Seasonal changes in supercooling capacity and major cryoprotectants of overwinteringAsian longhorned beetle (Anoplophora glabripennis) larvae

Abstract

1 The Asian longhorned beetle is a destructive trunk borer in forests and urban landscape trees. 2 Dynamic changes in the supercooling capacity of Anoplophora glabripennis larvae in a natural population and the mechanism of cold hardiness during different overwintering periods at physiological and biochemical levels were explored. 3 The results showed that the supercooling point of overwintering larvae decreased initially before increasing subsequently with seasonal changes in ambient temperature. Fresh mass and glycogen tended to decrease initially and then reached their minimum levels in January. Total amounts of low molecular weight substances and free amino acids in the haemolymph increased gradually as the ambient temperature decreased. Glycerol (779.80 ± 29.10 μm/mL) and trehalose (104.35 ± 12.38 μm/mL) concentrations were always higher than those of glucose and mannitol. All low molecular weight substances (besides trehalose) were almost metabolized by early spring. The concentrations of serine, phenylalanine, valine, leucine, proline, glutamic acid and alanine all reached their highest level in the colder winter months. 4 The results of the present study suggest that A. glabripennis larvae accumulate cryoprotectants to improve their supercooling capacity, and enhance cold hardiness by reducing the supercooling point with respect to a decrease in ambient temperature until freezing temperatures appear. Anoplophora glabripennis larvae are a freeze-tolerant insect.

Autumn shifts in cold tolerance metabolites in overwintering adult mountain pine beetles

“…In European populations of Ips typographus (Coleoptera: Curculionidae), trehalose undergoes a similar increase through October in response to cold temperatures [30]. Trehalose can also act as a cryoprotectant, stabilizing proteins at cold temperatures and keeping cellular membranes intact [31]. Increasing the durability of cellular membranes would reduce cellular damage in the event of changing osmotic pressure or ice crystal formation.…”

Cold tolerance of Trissolcus japonicus and T. cultratus, potential biological control agents of Halyomorpha halys, the brown marmorated stink bug

“…However, during the onset of fall and through the winter, these strategies may change as insects acclimatize to decreasing temperatures and photoperiods (Hefty, 2016). Acclimatization can result in an increase in cold tolerance over the course of a season (Crosthwaite et al, 2011;Feng et al, 2016;Udaka and Sinclair, 2014). Therefore, it is important to try to quantify indices of cold tolerance after prolonged exposure to cold temperatures and shorter photoperiods to see if there are any changes over time.…”

Autumn shifts in cold tolerance metabolites in overwintering adult mountain pine beetles

“…In European populations of Ips typographus (Coleoptera: Curculionidae), trehalose undergoes a similar increase through October in response to cold temperatures (Koštál et al 2011). Trehalose can also act as a cryoprotectant, stabilizing proteins at cold temperatures and keeping cellular membranes intact (Feng et al 2016). Increasing the durability of cellular membranes would reduce cellular damage in the event of changing osmotic pressure or ice crystal formation.…”