Search results for "Hatching"
showing 10 items of 98 documents
Male Investments in High Quality Sperm Improve Fertilization Success, but May Have Negative Impact on Offspring Fitness in Whitefish.
2015
Many ejaculate traits show remarkable variation in relation to male social status. Males in disfavoured (subordinate) mating positions often invest heavily on sperm motility but may have less available resources on traits (e.g., secondary sexual ornaments) that improve the probability of gaining matings. Although higher investments in sperm motility can increase the relative fertilization success of subordinate males, it is unclear whether status-dependent differences in sperm traits could have any consequences for offspring fitness. We tested this possibility in whitefish (Coregonus lavaretus L.) by experimentally fertilizing the eggs of 24 females with the sperm of either highly-ornamente…
Extreme tolerance to environmental stress of sexual and parthenogenetic resting eggs ofEucypris virens(Crustacea, Ostracoda)
2012
Summary 1. The freshwater ostracod (Ostracoda), Eucypris virens, is commonly found in European temporary pools, where its long-term persistence completely relies on the build-up of resting egg banks. Extreme tolerance of dormant eggs and seeds is widely assumed, but freshwater ostracod eggs are relatively poorly studied. The study of ostracod resting eggs is of particular relevance as it may yield the key to understanding the distribution of the sexes in many species capable of both sexual and asexual reproduction. 2. We assessed the tolerance of dried resting eggs produced by females originating from three populations with males and three all-female E. virens populations. Hatching time and…
Embryonic development in corkwing wrasse, Symphodus melops
2019
Corkwing wrasse, Symphodus melops, is one of the main species used as cleaner fish to combat sea lice infestation in salmon aquaculture; however, there is little knowledge about its biology. Here, we describe the embryonic development of this species and examine the viability of the eggs under three temperature regimes. The experiments were conducted at three water temperature regimes, 12, 15, and 18°C, which resemble common sea water temperatures registered during the spawning season of corkwing wrasse at different latitudes along the Norwegian coast. Corkwing wrasse spawn small spherical eggs of 0.75–0.80 mm in diameter (mean 0.78, CV = 3.6%) with several oil droplets and go through eight…
Maternal antibodies in a wild altricial bird: effects on offspring immunity, growth and survival
2006
1. In many animals immunity is not fully developed until adulthood but the young still need protection against various sets of pathogens. Thus, bird nestlings are highly dependent on antibodies received from their mother (in the eggs) during their rapid early growth period. The relationship between maternal immunity and the development of neonates' own immunity has been poorly studied. 2. It has been suggested that immune function plays an important part in mediating resource competition between different life-history traits, e.g. growth and reproduction. Maternal investment of antibodies has potentially permanent effects on offspring phenotype. Thus, the trade-offs between the immune funct…
Egg and larval load assessment and its influence on oviposition behaviour of the leaf beetle Galerucella nymphaeae
1993
The oviposition behaviour of the water-lily beetle Galerucella nymphaeae was examined. This species is a specialist herbivore on the floating leaves of nymphaeids Nymphaeaceae and especially on the yellow water-lily, Nuphar lutea. Females lay their eggs in clutches on the leaves, and after hatching, the larvae feed on the leaves. The quality of the leaves decreases quickly after the larvae hatch, and eventually the leaves will sink below the water surface, whereupon the eggs, 1st-instar larvae and pupae are killed by drowning. The influence of conspecific eggs, larvae and feeding tracks on the oviposition preferences of the beetles was tested. Females were allowed to choose between fresh le…
Echinostoma friedi: the effect of age of adult worms on the infectivity of miracidia.
2004
AbstractThe effect of ageing of adults ofEchinostoma friedi(Trematoda: Echinostomatidae) on the infectivity of miracidia yielded was analysed. Miracidia were obtained after hatching of eggs obtained from adult worms ofE. friedicollected weekly during the course of experimental infections in golden hamsters. Miracidial infectivity, measured in terms of percentage of infection inLymnaea peregra, was significantly influenced by the age of the adult worms from which the miracidia were derived. Infective miracidia only were obtained from adult worms in the age range from 4 to 9 weeks post-infection. Infectivity was maximal in those miracidia derived from adults collected 8 and 9 weeks post-infec…
Toxicity of lindane, atrazine, and deltamethrin to early life stages of zebrafish (Brachydanio rerio).
1990
Fertilized eggs of zebrafish were exposed under flow-through conditions to several concentrations of the following pesticides: lindane 40, 80, 110, 130, and 150 micrograms/liter; atrazine 300, 1300, and 9100 micrograms/liter; deltamethrin 0.5, 0.8, and 1.2 micrograms/liter. Hatching, abnormalities in development (external deformations, edema, etc.), and mortality were recorded over a period of 35 days. At the end of the experiment, the body lengths of the fish were measured. Survival of juvenile fish after 35 days was reduced by increasing concentrations of all xenobiotics tested: lindane enhanced the mortality from 110 micrograms/liter and atrazine from 1300 micrograms/liter, and deltameth…
New data on the early development of Hysterothylacium aduncum (Nematoda, Anisakidae).
1998
This note reports on incidental observations of the early development of the third-stage larvae of Hysterothylacium aduncum from gadid fishes. Gravid H. aduncum females were collected from Pollachius virens, Pollachius pollachius. Gadus morhua, and Molva molva in Norwegian waters. The eggs were incubated at 20 per thousand salinity and 5 C. Spontaneous hatching of third-stage larvae was observed 10-25 days after egg deposition. These larvae were long lived and could infect Acartia tonsa copepods, the infections being maintained for up to 34 days. The morphology of the third-stage larvae in the copepods and some traits of the life cycle were similar to those reported in previous studies. How…
Oncomiracidial development, survival and swimming behaviour of the monogenean Sparicotyle chrysophrii (Van Beneden and Hesse, 1863)
2012
Abstract Oncomiracidial development of Sparicotyle chrysophrii , a monogenean parasite of Sparus aurata , was analysed using 450 eggs. Parasite morphological changes in time, data on hatching success, as well as oncomiracidial survival and swimming behaviour were recorded. Eggs were maintained at 20 °C and exposed to LD 12:12. They were observed under the stereomicroscope every 8 h until they hatched. Thereafter, 155 oncomiracidia were isolated in separate wells and observed every 2 h until their death. Most of the hatchings occurred in a short period of time (approximately 24 h). Hatching success was 87% and the hatching period ranged from 5 to 10 days after deposition, with most of the ha…
Pathogenicity bioassays of isolates of Beauveria bassiana on Rhynchophorus ferrugineus
2014
BACKGROUND The control of Rhynchophorus ferrugineus (Olivier), the main palm pest in the Mediterranean Basin, is problematic because of its biology and the current restrictions in many European countries on the use of chemical insecticides in urban areas. Entomopathogenic fungi have been studied as potential biological control agents, but information on their natural incidence is limited. Strains of Beauveria bassiana (Balsamo) Vuillemin were isolated from symptomatic insects collected on dead palms, and their pathogenicity against different instars of R. ferrugineus was evaluated in the laboratory. RESULTS The overall percentage of infected insects found in Canary palms was 7%. In laborato…