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PubMed1989

Density dependence in establishment, growth and worm fecundity in intestinal helminthiasis: the population biology of Trichuris muris (Nematoda) infection in CBA/Ca mice.

The results are presented of an experimental study of the population biology of chronic Trichuris muris (Nematoda) infection in cortisone-treated CBA/Ca mice. Attention is focused upon both the validity of the common use of faecal egg counts to demonstrate density dependence in helminth fecundity, and the identification of other possible density-dependent mechanisms that may regulate worm numbers in chronic trichuriasis. The results show that faecal egg counts, although demonstrating high daily variation, are not an artefact of host faecal output but a significant density-dependent function of worm burden. This finding contrasts with the observations on Heligmosomoides polygyrus infection in outbred MFI mice, but accords with similar studies in a wide variety of host - helminth systems. Worm establishment in the murine host is found to be a density related function of infection dose. This is attributed to the probable existence of a physical gut-carrying capacity in the murine host for T. muris. Worm distribution in the gut is also shown to the density dependent, with worms being displaced from the caecum to the colon at increasing intensities of infection. The sex ratio of the adult parasites, however, is found to be both unitary and independent of worm burden. Evidence for a significant density-dependent decline in female T. muris growth or size is presented. The results also show a significant positive association between female T. muris weight and per capita fecundity. These findings indicate that the stunted growth of individual worms at high parasite densities may be a potential mechanism underlying density dependence in helminth fecundity.

Animals↗

PubMedDate not supplied

[Influence of some medium factors on the fecundity of Biomphalaria glabrata (Say, 1818) Mollusca, Pulmonata) in laboratory conditions].

In different samples of fresh waters we studied the fecundity of Biomphalaria glabrata. We tested, too, the influence of different concentrations of Na, Ca, Mg, and K-salts. The snail, B. glabrata, is not affected by very high rates of those salts but eggs laying is getting down when the amount of NaCl is between 2000 and 4000 mg/1, of MgCl2 between 410 and 763 mg/1 and KCl between 330 and 760 mg/1. The rate in Ca seems inactive in the field of fecundity but, in an other hand, high concentrations of Ca suppressed the inhibiting effect of the high rates in Mg. B. glabrata is not affected by high rates in Mg, when Mg/Ca is Low. The inhibiting effect of Mg begins when Mg/Ca is around 30. The importance of different kinds of substratum for eggs lying on fecundity was also studied.

Animals↗

PubMed1992

Eggs, enzymes, and evolution: natural genetic variants change insect fecundity.

Phosphoglucose isomerase genotypes in the butterfly Colias differ dramatically in biochemical properties. These differences were evaluated earlier, using metabolic network theory, to predict, successfully, their effects on glycolytic metabolism and hence on Colias flight capacity and several consequent fitness components in the wild. Female egg-laying, not previously studied, also depends on flight, so female fecundity is now predicted to differ among these genotypes. An experimental design incorporating the thermal ecology of Colias confirms these predictions in a cool habitat. Thus female fecundity differences among animal enzyme polymorphs have now been found. Quantitative reconstruction of the selection regime for phosphoglucose isomerase genotypes in Colias can now begin. The most heat-stable genotypes are the least fecund, suggesting that global warming, if it occurs, may have severe impacts, through population genetics, on demography of thermally sensitive creatures.

Analysis of Variance↗

PubMed1992

Sublethal effects of insecticides on adult longevity and fecundity of German cockroaches (Dictyoptera: Blattellidae).

The effects of sublethal concentrations of chlorpyrifos, cyfluthrin, and hydramethylnon on adult longevity and fecundity of German cockroaches, Blattella germanica (L.), were investigated. Longevity of males declined linearly with increasing doses of insecticide. An LD50 of cyfluthrin decreased male longevity by 52%, whereas an LD50 of hydramethylnon reduced male longevity by 81%. Longevity of females increased linearly with increasing sublethal doses of chlorpyrifos, whereas all doses of both cyfluthrin and hydramethylnon decreased longevity of females. Fecundity increased linearly with increasing sublethal doses of chlorpyrifos. Number of oothecae formed, oothecae hatched, and number of offspring produced in each ootheca increased with increasing sublethal concentrations of chlorpyrifos. In contrast, fecundity declined with increasing sublethal concentrations of cyfluthrin and hydramethylnon. Formation of the first ootheca occurred approximately 8 d after mating for untreated females but generally longer with sublethal concentrations of all insecticides. The period between oothecae hatch and the formation of subsequent oothecae increased with successive oothecae in all treatments.

