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Hatching Time (hatching + time)
Selected AbstractsAdaptation of a generalist moth, Operophtera brumata, to variable budburst phenology of host plantsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2002Olli-Pekka Tikkanen Abstract The adaptation of three allopatric populations of a generalist moth, Operophtera brumata (L.), on two tree species, Prunus padus (L.) and Quercus robur (L.) which represent the extremes of the timing of budburst in spring, was studied in Finland and Sweden. The synchrony of the hatching and budbursting was monitored, and its importance to dispersal and growth of larvae was assessed by rearing cohorts of larvae, whose hatching dates were manipulated, on both hosts. In addition, the realised heritability of the hatching time was estimated. Experimental populations hatched in approximate synchrony with the budburst of their original host species. As a result of the manipulation of the hatching dates of larvae, the growth rates of larvae decreased and the dispersal rates increased on both hosts in relation to the ageing of foliage. The realised heritability of hatching times was rather high (0.63). There were fewer differences in the host use efficiency and behaviour of the experimental populations than in the hatching phenology. The synchrony of hatching with the budburst of the local dominant host plant is probably a result of stabilising selection. [source] Cyst-based toxicity tests XII,Development of a short chronic sediment toxicity test with the ostracod crustacean Heterocypris incongruens: Selection of test parametersENVIRONMENTAL TOXICOLOGY, Issue 6 2002Belgis Chial Abstract Experiments were carried out with neonates of the freshwater ostracod Heterocypris incongruens hatched from cysts in order to develop a new culture/maintenance-free solid-phase microbiotest for the toxicity assessment of contaminated sediments. Based on preliminary investigations, a number of test parameters were investigated for a short-chronic assay: hatching time, size of the cups of the multiwell test plates, feeding of the test organisms prior to the test, amount of supplemental algal food, volume of sediment, and duration of the test. On the basis of the findings, a test protocol was formulated for a 6-day assay in 12-cup multiwell plates with 10 organisms per cup and 3 replicates. The test organisms were collected 52 h after the start of the incubation of the cysts in standard freshwater at 25°C under continuous illumination after a 4-h prefeeding with 1.3 mg/mL Spirulina. The test biota in the cups were exposed to 300 ,L of test sediment in 2 mL of standard freshwater with 3 × 107 live algal cells (Raphidocelis subcapitata) as food supplement. Calibrated sand was used as a reference sediment. Mortality and growth of the ostracods were determined after 6 days' incubation at 25°C in darkness. The selected test parameters for the new microbiotest were found adequate for toxicity determination of natural sediments compared with the 10-day contact test with the amphipod Hyalella azteca. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 520,527, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10085 [source] Effects of temperature on the post-diapause embryonic development and the hatching time in three grasshopper species (Orth., Acrididae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2004S. G. Hao Abstract: A study was conducted to determine the effects of six constant temperatures (15, 20, 25, 30, 35 and 40°C) on the post-diapause embryonic development and the hatching time in three grasshopper species ,Omocestus haemorrhoidalis (Charp.), Calliptamus abbreviatus Ikonn. and Chorthippus fallax (Zub.) , from the Inner Mongolian steppe. The results indicate that the species differ in the developmental rates, survival curves and cumulative hatching probabilities. The eggs of O. haemorrhoidalis had the fastest developmental rate with a low developmental threshold temperature of 9.9°C and the sum of effective temperature (SET) 211.2 degree-days (DD). The corresponding values were 10.9°C and 210.6 DD for C. abbreviatus, 10.5°C and 240.2 DD for Ch. fallax respectively. The SET at which 50% of post-diapause eggs hatched were 252.0 DD for O. haemorrhoidalis, 262.8 DD for C. abbreviatus, and 273.3 DD for Ch. fallax. The predicted maximal hatch ability of O. haemorrhoidalis (91.17%), C. abbreviatus (75.67%) and Ch. fallax (94.07%) occurred at 23.7, 29.0 and 31.3°C, respectively. The thermal death points of each species were reached at 43.3, 45.0 and 48.6°C. The optimal temperature ranges were 12.2,35.2°C for O. haemorrhoidalis, 21.7,36.3°C for C. abbreviatus and 20.9,41.7°C for Ch. fallax respectively. These results suggest that O. haemorrhoidalis adapt to hatch at a lower temperature