Search results for "Reproduction"

Effect of an Acaricide on the Reproduction and Survival of Daphnia magna

1999

Toxicity of Dimethoate to Some Soil Animal Species in Different Soil Types

1996

Toxicity of dimethoate (insecticide) to an earthworm (Aporrectodea caliginosa tuberculata), a collembola (Folsomia candida), and an enchytraeid worm (Enchytraeus crypticus/variatus) was studied in three different soil types (artificial soil, clayey soil, and humus sandy soil). Parameters measured were survival and biomass change of the earthworms and survival and reproduction of the collembolas and enchytraeids. The degradation of dimethoate was analyzed too. Toxic effects were observed at the concentrations of some mg/kg dry soil. The biomass reduction of the earthworms occurred at lower concentrations than reduction in survival. The collembolas were more susceptible to dimethoate than the…

Temperature–Time Relationship in Collembolan Response to Chemical Exposure

1999

Abstract Effects of temperature on chemical toxicity to a collembolan, Folsomia candida , in relation to time were studied in this experiment. Field soil was used as a test substrate. Collembolans were incubated at three different temperatures (+13, +16, and +19°C) and in two different dimethoate concentrations (1 and 3 mg/kg), clean soil serving as the control. Four destructive samplings were done at 2-week intervals. Dimethoate degradation was also analyzed. Dimethoate 1 mg/kg had a slight effect on both adult growth and reproduction, whereas 3 mg/kg was fatal to F. candida in the soil used. Toxic effects tended to last longer at low temperature than at high temperature, but the differenc…

Population dynamics in Daphnia magna as modified by chronic tetradifon stress.

2000

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F0-generation) were exposed during 21 days to different tetradifon (4-chlorophenyl 2,4,5-trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5 x 10(5) cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F1 generation (1st and 3rd broods). Reproduction was still …

Genetic diversity in populations of asexual and sexual bag worm moths (Lepidoptera: Psychidae).

2004

Abstract Background Despite the two-fold cost of sex, most of the higher animals reproduce sexually. The advantage of sex has been suggested to be its ability, through recombination, to generate greater genetic diversity than asexuality, thus enhancing adaptation in a changing environment. We studied the genetic diversity and the population structure of three closely related species of bag worm moths: two strictly sexual (Dahlica charlottae and Siederia rupicolella) and one strictly asexual (D. fennicella). These species compete for the same resources and share the same parasitoids. Results Allelic richness was comparable between the sexual species but it was higher than in the asexual spec…

Risk Communication in Assisted Reproduction in Latvia: From Private Experience to Ethical Issues

2013

The aim of this paper is to analyze the process of risk communication in the context of assisted reproduction in Latvia. The paper is based on a qualitative methodology and two types of data: media analysis and 30 semi-structured interviews (11 patients, 4 egg donors, 15 experts). The study explores a broad definition of risk communication and explores three types of risks: health, psychosocial, and moral. We ask (1), who is involved in risk communication, (2), how risks are discussed using different channels of communication, and (3), what ethical problems arise during this process. In the process of analysis, we identified four types of information channels and two strategies of risk comm…

Effect of sperm concentration and storage temperature on goat spermatozoa during liquid storage

2020

The use of cooled semen is relatively common in goats. There are a number of advantages of cooled semen doses, including easier handling of artificial insemination (AI) doses, transport, more AI doses per ejaculate, and higher fertility rates in comparison with frozen AI doses. However, cooled semen has a short shelf life. The objective of this study was to examine the effect of temperature and sperm concentration on the in vitro sperm quality during liquid storage for 48 h, including sperm motility and kinetics, response to oxidation, mitochondrial membrane potential (MMP) and DNA fragmentation in goats. Three experiments were performed. In the first, the effects of liquid preservation of …

Factors affecting abundance of Triaenophorus infection in Cyclops strenuus, and parasite-induced changes in host fitness.

2000

Factors affecting the abundance of Triaenophorus crassus and Triaenophorus nodulosus procercoids in their copepod first intermediate host, Cyclops strenuus, and effects of infection on feeding behaviour, reproduction and survival of the host were studied experimentally. When exposed to the same number of coracidia, copepods harboured considerably less procercoids in the trials where ciliates or Artemia salina nauplii were given as alternative food items. The prevalence of infection was higher in adult copepods as compared with copepodite stage IV and stage V, and higher in stage V than in stage IV. The prevalences in adult females and males did not differ significantly from each other. The …

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…

Effects of 3,4-dichloroaniline on fish populations. Comparison between r- and K-strategists: A complete life cycle test with the guppy (Poecilia reti…

1991

In order to compare data derived from life cycle tests with zebrafish (Brachydanio rerio Ham.- Buch.), an r-strategist, with data of fish exhibiting a differing strategy of reproduction, a complete life cycle test with the guppy (Poecilia reticulata Peters) was performed with the chemical 3,4-dichloroaniline. The generation of guppies exposed during the whole life span (FI) reacted with more sensitivity than the generation exposed only as adults (Fo): Growth of adult females and reproduction was reduced significantly at 200 Μg/L in Fo, and even at 2 and 20 Μg/L in FI. The survival rates of the early life stages were not influenced at the tested concentrations. There is hardly any difference…