavioral responses showed that all aldehydes exhibited dose-dependent responses, with hexanal having the highest attractant rate of 74.56%. These compounds have the potential to be used for monitoring P. interpunctella and its integrated management program.
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Affiliation(s)
- Jinyu Zhao
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Ruirui Zheng
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Xiaofei Li
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Zhishen Lyu
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Li Ma
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Chengfei Song
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Xingtao Qie
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Xizhong Yan
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
| | - Chi Hao
- College of Plant Protection, Shanxi Agricultural University, Taigu 030801, P. R. China
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Jimenez AC, Heist CA, Navaei M, Yeago C, Roy K. Longitudinal two-dimensional gas chromatography mass spectrometry as a non-destructive at-line monitoring tool during cell manufacturing identifies volatile features correlative to cell product quality. Cytotherapy 2022; 24:1136-1147. [PMID: 35882596 DOI: 10.1016/j.jcyt.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/14/2022] [Accepted: 06/04/2022] [Indexed: 11/03/2022]
Abstract
BACKGROUND AIMS Cell therapies have emerged as a potentially transformative therapeutic modality in many chronic and incurable diseases. However, inherent donor and patient variabilities, complex manufacturing processes, lack of well-defined critical quality attributes and unavailability of in-line or at-line process or product analytical technologies result in significant variance in cell product quality and clinical trial outcomes. New approaches for overcoming these challenges are needed to realize the potential of cell therapies. METHODS Here the authors developed an untargeted two-dimensional gas chromatography mass spectrometry (GC×GC-MS)-based method for non-destructive longitudinal at-line monitoring of cells during manufacturing to discover correlative volatile biomarkers of cell proliferation and end product potency. RESULTS Specifically, using mesenchymal stromal cell cultures as a model, the authors demonstrated that GC×GC-MS of the culture medium headspace can effectively discriminate between media types and tissue sources. Headspace GC×GC-MS identified specific volatile compounds that showed a strong correlation with cell expansion and product functionality quantified by indoleamine-2,3-dioxygenase and T-cell proliferation/suppression assays. Additionally, the authors discovered increases in specific volatile metabolites when cells were treated with inflammatory stimulation. CONCLUSIONS This work establishes GC×GC-MS as an at-line process analytical technology for cell manufacturing that could improve culture robustness and may be used to non-destructively monitor culture state and correlate with end product function.
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Affiliation(s)
- Angela C Jimenez
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, Georgia, USA; Marcus Center for Therapeutic Cell Characterization and Manufacturing (MC3M), Georgia Institute of Technology, Atlanta, Georgia, USA; National Science Foundation Engineering Research Center (ERC) for Cell Manufacturing Technologies (CMaT), Atlanta, Georgia, USA
| | - Christopher A Heist
- Georgia Tech Research Institute (GTRI), Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Milad Navaei
- Georgia Tech Research Institute (GTRI), Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Carolyn Yeago
- Marcus Center for Therapeutic Cell Characterization and Manufacturing (MC3M), Georgia Institute of Technology, Atlanta, Georgia, USA; National Science Foundation Engineering Research Center (ERC) for Cell Manufacturing Technologies (CMaT), Atlanta, Georgia, USA
| | - Krishnendu Roy
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, Georgia, USA; Marcus Center for Therapeutic Cell Characterization and Manufacturing (MC3M), Georgia Institute of Technology, Atlanta, Georgia, USA; National Science Foundation Engineering Research Center (ERC) for Cell Manufacturing Technologies (CMaT), Atlanta, Georgia, USA.
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Li Q, Gong D, Wang Y, Wang H, Wang W, Wu G, Guo H, Wang B. Accelerated toluene degradation over forests around megacities in southern China. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 230:113126. [PMID: 34974359 DOI: 10.1016/j.ecoenv.2021.113126] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 06/14/2023]
Abstract
Toluene is a typical anthropogenic pollutant that has profound impacts on air quality, climate change, and human health, but its sources and sinks over forests surrounding megacities remain unclear. The Nanling Mountains (NM) is a large subtropical forest and is adjacent to the Pearl River Delta (PRD) region, a well-known hotspot for toluene emissions in southern China. However, unexpectedly low toluene concentrations (0.16 ± 0.20 ppbv) were observed at a mountaintop site in NM during a typical photochemical period. A backward trajectory analysis categorized air masses received at the site into three groups, namely, air masses from the PRD, those from central China, and from clean areas. The results revealed more abundant toluene and its key oxidation products, for example, benzaldehyde in air masses mixed with urban plumes from the PRD. Furthermore, a more than three times faster degradation rate of toluene was found in this category of air masses, indicating more photochemical consumption in NM under PRD outflow disturbance. Compared to the categorized clean and central China plumes, the simulated OH peak level in the PRD plumes (15.8 ± 2.2 × 106 molecule cm-3) increased by approximately 30% and 55%, respectively, and was significantly higher than the reported values at other background sites worldwide. The degradation of toluene in the PRD plumes was most likely accelerated by increased atmospheric oxidative capacity, which was supported by isoprene ozonolysis reactions. Our results indicate that receptor forests around megacities are not only highly polluted by urban plumes, but also play key roles in environmental safety by accelerating the degradation rate of anthropogenic pollutants.
