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Dietary effects of phytoecdysteroids on growth and developement of insects

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phytoecdysteroids affect the larval pupal and adult growth and developements of insects. it affects the digestion, pupation, moulting, reproduction, fecundity in insects. Also enhances silk production

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Dietary effects of phytoecdysteroids on growth and developement of insects

  1. 1. Dietary effects of Phytoecdysteroids on growth and development of insects Submitted by: K.V. NAGARJUNA REDDY
  2. 2. Introduction • Ecdysteroids - control moulting and metamorphosis in insects. • Regulate biochemical and physiological processes • Ecdysone (E) first isolated by Butenandt and Karlson in 1954 from silkworm pupae. • Subsequently, 20-hydroxyecdysone (20 HE) was identified from a number of arthropod sources Structure of a typical ecdysteroid
  3. 3. • Phytoecdysteroids - Analogues of ecdysteroids occurring in plant species. • Nakanishi et al. (1966) isolated three polyhydroxylated steroids (Ponasterones A, B and C). • Takemoto’s group isolated 20E and inokosterone from the roots of Achyranthes fauriei. • 20 HE found in the wood of Podocarpus elatus (Galbraith and Horn, 1966), the rhizomes of Polypodium vulgare (Heinrich and Hoffmeister, 1967) and in dry pinnae of Pteridinium aquilinum (Kaplanis et al., 1967).
  4. 4. Distribution of ecdysteroids in the plant world • Occur in over 100 terrestrial plant families representing ferns, gymnosperms and angiosperms. • Phytoecdysteroids detected in 27 families of the Pteridophyta, 10 families of Gymnospermae and 74 families of angiosperms. • Majority of these families are within eleven orders: Liliales, Ranunculales, Urticales, Malvales, Violales, Capparales, Rosales, Sapindales, Polemoniales and Scrophulariales. • Phytoecdysteroids occur in relatively high concentration in many plants and comprise 0.001- 3% of the dry weight and have been isolated from all parts of plants in much higher amounts than those present in arthropods.
  5. 5. Table 1. List of few Phytoecdysteroids. Ponasterone A Ajugasterone B 29-norcyasterone 1-epi-integristerone Dacryhainansterone Rapisterone C Paristerone Tenuifoliosides A and B 22-oxo-cyasterone 5α-polypodine B 22-deoxy-20,21-dihydroxyecdysone Praemixisterone Viperidinone Inokosterone Stachysterone A Turkesterone Makisterone D Stachysterone C 22-dehydro-12 hydroxycyasterone Amarasterone B Decumbesterone A Sogdisterone Gerardiasterone Cheilanthones A and B Silenosterone Rapisterone Makisterone A Poststerone Venustone Makisterone C 4α-hydroxypinnasterol Canescensterone Amarasterone B Kaladasterone Rubrosteron Sidisterone Podecdysone B Carthamosterone Poststerone Carpesterol Taxisterone (22-deoxyecdysterone) 29-norsengosterone
  6. 6. Chemistry of phytoecdysteroids • Phytoecdysteroids - triterpenoids • Polar steroids with sugar-like solubility properties • Lack polyhydroxylated side chain- lipophilic. • (Cyclo pentano- perhydrophenanthrene carbon skeleton) cholest-7-en-6-one carbon skeleton (C27) • Hydroxylated with 2-8 hydroxyl groups. • Over 1,000 possible structures - various analogues differ in the number and site of hydroxylations, the length and structure of the carbon side chain.
  7. 7. Diversity of phytoecdysteroid structures
  8. 8. Biological significance of phytoecdysteroids to plants • Two main hypotheses • PEs have a hormonal role within the plant - little evidence • PEs possess insect moulting hormone activity - participate in the defence of plants against non- adapted phytophagous invertebrates • PEs - hormonal disruptors and toxins for insects and other invertebrates • Plants ʻturn onʼ the production of phytoecdysteroids when under stress, animal attack or other conditions
  9. 9. Mechanism of action
  10. 10. Effects on growth and development of insects Inhibition of digestive enzymes: - Cytotoxic effects on epithelial cells synthesizing digestive enzymes (α- amylase). - Direct inhibition of enzyme activity - Indirectly perturbation of neuropeptides (Sulfakinin) involved in alpha-amylase signalling and regulation. Test insects References Tribolium castaneum Ajaha et al. 2019, Jbilou et al. 2008 Plodia interpunctella Bouayad et al. 2012, Rharrabe et al. 2009 Spodoptera eridania Shannag et al. 2015
  11. 11. Table: Effect of 20-hydroxyecdysone on alpha-amylase activity of Tribolium castaneum larvae after 7d of treatment. Treatment α-Amylase (µg of starch consumed /larva) Control 174.63 ± 1.7a 300 ppm 161.25 ± 2.06b 600 ppm 150.53 ± 2.5b 900 ppm 145.15 ± 2.2c 1,200 ppm 134.95 ± 1.9c Starved 132.38 ± 2.6c Means in the same column followed by different letters indicate that the difference between controls and treated or starved larvae is statistically significant as determined by the Tukey’s HSD test. Between the letters ‘a’ and ‘b’, the effect is significant (P < 0.05). Between the letters ‘a–c’, the effect is very significant (P < 0.01). Between the letters ‘a–d’, the effect is very highly significant (P < 0.001).
