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Abstract

The present study was undertaken to screen the pesticidal activity of extra cellular metabolites derived from entomopathogenic fungus Metarhizium anisopliae against Spodoptera litura and Aphis crassivora an important aphid pest under laboratory and pot culture condition. Fungal strain used in the study was isolated from the soil by serial dilution technique. Isolated fungal strain was mass multiplied in a liquid medium sabouraud maltose yeast extract broth under optimum condition (28 • C). Culture fil-trate and the collected culture derived from the medium was used for the source of metabolites. The culture filtrate was extracted with ethyl acetate, acetone and the concentrated extract was screened for pesticidal activity against Spodoptera litura and Aphis crassivora adopting leaf disc and pot culture assay respectively. Extracted metabolites showed pesticidal activity against both insect pests. However, notable effect was recorded in ethyl acetate derived metabolites. The ethyl acetate extract treatment recorded 91.2% mortality at a concentration of 100 μg against Spodoptera litura and 100% mortality at a concentration of 100 μg against Aphis crassivora. Phyto-toxicity was determined by measuring the germination index (GI) of groundnut seeds by exposing it to the crude metabolites extracted in ethyl acetate and acetone. The results showed that the germination index was high on ethyl acetate extract which was recorded to be 98.0% and germination index of acetone extract was found to be 90.0%. Production of insecticidal metabolites from M. anisopliae under laboratory condition proposed the possible utilization of metabolites as an effective, safe pesticidal agent against economic important insect pests. No impact on the seedling emergence revealed non phytotoxic effect of the metabolites. K E Y W O R D S Aphis craccivora, metabolites, Metarhizium anisopliae, Spodoptera litura

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... Seedling emergence was recorded in the respective treatment group. Further confirmation of the phytotoxic effect was studied by in silico analysis [36]. ...
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Pesticides are contributing in current agriculture to fulfil the need of raising population. Uses of pesticides are not limited to agriculture, but they are also used to control over domestic pests, disease insect vectors and home gardening. But they are very toxic in nature and pose acute risks on the human health and the environment. They negatively affected the agricultural workers and trigger social conflicts when employed extensively and without safety measures. Further, they also have adverse effects on the neighbouring communities. Chiefly, agriculture workers meet with both direct and indirect exposure with these chemicals. Common man comes in contact with these chemicals by skin contacting which is due to leaking and drifting of pesticides during mixing and causing serious threat to human health such as diabetes, reproductive disorders, neurological dysfunction, cancer and respiratory disorders. In this review, we discussed classification, mechanisms, benefits and adverse effects of the pesticides on both human beings and the environment. We had also discussed some remedial measures to mitigate their toxicity. In future, research is needed to develop innovative ideas in current farming which are able to decrease the application of chemical pesticides.j
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Biopesticides have proven to be suitable for the control of agricultural diseases and insects. Natural products and micro-organisms have been used as biopesticides worldwide as they can be sourced from the environment, they are generally safe to non-target organisms including humans, they have reduced persistence in the environment, and they are potentially acceptable for use in organic agriculture. Compared with synthetic pesticides, new biopesticides can gain regulatory approval faster. They can also be developed in less time and are much less expensive to develop. In China, some biopesticides currently being developed may be suitable alternatives to chemical pesticides such as Bacillus thuringiensis, Jinggangmycin, pyrethrins and brassinolide. This review summarizes the mode of action of biopesticides and describes their current development for use in agriculture.
Article
The insect-pathogenic fungus Metarhizium rileyi is highly sensitive to nutritional and environmental conditions which makes it difficult to produce as a stable biopesticide. In this study, a Colombian isolate of this fungus was produced in bulk, and conidia were formulated as an emulsifiable concentrate (EC). The stability of formulated conidia was studied. Conidial viability was maintained at >85 % viability for 12 m under refrigeration and for >three months at 18 °C. The pH values were stable, while contaminant content was significantly reduced. The efficacy of the EC to control Spodoptera frugiperda (Smith) was correlated with the storage time using different mathematical models, and conservative values of six and 12 months at 8 °C and 18 °C respectively, were established. Finally, the EC was evaluated in maize plants under glasshouse conditions. The LC50 and LC90 were estimated to be 1.17 × 10⁴ and 4.03 × 10⁶ conidia/mL respectively and a 57 % reduction in recent damage of plants was achieved. This study demonstrated the potential of M. rileyi formulated as EC to control S. frugiperda in maize. Therefore, it is necessary to continue developing this biopesticide, in order to deliver a new tool to be integrated in pest management programs.
