Biodegradation of pesticide in agricultural soil employing entomopathogenic fungi: Current state of the art and future perspectives

Biological Diversity Associated with Pesticides Residues in Certain Egyptian Watercourses

The aquatic environment has been contaminated by pyrethroids and triazole pesticide applications, which pose serious health risks to the aquatic ecosystem and human beings. Therefore, the current study aims to evaluate water quality parameters, fungal diversity, and distribution of snails and aquatic plants of certain Egyptian water courses contaminated with pyrethroids and triazole pesticides. Seasonal samples were taken throughout 2021 from different water courses at Giza Governorate and Tanta (Gharbeya Governorate). Qualitative and quantitative surveys showed significant differences in water physical parameters between the two investigated governorates. Deltamethrin, permethrin, Es-fenvalerate, and lambada-cyhalothrin showed the highest pyrethroids concentrations, while tebuconazole, tetraconazole, and difenoconazole were the highest triazole concentrations. Fungal diversity displayed 21 molecularly identified fungal species related to four fungal genera: Aspergillus, Fusarium, Penicillium, and Trichoderma. Penicillium sp. and Aspergillus niger were the most frequent species. Snail diversity recorded 10 and 9 species in Giza and Tanta, respectively. Physa acuta was the most abundant snail. Ten species of aquatic plants were observed in Giza, while six species were observed in Tanta. Specifically, Eichhornia crassipes and Lemna gibba were the dominant species in the two governorates, with the relative abundance (39 and 22%) in Giza and (27 and 23%) in Tanta, respectively. Water quality parameters and seasonal variations could control fungal diversity, snails, and aquatic plant distribution. Different relations between pesticides and biological communities may reflect the ability/inability of certain snails and fungi species to commensalism with pesticide concentrations. Continuous pesticide monitoring is essential for life below water and aligns with SDG14.

Metabolic mechanism of lignin-derived aromatics in white-rot fungi

White-rot fungi, such as Phanerochaete chrysosporium, play a crucial role in biodegrading lignocellulosic biomass including cellulose, hemicellulose, and lignin. These fungi utilise various extracellular and intracellular enzymes, such as lignin peroxidases, manganese peroxidases, versatile peroxidases, monooxygenases, and dioxygenases, to degrade lignin and lignin-derived aromatics, thereby significantly contributing to the global carbon cycle with potential applications in industrial bioprocessing and bioremediation. Although the metabolism of lignin fragments in P. chrysosporium has been studied extensively, the enzymes involved in fragment conversion remain largely unknown. This review provides an overview of the current knowledge regarding the metabolic pathways of lignin and its fragments by white-rot fungi. Recent studies have elucidated the intricate metabolic pathways and regulatory mechanisms of lignin-derived aromatic degradation by focusing on flavoprotein monooxygenases, intradiol dioxygenases, homogentisate dioxygenase-like proteins, and cytochrome P450 monooxygenases. Metabolic regulation of these enzymes demonstrates the adaptability of white-rot fungi in degrading lignin and lignin-derived aromatics. The interplay between the central metabolic pathways, haem biosynthesis, and haem-dependent NAD(P)H regeneration highlights the complexity of lignin degradation in white-rot fungi. These insights improve our understanding of fungal metabolism and pave the way for future studies aimed at leveraging these fungi for sustainable biotechnological applications. KEY POINTS: • White-rot fungi use enzymes to degrade lignin, and play a role in the carbon cycle. • Oxygenases are key enzymes for converting lignin-derived aromatics. • White-rot fungi adapt to metabolic changes by controlling the TCA/glyoxylate bicycle.

Secondary metabolites in Cordyceps javanica with insecticidal potential

Cordyceps javanica has been registered as a fungal insecticide in several countries. However, little is known about whether metabolic toxins are involved in the insecticidal process. In this research, we assessed the insecticidal activity of the fermentation broth of C. javanica. Myzus persicae mortality differed when exposed to the metabolized C. javanica broths at 3 days post fermentation (DPF) and 5 DPF. Comparison of the metabolic fluid at 3 DPF and 5 DPF revealed a key alkaloid, heteratisine, which was found to have insecticidal activity and acetylcholinesterase (AChE) inhibitory activity. Heteratisine has high insecticidal activity against adult M. persicae, the absolute 50% lethal concentration (LC50) was only 0.2272 mg/L. Heteratisine showed high inhibitory activity on AChE with the 50% maximal inhibitory concentration (IC50) of 76.69 μM. Molecular docking and dynamic simulations showed that heteratisine conjugation occurs at the peripheral anionic site (PAS) of the AChE of M. persicae, leading to suppression of enzyme activity. Heteratisine was rarely found in fungal metabolites, which helps us to understand the complex and elaborate insecticidal mechanism of C. javanica.

Biology, classification, and entomopathogen-based management and their mode of action on Tuta absoluta (Meyrick) in Asia

Tuta absoluta, known as the South American tomato leaf miner, significantly impacts tomato plants (Solanum lycopersicum) economically on a global scale. This pest, belonging to the Gelechiidae family, is native to South America and was first identified in Peru in 1917. Since its discovery, T. absoluta has rapidly spread to Europe, Africa, and Asia, severely threatening tomato production in these regions. The widespread application of chemical pesticides against this pest has resulted in significant environmental harm, including contamination of soil and water, and has had negative effects on non-target species such as beneficial insects, birds, and aquatic life. Although substantial research has been conducted, biological control methods for T. absoluta remain insufficient, necessitating further study. This review covers the Biology, Classification, and Entomopathogen-Based Management of T. absoluta (Meyrick) in Asia. It provides essential insights into the pest's life cycle, ecological impacts, and the potential of entomopathogens as biocontrol agents. The detailed information presented aims to facilitate the development of sustainable pest control strategies, minimizing environmental impact and promoting the use of entomopathogens as viable alternatives to chemical pesticides in controlling T. absoluta insect pest.

Biocontrol effects of chemical molecules derived from Beauveria bassiana against larvae of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

In this study, we conducted tests on the isolation, identification, characterization, and extraction of chemical molecules from Beauveria bassiana against Tuta absoluta larvae. The enzyme responses of T. absoluta to the crude extract were examined 24 h after treatment, and the number of dead larvae was calculated 24 and 48 h after treatment. Molecular docking studies were conducted to assess the interaction of important molecules with the acetylcholinesterase enzyme. The larvicidal activity of crude chemicals from fungi was high 24 h after treatment, with LC50 and LC90 values of 25.937 and 33.559 μg/mL, respectively. For a period of 48 h, the LC50 and LC90 values were 52.254 and 60.450 μg/mL, respectively. The levels of acetylcholinesterase, α-carboxylesterase, and β-carboxylesterase enzymes were lower in the treatment group after 24 h compared to the control group. The GC-MS test revealed that the crude extract consisted mainly of 9,10-octadecadienoic acid, which was the primary compound. Docking results indicated that 9,10-octadecadienoic acid showed a strong interaction with acetylcholinesterase (AChE). Our findings suggest that the chemical molecule 9,10-octadecadienoic acid derived from the entomopathogenic fungus B. bassiana is more toxic to T. absoluta larvae. We plan to conduct studies to test its effectiveness in semi-field conditions and to evaluate its stability in field conditions. We believe that this 9,10-octadecadienoic acid molecule could be used to control T. absoluta larvae in the near future without causing environmental pollution.