~ 163 ~ Journal of Entomology and Zoology Studies 2014; 2 (2): 163-170 ISSN 2320-7078 JEZS 2014; 2 (2): 163-170 © 2014 JEZS Received: 03-03-2014 Accepted: 10-05-2014 Koushik Ponnanna CR Drosophila Stock Center, Department Of Studies in Zoology, University of Mysore, Manasagangothri, Mysore- 570006. Email: koushik.c.r@gmail.com Krishna MS Drosophila Stock Center, Department Of Studies in Zoology, University of Mysore, Manasagangothri, Mysore- 570006 Email: drosokrish@gmail.com Correspondence: Krishna MS Drosophila Stock Center, Department Of Studies in Zoology, University of Mysore, Manasagangothri, Mysore- 570006 Email: drosokrish@gmail.com Short term sub lethal temperature treatment increases starvation resistance in D. melanogaster Koushik Ponnanna CR and Krishna MS ABSTRACT Today’s changing environment imposes challenge to the regular homeostasis of organisms, which forces them to face periods of stressful conditions. The changing environmental conditions can evoke a genetic response in organisms which is of a major interest of study in population biology. Influence of short term sub lethal temperature exposure on starvation resistance has been studied in out bred population of Drosophila melanogaster. It was noticed that short term sub lethal temperature treated flies significantly mated faster, copulated longer, transferred greater quantity of Accessory proteins to mated females and these females had greater resistance to starvation than untreated flies suggesting that during extreme thermal conditions and food deprivation, mating is highly beneficial for females as it confers resistance towards starvation. This study rules out the idea that mating may impair female fitness as proposed earlier. Keywords: Drosophila melanogaster, starvation resistance, sub lethal temperature, accessory gland proteins 1. Introduction The homeostasis of organisms has been under constant pressure due to the changing environment which has forced them to face periods of stressful conditions [11] . The changing environmental conditions can evoke a genetic response in organisms which is of a major interest of study in population biology. Drastic changes caused by environment and human activities impart mechanisms which allow the species to survive and adapt to such changes. Focus on such genetic response can help in understanding the adaptation mechanisms [1] . Temperature function has been investigated and characterized for extreme conditions and tolerance of cold and heat stress [16][18] . Except that in nature, there is a greater chance for the ectotherms to undergo transient weather conditions that will have direct effect on their body temperature [20] . Most of the present research focuses on studies carried out by maintaining organisms in the laboratory under fixed rearing temperatures. Not much data is available with regards to short-term exposure to extreme temperatures except in regards with few [4, 7, 21, 33, 36] .Studies in D. melanogaster for chronic temperature exposure have provided a lot of information pertaining to the performance and life history traits [8, 16] . As observed by Levins, [22] pre-exposure to a non-lethal high temperature can improve the fitness of flies exposed to heat stress. Fecundity has been shown to increase with temperature upto 25 °C with a marking decrease between 28° to 30° [9, 19, 24, 30, 32] . Pretreatment has shown improved survival rate for both sexes of D. buzzatii with an increased probability of females producing any offspring following the stress. Negative effects of short term high temperature exposure have been associated with the induction of the heat shock response as a protein quality control system [34] . Benefits of a short term high temperature treatment are usually not instantaneous, tending to reach a maximum several hours after the treatment [6] , with hardening‐induced changes in gene expression that mostly return to its normal values after about 4h. Thus, negative and positive consequences of short term temperature treatment run on a different time course. For instance, a mild heat stress reduces fecundity only during the time of exposure, while benefits of this hardening treatment on heat resistance and longevity can last much longer [14] .