Sterol content in the artificial diet of Mythimna separata affects the metabolomics of Arma chinensis (Fallou) as determined by proton nuclear magnetic resonance spectroscopy

Abstract

Insects cannot synthesize sterols and must obtain them from plants. Therefore, reducing plant sterol content or changing sterol type might be an effective pest control strategy. However, the impacts of these changes on pests' natural predators remain unknown. Here, we fed artificial diets with reduced sterol content to Mythimna separata (Walker) (Lepidoptera: Noctuidae) and investigated the effects on its natural predator, Arma chinensis (Fallou) (Hemiptera: Pentatomidae). Reduced sterol content in M. separata (MS1, MS2, and MS5) was achieved by feeding them artificial diets prepared from a feed base subjected to one, two, or five cycles of sterol extractions, respectively. The content of most substances increased in A. chinensis (AC) groups feeding on MS2 and MS5. The content of eight substances (alanine, betaine, dimethylamine, fumarate, glutamine, glycine, methylamine, and sarcosine) differed significantly between the control (AC0) and treated (AC1, AC2, and AC5) groups. Metabolic profiling revealed that only AC5 was significantly distinct from AC0; the major substances contributing to this difference were maltose, glucose, tyrosine, proline, O-phosphocholine, glutamine, allantoin, lysine, valine, and glutamate. Furthermore, only two metabolic pathways, that is, nicotinate and nicotinamide metabolism and ubiquinone and other terpenoid-quinone biosynthesis, differed significantly between AC1 and AC5 and the control, albeit with an impact value of zero. Thus, the sterol content in the artificial diet fed to M. separata only minimally affected the metabolites and metabolic pathways of its predator A. chinensis, suggesting that A. chinensis has good metabolic self-regulation with high resistance to sterol content changes.

A Semi-Synthetic Diet and the Potential Important Chemicals for Mythimna separata (Lepidoptera: Noctuidae)

“…As one example, studies on insect sterol physiology are largely dependent on the availability of a sterol-free diet (Noland 1954; Kaplanis et al 1960; Jing et al 2012, 2014). Removing sterols from bulk materials is a costly and time-consuming process, and cumulated sterol residues in extracted materials can sometimes meet insect sterol requirement (Guo et al 2017). Phytosterols such as campesterol, stigmasterol, and sitosterol were successfully removed by the extractions (Table 1) and M. separata larvae were arrested in the first or second instar on Ch-extracted CLP (19%) diet unless cholesterol was added (Supp Fig.…”

Chromosome-level genome assembly of the predatory stink bug Arma custos

“…Notably, it has shown effective management of notorious invasive pests such as the fall webworm Hyphantria cunea , the Colorado potato beetle Leptinotarsa decemlineata , and the fall armyworm Spodoptera frugiperda through the augmentative release 6 – 8 . However, limited attention has been given to the investigation of the biological characteristics 9 – 11 , artificial rearing methods 3 , 5 , 12 , chemoecology 13 , response to temperature and drought stresses 8 , 14 – 17 , and developmental regulation by miRNA 18 of this predatory bug. In terms of its genetic information, only the mitochondrial genome and several transcriptomic datasets are available as the current genetic resources 13 , 15 , 16 , 18 , 19 .…”

Conservation motifs - a novel evolutionary-based classification of proteins

“…We identified 102 proteins (Supplementary Table 1.1, see Methods) and found that 14 proteins were related to 'steroid biosynthetic processes' (p-value: 4.88e-10, Supplementary Table 2.4). It was previously reported that insects cannot synthesize cholesterol and other sterols and that they obtain sterols externally from plants 43 , which they then convert to cholesterol to ensure normal growth, development, and reproduction 44,45 . This insect Clade Loss motif helps explain observations with a simple rationale and analysis.…”