scholarly journals Enzymes of ecdysteroid transformation and inactivation in the midgut of the cotton leafworm, Spodoptera littoralis: properties and developmental profiles

1995 ◽  
Vol 312 (2) ◽  
pp. 561-568 ◽  
Author(s):  
T J Webb ◽  
R Powls ◽  
H H Rees
Keyword(s):  
Spodoptera Littoralis ◽  
Larval Instar ◽  
Physiological Significance ◽  
Peak Activity ◽  
Cotton Leafworm ◽  
Clear Preference ◽  
Prothoracic Glands ◽  
Developmental Profiles

In the midgut cytosol of Lepidoptera, ecdysteroids undergo inactivation by transformation via the 3-dehydro derivative to the corresponding 3-epiecdysteroid (3 alpha-hydroxy) and by phosphate conjugation. The oxygen-dependent oxidase catalyses formation of 3-dehydroecdysteroid, which can be reduced either irreversibly by 3-dehydroecdysone 3 alpha-reductase to 3-epiecdysteroid, or by 3-dehydroecdysone 3 beta-reductase back to the initial ecdysteroid. Furthermore, these ecdysteroids undergo further inactivation by phosphorylation. These ecdysteroid transformations have been investigated in last instar larvae of the cotton leafworm, Spodoptera littoralis. The products of the phosphorylation have been characterized as predominantly ecdysteroid 2-phosphate accompanied by smaller amounts of the corresponding 22-phosphate. The phosphotransferases require Mg2+ and ATP. Whereas the 3-dehydroecdysone 3 alpha-reductase has a clear preference for NADPH rather than NADH, the corresponding 3 beta-reductase markedly favours NADH. The physiological significance of the latter enzyme is unclear. The profiles of the various enzymic activities in dialysed midgut cytosol supplemented with appropriate cofactors were determined throughout the last larval instar. All activities were detectable throughout the instar, but the respective enzymes exhibited maxima at different times. Ecdysone oxidase showed a peak early in the instar, with 3-dehydroecdysone 3 alpha-reductase increasing to a peak as the former activity declined. The 3-dehydroecdysone 3 beta-reductase exhibited peak activity late in the instar, a profile similar to that observed for the corresponding haemolymph enzyme involved in reduction of the 3-dehydroecdysone product of the prothoracic glands to ecdysone. Thus, the significance of the midgut 3 beta-reductase may be related to production of active hormone. Both ecydsteroid 22- and 2-phosphotransferases showed high activities early in the instar and then declined. The physiological significance of the profiles for the ecdysone oxidase, the 3-dehydroecdysone 3 alpha-reductase and phosphotransferases is unclear.

scholarly journals Characterization of a sterol carrier protein 2/3-oxoacyl-CoA thiolase from the cotton leafworm (Spodoptera littoralis): a lepidopteran mechanism closer to that in mammals than that in dipterans

2004 ◽  
Vol 382 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Hajime TAKEUCHI ◽  
Jian-Hua CHEN ◽  
John R. JENKINS ◽  
Masanori BUN-YA ◽  
Philip C. TURNER ◽  
...  
Keyword(s):  
Spodoptera Littoralis ◽  
De Novo ◽  
Larval Instar ◽  
Constitutive Expression ◽  
Northern Blotting ◽  
Malpighian Tubules ◽  
Carrier Protein ◽  
Sterol Carrier Protein ◽  
Cotton Leafworm ◽  
Sterol Carrier Protein 2

Numerous invertebrate species belonging to several phyla cannot synthesize sterols de novo and rely on a dietary source of the compound. SCPx (sterol carrier protein 2/3-oxoacyl-CoA thiolase) is a protein involved in the trafficking of sterols and oxidation of branched-chain fatty acids. We have isolated SCPx protein from Spodoptera littoralis (cotton leafworm) and have subjected it to limited amino acid sequencing. A reverse-transcriptase PCR-based approach has been used to clone the cDNA (1.9 kb), which encodes a 57 kDa protein. Northern blotting detected two mRNA transcripts, one of 1.9 kb, encoding SCPx, and one of 0.95 kb, presumably encoding SCP2 (sterol carrier protein 2). The former mRNA was highly expressed in midgut and Malpighian tubules during the last larval instar. Furthermore, constitutive expression of the gene was detected in the prothoracic glands, which are the main tissue producing the insect moulting hormone. There was no significant change in the 1.9 kb mRNA in midgut throughout development, but slightly higher expression in the early stages. Conceptual translation of the cDNA and a database search revealed that the gene includes the SCP2 sequence and a putative peroxisomal targeting signal in the C-terminal region. Also a cysteine residue at the putative active site for the 3-oxoacyl-CoA thiolase is conserved. Southern blotting showed that SCPx is likely to be encoded by a single-copy gene. The mRNA expression pattern and the gene structure suggest that SCPx from S. littoralis (a lepidopteran) is evolutionarily closer to that of mammals than to that of dipterans.

scholarly journals Immunological analysis of developmental changes in ecdysone 20-mono-oxygenase expression in the cotton leafworm, Spodoptera littoralis

1994 ◽  
Vol 299 (3) ◽  
pp. 711-717 ◽  
Author(s):  
J H Chen ◽  
T Hara ◽  
M J Fisher ◽  
H H Rees
Keyword(s):  
Spodoptera Littoralis ◽  
Fat Body ◽  
Specific Activity ◽  
Larval Instar ◽  
Close Correlation ◽  
Developmental Changes ◽  
Cotton Leafworm ◽  
Oxygenase Activity ◽  
Adrenodoxin Reductase ◽  
Cytochrome P 450

