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Guy Smagghe - One of the best experts on this subject based on the ideXlab platform.
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Cloning and functional analysis of the ecdysteroid receptor complex in the opossum shrimp Neomysis integer (Leach, 1814).
Aquatic Toxicology, 2013Co-Authors: R. De Wilde, Thomas Soin, Luc Swevers, Pierre Rouge, K Cooreman, Olivier Christiaens, Colin R. Janssen, Guy SmaggheAbstract:a b s t r a c t In this paper, the non-target effects of Tebufenozide were evaluated on the estuarine crustacean, the opposum shrimp Neomysis integer (Leach, 1814). Tebufenozide is a synthetic non-steroidal ecdysone agonist insecticide and regarded as potential endocrine-disrupting chemical (EDC). N. integer is the most used crustacean in ecotoxicological research in parallel to Daphnia sp. and has been proposed for the regulatory testing of potential EDCs in the US, Europe and Japan. Major results were: (i) cDNAs encoding the ecdysteroid receptor (EcR) and the retinoid-X-receptor (RXR), were cloned and sequenced, and subsequent molecular phylogenetic analysis (maximum likeli- hood and neighbor-joining) revealed that the amino acid sequence of the ligand binding domain (LBD) of N. integer EcR (NiEcR) clusters as an outgroup of the Crustacea, while NiRXR-LBD clusters in the Malacos- tracan clade (bootstrap percentage = 75%). (ii) 3D-modeling of ligand binding to NiEcR-LBD demonstrated an incompatibility of the insecticide Tebufenozide to fit into the NiEcR-ligand binding pocket. This was in great contrast to ponasterone A (PonA) that is the natural molting hormone in Crustacea and for which efficient docking was demonstrated. In addition, the heterodimerization of NiEcR-LBD with the com- mon shrimp Crangon crangon (Linnaeus, 1758) RXR-LBD (CrcRXR-LBD) was also modeled in silico. (iii) With use of insect Hi5 cells, chimeric constructs of NiEcR-LBD and CrcRXR-LBD fused to either the yeast Gal4-DNA binding domain (DBD) or Gal4-activation domain (AD) were cloned into expression plasmids and co-transfected with a Gal4 reporter to quantify the protein-protein interactions of NiEcR-LBD with CrcRXR-LBD. Investigation of the ligand effect of PonA and Tebufenozide revealed that only the presence of PonA could induce dimerization of this heterologous receptor complex. (iv) Finally, in an in vivo toxicity assay, N. integer juveniles were exposed to Tebufenozide at a concentration of 100 g/L, and no effects against the molting process and nymphal development were scored.
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insect growth regulators as potential insecticides to control olive fruit fly bactrocera oleae rossi insect toxicity bioassays and molecular docking approach
Pest Management Science, 2013Co-Authors: Paloma Bengochea, Pilar Medina, Pierre Rouge, Olivier Christiaens, Fermin Amor, Elisa Vinuela, Guy SmaggheAbstract:BACKGROUND: Olive fruit fly, Bactrocera oleae (Rossi), is a key pest in olive orchards, causing serious economic damage. To date, the pest has already developed resistance to the insecticides commonly applied to control it. Thus, in searching for new products for an accurate resistance management programme, targeting the ecdysone receptor (EcR) might provide alternative compounds for use in such programmes. RESULTS: Residual contact and oral exposure in the laboratory of B. oleae adults to the dibenzoylhydrazine-based compounds methoxyfenozide, Tebufenozide and RH-5849 showed different results. Methoxyfenozide and Tebufenozide did not provoke anynegativeeffectsontheadults,butRH-5849killed98-100%ofthetreatedinsects15 daysaftertreatment.Theligand-binding domain (LBD) of the EcR of B. oleae (BoEcR-LBD) was sequenced, and a homology protein model was constructed. Owing to a restrictedextentoftheligand-bindingcavityoftheBoEcR-LBD,dockingexperimentswiththethreetestedinsecticidesshowed a severe steric clash in the case of methoxyfenozide and Tebufenozide, while this was not the case with RH-5849. CONCLUSION: IGR molecules similar to the RH-5849 molecule, and different from methoxyfenozide and Tebufenozide, might have potential in controlling this pest. c � 2012 Society of Chemical Industry
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Tebufenozide distorted codling moth larval growth and reproduction and controlled field populations
Annals of Applied Biology, 2004Co-Authors: Guy Smagghe, Pilar Medina, Flor Budia, Dany Bylemans, Jesus Avilla, Elisa VinuelaAbstract:Summary The activity of the ecdysteroid agonist Tebufenozide was evaluated on the codling moth, Cydia pomonella. Tebufenozide affected larval feeding and growth, showing clear symptoms of a double head capsule. Under the SEM and TEM, symptoms of precocious apolysis of the larval integument were observed. Although this process was accompanied with a great inhibition of locomotion, muscle attachment to the new cuticle seemed not to be affected confirming the primary mode of action of Tebufenozide as ecdysteroid-like. In addition, Tebufenozide exerted a sterilising action in female and male adults in the laboratory. Finally, the potency of Tebufenozide was evaluated in an experimental orchard for commercial apple production in Belgium being, at least, as effective as diflubenzuron.
