Cold Acclimation of Trogoderma granarium Everts Is Tightly Linked to Regulation of Enzyme Activity, Energy Content, and Ion Concentration

Abstract

In this study, cold hardiness and some physiological characteristics of the Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) larvae, were investigated under different thermal regimes, i.e., control, cold-acclimated (CA), fluctuating-acclimated (FA), and rapid cold-hardened (RCH). In all the regimes, the larval survival rate decreased with a decrease in temperature. CA larvae showed the highest cold hardiness following 24 h exposure at -15 and -20°C. Control larvae had the highest glycogen content (34.4 ± 2.3 μg/dry weight). In contrast, CA larvae had the lowest glycogen content (23.0 ± 1.6 μg/dry weight). Change in trehalose content was reversely proportional to changes in glycogen content. The highest myo-inositol and glucose contents were detected in CA larvae (10.7 ± 0.4 μg/dry weight) and control (0.49 ± 0.03 μg/dry weight), respectively. In control and treated larvae, [Na+] decreased, though [K+] increased, with increasing exposure time. The shape of the thermal reaction curve of AMP-depended protein kinase and protein phosphatase 2C followed the same norm, which was different from protein phosphatase 1 and protein phosphatase 2A. Protein phosphatase 2A and 2C showed a complete difference in thermal reaction norms. Indeed, thermal fluctuation caused the highest changes in the activity of the enzymes, whereas the RCH showed the lowest changes in the activity of the enzymes. Our results showed a significant enhancement of larval cold tolerance under CA regime, which is related to the high levels of low molecular weight carbohydrates under this regime. Our results showed that among the different thermal regimes tested, the CA larvae had the lowest supercooling point (about -22°C) and the highest cold hardiness following 24 h exposure at -15 and -20°C.

Effects of rapid cold-hardening and cold acclimation on egg survival and cryoprotectant contents in Ceracris kiangsu (Orthoptera: Arcypteridae)

“…The biochemical mechanisms associated with cold tolerance induced by RCH and ACC may exhibit species-specific variations. For example, certain insect species may accumulate identical cryoprotectants following exposure to RCH and ACC according to studies conducted by Overgaard et al (2007), Michaud and Denlinger (2007), Koštál et al (2011), and Izadi et al (2019, whereas others may accumulate distinct substances, as demonstrated by Mohammadzadeh and Izadi (2018). In the present study, the survival rates of overwintering C. kiangsu eggs collected from the field were positively correlated with the duration of RCH treatment, whereas the survival rates of ACC treated eggs had a negative correlation as the duration of treatment increased.…”

“…The ability of insects to endure exposure to low temperatures, known as cold tolerance or cold hardiness, depends on various factors, such as the developmental stage, genetic potential, intensity and duration of cold, and nutritional and physiological status of the insect species (Lee 1989, Izadi et al 2019). Insects may enhance their survival rate at sub-zero temperatures through either rapid cold-hardening (RCH) or cold acclimation (ACC), which refer to brief or prolonged pre-exposure to less severe low temperatures, respectively (Shintani and Ishikawa 2007, Lee and Denlinger 2010, Mohammadzadeh and Izadi 2018, Pei et al 2023). The ACC response typically requires weeks or months to achieve maximal cold tolerance and it occurs frequently in diapausing insects.…”

Gradually Increasing the Temperature Reduces the Diapause Termination Time of Trichogramma dendrolimi While Increasing Parasitoid Performance

“…In addition, fluctuating temperature also regulated the activity of the enzymes. For example, in the Khapra beetle, Trogoderma granarium , the individuals under fluctuating temperatures had the highest changes in the activity of the enzymes, which was significantly higher than that under rapid cold-hardened conditions [ 54 ].…”

Biochemical Toxic Response of Phosphine on Human Health Estimated From Enzymatic Variance in Trogoderma granarium

“…Furthermore, the whole body of the acclimatized larvae of Khapra beetles was used and homogenized with the help of centrifuging. 11 …”