  12. 12. Reduction in larval proteins - Deterioration of the internal tissues of insects - Strong mobilization of proteins as response to the nutritional stress Test insect Phytoecdysteroids References Plodia interpunctella 20-hydroxyecdysone Rharrabe et al. 2008, 2009 Bombyx mori Phytoecdysteroids from Radix achyranthes Miao et al. 2004 Tribolium castaneum 20-hydroxyecdysone Ajaha et al. 2019
  13. 13. Table: Effect of 20-hydroxyecdysone on protein activity of Tribolium castaneum larvae after 7 d of treatment. Treatment Protein (µg/larvae) Control 233.15 ± 24a 300 ppm 151.32 ± 15b 600 ppm 149.13 ± 5b 900 ppm 110.07 ± 20c 1,200 ppm 95.7 ± 16c Starved 48.34 ± 7.7d Means in the same column followed by different letters indicate that the difference between controls and treated or starved larvae is statistically significant as determined by the Tukey’s HSD test. Between the letters ‘a’ and ‘b’, the effect is significant (P < 0.05). Between the letters ‘a–c’, the effect is very significant (P < 0.01). Between the letters ‘a–d’, the effect is very highly significant (P < 0.001).
  14. 14. Precocious pupation and adult emergence/ Abnormal adults - Emerged ones display structural abnormalities- deformed wings, remnants of moult skin, pupal cover and head capsule). - The effect on pupation a consequence of hormonal balance disruption with internal levels of ecdysone. Test insect References Tribolium castaneum Ajaha et al. 2019 Leptinotarsa decemlineata Zolotar’ et al. 2001 Plodia interpunctella Rharrabe et al. 2009 Bombyx mori – Inkosterone Shigematsu et al. 1974 Cynthia cardui Blackford and Dinan, 1997 Anticarsia gemmatalis Macedo et al. 2011 Bemisia tabaci, Oligonychus perseae - Ajuga iva extracts Radi et al. 2011 Spodoptera littoralis Leena et al. 2020
  15. 15. Morphological changes in the larvae, pupae and adults of T. castaneum Doseof20HE
  16. 16. Figure: Adult Bemisia tabaci mortality rates obtained after ecdysterone and cyasterone extracted from Ajuga iva, compared with a commercial ecdysterone standard and a water control.
  17. 17. Fig : Metamorphosis of control and treated S. littoralis larvae. Pupation of S. littoralis larvae after 15 days of exposure (feeding for 4 days) on A. iva crude leaf extract. Control (A), 250 µg/µl A. iva crude leaf extract (B) and 250 µg/µl of three fractionated and purified phytoecdysteroids from A. iva leaf extract fractions (20-hydroxyecdysone, makisterone A and cyasterone) (C). Deficient development of pupation in (b) and (c) is due to disturbed levels of the ecdysteroids responsible for molting.
  18. 18. Fig : Effect of 20-hydroxyecdysone on adult emergence of Tribolium castaneum. Each point represents the mean ± SE.
  19. 19. Larval death - Insects die in the juvenile stages with abnormalities. - Disruption involves a number of effects - inhibition of growth, induction of supernumerary larval instars, death without moulting, head capsule apolysis, uncoordinated writhing side-to-side larval movements unable to maintain their balance, haemolymph emanation followed by hind-gut extrusion and death during or after induced moulting. - Cytotoxicity of phytoecdysteroids on the larvae’s midgut.
