scholarly journals Effects of saturation deficit on desiccation resistance and water balance in seasonal populations of the tropical drosophilidZaprionus indianus

2016 ◽  
Vol 219 (20) ◽  
pp. 3237-3245 ◽  
Author(s):  
Bhawna Kalra ◽  
Ravi Parkash
Keyword(s):  
Water Balance ◽  
Desiccation Resistance ◽  
Saturation Deficit

scholarly journals Desiccation resistance and water balance in populations of the maize weevil Sitophilus zeamais

2015 ◽  
Vol 64 ◽  
pp. 146-153 ◽  
Author(s):  
Nelsa Maria P. Guedes ◽  
Lucas S. Braga ◽  
Conrado A. Rosi-Denadai ◽  
Raul Narciso C. Guedes
Keyword(s):  
Water Balance ◽  
Sitophilus Zeamais ◽  
Desiccation Resistance ◽  
Maize Weevil

Ecological studies of larval ticks in South Africa (Acarina: Ixodidae)

Parasitology ◽  
1972 ◽  
Vol 65 (3) ◽  
pp. 469-490 ◽  
Author(s):  
J. G. H. Londt ◽  
G. B. Whitehead
Keyword(s):  
South Africa ◽  
Relative Humidity ◽  
Water Balance ◽  
Field Data ◽  
Amblyomma Hebraeum ◽  
Ecological Studies ◽  
Saturation Deficit ◽  
Vegetation Height ◽  
Boophilus Decoloratus ◽  
Glass Rods

The distribution of larval ticks in relation to vegetation cover was studied on two coastal farms in the Port Alfred district of the Cape Province. The following five species were found: Boophilus decoloratus (Koch), Amblyomma hebraeum Koch, Ixodes pilosus Koch, Haemaphysalis silacea Robinson and Rhipicephalus evertsi Neumann. B. decoloratus predominated in short protected vegetation, I. pilosus and H. silacea in short covered vegetation and A. hebraeum in medium-to-tall protected vegetation. R. evertsi was collected in too small numbers to allow any correlation to be established. Both I. pilosus and H. silacea demonstrated activity peaks during the winter months. Microclimatic measurements indicated that larval ticks were not usually collected in microhabitats which experienced midday saturation deficits in excess of approximately 10 mm Hg. Behavioural studies on larval ticks climbing glass rods demonstrated the possible association of larvae with a definite vegetation height. The optimal vegetation heights were correlated with field data. The water balance of some tick species was studied and it was found that at 26 °C a relative humidity of 70% or more (i.e. above 7·53 mm Hg saturation deficit) was required by these larvae. Larvae lost water to the atmosphere at humidities lower than this value and took up water vapour from the atmosphere at values higher than 70% R.H. They were shown to be able to imbibe water through the mouthparts, and this possibly has survival value.

scholarly journals An experimental test of the relationship between melanism and desiccation survival in insects

2014 ◽  
Author(s):  
Subhash Rajpurohit ◽  
Lisa Marie Peterson ◽  
Andrew Orr ◽  
Anthony J. Marlon ◽  
Allen G Gibbs
Keyword(s):  
Water Balance ◽  
Experimental Test ◽  
Desiccation Tolerance ◽  
Experimental Evolution ◽  
Drosophila Species ◽  
Desiccation Resistance ◽  
Body Pigmentation ◽  
And Control ◽  
The Relationship

We used experimental evolution to test the ?melanism-desiccation? hypothesis, which proposes that dark cuticle in several Drosophila species is an adaptation for increased desiccation tolerance. We selected for dark and light body pigmentation in replicated populations of D. melanogaster and assayed traits related to water balance. We also scored pigmentation and desiccation tolerance in populations selected for desiccation survival. Populations in both selection regimes showed large differences in the traits directly under selection. However, after over 40 generations of pigmentation selection, dark-selected populations were not more desiccation-tolerant than light-selected and control populations, nor did we find significant changes in carbohydrate amounts that could affect desiccation resistance. Body pigmentation of desiccation-selected populations did not differ from control populations after over 140 generations of selection. Our results do not support an important role for melanization in Drosophila water balance.