range, C. abbreviatus adapt to mid-temperature range, while Ch. fallax adapt to hatch at a higher temperature range. Although the SET of Ch. fallax is more than that of the other two species, it is not sufficient to explain the hatching sequence of the species in springtime. The results also indicate that Ch. fallax and O. haemorrhoidalis have wider adaptive temperature range than C. abbreviatus. [source] Postnatal effects of incubation length in mallard and pheasant chicksOIKOS, Issue 3 2004Jan-Åke Nilsson Eggs of mallard ducks (Anas platyrhynchos) and ring-necked pheasants (Phasianus colchicus) were incubated in clutches arranged to stimulate embryos to hatch earlier or later than normal. This manipulation of hatching time was achieved by combining eggs of different age in the same clutch. To ensure hatching synchrony, embryos communicate with each other during the last stage of incubation, resulting in either a delay or an acceleration of hatching. Embryos of both species that accelerated their hatching time suffered a higher mortality rate after hatching. Combining mortality with the proportion of hatchlings that suffered from leg deformities, impeding their movements, resulted in a cost also to pheasant chicks delaying their hatching. Chicks of both species accelerating hatching time had a lower minimum mass and a shorter tarsus length than control chicks, whereas chicks delaying hatching time either grew as well or slightly better than control chicks. Mallard chicks had better balance and mobility immediately after hatching the longer they stayed in the egg. This indicates that the period immediately before hatching, is an important period for muscular and organ maturity. Reducing this period results in costs affecting post-hatching survival. The strategy to assure synchronous hatching in mallards and pheasants probably reflect a trade-off between the negative effects of shifting the age at hatching away from normal and differences in predation risk during different stages of reproduction. [source] The effect of maternal size on larval characteristics of Persian sturgeon Acipenser persicusAQUACULTURE RESEARCH, Issue 9 2009Rajab Mohammad Nazari Abstract The objective of this work was to study the relationship between female size (weight) and variables of egg and larval stage of Persian sturgeon Acipenser persicus. In this study, 19 female breeders were captured in Caspian Sea and fertilized by routine methods. Positive significant correlations (P<0.05) were established between female weight and ovulated eggs per female, time of second mitosis division and volume of yolk-sac at hatching. There was not significant correlation (r=0.33, P=0.161) between female weight and egg diameter. Female weight was not affected weight of larvae at hatching time (r=0.37, P=0.119), as well as larval length (r=,0.14, P=0.558) and larval weight at the end of the experiment (48 hours after first feeding) (r=0.16, P=0.491). Mortality rate during yolk-sac absorption was higher with increased female weight but their correlation was not significant (r=0.40, P=0.076). During the first feeding stage, mortality rate was 13.39% and there was no significant correlation between mortality rate in this period and female weight (r=,0.12, P=0.613). Conclusively, as a result female size influenced fecundity, time of second mitosis division and yolk-sac volume at hatching time without affecting mortality rate during yolk-sac absorption and first feeding stage in Persian sturgeon. Thus, smaller female broods do not cause more mortality than larger ones in larval production and they can be used in reproduction procedure. [source] Vibration Analysis on Incubating Eggs and Its Relation to Embryonic DevelopmentBIOTECHNOLOGY PROGRESS, Issue 3 2003Bart J. Kemps Coucke (1998) was the first to use acoustic resonance analysis to monitor embryo development in chicken eggs. He remarked that at around 100 hours of incubation, the course of the resonant frequency and damping changed abruptly in the case of fertile eggs. He also showed that these changes were related to a physiologic event during early embryonic development. The objective of our study is to monitor the course of the vibration parameters during the early incubation of chicken eggs and to relate these changes to egg and embryo characteristics. A total of 72 Hybro eggs were incubated vertically in a small incubator at standard conditions. Several egg parameters were measured before incubation. During the early stages of incubation the vibration behavior of these eggs was monitored. The time at which the damping of the vibration suddenly changed, the diameter of the eggs and their interaction were found to be significant explanatory variables in order to predict hatching time. A correlation coefficient r of 0.72 was obtained. [source] | |||||||||||||