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toxicity and pharmacokinetics of insect growth regulators and other novel insecticides on pupae of hyposoter didymator hymenoptera ichneumonidae a parasitoid of early larval instars of lepidopteran pests
Journal of Economic Entomology, 2003Co-Authors: Marcela Ines Schneider, Guy Smagghe, A Gobbi, Elisa VinuelaAbstract:Susceptibility of the lepidopteran parasitoid Hyposoter didymator (Thunberg) to seven modern insecticides, azadirachtin, diflubenzuron, halofenozide, methoxyfenozide, pyriproxyfen, Tebufenozide, and spinosad, was tested in the laboratory. Pupae were exposed to different doses of each compound by direct topical application. At the field recommended doses, methoxyfenozide and Tebufenozide had no effect on H. didymator. Halofenozide had a low effect on both adult emergence and adult survival but the progeny size and parasitism capacity were not affected. Diflubenzuron was moderately toxic to the parasitoid, while azadirachtin, pyriproxyfen and spinosad were very toxic, affecting all its life parameters. In the pyriproxyfen and spinosad treatments, no progeny was obtained. As a second approach of this study, we determined the rate of penetration through the pupal cocoon and absorption in the parasitoid body as pharmacokinetic parameters important for toxicity. Most of the radioactivity was retained in the silken cocoon, indicating a low accumulation in the parasitoid body. Among all compounds tested, diflubenzuron exhibited the highest absorption in the parasitoid body, followed by pyriproxyfen. For halofenozide, methoxyfenozide and Tebufenozide, low absorption (<2%) was found. In addition, we tested for the presence of molting hormone receptors in Hyposoter tissues using a monoclonal antibody 9B9. Our data suggest that the use of diflubenzuron azadirachtin, pyriproxyfen, halofenozide, and spinosad in combination with H. didymator in integrated pest management (IPM) programs should be carefully evaluated. Methoxyfenozide and Tebufenozide could be considered safe for this parasitoid.
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toxicity and absorption of azadirachtin diflubenzuron pyriproxyfen and Tebufenozide after topical application in predatory larvae of chrysoperla carnea neuroptera chrysopidae
Environmental Entomology, 2003Co-Authors: Pilar Medina, Flor Budia, Luc Tirry, Guy Smagghe, Eladio VinuelaAbstract:Abstract Susceptibility of the generalist predator, the lacewing Chrysoperla carnea (Stephens), to the insect growth regulators azadirachtin, diflubenzuron, pyriproxyfen, and Tebufenozide was tested in the laboratory. Third instars were topically treated with different doses of formulated materials of each compound by direct topical exposure. At maximum field-recommended dose, pyriproxyfen and Tebufenozide were harmless to C. carnea, whereas azadirachtin and diflubenzuron were harmful (respective LD90s were 24.5 and 6.9 ng active ingredient [AI] per insect). At sublethal doses of azadirachtin and diflubenzuron, females laid fertile eggs, but azadirachtin caused a slight negative effect on oviposition. Pyriproxyfen and Tebufenozide had no effect on oviposition and egg fertility. As a second approach of this study, toxicity data are discussed in relation to the rate of penetration and excretion after topical application. One hour after administration, ≈80% of pyriproxyfen had penetrated; whereas for diflube...
Jinliang Shen - One of the best experts on this subject based on the ideXlab platform.
