A trade-off between desiccation resistance and developmental humidity for pupation height in the North Indian seasonal population of Drosophilid-Zaprionus indianus.

Drosophila larvae and pupae are vulnerable to seasonal abiotic stressors such as humidity and temperature. In wild low-humidity habitats, desiccation stress can occur as Drosophila larvae forsake wet food in search of a drier pupation site. Henceforth, the hypothesis that developmental humidity impacts pupation height, affecting larval and pupae water balance and fitness-related traits, was examined.

Adaptive changes in energy reserves and effects of body melanization on thermal tolerance in Drosophila simulans.

Seasonally polyphenic types have been documented in many Drosophilids, which differ significantly during thermal stress. Although Drosophila simulans is a sibling species to Drosophila melanogaster, both thrive in the temperate and tropical climates, but various climatic factors are expected to impact their distribution and abundance. As a result, D.

Developmental and adult acclimation impact cold and drought survival of invasive tropical Drosophila kikkawai.

Narrow distribution patterns of tropical Drosophila species are limited by lower resistance to cold or drought. In the invasive tropical Drosophila kikkawai, we tested whether developmental and adult acclimations at cooler temperatures could enhance its stress resistance level. Adult acclimation of winter collected body color morphs revealed a significant increase in the level of cold resistance.

Plastic changes in cold and drought tolerance of Drosophila nepalensis correlate with sex-specific differences in body melanization, cuticular lipid mass, proline accumulation, and seasonal abundance.

Autumn-collected flies of Himalayan Drosophila nepalensis differ in body color phenotypes (males more melanized relative to females) and in their behavior (males abundant in the open sites vs. shelters-seeking females). In contrast, winter-collected flies of both sexes are equally melanized and abundant in the open sites.

Cold acclimation conditions constrain plastic responses for resistance to cold and starvation in .

In montane species, cold-induced plastic changes in energy metabolites are likely developed to cope with cold and starvation stress. Adult reared at 15°C were acclimated at 0°C or 7°C for durations of up to 6 days (fed or unfed conditions). Such flies were tested for plastic changes in resistance to cold or starvation stress as well as for possible accumulation and utilization of four energy metabolites (body lipids, proline, trehalose and glycogen).

Heat- and humidity-induced plastic changes in body lipids and starvation resistance in the tropical fly during wet and dry seasons.

Insects in tropical wet or dry seasons are likely to cope with starvation stress through plastic changes (developmental as well as adult acclimation) in energy metabolites. Control and experimental groups of flies were reared under wet or dry conditions, but adults were acclimated at different thermal or humidity conditions. Adult flies of the control group were acclimated at 27°C and low (50%) or high (60%) relative humidity (RH).

Tropical of wet-dry seasons show cross resistance to heat, drought and starvation.

Plastic responses to multiple environmental stressors in wet or dry seasonal populations of tropical species have received less attention. We tested plastic effects of heat hardening, acclimation to drought or starvation, and changes in trehalose, proline and body lipids in flies reared under wet or dry season-specific conditions. Wet season flies revealed significant increase in heat knockdown, starvation resistance and body lipids after heat hardening.

Cross-tolerance effects due to adult heat hardening, desiccation and starvation acclimation of tropical drosophilid-Zaprionus indianus.

Some insect taxa from polar or temperate habitats have shown cross-tolerance for multiple stressors but tropical insect taxa have received less attention. Accordingly, we considered adult flies of a tropical drosophilid-Zaprionus indianus for testing direct as well as cross-tolerance effects of rapid heat hardening (HH), desiccation acclimation (DA) and starvation acclimation (SA) after rearing under warmer and drier season specific simulated conditions. We observed significant direct acclimation effects of HH, DA and SA; and four cases of cross-tolerance effects but no cross-tolerance between desiccation and starvation.

Effects of saturation deficit on desiccation resistance and water balance in seasonal populations of the tropical drosophilid Zaprionus indianus.

Seasonally varying populations of ectothermic insect taxa from a given locality are expected to cope with simultaneous changes in temperature and humidity through phenotypic plasticity. Accordingly, we investigated the effect of saturation deficit on resistance to desiccation in wild-caught flies from four seasons (spring, summer, rainy and autumn) and corresponding flies reared in the laboratory under season-specific simulated temperature and humidity growth conditions. Flies raised under summer conditions showed approximately three times higher desiccation resistance and increased levels of cuticular lipids compared with flies raised in rainy season conditions.

Cold and desiccation stress induced changes in the accumulation and utilization of proline and trehalose in seasonal populations of Drosophila immigrans.

Changes in the levels of energy metabolites can limit survival ability of Drosophila species under stressful conditions but this aspect has received less attention in wild populations collected in different seasons. We tested cold or desiccation triggered changes in the accumulation or utilization of two energy metabolites (trehalose and proline) in Drosophila immigrans flies reared under season specific environmental conditions. Such D.

Sex-specific divergence for body size and desiccation-related traits in Drosophila hydei from the western Himalayas.

Sex-specific-differences are a widespread source of genetic variation in various Drosophila species. In the present study, we have examined desiccation survival in males and females of Drosophila hydei from colder and drier montane conditions of the western Himalayas (altitudinal populations; 600-2202 m). In contrast with most other studies in drosophilids, D.

Developmental acclimation to low or high humidity conditions affect starvation and heat resistance of Drosophila melanogaster.

Several Drosophila species originating from tropical humid localities are more resistant to starvation and heat stress than populations from high latitudes but mechanistic bases of such physiological changes are largely unknown. In order to test whether humidity levels affect starvation and heat resistance, we investigated developmental acclimation effects of low to high humidity conditions on the storage and utilization of energy resources, body mass, starvation survival, heat knockdown and heat survival of D. melanogaster.

