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Scott AM, Johnson NS, Siefkes MJ, Li W. Synergistic behavioral antagonists of a sex pheromone reduce reproduction of invasive sea lamprey. iScience 2023; 26:107744. [PMID: 37810212 PMCID: PMC10550721 DOI: 10.1016/j.isci.2023.107744] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/18/2023] [Accepted: 08/24/2023] [Indexed: 10/10/2023] Open
Abstract
Sex pheromones impart maximal attraction when their components are present at optimal ratios that confer balanced olfactory inputs in potential mates. Altering ratios or adding pheromone analogs to optimal mixtures may disrupt balanced olfactory antagonism and result in reduced attraction, however, tests in natural populations are lacking. We tested this hypothesis in sea lamprey (Petromyzon marinus), a fish whose male sex pheromone attracts females when two critical components, 3-keto petromyzonol sulfate (3kPZS) and petromyzonol sulfate (PZS), are present at certain ratios. Here, we report a pheromone analog, petromyzonol tetrasulfate (3sPZS), reduced female attraction to 3kPZS but not to PZS. 3sPZS mixed with additional PZS synergistically disrupted female attraction to the male pheromone and reduced spawning by 97% in a high-density population. Our results provide evidence of balanced olfactory antagonism in a vertebrate and establish a tactic to disrupt spawning of sea lamprey, a destructive invader of the Laurentian Great Lakes.
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Affiliation(s)
- Anne M. Scott
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA
| | - Nicholas S. Johnson
- U.S. Geological Survey, Great Lakes Science Center, Hammond Bay Biological Station, Millersburg, MI 49759, USA
| | | | - Weiming Li
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA
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Yan TK, Asari A, Salleh SA, Azmi WA. Eugenol and Thymol Derivatives as Antifeedant Agents against Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) Larvae. INSECTS 2021; 12:insects12060551. [PMID: 34199269 PMCID: PMC8231963 DOI: 10.3390/insects12060551] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/31/2021] [Accepted: 06/09/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary Rhynchophorus ferrugineus or the red palm weevil (RPW) is a major invasive insect pest that causes severe problems for palm cultivations and, in turn, for the palm industries worldwide. The current practice for controlling RPW in Malaysia mainly involves the use of synthetic pesticides. However, synthetic pesticides should not be encouraged because they are highly toxic and persistent in the environment and as such, can cause deterioration to the ecosystem and human health. Essential oil (EO) derivatives from eugenol and thymol were tested as potential natural compounds for controlling RPW. We evaluated the effect of eight EO derivatives from eugenol and thymol against the fourth instar larvae of RPW. Feeding contact bioassay was conducted for 14 days with different concentrations of these derivatives, in three replications for each treatment. All the derivatives showed feeding deterrent effects against RPW larvae, particularly 4-allyl-2-methoxy-1-(4-trifluoromethyl-benzyloxy)-benzene and 2-isopropyl-4-methyl-2-((4-nitrobenzyl) oxy) benzene, which demonstrated the most effective antifeedant properties in the eugenol and thymol derivative group. Overall, our findings revealed that both eugenol and thymol derivatives showed similar antifeedant activity against RPW larvae. However, the ether derivatives showed a stronger antifeedant effect than that of esters. Both eugenol and thymol are effective against RPW and have the potential to be investigated further as botanical insecticides for the management of RPW in the future. Abstract Coconut palms in Malaysia are infested by a destructive invasive pest, RPW since 2007, and the pest’s population is difficult to control. At present, RPW control management mainly relies on the use of monocrotophos, which is administered by the trunk injection method. However, this pesticide can negatively impact human health and the ecosystem. Plant EO that can be used as a bio-pesticide is highly recommended as an alternative to monocrotophos because of its target-specific and eco-friendly properties. The antifeedant activity of eight eugenol and thymol derivatives from clove and thyme EOs were tested against the fourth instar larvae of RPW through oral bioassay for 14 days. Relative growth rate (RGR), relative consumption rate (RCR), the efficiency of conversion of ingested food (ECI), and the feeding deterrent index (FDI) were compared and analyzed. All of the derivatives showed antifeedant activity, particularly the eugenol derivative, 4-allyl-2-methoxy-1-(4-trifluoromethyl-benzyloxy)-benzene (FDI = 54.14%) and the thymol derivative, 2-isopropyl-4-methyl-2-((4-nitrobenzyl) oxy) benzene (FDI = 53.88%). Both of them showed promising results on their ability to be the most effective antifeedant agents in each derivative group. There was no significant difference in the effectiveness of the eugenol-based and thymol-based derivatives, but the ether derivative group (FDI = 45.63%) had a significantly stronger effect than the ester derivative group (FDI = 39.71%). This study revealed that the compound in ether form is more effective than the compound in ester form as an antifeedant agent against RPW larvae, regardless of the plant EO that the compound is derived from.
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Affiliation(s)
- Tay Karh Yan
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia; (T.K.Y.); (A.A.)
| | - Asnuzilawati Asari
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia; (T.K.Y.); (A.A.)
| | - Siti Aishah Salleh
- Department of Agriculture, Quarantine and Crop Protection Section, Kuala Terengganu 20050, Terengganu, Malaysia;
| | - Wahizatul Afzan Azmi
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia; (T.K.Y.); (A.A.)
