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.