Diversity of detoxification pathways of ingested ecdysteroids among phytophagous insects (original) (raw)
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Species Specificity of Changes in Ecdysteroid Metabolism in Response to Ecdysteroid Agonists
Pesticide Biochemistry and Physiology, 2002
Administration of the nonsteroidal ecdysteroid agonist RH-5849 or 20-hydroxyecdysone to final larval instar tobacco hornworm, Manduca sexta, has been shown to induce an ecdysteroid inactivation enzyme, ecdysteroid 26-hydroxylase, and the cytosolic inactivation enzymes ecdysone oxidase and ecdysteroid phosphotransferase. In this work, we show that induction of ecdysteroid 26-hydroxylase by the ecdysteroid agonists RH-5849, RH-5992 (tebufenozide), and RH-0345 (halofenozide) appears universal in lepidopteran species that show susceptibility to the agonists. Interestingly, the waxmoth, Galleria mellonella, which shows very low susceptibility to the agonists but whose ecdysteroid receptor is capable of binding the agonist, shows no induction of a 26-hydroxylase activity. It appears that the more potent ecdysteroid agonists in Lepidoptera, RH-5992 and RH-0345, show in general a greater induction of 26-hydroxylase than RH-5849. Feeding RH-5849 to the dipteran housefly Musca domestica results in the induction of an ecdysteroid phosphotransferase. The low toxicity of these ecdysteroid agonists in orthopteran and coleopteran orders also correlates with a lack of induction of ecdysteroid 26-hydroxylase activity. We propose that in species where ecdysteroid agonists are effective in stimulating an untimely premature molt, a response to a state of hyperecdysonism elicited by the agonists is induction of enzymes of ecdysteroid inactivation. ᭧ 2002 Elsevier Science (USA)
Journal of Insect Science, 2019
Plants present a delimited reservoir of biologically active compounds. Many plants synthesize several compounds of secondary metabolism, such as alkaloids, terpenoids, phenolics, steroids, etc. Such compounds are generally thought to be involved in plant–insect interactions. Phytoecdysteroids are a class of chemicals that plants synthesize; these compounds are analogues of molting hormones produced by insects. In this work, the effect of the 20-hydroxyecdysone, which is a molecule that belongs to the family of phytoecdysteroids, was tested on an insect pest, Tribolium castaneum (Herbst). Firstly, the effect of this molecule on post-embryonic development parameters was tested after ingestion at 300, 600, 900, and 1,200 ppm. Secondly, the effect of the 20-hydroxyecdysone was also tested on the biological parameters (proteins, alpha-amylase, detoxification enzymes). The results of the post-embryonic parameters test showed an important induction of larval mortality and a significant red...
Spanish Journal of Agricultural Research, 2008
It has been determined the antifeedant activity of a mixture of limonoids 1,7-di-O-acetylhavanensin and 3,7-di-Oacetylhavanensin (F18), isolated from seeds of Trichilia havanensis Jacq. (Meliaceae), and the neo-clerodane diterpene scutecyprol A, isolated from Scutellaria valdiviana (Clos) Epling (Labiatae), on fifth instar larvae of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). Choice and no-choice feeding assays, nutritional tests, and post-treatment studies indicated that scutecyprol A acts as an insect feeding deterrent against S. exigua, whereas the antifeedant activity of F18 is likely associated with a toxic mode of action. In addition, it was tested the hypothesis that S. exigua larvae will try to metabolize the compounds that are toxic by the induction of their detoxication systems, whereas no such induction happens for those compounds that are deterrents. The mixture of limonoids F18 significantly increased glutathione S-transferases during the treatment and post-treatment periods, whereas esterases were inhibited during the treatment period. On the contrary, scutecyprol A did not have any significant effect on any of the enzymatic processes. Hence, the metabolic response of S. exigua larvae to the ingestion of the secondary metabolites tested depends on their mode of action.
Archives of Insect Biochemistry and Physiology, 1987
converted to a radiolabeled C2, nonecdysteroid conjugate as well as ecdysteroid conjugates, which in ovaries and newly-laid eggs consist mainly of labeled 26-hydroxyecdysone 26-phosphate. During embryogenesis, as the level of 26-hydroxyecdysone 26-phosphate decreases there is a concurrent increase in the amount of a new, labeled ecdysteroid conjugate. This conjugate, which is the major ecdysteroid conjugate (9.4 pg/g) in 0-to l-hourold larvae was identified as 26-hydroxyecdysone 22-glucoside by nuclear magnetic resonance and chemical ionization mass spectrometry. This is the first ecdysteroid glucoside to be identified from an insect. The disappearance of 26-hydroxyecdysone 26-phosphate in 0to I-hour-old larvae indicates that the 26hydroxyecdysone 22-glucoside is derived from 26-hydroxyecdysone 26-phosphate. 3-Epi-26-hydroxyecdysone was the major free ecdysteroid isolated from these larvae and 3-epi-20,26-dihydroxyecdysone was the next most abundant ecdysteroid isolated. Interestingly, the 0to I-hour-old larvae contained the highest levels of 3a-ecdysteroids per gram of insect tissue (8.7 &g) to be isolated from an insect, yet there was a complete absence of the corresponding free 3fi-epimers. The ecdysteroid conjugate profiles of ovaries and 0-to I-hour-old larvae are discussed. Methodology is presented that permits the efficient separation of free and conjugated ecdysteroids and nonecdysteroid conjugates (C2,-steroid conjugates).