- Institute of Tropical Biodiversity and Sustainable Development, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia
- Correspondence:
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Godoy R, Machuca J, Venthur H, Quiroz A, Mutis A. An Overview of Antennal Esterases in Lepidoptera. Front Physiol 2021; 12:643281. [PMID: 33868009 PMCID: PMC8044547 DOI: 10.3389/fphys.2021.643281] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/15/2021] [Indexed: 12/02/2022] Open
Abstract
Lepidoptera are used as a model for the study of insect olfactory proteins. Among them, odorant degrading enzymes (ODEs), that degrade odorant molecules to maintain the sensitivity of antennae, have received less attention. In particular, antennal esterases (AEs; responsible for ester degradation) are crucial for intraspecific communication in Lepidoptera. Currently, transcriptomic and genomic studies have provided AEs in several species. However, efforts in gene annotation, classification, and functional assignment are still lacking. Therefore, we propose to combine evidence at evolutionary, structural, and functional level to update ODEs as well as key information into an easier classification, particularly of AEs. Finally, the kinetic parameters for putative inhibition of ODEs are discussed in terms of its role in future integrated pest management (IPM) strategies.
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Affiliation(s)
- Ricardo Godoy
- Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Temuco, Chile
- Centro de Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Temuco, Chile
| | - Juan Machuca
- Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Temuco, Chile
- Centro de Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Temuco, Chile
| | - Herbert Venthur
- Centro de Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Temuco, Chile
| | - Andrés Quiroz
- Centro de Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Temuco, Chile
| | - Ana Mutis
- Centro de Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Temuco, Chile
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Huang J, Tian S, Ren K, Chen Y, Lin S, Chen Y, Tian H, Zhao J, Wang C, Wei H, Gu X. Effect of Treatment With 3-Octylthio-1,1,1-Trifluoropropan-2-One in the Diamondback Moth (Lepidoptera: Plutellidae) to the Toxicity of Diafenthiuron, Indoxacarb, and Bacillus thuringiensis. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:1419-1425. [PMID: 32173761 DOI: 10.1093/jee/toaa041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Indexed: 06/10/2023]
Abstract
The diamondback moth, Plutella xylostella (L.), is a worldwide insect pest of cruciferous crops. Although insecticides have long been used for its control, diamondback moth rapidly evolves resistance to almost any insecticide. In insects, juvenile hormone (JH) is critically involved in almost all biological processes. The correct activity of JH depends on the precise regulation of its titer, and juvenile hormone esterase (JHE) is the key regulator. Thus, JH and JHE have become important targets for new insecticide development. Trifluoromethyl ketones are specific JHE inhibitors, among which 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP) has the highest activity. The interaction effects between pretreatment with or combination of OTFP and the insecticides diafenthiuron, indoxacarb, and Bacillus thuringiensis (Bt) were investigated in diamondback moth larvae to determine OTFP's potential as an insecticide synergist. In third-instar larvae, both pretreatment and combination treatment with OTFP decreased or antagonized the toxicities of diafenthiuron, indoxacarb, and Bt at all set concentrations. In fourth-instar larvae, combination treatment with OTFP decreased or antagonized the toxicities of diafenthiuron and indoxacarb at all set concentrations. However, it increased or synergized the toxicity of Bt at lower concentrations despite the limited effect at higher concentrations. Our results indicated that the effect of OTFP on the toxicities of insecticides varied with the type and concentration, larval stage, and treatment method. These findings contribute to the better use of OTFP in diamondback moth control.
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Affiliation(s)
- Jingfei Huang
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Sufen Tian
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Ke Ren
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yong Chen
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Shuo Lin
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Yixin Chen
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Houjun Tian
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Jianwei Zhao
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Changfang Wang
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Hui Wei
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, China
- Fujian Key Laboratory for Monitoring and Integrated Management of Crop Pests, Fuzhou, China
| | - Xiaojun Gu
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
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A pheromone antagonist liberates female sea lamprey from a sensory trap to enable reliable communication. Proc Natl Acad Sci U S A 2020; 117:7284-7289. [PMID: 32184327 PMCID: PMC7132252 DOI: 10.1073/pnas.1921394117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many animals, males deceive females into mating using traits that mimic cues of food, predators, preferred habitats, or offspring in need of care. However, if and how these deceptive signals guide reliable communication without females confusing the mimic and the model remain unclear. We discovered that female sea lamprey discriminate a nonsexual cue of productive habitat from the deceptive male sex pheromone that mimics it and identify a pheromone antagonist as the underlying mechanism. Our results implicate a means by which females can detect and benefit from male deceit and could have applications for control of destructive populations of sea lamprey in the Laurentian Great Lakes. The evolution of male signals and female preferences remains a central question in the study of animal communication. The sensory trap model suggests males evolve signals that mimic cues used in nonsexual contexts and thus manipulate female behavior to generate mating opportunities. Much evidence supports the sensory trap model, but how females glean reliable information from both mimetic signals and their model cues remains unknown. We discovered a mechanism whereby a manipulative male signal guides reliable communication in sea lamprey (Petromyzon marinus). Migratory sea lamprey follow a larval cue into spawning streams; once sexually mature, males release a pheromone that mimics the larval cue and attracts females. Females conceivably benefit from the mimetic pheromone during mate search but must discriminate against the model cue to avoid orienting toward larvae in nearby nursery habitats. We tested the hypothesis that spawning females respond to petromyzonol sulfate (PZS) as a behavioral antagonist to avoid attraction to the larval cue while tracking the male pheromone despite each containing attractive 3-keto petromyzonol sulfate (3kPZS). We found 1) PZS inhibited electrophysiological responses to 3kPZS and abated preferences for 3kPZS when mixed at the same or greater concentrations, 2) larvae released more PZS than 3kPZS whereas males released more 3kPZS than PZS, and 3) mixtures of 3kPZS and PZS applied at ratios measured in larval and male odorants resulted in the discrimination observed between the natural odors. Our study elucidates how communication systems that arise via deception can facilitate reliable communication.
