Seasonal Change of Gelycerol Contents in Insect Larvae(case studyZayanderud river)

In recent years, global climate change and water resources drought was the most important enviromental stress in aquatic life to be tolerable levels of temperature and humidity changes. The thermal shock and drying in summer, and cold shock and freezing in winter are the factors for determination of survival strategy invertebrates. Diapause and anhydrobiosis are the adaptation for survival in organisms. The accumulation of sugurs and polyol are the common physiological characteristic among anhydrobiotic organisms. The sampling carried out for one year from autumn 2015 to summer 2016 each season from two The amount of glycerol were 18.31, 7.65, 17.63 and 23.21 µg/mg wet weight for Simuliidae during spring, summer, autumn and winter, respectively.; and for Tipulidae were 8.19, 7.36, 30.35 and 8.97 µg/mg wet weight; and for Baetidae were 44.43, 17.85, 38.07 and 11.13 µg/mg wet weight. In Simuliidae the glycerol contents did not significant differences among summer and autumn (P > 0.05) while had significant differences (P < 0.05) in other seasons. In Tipulidae the glycerol had not significant differences in spring and summer (P > 0.05) and also had not significant differences in spring and winter (P > 0.05) while had significant differences (P < 0.05) in autumn with the other seasons. In the Baetidae the glycerol contents showed significant differences among different seasons (P < 0.05). The increasing polyols with of low molecular weight associated with diapause and anhydrobiosis In early autumn the insect larvae which exposed to cold shock increased the cryoprotectant components and consumed them as antifreezing. In addition, the insect larvae increased the antifreezing agents which make them to survive in the high temperature and desiccation during summer. This study illustrated that the insect larvae response to environment ecological conditions by glycerol content, especially during freezing and desiccation.