Search results for "Larva"
showing 10 items of 632 documents
Influence of larval transport and temperature on recruitment dynamics of North Sea cod (Gadus morhua) across spatial scales of observation
2020
The survival of fish eggs and larvae, and therefore recruitment success, can be critically affected by transport in ocean currents. Combining a model of early‐life stage dispersal with statistical stock–recruitment models, we investigated the role of larval transport for recruitment variability across spatial scales for the population complex of North Sea cod (Gadus morhua). By using a coupled physical–biological model, we estimated the egg and larval transport over a 44‐year period. The oceanographic component of the model, capable of capturing the interannual variability of temperature and ocean current patterns, was coupled to the biological component, an individual‐based model (IBM) tha…
Female Oviposition Decisions and Their Impact on Progeny Life-History Traits
2008
An important factor affecting the life-history of an organism is parental investment in reproduction: reproductive decisions are almost invariably costly. Therefore, reproductive decisions should be beneficial in terms of increased offspring number or fitness. For example, egg laying decisions in many insects can influence resource availability of the offspring through changes in the larval density, and resource availability will have effects on many life-history traits. Here we studied whether female reproductive decisions affect offspring fitness in Callosobruchus maculatus seed beetles. Females laid more eggs on black-eye beans than on mung beans. However, when the difference in the surf…
Functional response of suspension feeding anuran larvae to different particle sizes at low concentrations (Amphibia)
1992
The influence of particle size, initial particle concentration and larval stage on the ingestion rate, ‘retention efficiency’, and filtering rate of anuran larvae with varying filter apparatus anatomy and different life histories was investigated for four species. Larvae of premetamorphic Stages 28 and 32 and prometamorphic Stage 40 were selected for filtering experiments on the basis of their different growth rates. Three different sizes of silica gel particles were offered as mock food. Particle concentration was measured photometrically. The Michaelis-Menten model was used to describe the dependency of ingestion rate, filtering rate, and ‘retention efficiency’ upon initial particle conce…
Toxicity of 3,4-dichloroaniline to perch (Perca fluviatilis) in acute and early life stage exposures
1993
Abstract The toxitity of 3,4-dichloroaniline to perch was investigated in order to compare the sensitivity of crucial life stages with common test fish like zebrafish. Although in the acute toxicity test perch were more sensitive by a factor of five, larval sensitivity was in the same range in both species as well as in other egg-laying species. In spite of different water temperature and size, the zebrafish is a good model to predict early life stage toxicity of 3,4-DCA to the compared European freshwater species. Perch larvae are not suited for early life stage tests, as they are sensible towards experimental conditions and perform early cannibalism.
Parasite transmission in aquatic ecosystems under climate change: joint effects of temperature, host behavior and elimination of parasite larvae by p…
2019
AbstractA moderate raise in temperature was suggested to enhance the impact of parasites on aquatic ecosystems. Under higher temperatures, poikilothermic animals (e.g. fish), increase their activity, which can result in a more frequent encounter with parasites. However, temperature increase may also trigger processes counteracting an increased risk of parasitic infections. For instance, removal of free-living stages of parasites by filter-feeding organisms can increase with temperature and potentially mitigate disease risk in ecosystems under climate change.In our study, we aimed to find out whether an increased infection transmission under higher temperatures can be, at least, partly compe…
Introduction to Symposium: Poecilogony--A Window on Larval Evolutionary Transitions in Marine Invertebrates
2012
Poecilogony is the intraspecific variation in developmental mode that has been described in some marine invertebrates. Poecilogonous species produce different larval forms (e.g., free-swimming planktotrophic larvae as well as brooded lecithotrophic or adelphophagic larvae). Poecilogony can be a controversial topic, since it is difficult to identify and characterize the phenomenon with certainty. It has been challenging to determine whether poecilogony represents developmental polymorphism with a genetic basis or developmental polyphenism reflecting plastic responses to environmental cues. Other outstanding questions include whether common mechanisms underlie the developmental variation we o…
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…
Biological Responses of <I>Rhynchophorus ferrugineus</I> (Coleoptera: Curculionidae) to <I>Steinernema carpocapsae</I> (Nemat…
2013
Rhynchophorus ferrugineus (Olivier 1790) (Coleoptera: Curculionidae) is becoming a serious problem in Mediterranean areas where it is well-adapted, and now is present even in the United States (California). The infestations are primarily in urban areas where chemical control is not advisable and million of Euros are spent to control it. The effects of the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Steinernematidae) on mortality, growth, as well as the immune activity of R. ferrugineus larvae, were investigated. R. ferrugineus mortality exhibited a positive trend with the dosage and duration of exposure to S. carpocapsae. The median lethal dose and median lethal time, impor…
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…
Intra- and Trans-Generational Phenotypic Responses of the Greater Wax Moth, Galleria mellonella, to a Low-Nutrition Larval Diet
2020
We investigated the intra- and trans-generational effects of larval diet on immune function, body size and development time of the greater wax moth, Galleria mellonella (Lepidoptera: Pyralidae). We found that moths reared on a diet diluted with cellulose (a low-nutrition diet) were about one-third smaller, had about one-fifth longer development time and exhibited about 10% stronger encapsulation responses as compared with moths reared on the standard diet. The low-nutrition parental diet prolonged the development time of male offspring that were fed the low-nutrition diet by about 4% and the development time of female offspring that were fed the standard diet by about 1%. However, females t…