Effects of body-size variation on flight-related traits in latitudinal populations of Drosophila melanogaster.

In the present study, we tested the hypothesis whether flight-related traits such as wing area, flight-muscle ratio, wing loading and dispersal yield evidence of geographical variation in nine wild-collected as well as laboratory-reared (at 21°C) latitudinal populations of Drosophila melanogaster from the Indian subcontinent. We observed positive clinal variation in the wing-thorax ratio, wing aspect ratio and wing area, along a latitudinal gradient for both the sexes. In contrast, geographical changes in three parameters of flight ability, i.

Seasonal changes in humidity impact drought resistance in tropical Drosophila leontia: testing developmental effects of thermal versus humidity changes.

Drosophila leontia is native to highly humid equatorial tropical habitats but its desiccation sensitivity (~10h) is not consistent with its abundance during the drier autumn season in the subtropical regions. We have tested the effects of developmental acclimation on desiccation resistance and water balance related traits of D. leontia collected during rainy and autumn seasons.

Sex-specific differences in desiccation resistance and the use of energy metabolites as osmolytes in Drosophila melanogaster flies acclimated to dehydration stress.

In the Indian subcontinent, there are significant between-population variations in desiccation resistance in Drosophila melanogaster, but the physiological basis of adult acclimation responses to ecologically relevant humidity conditions is largely unknown. We tested the hypothesis that increased desiccation resistance in acclimated flies is associated with changes in cuticular permeability and/or content of energy metabolites that act as osmolytes. Under an ecologically relevant humidity regime (~50 % relative humidity), both sexes showed desiccation acclimation which persisted for 2-3 days.

Divergent strategies for adaptations to stress resistance in two tropical Drosophila species: effects of developmental acclimation in D. bipectinata and the invasive species D. malerkotliana.

Previous studies on two tropical Drosophila species (D. malerkotliana and D. bipectinata) have shown lower resistance to stress-related traits but the rapid colonization of D.

Divergence of water balance mechanisms and acclimation potential in body color morphs of Drosophila ananassae.

Drosophila ananassae is a desiccation sensitive species, but the physiological basis of its abundance in the drier subtropical areas is largely unknown. We tested the hypothesis whether body color morphs of D. ananassae differ in the mechanistic basis of water conservation as well as desiccation acclimation potential, consistent with their distribution under dry or wet habitats.

Sex-specific divergence for adaptations to dehydration stress in Drosophila kikkawai.

Several studies on diverse Drosophila species have reported higher desiccation resistance of females, but the physiological basis of such sex-specific differences has received less attention. We tested whether sex-specific differences in cuticular traits (melanic females and non-melanic males) of Drosophila kikkawai correspond with divergence in their water balance mechanisms. Our results are interesting in several respects.

Rapid effects of humidity acclimation on stress resistance in Drosophila melanogaster.

We tested the hypothesis whether developmental acclimation at ecologically relevant humidity regimes (40% and 75% RH) affects desiccation resistance of pre-adults (3rd instar larvae) and adults of Drosophila melanogaster Meigen (Diptera: Drosophilidae). Additionally, we untangled whether drought (40% RH) acclimation affects cold-tolerance in the adults of D. melanogaster.

Invasion and adaptation of a warm-adapted species to montane localities: effect of acclimation potential.

Drosophila ananassae has successfully invaded the cold and dry montane localities of the Western Himalayas in recent years. The ability of this desiccation- and cold-sensitive tropical species to evolve in response to seasonal changes in montane localities is largely unknown. Here, we investigated how this sensitive species adapt to seasonally varying environmental conditions that are lethal to its survival.

Direct and correlated responses to laboratory selection for body melanisation in Drosophila melanogaster: support for the melanisation-desiccation resistance hypothesis.

For Drosophila melanogaster, cuticular melanisation is a quantitative trait, varying from no melanin to completely dark. Variation in melanisation has been linked with stress resistance, especially desiccation, in D. melanogaster and other species.

Divergence of water balance mechanisms in two sibling species (Drosophila simulans and D. melanogaster): effects of growth temperatures.

Drosophila simulans is more abundant under colder and drier montane habitats in the western Himalayas as compared to its sibling D. melanogaster but the mechanistic bases of such climatic adaptations are largely unknown. Previous studies have described D.

Divergence of desiccation-related traits in two Drosophila species of the takahashii subgroup from the western Himalayas.

Drosophila nepalensis is more abundant under colder and drier montane habitats in the western Himalayas compared with Drosophila takahashii, but the mechanistic basis of such a climatic adaptation is largely unknown. We tested the hypothesis that divergence in the physiological basis of desiccation-related traits is consistent with species-specific adaptations to climatic conditions. Drosophila nepalensis showed approximately twofold higher desiccation resistance, hemolymph content as well as carbohydrate content than D.

Divergent strategies for adaptation to desiccation stress in two Drosophila species of immigrans group.

Water balance mechanisms have been investigated in desert Drosophila species of the subgenus Drosophila from North America, but changes in mesic species of subgenus Drosophila from other continents have received lesser attention. We found divergent strategies for coping with desiccation stress in two species of immigrans group--D. immigrans and D.

Divergence of larval resource acquisition for water conservation and starvation resistance in Drosophila melanogaster.

Laboratory selection experiments have evidenced storage of energy metabolites in adult flies of desiccation and starvation resistant strains of D. melanogaster but resource acquisition during larval stages has received lesser attention. For wild populations of D.