Biosynthesis of Silver Nanoparticles Mediated by Entomopathogenic Fungi: Antimicrobial Resistance, Nanopesticides, and Toxicity

Abstract

Silver nanoparticles are widely used in the biomedical and agri-food fields due to their versatility. The use of biological methods for the synthesis of silver nanoparticles has increased considerably due to their feasibility and high biocompatibility. In general, microorganisms have been widely explored for the production of silver nanoparticles for several applications. The objective of this work was to evaluate the use of entomopathogenic fungi for the biological synthesis of silver nanoparticles, in comparison to the use of other filamentous fungi, and the possibility of using these nanoparticles as antimicrobial agents and for the control of insect pests. In addition, the in vitro methods commonly used to assess the toxicity of these materials are discussed. Several species of filamentous fungi are known to have the ability to form silver nanoparticles, but few studies have been conducted on the potential of entomopathogenic fungi to produce these materials. The investigation of the toxicity of silver nanoparticles is usually carried out in vitro through cytotoxicity/genotoxicity analyses, using well-established methodologies, such as MTT and comet assays, respectively. The use of silver nanoparticles obtained through entomopathogenic fungi against insects is mainly focused on mosquitoes that transmit diseases to humans, with satisfactory results regarding mortality estimates. Entomopathogenic fungi can be employed in the synthesis of silver nanoparticles for potential use in insect control, but there is a need to expand studies on toxicity so to enable their use also in insect control in agriculture.

Insecticidal Effect of Zinc Oxide Nanoparticles against Spodoptera frugiperda under Laboratory Conditions

“…Also, when leaves infested by Aphis nerii were dipped into various concentrations of NPs, there was a significant effect on their development [24]. Studies have been carried out on the insecticidal effects of silver nanoparticles and have shown that they can manage the insects that damage crops such as Spodoptera littoralis [28]. Another study using biosynthesized AgNPs showed larvicidal toxicity against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus [29].…”

Synthesis of Metarhizium anisopliae–Chitosan Nanoparticles and Their Pathogenicity against Plutella xylostella (Linnaeus)

“…Banu and Balasubramanian [29] found the LC 50 value of 0.79 ppm for B. bassiana AgNPs against second instar larvae of Aedes aegypti. Santos et al [50,51] also discussed and elaborated on the synthesis and toxicity of nanoparticles mediated by entomopathogenic fungi. The possible mechanism of action of M. anisopliae-chitosan nanoparticles can be explained by different phenomena or hypotheses, such as: (1) enhanced degradation of the insect cuticle or delayed ecdysis in response to M. anisopliae-chitosan due to a combined action of extracellular hydrolytic enzymes produced by fungi known for their effect on an insect cuticle [41,[52][53][54]; or (2) decreased efficiency to convert the consumed food into a growth and energy source through the possible diversion of energy from growth to the detoxification process [10,.…”

Characterization and Evaluation of Antimicrobial Potential of Trigonella incise (Linn) Mediated Biosynthesized Silver Nanoparticles

“…Therefore, the need for environmentally friendly production of Ag NPs has attracted attention in biogenic approaches. Several microorganisms, such as algae [ 16 ], bacteria [ 17 ] and fungi [ 18 ], have been utilized to demonstrate the use of successful synthesis of Ag NPs that reduces chemical expenses and chemical toxicity, and provides easy extraction. On the other hand, plant-based methods employed in Ag NPs synthesis are among the most widely used biological methods, due to their wide distribution, safe handling, ease of availability, and being a good source of metabolites.…”