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Dominguez A, Puigmartı́ M, Bosch MP, Rosell G, Crehuet R, Ortiz A, Quero C, Guerrero A. Synthesis, Functional Assays, Electrophysiological Activity, and Field Tests of Pheromone Antagonists of the Tomato Leafminer, Tuta absoluta. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:3523-3532. [PMID: 27088783 DOI: 10.1021/acs.jafc.6b00674] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The tomato leafminer, Tuta absoluta, is one of the major pests of tomato and other Solanaceae in many regions worldwide. In the search for new strategies to control this pest, we present herewith the stereoselective synthesis, electrophysiological activity, functional analysis, and field tests of new chemicals as possible antagonists of the sex pheromone of the leafminer. The chemicals are methyl ketone (MK) and trifluoromethyl ketone (TFMK) structural analogues of both components of the pheromone. Most of the chemicals exerted per se some electrophysiological activity and inhibited the electroantennographic response to the pheromone when vapors of the inhibitor were passed over the antennae. Except TFMK 3, which elicited a modest effect, the compounds did not exhibit antiesterase activity on the pheromone-degrading enzymes of the antennae, but in the field the chemicals, particularly MK 5, notably decreased the number of catches when mixed with the pheromone in 1:1 and 10:1 ratios, regardless the infestation level of the plot. These results suggest that MK 5 is a good behavioral antagonist of the pheromone to be considered as a putative agent to control the pest in new future integrated pest management (IPM) strategies.
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Affiliation(s)
- Aroa Dominguez
- Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (CSIC) , Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Marc Puigmartı́
- Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (CSIC) , Jordi Girona 18-26, 08034 Barcelona, Spain
| | - M Pilar Bosch
- Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (CSIC) , Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Gloria Rosell
- Department of Pharmacology and Therapeutic Chemistry, Unit Associated to CSIC, Faculty of Pharmacy, University of Barcelona , Avinguda Diagonal s/n, 08028 Barcelona, Spain
| | - Ramon Crehuet
- Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (CSIC) , Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Antonio Ortiz
- Department of Inorganic and Organic Chemistry, EPSL, University of Jaén , Linares (Jaén), Spain
| | - Carmen Quero
- Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (CSIC) , Jordi Girona 18-26, 08034 Barcelona, Spain
| | - Angel Guerrero
- Department of Biological Chemistry and Molecular Modelling, Institute of Advanced Chemistry of Catalonia (CSIC) , Jordi Girona 18-26, 08034 Barcelona, Spain
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Sans A, Gago R, Mingot A, García W, Bosch D, Coll J, Rosell G, Bosch MP, Riba M, Guerrero A. Electrophilic derivatives antagonise pheromone attraction in Cydia pomonella. PEST MANAGEMENT SCIENCE 2013; 69:1280-1290. [PMID: 23554261 DOI: 10.1002/ps.3500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 11/19/2012] [Accepted: 01/29/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Pheromone antagonists are good disruptants of the pheromone communication in insects and, as such, have been used in mating disruption experiments. In this study, new non-fluorinated electrophilic keto derivatives structurally related to the pheromone of Cydia pomonella (codlemone) have been synthesised and tested as putative pheromone antagonists. RESULTS Codlemone (1) was prepared in excellent stereoselectivity in a new, iterative approach involving two Horner-Wadsworth-Emmons reactions. Methyl ketone (2), keto ester (3) and diketone (4) were obtained from codlemone in straightforward approaches in good overall yields and excellent stereochemical purity (≥98% E,E). In electrophysiology, only compound 2 displayed inhibition of the antennal response to the pheromone after presaturation of the antennal receptors. Compounds 2 to 4 did not inhibit the pheromone-degrading enzyme responsible for codlemone metabolism, but mixtures of ketone 2 and diketone 4 with codlemone elicited erratic flights on males in a wind tunnel. In the field, blends of either compound (2 or 4) with the pheromone caught significantly fewer males than codlemone alone. CONCLUSION Codlemone and the potential antagonists 2 to 4 have been synthesised in good yields and excellent stereoselectivity. These chemicals behave as pheromone antagonists of the codling moth both in the laboratory and in the field.