Article
Poisoning from pesticides is a global public health problem and accounts for nearly 300,000 deaths worldwide every year. Exposure to pesticides is inevitable; there are different modes through which humans get exposed to pesticides. The mode of exposure is an important factor as it also signifies the concentration of pesticides exposure. Pesticides are used extensively in agricultural and domestic settings. These chemicals are believed to cause many disorders in humans and wildlife. Research from past few decades has tried to answer the associated mechanism of action of pesticides in conjunction with their harmful effects. This perspective considers the past and present research in the field of pesticides and associated disorders. We have reviewed the most common diseases including cancer which are associated with pesticides. Pesticides have shown to be involved in the pathogenesis of Parkinson’s and Alzheimer’s diseases as well as various disorders of the respiratory and reproductive tracts. Oxidative stress caused by pesticides is an important mechanism through which many of the pesticides exert their harmful effects. Oxidative stress is known to cause DNA damage which in turn may cause malignancies and other disorders. Many pesticides have shown to modulate the gene expression at the level of non-coding RNAs, histone deacetylases, DNA methylation patterns suggesting their role in epigenetics.
Article
In the present study, enhanced pesticidal activity and biocompatibility of chitosan nanocomposite prepared with biocompatible polymer chitosan - insecticidal metabolites derived from potential fungal biopesticidal agent Nomuraea rileyi were studied. Insecticidal metabolites were isolated from the culture filtrate of fungal strain grown in sabouraud maltose yeast extract broth (SMYB) and the collected filtrate was extracted with ethyl acetate followed by purification using G-60 silica gel column. Chitosan nanocomposite was prepared with metabolites thus acquired by ionic gelation method. Synthesized nanocomposite was found to have high stability, uniformly dispersed particles with high loading and entrapment efficiency. Insecticidal activity was studied by determination of cumulative mortality against larval instars of Spodoptera litura and changes in biochemical composition of midgut, hemolymph macromolecules which revealed that the nanocomposite was effective against all the larval stages in terms of high mortality, drastic reduction of midgut and hemolymph macromolecules biochemical composition. Biocompatibility of nanocomposite was carried out by evaluation of developmental toxicity against zebrafish and in vitro hemolysis with peripheral blood cells. Chitosan nanocomposite treatment was not induced any toxic effect on the developmental stages of zebra fish. Hemolysis was also not recorded in the nanocomposite treatment. The observed results imply that insecticidal metabolites fabricated chitosan nanocomposite prepared in our present system is a promising candidates for pest control against economically important insect pests without affecting non-target organisms.
Article
Destruxins, cyclic hexadepsipeptide toxins, secreted by the entomopathogenic fungus, Metarhizium anisopliae through extracellular synthesis. The present study reports a new approach for the analysis of DTXs produced by the fungal strain Metarhizium anisoliae Tk6, using FRIR-HPLC-LC-MS and H1 NMR. The results also showed that production of the major DTXs A, B, C, and E have to be determined in Czapek Dextrose (CD) liquid culture filtrate from 9 to 12 days post-inoculation. Purified DTX were further tested in bioassays to assess their effects of Aedes aegypti mosquitoes. The four major purified DTX compounds were found to cause a toxic effect on the larval developmental stages of mosquitoes with high mortality rates. However, DTX E outperformed the other three DTXs by causing the highest mortality three days after inoculation. This result gives an alternative approach of using DTXs in mosquitoes control and used as a new method for other pest management.
