scholarly journals Desiccation resistance of wild and mass-reared Bactrocera tryoni (Diptera: Tephritidae)

2013 ◽  
Vol 103 (6) ◽  
pp. 690-699 ◽  
Author(s):  
C.W. Weldon ◽  
S. Yap ◽  
P.W. Taylor
Keyword(s):  
Water Stress ◽  
Sterile Insect Technique ◽  
Reproductive Development ◽  
Desiccation Resistance ◽  
Sharp Decline ◽  
Bactrocera Tryoni ◽  
Dehydration Tolerance ◽  
Dry Conditions ◽  
Access To Food ◽  
Adult Mass

AbstractIn pest management programmes that incorporate the sterile insect technique (SIT), the ability of mass-reared insects to tolerate dry conditions may influence their survival after release in the field. In the present study, desiccation resistance of adult mass-reared Queensland fruit flies, Bactrocera tryoni (Frogatt) (Diptera: Tephritidae), that are routinely released in SIT programmes was compared with that of wild flies at 1, 10 and 20 days after adult eclosion. Under dry conditions without access to food or water, longevity of mass-reared B. tryoni was significantly less than that of their wild counterparts. Desiccation resistance of mass-reared flies declined monotonically with age, but this was not the case for wild flies. The sharp decline in desiccation resistance of mass-reared flies as they aged was likely explained by decreased dehydration tolerance. As in an earlier study, desiccation resistance of females was significantly lower than that of males but this was particularly pronounced in mass-reared females. Female susceptibility to dry conditions corresponded with declining dehydration tolerance with age and associated patterns of reproductive development, which suggests that water content of their oocyte load is not available for survival during periods of water stress.

Water stress affects the productivity, growth components, competitiveness and water relations of phalaris and white clover growing in a mixed pasture

1992 ◽  
Vol 43 (3) ◽  
pp. 659 ◽  
Author(s):  
L Guobin ◽  
DR Kemp ◽  
GB Liu
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
White Clover ◽  
Leaf Growth ◽  
Leaf Water ◽  
Water Potentials ◽  
Relative Water ◽  
Dry Conditions ◽  
Leaf Appearance ◽  
Water Contents

The effect of water stress during summer and recovery after rain on herbage accumulation, leaf growth components, stomatal conductance and leaf water relations of white clover (Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) was studied in an established mixed pasture under dryland (dry) or irrigated (wet) conditions. Soil water deficits under dry conditions reached 150 mm and soil water potentials in the top 20 cm declined to nearly -2 MPa after 50 days of dry weather. Water stress severely restricted growth of both species but then after rain fell, white clover growth rates exceeded those of phalaris. Under irrigation, white clover produced twice the herbage mass of phalaris but under dry conditions herbage production was similar from both species. Leaf appearance rates per tiller or stolon were slightly higher for white clover than phalaris but were reduced by 20% under water stress in both species. Leaf or petiole extension rates were more sensitive to water stress than leaf appearance rates and declined by 75% in phalaris and 90% in white clover. The ratio of leaf or petiole extension rates on dry/wet treatments was similar for both species in relation to leaf relative water contents, but in relation to leaf water potentials phalaris maintained higher leaf growth rates. Phalaris maintained a higher leaf relative water content in relation to leaf water potentials than did white clover and also maintained higher leaf water potentials in relation to the soil water potential in the top 20 cm. Stomata1 conductances for both species declined by 80-90% with increasing water stress, and both species showed similar stomatal responses to bulk leaf water potentials and leaf relative water contents. It is suggested that the poorer performance of white clover under water stress may be due principally to a shallower root system than phalaris and not due to any underlying major physiological differences. The white clover cultivar used in this study came from the mediterranean region and showed some different responses to water stress than previously published evidence on white clover. This suggests genetic variation in responses to water stress may exist within white clover. To maintain white clover in a pasture under dry conditions it is suggested that grazing practices aim to retain a high proportion of growing points.

scholarly journals EFFECTS OF WATER STRESS ON PHYTOPHTHORA-INFECTED RHODODENDRONS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 647b-647
Author(s):  
Michelle Carratu ◽  
Roger J. Sauve
Keyword(s):  
Water Stress ◽  
Survival Rate ◽  
Survival Rates ◽  
Pine Bark ◽  
Peat Moss ◽  
Rooted Cuttings ◽  
Dry Conditions