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Affiliation(s)
- Albert Sans
- University of Lleida, Centre UdL-IRTA, Lleida, Spain
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Malo EA, Rojas JC, Gago R, Guerrero Á. Inhibition of the responses to sex pheromone of the fall armyworm, Spodoptera frugiperda. JOURNAL OF INSECT SCIENCE (ONLINE) 2013; 13:134. [PMID: 24766416 PMCID: PMC4014043 DOI: 10.1673/031.013.13401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Trifluoromethyl ketones reversibly inhibit pheromone-degrading esterases in insect olfactory tissues, affecting pheromone detection and behavior of moth males. In this work, (Z)-9-tetradecenyl trifluoromethyl ketone (Z9-14:TFMK), a closely-related analogue of the pheromone of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), was prepared and tested in electroantennogram and field tests as possible inhibitors of the pheromone action. The electroantennogram parameters, amplitude, and the repolarization time of the antennal responses of S. frugiperda males were affected by Z9-14:TFMK vapors. Exposure of male antennae to a stream of air passing through 100 μg of the ketone produced a significant reduction of the amplitude and an increase of 2/3 repolarization time signals to the pheromone. The effect was reversible and dose-dependent. In the field, the analogue significantly decreased the number of males caught when mixed with the pheromone in 10:1 ratio. The results suggest that Z9-14:TFMK is a mating disruptant of S. frugiperda and may be a good candidate to consider in future strategies to control this pest.
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Affiliation(s)
- Edi A Malo
- 1 Departamento de Entomología Tropical, El Colegio de la Frontera Sur (ECOSUR), Carretera Antiguo Aeropuerto Km 2.5, C.P. 30700, Tapachula, Chiapas, México
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Muñoz L, Bosch MP, Batllori L, Rosell G, Bosch D, Guerrero A, Avilla J. Synthesis of allylic trifluoromethyl ketones and their activity as inhibitors of the sex pheromone of the leopard moth, Zeuzera pyrina L. (Lepidoptera: Cossidae). PEST MANAGEMENT SCIENCE 2011; 67:956-964. [PMID: 21394886 DOI: 10.1002/ps.2139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 11/18/2010] [Accepted: 11/23/2010] [Indexed: 05/30/2023]
Abstract
BACKGROUND Trifluoromethyl ketones (TFMKs), structurally related to the pheromones, are good inhibitors of pheromone communication in insects. To determine their activity on Zeuzera pyrina L. (Lepidoptera: Cossidae), a polyphagous pest, the authors have prepared two diunsaturated TFMK analogues of the major (3) and the minor (4) pheromone components, and two monounsaturated ones (5, 6). Their biological activity in electroantennogram (EAG), wind tunnel and field tests is presented. RESULTS The synthetic strategy to obtain the allylic TFMKs 3 and 5 is based on the reactions of diene 10 and 1-octadecene with trifluoroacetaldehyde ethyl hemiacetal, followed by Dess-Martin oxidation of the resulting homoallylic trifluoromethyl alcohols. In EAG, topical application of analogues 3 and 4 on male antennae significantly reduced the pheromone response. In the wind tunnel, compound 4 reduced the number of contacts with the pheromone source. In the field, traps baited with mixtures of pheromone and inhibitors captured significantly fewer males than the pheromone alone. CONCLUSION An efficient synthesis of allylic TFMKs is reported, with good overall yield, regiospecificity and diastereoselectivity. These compounds are good inhibitors of the pheromone in electrophysiology, wind tunnel and field tests. The results show the importance of two unsaturations at positions 2 and 13 of the trifluoroacyl group in the structure of the analogues, the latter being critical for inhibitory activity.
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Affiliation(s)
- Lourdes Muñoz
- Departament de Quimica Biològica i Modelització Molecular (IQAC-CSIC), Barcelona, Spain
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Plettner E, Gries R. Agonists and antagonists of antennal responses of gypsy moth (Lymantria dispar) to the pheromone (+)-disparlure and other odorants. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:3708-3719. [PMID: 20192223 DOI: 10.1021/jf904139e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Insects use the sense of smell to guide many behaviors that are important for their survival. The gypsy moth uses a pheromone to bring females and males together over long distances. Male moth antennae are equipped with innervated sensory hairs that selectively respond to pheromone components and other odors. Host plant odors, in particular, are detected by moths and sometimes cause an enhancement of the antennal and behavioral responses of the moths to their pheromone. Inspired by naturally occurring agonists and antagonists of insect pheromone responses, we have screened, by electroantennogram (EAG) recordings, a collection of compound sets and of individual compounds. We have detected interference of some compounds with the EAG responses of male gypsy moth antennae to the pheromone. We describe three activities: (1) short-term inhibition or enhancement of mixed compound + pheromone plumes, (2) long-term inhibition of pure pheromone plumes following a mixed compound + pheromone plume, and (3) inhibition of the recovery phase of mixed compound + pheromone plumes. Long-term inhibition was robust, decayed within 30 s, and correlated with the inhibition of recovery; for both activities clear structure-activity patterns were detected. The commercial repellent N,N-diethyltoluamide (DEET) was included for comparison. The most active and reproducible short-term inhibitor was a mixture of 1-allyl-2,4-dimethoxybenzene and 2-allyl-1,3-dimethoxybenzene. The most active long-term inhibitors were a set of 1-alkoxy-4-propoxybenzenes, DEET, and 1-ethoxy-4-propoxybenzene. DEET was more specific in the olfactory responses it inhibited than 1-ethoxy-4-propoxybenzene, and DEET did not inhibit recovery, whereas 1-ethoxy-4-propoxybenzene did. Target sites for the three activities are discussed.