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Affiliation(s)
- Qinqin Li
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China
| | - Daocheng Gong
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China; Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China
| | - Yu Wang
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China; Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China
| | - Hao Wang
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China; Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China.
| | - Wenlu Wang
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China; Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China
| | - Gengchen Wu
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China; Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China
| | - Hai Guo
- Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China; Air Quality Studies, Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Boguang Wang
- Institute for Environmental and Climate Research, Jinan University, Guangzhou, China; Australia-China Centre for Air Quality Science and Management (Guangdong), Guangzhou 511443, China; Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, China.
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Bandeira PT, Fávaro CF, Francke W, Bergmann J, Zarbin PHG. Aggregation Pheromones of Weevils (Coleoptera: Curculionidae): Advances in the Identification and Potential Uses in Semiochemical-Based Pest Management Strategies. J Chem Ecol 2021; 47:968-986. [PMID: 34671912 DOI: 10.1007/s10886-021-01319-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/20/2021] [Accepted: 08/25/2021] [Indexed: 11/27/2022]
Abstract
With approximately 83,000 species described, Curculionidae is the largest family of beetles, comprising more than 80% of all weevil species worldwide. Many species of Curculionidae attack a wide range of native and orchards crops, as well as globally important stored products such as grains, flour, and seeds, being responsible for significant environmental and economic losses. This work provides an overview of the research in the identification of aggregation pheromones of Curculionidae, and their potential contributions to the development of semiochemical-based pest management strategies. The synergistic effect of the host plant volatiles in the attractiveness of weevil pheromones is also briefly reported, demonstrating the important role of these additional attractants in the chemical communication of curculionids.
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Affiliation(s)
- Pamela Taisline Bandeira
- Laboratório de Semioquímicos, Departamento de Química, Universidade Federal do Paraná, UFPR, Caixa Postal 19020, Curitiba, PR, 81531-990, Brazil
| | - Carla Fernanda Fávaro
- Laboratório de Controle Biológico e Semioquímicos, Universidade Estadual de Santa Cruz, Ilhéus, BA, 45662-900, Brazil
| | - Wittko Francke
- Institute of Organic Chemistry, University of Hamburg, 20146, Hamburg, Germany
| | - Jan Bergmann
- Instituto de Química, Pontificia Universidad Católica de Valparaíso, Avda. Universidad 330, Valparaíso, Chile
| | - Paulo Henrique Gorgatti Zarbin
- Laboratório de Semioquímicos, Departamento de Química, Universidade Federal do Paraná, UFPR, Caixa Postal 19020, Curitiba, PR, 81531-990, Brazil.
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8
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Park KC, McNeill MR, Suckling DM, Unelius CR. Olfactory Receptor Neurons for Plant Volatiles and Pheromone Compounds in the Lucerne Weevil, Sitona discoideus. J Chem Ecol 2020; 46:250-263. [PMID: 32048118 PMCID: PMC7142041 DOI: 10.1007/s10886-020-01160-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/19/2019] [Accepted: 01/31/2020] [Indexed: 11/29/2022]
Abstract
Antennal olfactory receptor neurons (ORNs) for pheromone-related and plant volatile compounds were identified and characterized in the lucerne weevil, Sitona discoideus (Gyllenhal), using the single sensillum recording technique. Our study using five pheromone-related compounds and 42 plant volatile compounds indicates that S. discoideus have highly specialized ORNs for pheromone and plant volatile compounds. Different groups of ORNs present in both males and females of S. discoideus were highly sensitive to 4-methylheptane-3,5-dione (diketone) and four isomers (RR, RS, SR and SS) of 5-hydroxy-4-methylheptan-3-one, respectively. Our results also indicate that male S. discoideus, using the sensory input from antennal ORNs, can distinguish both diketone and the RR-isomer from others, and RS- and SS-isomers from others, although it was unclear if they can distinguish between RS-isomer and SS-isomer, or between diketone and the SR-isomer. It also appeared that female S. discoideus could distinguish between RS-isomer and SS-isomers. The antennae of S. discoideus thus contain sex-specific sets of ORNs for host- and non-host plant volatile compounds. Both sexes of S. discoideus have highly sensitive and selective ORNs for some green-leaf volatiles, such as (Z)-3-hexenol and (E)-2-hexenal. In contrast, male antennae of S. discoideus house three distinct groups of ORNs specialized for myrcene and (E)-β-ocimene, 2-phenylethanol, and phenylacetaldehyde, respectively, whereas female antennae contain three groups of ORNs specialized for (±)-linalool and (±)-α-terpineol, myrcene and (E)-β-ocimene, (±)-1-octen-3-ol, and 3-octanone. Our results suggest that S. discoideus use a multi-component pheromone communication system, and a sex-specific set of ORNs with a narrow range of response spectra for host-plant location.