  20. 20. Test insect References Brevicoryne brassicae Pavela et al. 2005 Cynthia cardui Blackford and Dinan, 1997 Lobesia botrana Mondy et al. 1997 Anticarsia gemmatalis Macedo et al. 2011 Spodoptera litura, Helicoverpa armigera Balasubramanian et al. 2008 Tribolium castaneum Ajaha et al. 2019 Cryptorrhynchus lapathi Chi De-fu et al. 2002 Spodoptera littoralis Leena et al. 2020 Plutella xylostella Li et al. 2015
  21. 21. Fig : Effect of different concentrations of A. iva crude leaf extract on S. littoralis first instar (L1) larval (n = 110) mortality (mean ± SEM) (a), and larval weight gain (%) (mean ± SEM) of S. littoralis third instar (L3) larvae (b). Asterisks above columns indicate significant difference (p ≤ 0.05) by t-test (t108 = 6.105, 4.308 and 3.220 for 50, 100 and 250 µg/µl, respectively); p < 0.001 for all treatments, Levene’s test p = 0.326 (a), and by repeated measures ANOVA (F3.104 =20.334, 17.246 and 13.007 for 50, 100 and 250 µg/µl, respectively); p < 0.001, Mauchly’s test p = 0.152 (b) between treatments and the control
  22. 22. Fig: The morphological changes in diamondback moth larvae and a pupae caused by ingestion of exogenous dietary 20-hydroxyecdysone. a. Exosmosis of ecdysial fluid and an additional molt b. failure to shed the head capsule c. failure to shed the exuvium d. bulging of the hindgut e. deformed pupa
  23. 23. Cannibalism The stressful conditions (high population and scarce food) when phytoecdysteroids are present in the larval food can induce cannibalism Test insect Reference Plodia interpunctella Rharrabe et al. 2009
  24. 24. Fig: Effect of different phytoecdysteroids, at a concentration of 200 ppm, on P. interpunctella larval cannibalism. Each data point represents the mean ± standard error of five replicates
  25. 25. Anti-feedant activity - Phytoecdysteroids - deterrent action - detected by maxillary and labial palps of the insects Test insect References Leptinotarsa decemlineata Khalilova et al. 2002 Popillia japonica, Cerotoma trifurcate, Diabrotica virgifera virgifera, Trirhabda canadensis Jurenka et al. 2017
  26. 26. Table: Various concentrations of phytoecdysteroid affected feeding by 3 species of chrysomelids on preferred host plants in a choice assay. Values represent mean % defoliation ± SEM BLB = bean leaf beetle (Cerotoma trifurcate) feeding on soybean leaves; WCRW = western corn rootworm (Diabrotica virgifera virgifera) feeding on maize leaves; GLB = goldenrod leaf beetle (Trirhabda canadensis) feeding on common goldenrod. Letters indicate significant differences between treatments within a column P<0.05 (ANOVA followed by Fisher’s LSD test). A (F = 21.89; df = 3, 8; P = 0.0003) b (F = 25.69; df = 3, 8; P = 0.0002) c (F = 23.23; df = 1, 21; P = 0.0004) d (F = 37.67; df = 3, 16; P = 0.0001).
  27. 27. Reduced fecundity/ fertility. - Phytoecdysteroids target ovarian development - disruption in ecdysteroid titres - egg abortion during oogenesis, - less fecundity - mortality of adults (indirect effect) - less fertility
  28. 28. Test insect Phytoecdysteroids References Brevicoryne brassicae ajugasterone C (ajuC) and polypodine B (polyB) Pavela et al. 2005 Anticarsia gemmatalis Talisine Macedo et al. 2011 Helicoverpa armigera Extracts of C. farinosa Rajkumar et al. 2000 Glossina morsitans Whitehead, 1981 Bemisia tabaci, Oligonychus perseae Ajuga iva extracts Radi et al. 2011
  29. 29. Effect of ecdysterone and cyasterone from Ajuga iva on Bemisia tabaci fecundity (A) and fertility (B). The treatments were compared with a commercial ecdysterone standard and a water control.
  30. 30. Improvement of silk yields - Larvae of the silkworm (4th and 5th instars) - Enhance synchronous development - Co-administration with juvenile hormone analogue elevate silk yield. - Posterior division of the silk gland and the fat body
  31. 31. CONCLUSION - Renewed attention - Phytoecdysteroids - defensive substances against phytophagous insects - Are phytoecdysteroids feasible for crop protection ? - Not an alternative - Integrated pest management strategies
  32. 32. THANK YOU

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