scholarly journals Sexual dimorphism for water balance mechanisms in montane populations of Drosophila kikkawai

2010 ◽  
Vol 6 (4) ◽  
pp. 570-574 ◽  
Author(s):  
Ravi Parkash ◽  
Vineeta Sharma ◽  
Bhawna Kalra
Keyword(s):  
Sexual Dimorphism ◽  
Water Balance ◽  
Cuticular Lipids ◽  
Clinal Variation ◽  
Western Himalayas ◽  
Desiccation Resistance ◽  
Cuticular Transpiration ◽  
Ecological Success ◽  
Water Proofing

Conservation of water is critical to the ecological success of Drosophila species living in the drier montane localities of the Western Himalayas. We observed clinal variation in desiccation resistance for both sexes of Drosophila kikkawai from an altitudinal transect (512–2226 m above sea level). Since more than 90 per cent of body water is lost through cuticular transpiration, the target of selection may be cuticular lipids or cuticular melanization. We tested whether melanic females and non-melanic males of D. kikkawai have similar mechanisms of desiccation resistance. There is clinal variation in the amount of cuticular lipids per fly in males, but not in females. By contrast, for females, elevational increase in melanization is positively correlated with desiccation resistance and negatively with cuticular water loss, but there is no variation in the amount of cuticular lipids. Thus, sexual dimorphism for the mechanism of desiccation resistance in D. kikkawai matches the water proofing role of body melanization as well as cuticular lipids.

Thermal developmental plasticity affects body size and water conservation of Drosophila nepalensis from the Western Himalayas

2014 ◽  
Vol 104 (4) ◽  
pp. 504-516 ◽  
Author(s):  
R. Parkash ◽  
C. Lambhod ◽  
D. Singh
Keyword(s):  
Body Size ◽  
Water Balance ◽  
Mass Culture ◽  
Growth Temperature ◽  
Water Loss ◽  
Water Conservation ◽  
Developmental Plasticity ◽  
Seasonal Abundance ◽  
Western Himalayas ◽  
Desiccation Resistance

AbstractIn the Western Himalayas, Drosophila nepalensis is more abundant during the colder and drier winter than the warmer rainy season but the mechanistic bases of such adaptations are largely unknown. We tested effects of developmental plasticity on desiccation-related traits (body size, body melanization and water balance traits) that may be consistent with changes in seasonal abundance of this species. D. nepalensis grown at 15°C has shown twofold higher body size, greater melanization (∼15-fold), higher desiccation resistance (∼55 h), hemolymph as well as carbohydrate content (twofold higher) as compared with corresponding values at 25°C. Water loss before succumbing to death was much higher (∼16%) at 15°C than 25°C. Developmental plastic effects on body size are associated with changes in water balance-related traits (bulk water, hemolymph and dehydration tolerance). The role of body melanization was evident from the analysis of assorted darker and lighter flies (from a mass culture of D. nepalensis reared at 21°C) which lacked differences in dry mass but showed differences in desiccation survival hours and rate of water loss. For adult acclimation, we found a slight increase in desiccation resistance of flies reared at lower growth temperature, whereas in flies reared at 25°C such a response was lacking. In D. nepalensis, greater developmental plasticity is consistent with its contrasting levels of seasonal abundance. Finally, in the context of global climate change in the Western Himalayas, D. nepalensis seems vulnerable in the warmer season due to lower adult as well as developmental acclimation potential at higher growth temperature (25°C).

Water balance, drought stress and yields for rainfed field crop rotations under present and future conditions in the Czech Republic

2015 ◽  
Vol 65 ◽  
pp. 175-192 ◽  
Author(s):  
P Hlavinka ◽  
KC Kersebaum ◽  
M Dubrovský ◽  
M Fischer ◽  
E Pohanková ◽  
...  
Keyword(s):  
Czech Republic ◽  
Drought Stress ◽  
Water Balance ◽  
Crop Rotations ◽  
Field Crop ◽  
The Czech Republic
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