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Affiliation(s)
- Erika Plettner
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
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Rosa E, Guerrero A, Bosch MP, Julià L. EPR/spin-trapping study of free radical intermediates in the photolysis of trifluoromethyl ketones with initiators. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2010; 48:198-204. [PMID: 20058258 DOI: 10.1002/mrc.2566] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Photolysis of trifluoromethyl ketones (TFMKs) 1a-1e versus the non-fluorinated ketones 2a-2b in the presence of radical initiators by electron paramagnetic resonance spectroscopy has been studied for the first time. The transient radicals generated after irradiation of the ketones were identified by trapping with 2-methyl-2-nitrosopropane (MNP) and 2,4,6-tri-tert-butylnitrosobenzene (TTBNB) as spin traps. TTBNB is a powerful, particularly useful spin trap in these kinds of processes producing anilino and nitroxyl spin adducts due to the ambivalent reactivity on the N and O atoms. In the presence of t-butylperoxide, short-chain TFMKs, such as 1,1,1-trifluoroacetone (1d) and hexafluoroacetone (1e), give rise to detection of the elusive trifluoromethyl radical. In contrast, long-chain TFMKs did not provide clues to prove formation of the trifluoromethyl radical but instead to radicals derived by abstraction of one alpha-methylene proton to the carbonyl. Although TFMKs are quite stable to photodegradation in the absence of initiator, methyl ketone 2b and phenyl ketone 3 produce radicals resulting from abstraction of a gamma-hydrogen to the carbonyl group.
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Affiliation(s)
- Esmeralda Rosa
- Department of Biological Chemistry and Molecular Modellization, IQAC (CSIC), Jordi Girona, 18-26, 08034 Barcelona, Spain
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Abstract
A survey of the new environmentally safe strategies used for insect control is presented. The survey includes mating disruption, pheromone antagonists as chemical communication inhibitors, pheromones and plant-based volatiles, attractant-and-kill, and push-pull strategies. Important successes have been obtained, particularly in mating disruption with significant reduction in pesticide use in low to moderate pest infestations. One important factor of concern is the high cost of semiochemicals and formulations containing them in comparison to the conventional insecticide treatments, and a combined effort by scientists, producers, and farmers should be made to reduce the cost of application of these semiochemicals.
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Jiang QY, Wang WX, Zhang Z, Zhang L. Binding specificity of locust odorant binding protein and its key binding site for initial recognition of alcohols. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2009; 39:440-447. [PMID: 19376226 DOI: 10.1016/j.ibmb.2009.04.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Accepted: 04/07/2009] [Indexed: 05/27/2023]
Abstract
Odorant binding proteins (OBPs) are required for olfaction perception, and thus may be possible targets for controlling the population of pests by interfering with their chemical communication. A single OBP LmigOBP1 has been identified in the antennae of Locusta migratoria, though four isoforms have been detected. Here, we have investigated the ligand-binding specificity of LmigOBP1 using 67 volatile odor compounds. Fluorescence assays indicate that LmigOBP1 does not bind fecal volatiles or green leaf odors, but shows high affinity for some linear aliphatic compounds, with pentadecanol and 2-pentadecanone being the strongest binding ligands. A 3-dimensional (3D) model of LmigOBP1 was built by homology modeling. Docking simulations based on this model suggested that Asn74 of LmigOBP1 is a key binding site, and this was validated by site-directed mutagenesis and fluorescence assays. We suggest that, as a general rule, a hydrophilic amino acid at the entrance of the binding cavity participates in initial recognition of ligands, and contributes to ligand-binding specificity of OBPs.
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Affiliation(s)
- Quan-Yong Jiang
- Key Lab for Biological Control of the Ministry of Agriculture, China Agricultural University, Beijing 100193, China
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Acín P, Carrascal M, Abián J, Guerrero A, Quero C. Expression of differential antennal proteins in males and females of an important crop pest, Sesamia nonagrioides. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2009; 39:11-19. [PMID: 18977441 DOI: 10.1016/j.ibmb.2008.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 08/11/2008] [Accepted: 09/06/2008] [Indexed: 05/27/2023]
Abstract
Pest damage causes important decrease in crop yield every year all over the world, particularly by Lepidoptera. Characterization of the antennal proteins implicated in the reproduction of Lepidoptera will help to develop new methods for pest management and contribute to sustainable agriculture and biodiversity maintenance. We present herein the characterization of some antennal proteins of Sesamia nonagrioides by proteomic techniques such as two-dimensional electrophoresis, MALDI-TOF MS, and electrospray ionization tandem mass spectrometry (ESI-MS/MS). The antennal proteins expressed in both sexes were analyzed and more than 800 spots were detected, finding 16 proteins differentially expressed between males and females. Most of the identified proteins were involved in olfaction. High levels of pheromone binding proteins (PBP1 and PBP2) were found as expected in males, but also in female antennae, although females did not electrophysiologically respond to their own pheromone. General odorant binding proteins (GOBP1 and GOBP2) were preferentially expressed in females but high levels were also detected in males. The expression was remarkably high in both sexes along the complete photoperiod. A sensitive proteomic methodology was developed to identify antennal proteins.
