تأثیر رژیم‌های دمایی روی فعالیت‌های آنزیمی لاروهای سن چهارم لمبه گندم، Trogoderma granarium Everts

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) is an important insect pest of stored products. Control of storage insect pests mainly has centered on the use of chemical pesticides. The problems associated with the use of many pesticides have led to do studies to find more environmentally safe control methods. Temperature is an important selective agent in nature. Consequently, temperature-induced plasticity which may help buffering detrimental effects of temperature variation has received considerable attention over recent decades. Laboratory studies have almost exclusively used constant temperatures, while in nature; temperature typically shows pronounced daily fluctuations. To overcome adverse effects of low temperature, several physiological mechanisms have been developed in insects of cold and temperate zones. In this study, activities of four enzymes (AMP-depended protein Kinase, protein phosphatase 1, protein phosphatase 2A and protein phosphatase 2C) of T. granarium larvae were investigated under different thermal regimes, i.e. control, cold-acclimated (CA), fluctuating-acclimated (FA) and rapid cold-hardened (RCH). Our results showed that the highest and lowest activities of AMP-depended protein kinase and protein phosphatase 2C were observed at CA and FA thermal regimes, respectively. But, no significant differences were observed in the activities of these two enzymes between control and CA. The highest and lowest activities of protein phosphatase 1 were observed at control and CA treatments, respectively. In case of protein phosphatase 2A the highest level of activity was recorded for control and FA thermal regimes, whereas, the lowest level of activity was showed in CA and RCH. These findings revealed that the shape of the thermal reaction in AMP-depended protein Kinase and protein phosphatase 2C follow a same norm that is different from those of protein phosphatase 1 and protein phosphatase 2A. Also, protein phosphatase 2A and 2C showed completely different thermal reaction norms. Thermal fluctuation cause the highest changes in the enzymes activities, whereas, the enzymes activities showed the lowest changes in RCH treatment. We demonstrate that the enzymes must be involved in regulating different facets of thermal acclimations of this insect