Article
Methanolic extract of Cocos nucifera (C. nucifera) were collected using Soxhlet apparatus. C. nucifera methanolic extract was used to prepare Nickel nanoparticles (Ni NPs). Eco-friendly synthesized Ni NPs were confirmed by several analytical techniques such as UV–Visible spectroscopy (UV–Vis), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray analysis (EDAX), Transmission Electron Microscope (TEM) and Zeta potential. The obtained results infer that green synthesized Ni NPs are in cubical shape with an average particle size of 47 nm. Synthesized Ni NPs were subjected to pesticidal activity against agricultural pest Callasobruchus maculates (C. maculates) which resulted in 97.31% mortality. These results were compared with commercially available standard Azadirachtin. Also we have studied larvicidal activity against Aedes ageypti (A. ageypti) larvae which resulted in LC 50 and LC 90 value of 259.24, 446.99 ppm respectiveley and the result proved to be significant which were processed by ANOVA LSD Tukey's test.
Article
The pathogenicity of four isolates each of the entomopathogenic fungi, Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. to apterous adult Aphis craccivora Koch was evaluated in the laboratory at 4 concentrations of conidia. All fungi isolates tested were found to be pathogenic to the insect but their virulence varied among species and isolates within species. Three isolates, B. bassiana CPD 11 and M. anisopliae CPD 4 and 5 caused significantly higher mortality than the other isolates at the various concentrations tested causing mortality of between 58–91%, 64 to 93% and 66–100%, respectively, at 7 days post treatment. At the highest concentration of 1 × 10conidiaml, these isolates produced the shortest LT50s of 3.5, 3.6 and 3.4 days, respectively. Their LC50s were 6.8 × 10, 3.1 × 10 and 2.7 × 10 conidia ml, respectively. The results indicate that these isolates are promising candidates for the control of the cowpea aphid but their pathogenicity to various aphid non‐target beneficial organisms within the cowpea agroecosystem warrant further investigation before initiating field control.
Article
The cyclodepsipeptide destruxin produced by the entomopathogen Metarhizium anisopliae (Metch.) was administered by different methods, topical application, ingestion and a combination of the two, in an attempt to minimize the mycotoxin dose for efficient management of the insect pest Spodoptera litura (Fab.). The insecticidal activity of destruxin on the larval stages of S. litura showed an ascending trend in LD(50) values with increasing age. The value for 12-day-old larvae in the combined application assay was as low as 0.045 microg g(-1) body weight of crude destruxin from M-19 strain when compared with the corresponding values of 0.17 microg g(-1) body weight in the ingestion assay and 0.237 microg g(-1) body weight in the topical application assay. On the other hand, values were higher in the treatments with crude destruxin from the low-virulence M-10 strain of M. anisopliae showing the least quantities of A and E components of destruxin. Laboratory bioevaluation showed the combination assay of ingestion and topical application of crude destruxin to be efficient in enhancing its insecticidal properties. The adopted combination assay apparently simulates application of the insecticide at field level. Quantitative differences between destruxins from low- and high-virulence strains of M. anisopliae are in accordance with its presumed role in virulence.
Microorganisms as a biopesticides
  • Kachhawa D.
Kachhawa, D. (2017). Microorganisms as a biopesticides. Journal of Entomology and Zoology Studies, 5(3), 468-473.
Determination and characterization of destruxin production in Metarhizium anisopliae Tk6 and formulations for Aedes aegypti mosquitoes control at the field level
  • L Rani
  • K Thapa
  • N Kanojia
  • N Sharma
  • S Singh
  • A S Grewal
  • A L Srivastav
  • J Kaushal
  • K Ravindran
  • K S Akutse
  • S Sivaramakrishnan
  • L Wang
Rani, L., Thapa, K., Kanojia, N., Sharma, N., Singh, S., Grewal, A. S., Srivastav, A. L., & Kaushal, J. (2021). An extensive review on the consequences of chemical pesticides on human health and environment. Journal of Cleaner Production, 283, 124657. Ravindran, K., Akutse, K. S., Sivaramakrishnan, S., & Wang, L. (2016). Determination and characterization of destruxin production in Metarhizium anisopliae Tk6 and formulations for Aedes aegypti mosquitoes control at the field level. Toxicon, 120, 89-96.