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Affiliation(s)
- Patricia Acín
- Department of Biological Organic Chemistry, IIQAB-CSIC, Jordi Girona 18-26, Barcelona, Spain
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15
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Chamorro ER, Sequeira AF, Zalazar MF, Peruchena NM. Theoretical analysis of the electronic properties of the sex pheromone and its analogue derivatives in the female processionary moth Thaumetopoea pytiocampa. Bioorg Med Chem 2008; 16:8535-45. [DOI: 10.1016/j.bmc.2008.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 07/28/2008] [Accepted: 08/04/2008] [Indexed: 11/28/2022]
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Rosa E, Barata C, Damásio J, Bosch MP, Guerrero A. Aquatic ecotoxicity of a pheromonal antagonist in Daphnia magna and Desmodesmus subspicatus. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2006; 79:296-303. [PMID: 16899308 DOI: 10.1016/j.aquatox.2006.06.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Revised: 06/23/2006] [Accepted: 06/24/2006] [Indexed: 05/11/2023]
Abstract
Evaluation of the ecotoxicological potential of (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK), a new biorational agent with high prospective features to control the Mediterranean corn borer Sesamia nonagrioides in infested maize fields, in comparison to the parent pheromone compound (Z)-11-hexadecenyl acetate (Z11-16:Ac) is described. Acute and sublethal toxicity tests of both compounds against the cladoceran Daphnia magna and the chlorophyte Desmodesmus subspicatus were conducted, the endpoints being immobilisation and feeding inhibition for Daphnia and growth rate inhibition for Desmodesmus. In addition, effects on B esterases including cholinesterase and carboxylesterase activities in Daphnia were also assessed to evaluate the mode of action of both chemicals. Toxicities of both compounds were moderate with EC(50) values ranging from 3.11 to 103.74mgl(-1) in algae growth, from 0.07 to 1.20mgl(-1) in Daphnia survival, and from 0.10 to 0.53mgl(-1) in Daphnia feeding rate. In all cases Z11-16:TFMK was more toxic than the naturally occurring pheromone component. Serine esterase assays showed a strong inhibition of the carboxylesterase activities in Daphnia at concentrations with apparently no effects on survival or feeding, suggesting that inhibition of other key esterases may be the possible mechanism of toxicity of this compound. The results obtained have been related with some physico-chemical properties of the compounds, such as water solubility and octanol-water partition coefficient, suggesting that Z11-16:TFMK may affect aquatic organisms at lower concentrations than expected from non-polar narcosis.
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Affiliation(s)
- Esmeralda Rosa
- Department of Biological Organic Chemistry, IIQAB (CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain
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17
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Jiménez O, Bosch MP, Guerrero A. A new, mild, and efficient synthesis of 2,2-difluoro-3-hydroxyacids through a selective haloform reaction. J Org Chem 2006; 70:10883-5. [PMID: 16356015 DOI: 10.1021/jo0518856] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Long-chain 2,2-difluoro-3-hydroxyacids have been synthesized in a new, straightforward manner by treatment of 4-hydroxy-1,1,1,3,3-pentafluoroalkyl ketones, easily obtained by reaction of pentafluoroenolate 2 with aldehydes and ketones, with base under mild conditions. The reaction sequence is marked by the selective cleavage of the CO-CF3 bond, as well as the absence of products arising from the alternative CO-CF2R bond cleavage. The process represents a convenient approach for the synthesis of 2,2-difluoro-3-hydroxyacids, as it is short, provides good to excellent yields under mild conditions, and uses hexafluoro-2-propanol, a very cheap reagent, as the fluorine source.
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Affiliation(s)
- O Jiménez
- Barcelona Science Parc, University of Barcelona, Josep Samitier 1-5, 08028-Barcelona, Spain
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18
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Abstract
We have isolated, cloned, and expressed a male antennae-specific pheromone-degrading enzyme (PDE) [Antheraea polyphemus PDE (ApolPDE), formerly known as Sensillar Esterase] from the wild silkmoth, A. polyphemus, which seems essential for the rapid inactivation of pheromone during flight. The onset of enzymatic activity was detected at day 13 of the pupal stage with a peak at day 2 adult stage. De novo sequencing of ApolPDE, isolated from day 2 male antennae by multiple chromatographic steps, led to cDNA cloning. Purified recombinant ApolPDE, expressed by baculovirus, migrated with the same mobility as the native protein on both native polyacrylamide and isoelectric focusing gel electrophoresis. Concentration of ApolPDE (0.5 microM) in the sensillar lymph is approximately 20,000 lower than that of a pheromone-binding protein. Native and recombinant ApolPDE showed comparable kinetic parameters, with turnover number similar to that of carboxypeptidase and substrate specificity slightly lower than that of acetylcholinesterase. The rapid inactivation of pheromone, even faster than previously estimated, is kinetically compatible with the temporal resolution required for sustained odorant-mediated flight in moths.
