Cold tolerance strategies of the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)

Youngjin Park,Mohammad Vatanparast

doi:10.1038/s41598-022-08174-4

Youngjin Park, Mohammad Vatanparast

Open Access

https://doi.org/10.1038/s41598-022-08174-4

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Journal: Scientific Reports	Publication Date: Mar 8, 2022
Citations: 6	License type: open-access

Affiliation: Animal and Plant Quarantine Agency

Abstract

The fall armyworm (FAW), Spodoptera frugiperda, is native to the tropical and subtropical areas of the American continent and is one of the world's most destructive insect pests and invaded Africa and spread to most of Asia in two years. Glycerol is generally used as a cryoprotectant for overwintering insects in cold areas. In many studies, the increase in glycerol as a main rapid cold hardening (RCH) factor and enhancing the supercooling point was revealed at low temperatures. There are two genes, including glycerol-3-phosphate dehydrogenase (GPDH) and glycerol kinase (GK), that were identified as being associated with the glycerol synthesis pathway. In this study, one GPDH and two GK sequences (GK1 and GK2) were extracted from FAW transcriptome analysis. RNA interference (RNAi) specific to GPDH or GK1 and GK2 exhibited a significant down-regulation at the mRNA level as well as a reduction in survival rate when the RNAi-treated of FAW larvae post a RCH treatment. Following a cold period, an increase in glycerol accumulation was detected utilizing high-pressure liquid chromatography and colorimetric analysis of glycerol quantity in RCH treated hemolymph of FAW larvae. This research suggests that GPDH and GK isozymes are linked to the production of a high quantity of glycerol as an RCH factor, and glycerol as main cryoprotectant plays an important role in survival throughout the cold period in this quarantine pest studied.

Highlights

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is native to the American continent’s tropical and subtropical regions[1]
The glycerol-3-phosphate dehydrogenase (GPDH) and glycerol kinase (GK) genes were predicted to be involved in the synthesis of glycerol, which is an important cryoprotectant in insects when temperatures are extremely low
Based on comparisons with other well-known insect proteins, the threedimensional structures of Sf-GPDH, Sf-GK1, and Sf-GK2 proteins were predicted using the homology modeling method (Fig. 3). These findings indicated that the sequences of Sf-GPDH and two Sf-GKs closely matched the homologous templates on the server, indicating that these protein models were reliable

Summary

Introduction

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is native to the American continent’s tropical and subtropical regions[1] It is a polyphagous insect, and due to its wide host range, it is one of the most dangerous pests affecting tropical annual c rops[2,3]. The geographical place, ecological climate, and climatic conditions of these areas are all intertwined Many seasonal pests, such as rice plant hoppers (Nilaparvata lugens (Stål), Sogatella furcifera (Horváth), and Laodelphax striatellus (Fallén)) and the oriental armyworm, Mythimna separate (Walker), can fly from China to Japan and the K orea[12–14]. According to a recent study on the cold hardiness of invasive FAW species in China, pupae and older larvae have a much higher survival rate than eggs and younger larvae, and FAW can live in some southern areas of China’s subtropical zone during the winter based on the SCPs of developmental stages at low temperatures and China’s climatic regionalization. To investigate the function of glycerol, we used RNA interference (RNAi) to knock down genes involved in glycerol biosynthesis and examined the intensity of RCH and glycerol accumulation

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Results

Conclusion