Contribution of insect gut microbiota and their associated enzymes in insect physiology and biodegradation of pesticides

Abstract

Synthetic pesticides are extensively and injudiciously applied to control agriculture and household pests worldwide. Due to their high use, their toxic residues have enormously increased in the agroecosystem in the past several years. They have caused many severe threats to non-target organisms, including humans. Therefore, the complete removal of toxic compounds is gaining wide attention to protect the ecosystem and the diversity of living organisms. Several methods, such as physical, chemical and biological, are applied to degrade compounds, but as compared to other methods, biological methods are considered more efficient, fast, eco-friendly and less expensive. In particular, employing microbial species and their purified enzymes makes the degradation of toxic pollutants more accessible and converts them into non-toxic products by several metabolic pathways. The digestive tract of insects is usually known as a superior organ that provides a nutrient-rich environment to hundreds of microbial species that perform a pivotal role in various physiological and ecological functions. There is a direct relationship between pesticides and insect pests: pesticides reduce the growth of insect species and alter the phyla located in the gut microbiome. In comparison, the insect gut microbiota tries to degrade toxic compounds by changing their toxicity, increasing the production and regulation of a diverse range of enzymes. These enzymes breakdown into their derivatives, and microbial species utilize them as a sole source of carbon, sulfur and energy. The resistance of pesticides (carbamates, pyrethroids, organophosphates, organochlorines, and neonicotinoids) in insect species is developed by metabolic mechanisms, regulation of enzymes and the expression of various microbial detoxifying genes in insect guts. This review summarizes the toxic effects of agrochemicals on humans, animals, birds and beneficial arthropods. It explores the preferential role of insect gut microbial species in the degradation process and the resistance mechanism of several pesticides in insect species. Additionally, various metabolic pathways have been systematically discussed to better understand the degradation of xenobiotics by insect gut microbial species.

Studying Plant–Insect Interactions through the Analyses of the Diversity, Composition, and Functional Inference of Their Bacteriomes

“…Other enzymes that could be involved are the dye-decolourizing peroxidase (DyP), glutathione-S-transferase (GST), and phenol oxidases that participate in the degradation of toluene or xylene [ 91 ]. One of the many functions attributed to the gut microbiota is the degradation of xenobiotics [ 3 , 25 , 91 , 93 ], thus, the efficiency of detoxification mechanisms might be better understood as the result of the interaction between these enzymes in both the plant and the insect [ 92 , 108 , 115 , 116 ].…”

Insights into insecticide-resistance mechanisms in invasive species: Challenges and control strategies

“…Insect metabolism is critical in the development of pesticide resistance against various groups of chemical pesticides, including carbamates, organophosphates, and synthetic pyrethroids. Insects metabolize insecticides to less toxic or non-toxic forms via a mechanism called “detoxification” ( Jaffar et al, 2022 ). Metabolic resistance is of huge importance and is also one of the most studied mechanisms in insects.…”

Comparative genomics of pesticide-degradingEnterococcussymbionts ofSpodoptera frugiperda(Lepidoptera: Noctuidae) leads to the identification of two new species and the reappraisal of insect-associatedEnterococcusspecies

“…7). Hydrolases (139) and transferases (223) were the major groups of functionally annotated enzymes followed by oxidoreductases (77), ligases (62), lyases (46), and isomerases (44) (Supplementary Table S10).…”