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Affiliation(s)
- Yuko Ishida
- Maeda-Duffey Laboratory, Department of Entomology, University of California, Davis, CA 95616, USA
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Muñoz L, Rosa E, Bosch MP, Guerrero A. A new, practical and efficient sulfone-mediated synthesis of trifluoromethyl ketones from alkyl and alkenyl bromides. Tetrahedron Lett 2005. [DOI: 10.1016/j.tetlet.2005.03.106] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Olivella S, Solé A, Jiménez O, Bosch MP, Guerrero A. New Selective Haloform-type Reaction Yielding 3-Hydroxy-2,2-difluoroacids: Theoretical Study of the Mechanism. J Am Chem Soc 2005; 127:2620-7. [PMID: 15725018 DOI: 10.1021/ja043522d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Experimental results of an unprecedented haloform-type reaction in which 4-alkyl-4-hydroxy-3,3-difluoromethyl trifluoromethyl ketones undergo base-promoted selective cleavage of the CO-CF(3) bond, yielding 3-hydroxy-2,2-difluoroacids and fluoroform, are rationalized using DFT (B3LYP) calculations. The gas-phase addition of hydroxide ion to 1,1,1,3,3-pentafluoro-4-hydroxypentan-2-one (R) is found to be a barrierless process, yielding a tetrahedral intermediate (INT), involving a DeltaG(r)(298 K) of -61.4 kcal/mol. The CO-CF(3) bond cleavage in INT leads to a hydrogen-bonded [CH(3)CHOHCF(2)CO(2)H...CF(3)](-) complex by passage through a transition structure (TS1) with a DeltaG()(298 K) of 20.8 kcal/mol and a DeltaG(r)(298 K) of 9.8 kcal/mol. This complex undergoes a proton transfer between its components, yielding a hydrogen-bonded [CH(3)CHOHCF(2)CO(2)...CHF(3)](-) complex. This process has associated with it a DeltaG()(298 K) of only 3.1 kcal/mol and a DeltaG(r)(298 K) of -43.3 kcal/mol. The CO-CF(2) bond cleavage in INT leads to a hydrogen-bonded [CH(3)CHOHCF(2)...CF(3)CO(2)H](-) complex by passage through a transition structure (TS3) with a DeltaG()(298 K) of 29.2 kcal/mol and a DeltaG(r)(298 K) of 25.1 kcal/mol. The lower energy barrier found for CO-CF(3) bond cleavage in INT is ascribed to the larger number of fluorine atoms stabilizing the negative charge accumulated on the CF(3) moiety of TS1, as compared to the number of fluorine atoms stabilizing the negative charge on the CH(3)CHOHCF(2) moiety of TS3. The solvent-induced effects on the two pathways, introduced within the SCRF formalism through PCM calculations, do not reverse the predicted preference of the CO-CF(3) over the CO-CF(2) bond cleavage of R in the gas phase.
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Affiliation(s)
- Santiago Olivella
- Departament de Química Orgànica Biologica, Institut d'Investigacions Químiques i Ambientals de Barcelona, CSIC, Jordi Girona 18, 08034-Barcelona, Catalonia, Spain.
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Pesenti C, Viani F. The Influence of Fluorinated Molecules (Semiochemicals and Enzyme Substrate Analogues) on the Insect Communication System. Chembiochem 2004; 5:590-613. [PMID: 15122631 DOI: 10.1002/cbic.200300829] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Can the introduction of fluorine atoms affect the bioactivity of natural semiochemicals? Can fluorine contribute in the creation of specific enzyme inhibitors to interrupt or disrupt the insect communication system? The first step for the bioactivity of a molecule is interaction with the biological sensor. Hydrogen and fluorine are almost bioisosteric and the receptor site of the enzyme can still recognize and accept the fluoro analogue of its natural substrate. However, the peculiar electronegativity of the fluorine atom can affect the binding, absorption, and transport of the molecule. The differences in the molecule's electronic properties can lead to differences in the chemical interactions between the receptor and the fluorinated substrate. Fluorine introduction can modify the metabolic stability and pathway of the semiochemicals in many different ways. Fluorinated analogues can show synergism, inhibition, or hyperagonism effects on insect behaviors, that is, the activity of the nonfluorinated parent compounds can be mimicked, lost, or increased. In any case, the fluorinated molecules can interact with the bioreceptors in a new and disrupting way. The semiochemicals are olfactory substances: fluorine can affect their volatility or smell. Production of semiochemicals from exogenous substances, perception at antennal receptors, and processing of biological responses are the main steps of communication among insects. In the production step, the fluorinated molecules can interact with enzymes that catalyze the biosynthesis of the natural pheromones. In the perception step, fluorinated semiochemicals can interact with the olfactory receptor cells; this often leads to totally unpredictable behaviors. Fluorinated molecules have been developed as probes to elucidate the complex chemorecognition processes of insects. Many of these molecules have been tested to find highly effective behavior-modifying chemicals. New analogues have been synthesized to investigate the metabolic pathway of a pheromone molecule and many of them are promising disrupting agents. Despite such titanic research efforts, the results have often been random, rational trends in the induced behaviors have sometimes been impossible to find, and practical applications of the fluorinated semiochemicals are still uncertain.