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inheritance fitness cost and mechanism of resistance to Tebufenozide in spodoptera exigua hubner lepidoptera noctuidae
Pest Management Science, 2009Co-Authors: Jinliang ShenAbstract:BACKGROUND: Tebufenozide has been used as a key insecticide for controlling beet armyworm, Spodoptera exigua (Hubner). To evaluate the risk of resistance evolution and to develop a better resistance management strategy, a field-collected population was selected with Tebufenozide in the laboratory. Thereafter, the inheritance and fitness cost of Tebufenozide resistance in S. exigua were investigated. RESULTS: After being selected with Tebufenozide for 61 generations, S. exigua developed a 92-fold resistance to the chemical. The degrees of dominance for the reciprocal cross progeny were − 0.2698 and − 0.2785. The resistant strain had a relative fitness of 0.71, with substantially lower rates of larval survival, pupal weight, pupation and oviposition per female, and prolonged larval and pupal duration. PBO significantly increased the toxicity of Tebufenozide (SR = 2) against resistant insects, and DEM and DEF also showed synergism with Tebufenozide. CONCLUSION: Tebufenozide resistance in S. exigua was inherited as autosomal, incompletely recessive and controlled by more than one gene. Development of the resistance may cost significant fitness for the resistant population. Mixed-function oxidases might play an important role in Tebufenozide resistance in S. exigua. This study provided valuable information for further understanding Tebufenozide resistance and for facilitating the development of resistance management strategies. Copyright © 2009 Society of Chemical Industry
Danny Degheele - One of the best experts on this subject based on the ideXlab platform.
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action of the ecdysteroid agonist Tebufenozide in susceptible and artificially selected beet armyworm
Pesticide Science, 1998Co-Authors: Guy Smagghe, Luc Tirry, Tarlochan S Dhadialla, Stefaan Derycke, Danny DegheeleAbstract:Abstract: Toxicity assays with Tebufenozide, the Ðrst commercial non-steroidalecdysteroid agonist, against a laboratory strain of the beet armyworm, Spodop-tera exigua (Hu” bner), demonstrated the promise of this new compound for thecontrol of this important pest. Experiments to select insects artiÐcially from thelaboratory strain by continuous exposure of larval instars to corresponding LC25doses of Tebufenozide for over 12 generations 14(G E15 months),0]G12:revealed no loss in susceptibility to the insecticide for up to Ðve generations.Moreover, retention and fate of 14C-labelled Tebufenozide were investigatedusing larvae from the selection experiments and the results compared withG6those for the susceptible larvae. In addition, piperonyl butoxide, an inhibitor(G0)of monooxygenases, when ingested by larvae along with Tebufenozide, increasedthe susceptibility of intoxicated larvae to this ecdysteroid agonist, indicating itsoxidative metabolism in Spodoptera larvae. 1998 Society of Chemical(Industry.Pestic. Sci., 54,27E34 (1998)Key words: Spodoptera exigua; Tebufenozide; ecdysteroid agonist; toxicity;resistance
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comparative toxicity and tolerance for the ecdysteroid mimic Tebufenozide in a laboratory and field strain of cotton leafworm lepidoptera noctuidae
Journal of Economic Entomology, 1997Co-Authors: Guy Smagghe, Danny DegheeleAbstract:We investigated whether tolerance can be induced after continuous application of the nonsteroidal ecdysteroid mimic Tebufenozide at about LC 30 over 5 generations of the cotton leafworm Spodoptera littoralis (Boisduval). After 2 and 4 generations, toxicity data showed that such continuous treatment did not result in a shift of insect susceptibility even after 4 generations in S. littoralis, indicating the difficulties in achieving resistance in this pest to Tebufenozide. Intoxicated larvae showed signs of premature and lethal molting within 24 h of treatment. In addition, Tebufenozide inhibited oviposition which resulted in loss of the specifically treated strain after 5 generations. In a 2nd series of experiments, the potency of the ecdysteroid agonists Tebufenozide and RH-5849 against 3rd instars of a laboratory and multiresistant field strain of S. littoralis was compared with the activity of 2 commonly used pyrethroid, organophosphorus, carbamate and benzoylurea insecticides against Lepidoptera. According to LC 50 s, teflubenzuron was the most potent compound, followed by cypermethrin and deltametrin, and Tebufenozide. The remaining compounds were 2-100 less effective than Tebufenozide. Our results indicate that resistance with Tebufenozide is difficult to achieve; however, further research on tolerance and cross-resistance is required before definitive conclusions can be drawn.