Phytophthora cinnamoni infected Rhododendrons subjected to moderate moisture levels had greater survival rates than at the wet or dry levels. We potted rooted cuttings of Rhododendron L. hybrid, “Lee's Dark Purple” in 3 liter containers using a mixture of 3 pine bark: 2 coarse builder's sand: 1 Canadian peat moss (by vol.) and infected them with P. cinnamoni. Tensiometers maintained the moisture levels of the treatments at 0, -5, -10, -15, and -20 kPa. After 90 days, measurements of the plants revealed virtually curvilinear results, with the highest survival rate, plant and root weights at -5 and -10 kPa. Investigation continues on susceptibility of Rhododendrons to P. cactorum, P. cryptogea, P. cinnamoni, and P. citrophthora under wet and dry conditions.

scholarly journals EVAPOTRANSPIRATION AND PHYSIOLOGICAL RESPONSES TO WATER STRESS OF SEVERAL PASTURE AND CROP SPECIES

1977 ◽  
pp. 70-78
Author(s):  
J.P. Kerr ◽  
H.G. Mcpherson
Keyword(s):  
Plant Physiology ◽  
Water Stress ◽  
Crop Yield ◽  
Water Loss ◽  
Leaf Growth ◽  
Physiological Responses ◽  
Crop Species ◽  
Stomatal Behaviour ◽  
Atmosphere System ◽  
Dry Conditions

The effect of water on pasture and crop yield is determined by many factors in the soil-plant-atmosphere system. Over recent years, Plant Physiology Division has been examining the system to better understand the principles to be applied in effectively managing pasture and crops under dryland and irrigation and to find criteria which could be used in breeding plants better adapted to dry conditions. The evapotranspiration of pastures and crops, the influence of pastures and crops on their water loss through leaf cover and stomatal behaviour, some of the consequences of water stress on leaf growth, as well as soil evaporation and drainage losses, are discussed.

scholarly journals Mild Water Stress Makes Apple Buds More Likely to Flower and More Responsive to Artificial Forcing— Impacts of an Unusually Warm and Dry Summer in Germany

Agronomy ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 274 ◽  
Author(s):  
Eduardo Fernandez ◽  
Eike Luedeling ◽  
Dominik Behrend ◽  
Stijn Van de Vliet ◽  
Achim Kunz ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Status ◽  
Dormancy Release ◽  
Flower Primordia ◽  
Apical Buds ◽  
Tree Phenology ◽  
Dry Conditions ◽  
Bud Phenology ◽  
Chill Portions ◽  
Mild Water Stress

Climate change may result in increasingly frequent extreme events, such as the unusually dry conditions that occurred in Germany during the apple growing season of 2018. To assess the effects of this phenomenon on dormancy release and flowering in apples, we compared irrigated and non-irrigated orchard blocks at Campus Klein-Altendorf. We evaluated bud development, dormancy release and flowering in the following season under orchard and controlled forcing conditions. Results showed that irrigated trees presented longer (39.2%) and thinner shoots compared to non-irrigated trees. In both treatments, apical buds developed a similar number of flower primordia per cyme (4–5), presenting comparable development and starch dynamics during dormancy. Interestingly, buds on non-irrigated shoots exposed to low chill levels responded earlier to forcing conditions than those on irrigated shoots. However, chill requirements (~50 Chill Portions) and bud phenology under field conditions did not differ between treatments. In spring, buds on non-irrigated trees presented a higher bloom probability (0.42) than buds on irrigated trees (0.30). Our findings show that mild water stress during summer influenced vegetative growth during the same season, as well as the response of buds to forcing temperatures and flowering of the following season. The differences between irrigation levels in the phenological responses of shoots under low-chill conditions point to a so-far understudied impact of water supply on chilling requirements, as well as subsequent bud behavior. Accounting for the effects of both the water status during summer and the temperature during the dormant season may be required for accurately predicting future tree phenology in a changing climate.

Effect of natural predators on Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) control by sterile insect technique (SIT)

2019 ◽  
Vol 75 (12) ◽  
pp. 3356-3362 ◽  
Author(s):  
Darshana N Rathnayake ◽  
Elizabeth C Lowe ◽  
Polychronis Rempoulakis ◽  
Marie E Herberstein
Keyword(s):  
Sterile Insect Technique ◽  
Fruit Fly ◽  
Bactrocera Tryoni
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