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Affiliation(s)
- Kye Chung Park
- The New Zealand Institute for Plant and Food Research Limited, Christchurch, 8140, New Zealand
| | - Mark R McNeill
- AgResearch Limited, Private Bag 4749, Christchurch, 8140, New Zealand
| | - David M Suckling
- The New Zealand Institute for Plant and Food Research Limited, Christchurch, 8140, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - C Rikard Unelius
- The New Zealand Institute for Plant and Food Research Limited, Christchurch, 8140, New Zealand. .,Faculty of Health and Life Sciences, Linnaeus University, 391 82, Kalmar, Sweden.
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Identification of Semiochemicals from Cowpea, Vigna unguiculata, for Low-input Management of the Legume Pod Borer, Maruca vitrata. J Chem Ecol 2020; 46:288-298. [PMID: 31953705 PMCID: PMC7142049 DOI: 10.1007/s10886-020-01149-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/02/2020] [Accepted: 01/08/2020] [Indexed: 12/26/2022]
Abstract
Cowpea, Vigna unguiculata L. Walp. (Fabaceae), is one of the most important food legumes grown on the African continent, as it provides an affordable source of dietary protein. Yields of cowpea are significantly reduced through damage by legume pod-borer, Maruca vitrata (Lepidoptera: Crambidae), caterpillars to flowers, tender leaves and pods. Semiochemical-based strategies are considered as environmentally benign and affordable for pest management, particularly on smallholder farms. In this study, we investigated the importance of cowpea flower volatiles as host location cues for egg-laying M. vitrata, and herbivore-induced plant volatiles (HIPVs) as M. vitrata repellents and natural enemy (Apanteles taragamae and Phanerotoma syleptae parasitoid) attractants. In oviposition choice assays, M. vitrata laid more eggs on flowering cowpea plants than non-flowering plants. Coupled gas chromatography-electrophysiology (GC-EAG) analysis using the antennae of female M. vitrata and an extract of flower volatiles collected by dynamic headspace collection revealed the presence of five EAG-active components that were identified by coupled GC-mass spectrometry (GC-MS) analysis as benzaldehyde, benzyl alcohol, acetophenone, a vinylbenzaldehyde isomer and (E)-cinnamaldehyde. A synthetic blend of the identified compounds, prepared using 3-vinylbenzaldehyde, induced M. vitrata to lay as many eggs on non-flowering cowpea as on flowering plants. The moths also preferred laying eggs on intact plants compared to M. vitrata-infested plants. As the emission of EAG-active floral compounds was determined to be lower in the headspace of infested cowpea flowers, the role of HIPVs emitted by M. vitrata-damaged leaves was also investigated. Of the compounds induced by larval damage, (E)-DMNT, indole, n-hexyl acetate, 1-octen-3-ol and linalool were shown by GC-EAG to possess electrophysiological activity. A synthetic blend of the EAG-active compounds, using racemic 1-octen-3-ol and linalool, significantly reduced egg numbers on flowering cowpea. Larval and egg parasitoids, i.e. A. taragamae and Ph. syleptae, respectively, of M. vitrata both preferred the Y-tube olfactometer arm treated with synthetic (E)-DMNT, whereas preference for racemic linalool and (E)-nerolidol was dose-dependent in A. taragamae. Our results provide the platform for the development of future semiochemical-based pest management strategies against M. vitrata on smallholder farms in West Africa.
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