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differential effects of nonsteroidal ecdysteroid agonists in coleoptera and lepidoptera analysis of evagination and receptor binding in imaginal discs
Insect Biochemistry and Molecular Biology, 1996Co-Authors: Guy Smagghe, Hilde Eelen, E Verschelde, Klaus Richter, Danny DegheeleAbstract:Abstract The effects of 20-hydroxyecdysone (20E) and the first nonsteroidal ecdysteroid agonists, RH-5849 and Tebufenozide (=RH-5992), were tested on in vitro cultured mesothoracical imaginal wing discs of last-instar larvae of the Colorado potato beetle, Leptinotarsa decemlineata Say, and the greater wax moth, Galleria mellonella L. In general, the response of the nonsteroidal agonists was qualitatively similar to that induced by 20E, although the concentrations required to induce evagination varied widely. The EC 50 of 20E, RH-5849 and Tebufenozide, that indicates the compound concentration which elicits evagination in 50% of the isolated imaginal discs, was 60.7, 461 and 757 nM, respectively, in L. decemlineata . In wing discs of G. mellonella the order of biological activity (expressed as EC 50 ) resulted in Tebufenozide (8.9 nM)>20E (321 nM)>RH-5849 (865 nM). In a second series of experiments, a competition receptor binding assay was developed with whole imaginal discs, and showed that the I 50 value of 20E, RH-5849 and Tebufenozide to compete 50% of the specifically bound amount of 3 H-ponasterone A in imaginal discs of L. decemlineata was 425, 740 and 1316 nM, respectively. In wing discs of G. mellonella that respective value was 106, 911 and 22 nM. The current results showed that the binding affinity (I 50 ) of 20E reached a similar level as the concentration to elicit a biological response (EC 50 ) in imaginal wing discs of the two insect species; a similar conclusion could be drawn for the two nonsteroidal ecdysteroid agonists. In this regard, it is suggested that the imaginal disc assay allows us to measure the potency of an ecdysteroid active compound on the one hand and its affinity to bind on the ecdysteroid receptors (EcRs) in competition with 3 H-ponasterone A on the other. In addition, the current data suggest that the specific activity and insect selectivity of the nonsteroidal agonists, especially the high toxicity of Tebufenozide for Lepidoptera and the nonsusceptibility of Coleoptera, is related to selective binding on the EcRs.
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action of a novel nonsteroidal ecdysteroid mimic Tebufenozide rh 5992 on insects of different orders
Pesticide Science, 1994Co-Authors: Guy Smagghe, Danny DegheeleAbstract:The nonsteroidal ecdysteroid agonist Tebufenozide (RH-5992) was tested on larval stages of a number of lepidopteran species by topical application and by feeding on treated leaves. LC50, values in the range 0.03–0.10 mg litre−1 were obtained for third to sixth instars of Spodoptera exempta (Walker) when insects were fed on leaves dipped in aqueous emulsions of the compound, while first to fifth instars of Spodoptera exigua (Hubner) were less susceptible (LC50 values in the range 2.5–10.5 mg litre−1). When insects were topically treated, susceptibility of last-instar larvae of Lepidoptera tested decreased in the order Spodoptera exempta, Mamestra brassicae L., Spodoptera littoralis (Boisd.) S. exigua and Galleria mellonella L. Tebufenozide induced a premature and lethal larval moult in larval Lepidoptera within 24 h of treatment. Most larvae died in their old larval cuticle. Other aberrations included inhibition of weight gain and feeding, extrusion of the hindgut, loss of hemolymph and an abnormal and lethal pupation. In contrast, Tebufenozide at similar doses/concentrations had no activity on larval instars of Leptinotarsa decemlineata (Say) and Diabrotica virgifera virgifera (LeConte), nymphs of Podisus sagitta (F.) and larvae of Locusta migratoria migratorioides (R. & F.). It had a chemosterilizing activity in S. exigua, resulting in a total inhibition of oviposition within two days of continuous treatment at doses of ⩾ 10 mg litre−1. On the other hand, all deposited eggs were viable. Similar effects on reproduction occurred in L. decemlineata, but at higher concentrations.
Arthur Retnakaran - One of the best experts on this subject based on the ideXlab platform.