… of Chromatography B, 2010
Ecdysteroids are polyhydroxylated steroids that function as molting hormones in insects. 20-Hydroxyecdysone (a 27C-ecdysteroid) is classically considered as the major steroid hormone of Drosophila melanogaster, but this insect also contains 28C-ecdysteroids. This arises from both the use of several dietary sterols as precursors for the synthesis of its steroid hormones, and its inability to dealkylate the 28C-phytosterols to produce cholesterol. The nature of Drosophila ecdysteroids has been re-investigated using both high-performance liquid chromatography coupled to enzyme immunoassay and a particularly sensitive nano-liquid chromatography-mass spectrometry methodology, while taking advantage of recently available ecdysteroid standards isolated from plants. In vitro incubations of the larval steroidogenic organ, the ring-gland, reveals the synthesis of ecdysone, 20-deoxy-makisterone A and a third less polar compound identified as the 24-epimer of the latter, while wandering larvae contain the three corresponding 20-hydroxylated ecdysteroids. This pattern results from the simultaneous use of higher plant sterols (from maize) and fungal sterols (from yeast). The physiological relevance of all these ecdysteroids, which display different affinities to the ecdysteroid receptors, is still a matter of debate.
Metabolism of ecdysteroids by a chitin-synthesizing insect cell line
Archives of Insect Biochemistry and Physiology, 1990
A chitin-synthesizing cockroach cell line (UMBGE-4) previously shown to secrete ecdysteroids was analyzed for its ability to metabolize potential precursors of ecdysone (e.g., 2-deoxyecdysonet 2,22-dideoxyecdysone, 2,22,25trideoxyecdysone, and cholesterol). All, except cholesterol, were actively metabolized by UMBGE-4 cells. However, all but 2-deoxyecdysone were converted to polar and hydrolyzable metabolites, and not to ecdysone. Labeling with cholesterol was unsuccessful. Labeling experiments with molting hormones, i.e., ecdysone and 20-hydroxyecdysone, confirmed that this cell line can metabolize ecdysteroids and allowed identification of some of the products. Molting hormones were converted into acetate conjugates and polar conjugates which were often double-conjugates, i.e., polar conjugates of acetate conjugates. Labeling experiments with ecdysone demonstrated that this cell line possesses a low ecdysone 20-hydroxylase activity. The capacity of UMBGE-2 cells, which do not synthesize chitin or ecdysteroids, was also examined. Neither ecdysone nor 20-hydroxyecdysone was significantly metabolized by UMBCE-2 cells. 2-Deoxyecdysone and 2,22-dideoxyecdysone were very slowly metabolized respectively to more polar compounds.
Presence and function of ecdysteroids in adult insects
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 1984
1. Ecdysteroids have been found in both male a 2. In Diptera vitellogenin synthesis is primarily controllq synthesis can easily be induced by ecdysone and 20-OH ecdy do not directly control vitellogenin synthesis in the fat bot 3. In vivo the ovary readily takes up [3H]ecdysone from 1 releases ecdysteroids. 4. A high ecdysteroid peak was found in non-reproducing 5. Ecdysteroids do occur in adult males but the titre in tl that found in females.
International journal of pest management, 2019
Non-target adults of Cydia pomonella are exposed to insecticide concentrations that may not result in mortality. The present study evaluates the response of biotransformation and antioxidant parameters to acetamiprid-sublethal exposure of surviving adults from both a laboratory-susceptible strain (LSS) and a field population (FP). Activities of 7-ethoxycoumarine O-deethylase (ECOD), glutathione S-transferases (GST) and catalase (CAT), as well as glutathione (GSH) content were examined. The FP displayed a significantly higher ECOD basal activity than the one from LSS. Acetamiprid exposure in FP elicited a significant increase in ECOD activities. GSH content was significantly affected in LSS and FP adults treated with 100 mg/L of acetamiprid. The FP responded to acetamiprid with both an increase of ECOD activity and GSH content in a concentration-dependent manner. CAT and GST activities from both LSS and FP were mostly unaffected by the concentrations of acetamiprid evaluated. Obtained results are helpful in anticipating the development of resistant pest populations to insecticides.
Ecdysteroids and related molecules in animals and plants
Archives of Insect Biochemistry and Physiology, 1997
Ecdysteroids represent a family of more than 250 members present in animals and plants. In addition, many more or less related molecules belonging to a very large group of "polyhydroxysterols" are present in both phyla. Of the several fundamental questions that remain unanswered at the moment, three major ones will be considered here: