Down-Regulation of P450 Genes Enhances Susceptibility to Indoxacarb and Alters Physiology and Development of Fall Armyworm, Spodoptera frugipreda (Lepidoptera: Noctuidae)

Abstract

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a pest of many important crops globally. Effective control is challenging, with the pest exhibiting resistance to different synthetic pesticides across various groups. However, the mechanisms employed by resistant insects for overexpression of relevant detoxification genes remain unclear. The activity of detoxification enzymes was investigated in this study. Additionally, using RNA interference (RNAi), a functional analysis was completed of two P450s genes in an indoxacarb resistant population of fall armyworms. Elevated resistance levels (resistance ratio = 31.37-fold) in indoxacarb-selected populations of FAW were observed after 14 generations. The qRT-PCR showed higher expression of two cytochrome P450 genes, CYP321A7 and CYP6AE43, in this selected population compared to the control population. RNAi was applied to knock down the P450 dsCYP321A7 and dsCYP6AE43 genes in the FAW larvae. Droplet feeding of the dsRNAs (CYP321A7 and CYP6AE43) via an artificial diet significantly increased mortality rates in the indoxacarb treated population. A shorter larval developmental time of FAW was detected in all dsRNAs-fed larvae. Correspondingly, larval mass was reduced by dsRNAs in indoxacarb resistant populations of fall armyworm. Larval feeding assays demonstrate that dsRNAs targeting, specifically of CYP321A7 and CYP6AE43 enzymes, could be a beneficial technique in the management of indoxacarb resistant populations. Further study on the potential use of dsRNA and its application should be conducted in efforts to counter the development of resistance in FAW against various insecticides in the field.

Molecular characterization and functional analysis of cytochrome P450-mediated detoxification CYP302A1 gene involved in host plant adaptation in Spodoptera frugieprda

“…Similarly, it has been reported that the midgut fat bodies and Malpighian tubules are frequently associated with higher P450 activity ( Hu et al., 2014 ;). In addition, the midgut is a highly crucial organ in the process of detoxification, and the genes that code for the detoxification enzymes involved in this process are frequently highly regulated in this organ ( Feyereisen, 2006a ; Hafeez et al., 2022 ). In this study, we investigated the expression profile of CYP302A1 in different tissues and developmental stages of S. frugiperda by quantitative RT-qPCR.…”

“…In this study, we used the droplet-feeding method for RNAi to prevent damage to S. frugiperda larvae as previously defined by ( Wang et al., 2018b ; Hafeez et al., 2022 ). The dsRNA was first diluted (250 μg/μL total volume of 500μL) in diethylpyrocarbonate (DEPC)-treated water before dsRNA feeding experiments.…”

Assessment of sublethal and transgenerational effects of spirotetramat, on population growth of cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae)

“…Sublethal and transgenerational effects of spirotetramat affected developmental physiology, indicating the role of sublethal concentrations in larval growth, development, and sensitivity to spirotetramat. In previous studies, Physiological and biochemical studies have shown that P450 enzymes are vital to in insect hormone metabolism pathways but details of the molecular processes remain unknown ( Iga and Kataoka, 2012 ; Hafeez et al, 2022 ). The growth and developmental physiology of B. brassicae was hindered after being treated with sublethal concentrations of spirotetramat, but how these sublethal concentrations regulate this process requires further study.…”

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

“…Due to their central function in pesticide metabolism, cytochrome P450s are frequently implicated in the development of insect resistance to these chemicals ( Guo et al, 2012 ; Panini et al, 2016 ). One of the most prevalent processes by which insect pests develop resistance to synthetic insecticides is the upregulation of certain detoxifying P450 enzymes within the insect ( Nelson, 2011 ; Hafeez et al, 2022a ; Luo et al, 2022 ). Because of this, insecticide resistance may develop as a result of changes in the activity of detoxifying enzymes in insects in response to exposure to pesticides.…”

“…Because of this, insecticide resistance may develop as a result of changes in the activity of detoxifying enzymes in insects in response to exposure to pesticides. Many insect orders, including Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera, have shown evidence of P450 overexpression leading to increased resistance to pesticides ( Bass et al, 2011 ; Johnson et al, 2012 ; Liang et al, 2015 ; Wang et al, 2015 ; Chen et al, 2017 ; Khan et al, 2021a ; Khan et al, 2021c ; Hafeez et al, 2022a ; Siddiqui et al, 2022b ).…”