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Affiliation(s)
- Cristina Pesenti
- Istituto di Chimica per il Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mancinelli 7, 20131 Milano, Italy
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Quero C, Rosell G, Jiménez O, Rodriguez S, Bosch MP, Guerrero A. New fluorinated derivatives as esterase inhibitors. Synthesis, hydration and crossed specificity studies. Bioorg Med Chem 2003; 11:1047-55. [PMID: 12614892 DOI: 10.1016/s0968-0896(02)00467-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A variety of new fluorinated chemicals have been prepared for the first time and tested as inhibitors of esterases, one of the main enzymes involved in pheromone catabolism, in two economically important pests, the Egyptian armyworm Spodoptera littoralis (SL) and the Mediterranean corn borer Sesamia nonagrioides (SN). Using the respective major component of the pheromone as substrate, the K(m) and V(max) of the antennal esterase of both insects resulted to be 5.66 x 10(-4) M and 8.47 x 10(-6) Mmin(-1) for SL and 1.61 x 10(-7) M and 1.25 x 10(-7) Mmin(-1) for SN, pointing out that SN esterase has a higher affinity for its corresponding substrate than SL. In general, the trifluoromethyl ketones (TFMKs) exhibited higher inhibitory potency than the corresponding difluoromethyl ketones (DFMKs) or difluoroaldehydes (DFAs). The compounds appeared to hydrate differently in aqueous solution, the extent of hydration following the order: alpha,alpha-DFMKs<alpha,alpha-difluoro-beta-thioalkylmethyl ketones<TFMKs<beta-thiotrifluoromethyl ketones<alpha,alpha-DFAs. No clear correlation has been found between the K(hyd) and the inhibitory potency and no specificity has been found when the chemicals were assayed on extracts of both insects.
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Affiliation(s)
- Carmen Quero
- Department of Biological Organic Chemistry, Institute of Chemistry and Environmental Research (CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain
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23
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Renou M, Berthier A, Guerrero A. Disruption of responses to pheromone by (Z)-11-hexadecenyl trifluoromethyl ketone, an analogue of the pheromone, in the cabbage armyworm Mamestra brassicae. PEST MANAGEMENT SCIENCE 2002; 58:839-844. [PMID: 12192910 DOI: 10.1002/ps.534] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The effects of (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK) a fluorinated pheromone analogue, on the responses to sex pheromone of the male cabbage armyworm, Mamestra brassicae, have been investigated in an actograph and by electroantennography (EAG). In spite of its structural proximity with the natural pheromone, Z11-16:TFMK was poorly active in EAG, and not active on male behaviour. When permeated in the air, Z11-16:TFMK reversibly inhibited the electroantennographic responses to (Z)-11-hexadecenyl acetate (Z11-16:Ac), the main component of the sex pheromone. In the actograph, the latency of the activation was increased and the intensity of the behavioural activity of males in response to Z11-16:Ac was significantly reduced in the presence of Z11-16:TFMK. These results, along with others previously reported by us, provide new pointers to the possible use of Z11-16:TFMK in pest-control strategies.
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Affiliation(s)
- Michel Renou
- INRA UR258, Phytopharmacie et Médiateurs Chimiques, Route de Saint Cyr, 78026 Versailles, France.
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24
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Riba M, Sans A, Bau P, Grolleau G, Renou M, Guerrero A. Pheromone response inhibitors of the corn stalk borer Sesamia nonagrioides. Biological evaluation and toxicology. J Chem Ecol 2001; 27:1879-97. [PMID: 11545377 DOI: 10.1023/a:1010468911352] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The behavioral activity of some trifluoromethyl ketones (TFMKs) as inhibitors of the pheromone activity of the corn stalk borer Sesamia nonagrioides (Lef.) (Lepidoptera: Noctuidae) is reported. The most closely-related analogue to the pheromone tested, (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK), elicited a significant decrease in the number of male catches in traps baited with mixtures with the pheromone in 1:1 and 10:1 ratios in comparison to the pheromone alone. The E isomer of the analogue as well as two highly hydrated ketones, 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP) and 1,1-difluoropentadecyl trifluoromethyl ketone, were inactive. Conversely, the saturated TFMKs n-dodecyl trifluoromethyl ketone and, particularly, n-hexadecyl trifluoromethyl ketone induced a synergistic effect when mixed with the synthetic pheromone in 10:1 ratio. However, in a wind tunnel these chemicals did not elicit any differential effect on flying moths attracted to a source containing a 10:1 blend of the analogue and the pheromone. In a dual choice bioassay with two dispensers, containing the pheromone alone, and mixtures of Z11-16:TFMK and the pheromone and separated 5 cm apart, males showed no particular preference for either dispenser. The ketone mixture, however, induced moths to execute erratic flights with frequent crosswind counter-turns and intersections with plume boundaries. The total number of contacts with the source were reduced when a control dispenser was paired with a dispenser containing Z11-16:TFMK and pheromone. Z11-16:TFMK and OTFP showed little toxicity on mice with a LD50 of 1 g/kg after the 6th day of treatment. For comparitive purposes, the major component of the pheromone, Z11-16:Ac, displayed a LD50 of 5 g/kg 6 days after application. Our results provide additional information about the activity of the TFMKs, which might be useful for the utilization of these chemicals in future pest control studies.
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Affiliation(s)
- M Riba
- Escola Tecnica Superior Enginyeria Agrària, UdL-IRTA, Lleida, Spain.
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