The developmental changes in ecdysone 20-mono-oxygenase during the sixth larval instar of the cotton leafworm, Spodoptera littoralis, were investigated. The specific activity of mitochondrial ecdysone 20-mono-oxygenase in the fat-body exhibited a distinct peak at 72 h, at which time the larvae stop feeding. Immunoblot analyses, using antibodies raised against components of vertebrate mitochondrial steroidogenic enzyme systems [anti-(cytochrome P-450scc), anti-(cytochrome P-450(11) beta), anti-adrenodoxin and anti-(adrenodoxin reductase) antibodies], revealed the presence of specific immunoreactive polypeptides in fat-body mitochondrial extracts. In addition, these antibodies effectively inhibited fat-body mitochondrial ecdysone 20-mono-oxygenase activity. This suggests that the S. littoralis steroid-hydroxylating system(s) may contain polypeptide components analogous to those present in vertebrates. A close correlation between developmental changes in mitochondrial ecdysone 20-mono-oxygenase activity and the abundance of polypeptides (approx. 66 kDa and 50 kDa) recognized by the anti-(cytochrome P-450(11) beta) antibody and a polypeptide (approx. 52 kDa) recognized by the anti-(adrenodoxin reductase) antibody were observed in both fat-body and midgut. These results suggest that developmental changes in the abundance of components of the ecdysone 20-mono-oxygenase system may play an important role in the developmental regulation of the enzyme expression and, hence, of 20-hydroxyecdysone titre.

scholarly journals Sublethal effects of emamectin benzoate on life table parameters of the cotton leafworm, Spodoptera littoralis (Boisd.)

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
El-Sayed Mokbel ◽  
Amal Huesien
Keyword(s):  
Life Table ◽  
Spodoptera Littoralis ◽  
Sublethal Effects ◽  
Lethal Effect ◽  
Reproductive Rate ◽  
Relative Fitness ◽  
Emamectin Benzoate ◽  
Cotton Leafworm ◽  
Sublethal Concentrations ◽  
Preovipositional Period

Abstract Background The cotton leafworm, Spodoptera littoralis (Boisd.), is a serious economic pest in Egypt. Pest control depends mainly on chemical control with several pesticides include conventional and modern insecticides. Comprehensive analysis of pesticides impacts needs to investigate sublethal effects in addition to lethal effect. Results In the current study, the leaf-dip bioassay method was used to evaluate emamectin benzoate (EMB) sublethal concentrations. Results showed that EMB proved high toxicity against S. littorals with LC50 value of 0.019 mg liter−1. Life table analysis showed that treatments with LC5 and LC15 prolonged larval period, mean longevity of males and females, mean generation time (T), doubling time (DT), adult preovipositional period (APOP), and total preovipositional period (TPOP) compared with control. On the contrary, net reproduction rates (R0), intrinsic rates of increase (r), finite rate (λ), fecundity, gross reproductive rate (GRR), and relative fitness were decreased compared to control. Conclusions The current study clarified that sublethal concentrations of EMB induce adverse effects and suppress the population growth of S. littorals. Our results would be useful to assess the overall effects of EMB on S. littorals and can contribute effectively in pest management.

scholarly journals Efficacy of the parasitoid, Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae) on the cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) egg masses

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Hend O. Mohamed
Keyword(s):  
Spodoptera Littoralis ◽  
Insect Pests ◽  
Single Layer ◽  
Control Agent ◽  
Physical Characteristics ◽  
Great Ability ◽  
Egg Masses ◽  
Cotton Leafworm ◽  
Lepidoptera Noctuidae ◽  
Trichogrammatoidea Bactrae

Abstract Background The Egyptian cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is one of the major insect pests, causing a significant damage on different cultivated agricultural crops. Developing an alternative non-chemical tool, an effective and environmentally friendly method to suppress pest's infestation is essentially needed. Therefore, biological control by releasing the egg parasitoids could be the most promising tool for integrated pest management. Results This study was designed to evaluate the efficacy of the egg parasitoid, Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae) as a bio-control agent against S. littoralis egg masses with different physical characteristics (number of egg layer and degree of scale density) in a no-choice and choice tests, under laboratory conditions. Also, the parasitoids’ fitness in terms of parasitism percentage, developmental period, adults’ emergence percentage, female offspring percentage, and longevity were investigated. The results revealed that T. bactrae wasps had a great ability to parasitize S. littoralis egg masses, but with different rates, related to their layers and scales’ thickness in both tests. The highest parasitism percentage was observed on one-layer eggs, followed by two layers. However, 3-layer eggs were the least preferable one. High numbers of adult emergencies (> 80%) were observed in all tested egg masses, except in the case of 3 layers with high scales. Furthermore, female-biased sex ratios were noticed at all examined eggs, with only the exception of high-scaly eggs with a single layer that recorded the lowest rate (≤ 45%). Besides, the survival of adult female parasitoids was not significantly affected in both tests. Conclusions T. bactrae could be used as a bio-control agent against S. littoralis egg masses with different physical characteristics based on the achieved results.

An endophytic Beauveria bassiana strain increases spike production in bread and durum wheat plants and effectively controls cotton leafworm (Spodoptera littoralis) larvae

2018 ◽  
Vol 116 ◽  
pp. 90-102 ◽  
Author(s):  
Antonio R. Sánchez-Rodríguez ◽  
Silvia Raya-Díaz ◽  
Ángel María Zamarreño ◽  
José María García-Mina ◽  
María Carmen del Campillo ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Beauveria Bassiana ◽  
Spodoptera Littoralis ◽  
Cotton Leafworm
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