Effect of Aspergillus flavus on the mortality and activity of antioxidant enzymes of Spodoptera litura Fab. (Lepidoptera: Noctuidae) larvae

Chadha

et al. 2020

Preprint

In an attempt to find toxicity of Aspergillus flavus in insects, Spodoptera litura was treated with A.flavus ethyl acetate extract and toxicity was assessed by analyzing the effect of fungal extract on antioxidant and cellular immune defense. In antioxidant defense, the lipid peroxidation (Malondialdehyde content) and antioxidant enzymes activities (Catalase, Ascorbate peroxidase, Superoxide dismutase) were examined. In cellular immune defense, effect of A. flavus extract was analyzed on haemocytes using Scanning Electron Microscopy (SEM). Ethyl acetate extract of A. flavus was administrated to the larvae of S.litura using artificial diet method having concentration 1340.84µg/ml (LC50 of fungus). The effect was observed using haemolymph of insect larvae for different time intervals (24, 48, 72 and 96). In particular, Malondialdehyde content and antioxidant enzymes activities were found to be significantly (p≤0.05) increased in treated larvae as compared to control. A. flavus ethyl acetate extract also exhibit negative impact on haemocytes having major role in cellular immune defense. Various deformities were observed in different haemocytes like cytoplasmic leakage and surface abnormalities etc. Furthermore, mammalian toxicity was analyzed with respect to DNA damage induced in treated rat relative to control. Genotoxicity on rat was assessed using different tissues of rat (blood, liver, and kidney) by comet assay. Non-significant effect of A. flavus extract was found in all the tissues (blood, liver, and kidney). Overall the study provides important information regarding the oxidative stress causing potential and immunosuppressant nature of A. flavus against S. litura and its non toxicity to mammals (rat).

supporting

confidence: 86%

Aspergillus Flavus Induced Oxidative Stress and Immunosuppressive Activity in Spodoptera Litura As Well As Safety for Mammals

Chadha

et al. 2020

Preprint

“…Moreover, Aspergillus was the most frequent genus associated with all of the insect's life stages, and eight species were identified of which Aspergillus flavus was the most common (Ismail & Abdel‐Sater, ). Nevertheless, this mould has also been reported as entomopathogenic for S. litura and was shown to have a toxic effect on this insect (Karthi et al, ; Kaur et al, ). Consequently, due to its toxic effect on Spodoptera we considered this mould as transient, but it could also be indigenous and further analyses are needed to elucidate this point.…”

Section: Discussionmentioning

confidence: 99%

Gut microbiota of Spodoptera frugiperda (J.E. Smith) larvae as revealed by metatranscriptomic analysis

Rozadilla

Cabrera

Virla

et al. 2020

J Applied Entomology

The invasive fall armyworm, Spodoptera frugiperda (J.E. Smith; Lepidoptera: Noctuidae), is considered one of the most harmful pests in corn, rice and cotton crops and has developed resistance to the most widespread methods used to control it, chemical insecticides and transgenic crops based on Bt toxins. On the other hand, gut microbiota plays an important role in the insect's fitness, and metatranscriptomic analyses of the insect host are an invaluable tool for identifying new pest control targets. Notwithstanding, there are extremely few reports on the functionally active profile of the gut microbiota in insects, especially in lepidopterans. Moreover, most studies have only described the bacterial community even though all the components of the microbiota, Bacteria, Archaea, fungi, protozoa and viruses, influence different physiological aspects of the insect host. This is the first time an unbiased and comprehensive metatranscriptomic approach has been used to describe the taxonomic and functional profile of the gut microbiota of S. frugiperda larvae, both bacterial and non‐bacterial. We identified novel and very active components which were putatively playing an important nutritional role, such as ammonia‐oxidizing Archaea and Bacteria, and a xylan‐ and hemicellulose‐degrading Actinobacteria. This analysis also allowed us to identify potential biocontrol agents.

“…Catalase and cytochrome P450 activity also decreased significantly in the treated groups as compared to control with F = 76.235, df = 3 and F = 907.269, df = 3 at p < 0.05 respectively while the different groups also showed significant differences with the incubation time after the treatment with F = 22.526, df = 3 and F = 196.556, df = 3 at p < 0.05 respectively. Decrease in the activity of CAT in the treated groups exposed to the different sub-lethal concentration of fungus may be due to the unbalanced generation of free radicals, which suppress the innate defense mechanism of the insect and also due to the ineffective role of this enzyme in managing the oxidative stress induced by the fungus [48,49].…”

Section: Effect Of Fungal Infection On Detoxifying Enzyme Activitymentioning

confidence: 99%

Evaluation of <i>Aspergillus niger</i> as a Biocontrol Agent in the Insect Pest Management of Red Cotton Bug, <i>Dysdercus koenigii</i> (Heteroptera: Pyrrhocoridae)

2019

The present work evaluates the efficacy of Aspergillus niger as a biocontrol agent against Dysdercus koenigii. Three concentrations (C1:1 × 104, C2:1 × 105 and C3:1 × 106 spores/mL respectively) were applied topically to the arthrodial membrane of adult insects and virulence of the fungi in terms of mortality was obtained, which was highest (66.66%) after 96 h post infection with 1 × 106 spores/mL. Its effect on cellular immune response was investigated. The decline in hemocyte count was highest in C3 group treated, i.e. 6992.66±216.34, followed by other groups. Differential hemocyte counts showed that granulocytes and plasmatocytes were the most affected hemocytes with count 26.33±0.66, 24±1.15 respectively in “C3” treated group in comparison to control, 33.66±2.07, 39.66±0.88 respectively. The humoral response was also studied by assessing the activity of four important antioxidant enzymes (superoxide dismutase, catalase, cytochrome p450 and glutathione-S-transferase) and lipid peroxidation that showed significant changes. Based on mortality test we can say that even the sub-lethal concentration can pose significant threat on insect pest. Our results further revealed that Aspergillus niger compromises the immunological parameters of insects and help us understand the underlying mechanism of insect response towards pathogens.