Larval Heat Stress Affects the Lifespan and Stress Resistance of Drosophila melanogaster Adults

In modern conditions of constant adverse effects on living organisms, such as environmental pollution or global climate change, the study of deeply conserved mechanisms that contribute to the adaptation of animals to such conditions is of particular relevance. The influence of stress suffered at early stages of development on the formation of fitness and the endocrine status of adults has been repeatedly shown in various species of mammals. However, similar studies on arthropods have not previously been carried out, and one of the key differences between the ontogeny of holometabolous insects from mammals is metamorphosis, including the formation of a pupa and the histolysis of tissues and organs with the subsequent formation of new structures from its products and imaginal discs, which are formed in early ontogenesis. As a result, an almost new organism, an imago, is formed. Are the metabolic changes that occurred in the insect's body under the influence of unfavorable external influences before the imaginal moult preserved, or does metamorphosis "erase" them? To answer this question, the effect of heat stress experienced by the larvae of Drosophila melanogaster on such signs of adult fitness as longevity, response to acute heat stress, and resistance to it is studied. The study results show that early mortality is reduced due to larval stress in both D. melanogaster males and females, although no changes in the maximum lifespan are recorded. At the same time, early stress leads to a decrease in resistance to acute heat stress and a corresponding drop in alkaline-phosphatase activity in both sexes. Thus, we can conclude that heat stress experienced by D. melanogaster during the larval stage is not "reset" by metamorphosis, and causes significant changes in the fitness of adult individuals.