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diapause disruption with Tebufenozide for early instar control of the spruce budworm choristoneura fumiferana
Pest Management Science, 2007Co-Authors: Daniel Doucet, Basil M Arif, Subba Reddy Palli, Michel Cusson, Éric Bauce, Bill L Tomkins, Caroline Frisco, Arthur RetnakaranAbstract:In North America, the eastern spruce budworm, Choristoneura fumiferana Clem., is an important coniferous pest against which Tebufenozide has proven effective as a control product. By acting as an ecdysone agonist, Tebufenozide can induce precocious moulting in late (fifth–sixth) instars but can also be carried over to the next generation owing to its persistence on foliage. The authors conducted laboratory experiments on first-instar larvae treated with Tebufenozide dissolved in acetone. Larvae exposed to doses equal to or above 0.1 µg cm−2 displayed precocious moulting in the second instar after hibernaculum spinning, which effectively disrupted diapause. Larger doses induced moulting in first instars. Evidence is provided that this dose–response difference is related to whether or not an effective dose of Tebufenozide is ingested by the first instar prior to the peak of moulting hormone (20-hydroxyecdysone) in first instars. Doses ineffective to kill first instars are carried over to the second instar, where they induce a precocious moult. This type of response to Tebufenozide is dependent on the presence of a moulting machinery (the EcR–USP receptor complex) that is ready for ecdysone transduction. Interestingly, ecdysone levels are low in second instars, as measured by a radioimmunoassay, which suggests that diapause in spruce budworm is maintained by a suppression of ecdysone production. Thus, diapause disruption by Tebufenozide may well provide an alternative control strategy for this important pest. Copyright © 2007 Society of Chemical Industry
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mode of action of the ecdysone agonist Tebufenozide rh 5992 and an exclusion mechanism to explain resistance to it
Pest Management Science, 2001Co-Authors: Arthur Retnakaran, Basil M Arif, Ivan Gelbic, Meenakshi Sundaram, William Tomkins, Tim R Ladd, M Primavera, Qili Feng, Reddy Palli, Peter J KrellAbstract:Spruce budworm larvae (Choristoneura fumiferana) upon ingesting Tebufenozide (RH-5992) stop feeding and go into a precocious, incomplete molt, leading eventually to death. Like 20-hydroxyecdysone (20E), Tebufenozide also acts at the receptor level and transactivates the expression of up-regulated genes but, because of its persistence, the down-regulated genes that are normally expressed in the absence of 20E are not expressed. While Tebufenozide is lepidopteran-specific, an analog, RH-5849, is effective on dipterans. This is reflected in the respective effects of the two compounds on Cf-203 (C. fumiferana - 203), a lepidopteran cell line and Dm-2 (Drosophila melanogaster - 2), a dipteran cell line. Cf-203 cells accumulated [ 14 C]Tebufenozide and expressed CHR3 (Choristoneura hormone receptor 3), but Dm-2 cells excluded the material and did not express DHR3 (Drosophila hormone receptor 3). Using yeast ABC (ATP binding cassette) transporter mutants, we determined that PDR5 (pleiotropic drug resistance 5) was responsible for the exclusion. We discovered recently that older instars of the white-marked tussock moth (Orgyia leucostigma) are resistant to Tebufenozide, perhaps as a result of such an exclusion system. We are currently cloning PDR5 (pleiotropic drug resistance 5), which is an essential step in studying the resistance mechanism.
Jose Eduardo Serrao - One of the best experts on this subject based on the ideXlab platform.
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toxicological and morphological effects of Tebufenozide on anticarsia gemmatalis lepidoptera noctuidae larvae
Chemosphere, 2018Co-Authors: Muhammad Fiaz, Luis Carlos Martinez, Angelica Platarueda, Wagner Gonzaga Goncalves, Muhammad Shareef, Jose Cola Zanuncio, Jose Eduardo SerraoAbstract:Abstract The velvetbean caterpillar, Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae), is an important soybean pest in the Americas. Tebufenozide, a novel nonsteroidal ecdysone agonist is used to control this pest. Bioassays were conducted to assess Tebufenozide toxicity and their ultrastructural effects on midgut of A. gemmatalis. The toxicity, survivorship, behavior response, and respiration rate for A. gemmatalis larvae after exposure to Tebufenozide were evaluated. Also, A. gemmatalis larvae were treated with LC50 obtained from Tebufenozide and changes were observed on their midgut cells after 24, 48 and 96 h. Tebufenozide was toxic to A. gemmatalis (LC50 = 3.86 mg mL−1 and LC90 = 12.16 mg mL−1) and survivorship was 95% for adults that had not been exposed to Tebufenozide, decreasing to 52% with LC50 and 27% with LC90 estimated value. Damage to midgut cells was increased with exposure time. These cells show damaged striated border with release of protrusions to the midgut lumen, damaged nuclear membrane and nucleus with condensed chromatin and increase in amount of autophagic vacuoles. Mitochondria were modified into nanotunnels which might be an evidence that Tebufenozide induces damage to cells, resulting in cell death, proved by immunofluorescence analyses. This insecticide also caused paralysis movement with change in homeostasis and compromised larval respiration. Thus, sublethal exposure to Tebufenozide is sufficient to disturb the ultrastructure of A. gemmatalis midgut, which might compromise insect fitness, confirming Tebufenozide a possible controlling insecticide.
