Effects of Temperature on Cuticular Lipids and Water Balance in a Desert Drosophila: is Thermal Acclimation Beneficial

Abstract

The desert fruit fly Drosophila mojavensis experiences environmental conditions of high temperature and low humidity. To understand the physiological mechanisms allowing these small insects to survive in such stressful conditions, we studied the effects of thermal acclimation on cuticular lipids and rates of water loss of adult D. mojavensis. Mean hydrocarbon chain length increased at higher temperatures, but cuticular lipid melting temperature (Tm) did not. Lipid quantity doubled in the first 14 days of adult life, but was unaffected by acclimation temperature. Despite these changes in cuticular properties, organismal rates of water loss were unaffected by either acclimation temperature or age. Owing to the smaller body size of warm-acclimated flies, D. mojavensis reared for 14 days at 33 degrees C lost water more rapidly on a mass-specific basis than flies acclimated to 25 degrees C or 17 degrees C. Thus, apparently adaptive changes in cuticular lipids do not necessarily result in reduced rates of water loss. Avoidance of high temperatures and desiccating conditions is more likely to contribute to survival in nature than changes in water balance mediated by surface lipids.

The Resistance of Drosophila melanogaster to Oxidative, Genotoxic, Proteotoxic, Osmotic Stress, Infection, and Starvation Depends on Age According to the Stress Factor

“…During aging, a protective function of the lipid layer of the cell membrane and cuticle are disrupted as well as a consequence of the decreased activity of antioxidant systems during aging. The supply of water in in an organism also decreases, leading to a more rapid onset of a water deficit in tissues [86,87]. Thus, our study allowed us to estimate changes of stress resistance with age to a wide range of factors.…”

Dehydration and infection elicit increased feeding in the western flower thrips,Frankliniella occidentalis, likely triggered by glycogen depletion

“…The copyright holder for this preprint (which this version posted July 15, 2022. ; https://doi.org/10.1101/2022.07.14.499040 doi: bioRxiv preprint dehydration. For longer term dehydration, if thrips are, in fact, able to acclimate to better resist dehydration, we would expect to see a shift toward lipid metabolism as they are vital to increasing water retention properties (Gibbs et al 1998).…”

“…Interestingly, proteolysis has been seen in other similar studies to be upregulated during dehydration stress as a means to presumably break down and replace damaged proteins (Rosendale et al 2016). Additionally, a fairly common mechanism used by many insects to reduce water loss is the accumulation of cuticular hydrocarbons (Benoit et al 2007, Gibbs et al 1998). The lack of upregulated GO terms pertaining to proteolysis and cuticular hydrocarbons indicate that these are potentially not strategies utilized by thrips in order to resist water loss and damage due to desiccation.…”

“…This transcriptional shift was determined to be due to virus modulation in order to better disseminate from the midgut, but there was also postulation that this also likely influenced the outer cuticle as well. Transpiration through the cuticle is a main avenue for water loss which can be mitigated through modifications of the cuticle following exposure to bouts of dehydration (Benoit et al 2007, Benoit 2010, Gibbs et al 1998). Potentially, virus modulation may inadvertently be influencing the cuticle in such a way that thrips reap the benefit of increased resistance to desiccation, offering a possible explanation as to why there was an observed difference in water loss rates.…”

Effects of Thermal Acclimation on the Tolerance of Bactrocera zonata (Diptera: Tephritidae) to Hydric Stress

“…Similarly, when exposed to a desiccating environment, heat acclimated butterflies gained from reduced loss of body mass, possibly resulting from increased retention of water (Fischer and Kirste, 2018). However, in other cases (e.g., Drosophila: Gibbs et al, 1998, Chirodica beetles: Terblanche et al, 2005, thermal acclimation did not contribute to increased desiccation tolerance (see Chown et al, 2011 for other examples). Accordingly, thermal acclimation may affect the plasticity and tolerance of insects to extreme environmental humidity conditions, but such effects seem to be subject to variation (Chown et al, 2011;Terblanche and Hoffmann, 2020).…”