Effects of starvation on the carbohydrate metabolism in Harmonia axyridis (Pallas)

Abstract

Trehalose plays an important role in energy storage, metabolism, and protection from extreme environmental conditions in insects. Trehalose is the main blood sugar in insects, and it can be rapidly used as an energy source in times of need. To elucidate the mechanisms of the starvation response, we observed the effects of starvation on trehalose and glycogen, trehalase activity, and the relative gene expression of genes in the trehalose and glycogen metabolic pathways in the invasive beetle Harmonia axyridis. Our results show that trehalose levels and the activities of two types of trehalases decreased significantly in the first 8 h of starvation, while the relative expression of HaTreh1-1 increased. While trehalose remained nearly constant at a relatively high level from 8 to 24 h, glycogen levels decreased significantly from 8 h to 24 h of starvation. Likewise, glycogen phosphorylase (HaGP) expression was significantly higher at 12 to 24 h starvation than the first 8 h, while the expression of glycogen synthase (HaGS) was relatively stable. Furthermore, trehalose decreased significantly from 24 h starvation to 72 h starvation, while trehalase activities and the relative expression of some HaTreh genes generally increased toward the end of the starvation period. The expression of trehalose-6-phosphate synthase (HaTPS) increased significantly, supporting the increase in trehalose synthesis. These results show that trehalose plays a key role in the energy provided during the starvation process through the molecular and biochemical regulation of trehalose and glycogen metabolism.

Selection and evaluation of reference genes for expression analysis using quantitative real-time PCR in the Asian Ladybird Harmonia axyridis (Coleoptera: Coccinellidae)

“…Moreover, RP49 was also used as internal control to study the expression of genes in the H . axyridis trehalase and glycogen metabolic pathways [ 51 , 52 ]. Vilcinskas et al [ 53 ] also used RPS3 , another member of ribosomal protein family, as a reference gene in a study of genes encoding antimicrobial peptides and proteins, while study of immunity-related genes was exclusive of our setting conditions.…”

Invertebrate Trehalose-6-Phosphate Synthase Gene: Genetic Architecture, Biochemistry, Physiological Function, and Potential Applications

“…During 18-h starvation, the maximum distance by which Harmonia axyridis moved initially increased and then decreased with time and falling levels of trehalose and glycogen as well as with the reduction in TPS expression. This indicates that insects need to consume trehalose to search for food (Tang et al, 2014b ; Shi et al, 2017 ). The Arctic collembolan Onychiurus arcticus can survive winter temperatures of −25°C by increasing trehalose concentrations, decreasing glycogen reserves, and reducing TRE activity as temperature decreases.…”

The distinct phenotypic signatures of dispersal and stress in an arthropod model: from physiology to life history

“…This is a physiological signature of a starved state, characterized by individuals relying on, and depleting, their body reserves, including carbohydrates (e.g. Dus et al, 2011;Shi et al, 2017;Zhang et al, 2019). Surprisingly, there were no other metabolic differences between tomato-and bean-exposed mites, Fig.…”