Animals↗

PubMed1992

Oviposition habits of Simulium kawamurae (Diptera: Simuliidae), with reference to seasonal changes in body size and fecundity.

Oviposition habits and seasonal changes in wing length, head width, and number of ovarioles of Simulium kawamurae Matsumura were investigated in Kyushu Island, Japan. Gravid flies swarmed over turbulent water and laid eggs on rock surfaces in the splash zone. Large, irregular egg masses often resulted from the mass oviposition by many females within the same small area. Oviposition occurred at dusk during spring-summer, shifting to earlier periods during autumn-winter. Fecundity increased linearly as a function of body size (i.e., both with the cube of wing length and of head width, showing a better fit with the latter). Spring flies had a larger mean body size and fecundity than both summer and autumn flies. Winter flies had wings as long as spring flies, but their head widths and fecundity were comparable to summer-autumn individuals. This indicated seasonal variation in the relative proportion of body structures.

Animals↗

PubMed1986

Chronological changes in fertility, fecundity and steroid hormone secretion during consecutive pregnancies in aging rats.

During aging in female rats the incidence of regular estrous cyclicity decreases progressively. Concomitant with this decrease are declines in both fertility and fecundity in aged females. The causes for these age-related losses in reproductive function are currently unknown. To reveal the biology and endocrinology of pregnancy in aging females, we performed a longitudinal study in a group of multiparous rats bred once every 2 mo. Beginning at 4 mo and continuing through 12 mo of age in the same individual females, we determined the chronological changes in estrous cyclicity and fertility; examined the number of implantation scars; estimated the fetal resorption rate; and assessed the patterns of progestin, androgen, and estrogen secretion during 5 consecutive gestations. During each pregnancy, blood samples were obtained from the mothers on Days 2, 5, 8, 11, 14, 16, and 19 for measurement of steroid hormone concentrations. Laparotomies were performed after parturition to count the number of implantation scars. To estimate the number of fetal resorptions, the difference between the number of implantation scars and the total number of pups delivered was calculated for each animal. Fertility during aging followed a similar but more dramatic pattern of decline than did the incidence of regular cyclicity. While almost all females became infertile when their regular ovulatory cycles ceased, an increasing proportion of middle-aged (10-12 mo of age) regularly cyclic rats also failed to reproduce successfully. These observations indicate that the loss of fertility in aging female rats is due largely, but not exclusively, to the cessation of regular ovulatory cycles. Beginning at 8 mo and continuing to 12 mo of age, a significant (p less than 0.01) decline in litter size was observed in these multiparous rats. This decline was associated with a similar decrease in the number of implantation scars. Neither the estimated number of fetal resorptions nor the number of dead pups delivered per pregnant rat changed significantly during 5 consecutive gestations. There were, however, age-related gradual increases in the percentage of fetal resorptions/implantation scars and of dead pups/total number of pups delivered. These data indicate that the age-related decline in fecundity is due mainly to reproductive failures early in gestation. The patterns of decreases in both fertility and fecundity found in repeatedly sampled and laparotomized females were similar to those seen in untreated multiparous rats.(ABSTRACT TRUNCATED AT 400 WORDS)

20-alpha-Dihydroprogesterone↗

PubMed1991

Immunization of mice and baboons with the recombinant Sm28GST affects both worm viability and fecundity after experimental infection with Schistosoma mansoni.

A member of the glutathione S-transferase family, Sm28GST has previously demonstrated a good ability to protect rodents against experimental infection with Schistosoma mansoni. In order to evaluate its efficacy in a model closer to man, two different protocols of immunization with recombinant Sm28GST were tested on baboons in a large-scale trial. Three injections in the presence of aluminium hydroxide as adjuvant resulted in a significant 38% reduction in the adult worm burden together with a trend for a lower percentage of inflammatory tissue in the liver. Individual levels of protection, ranging from 0 to 80%, underlined the heterogeneity of the immune response to this purified molecule in outbred primates. On the other hand, two injections of Sm28GST in the presence of aluminium hydroxide and Bordetella pertussis reduced female schistosome fecundity by 33%, with a more pronounced effect (66%) on faecal egg output; there was also a trend, in this protocol, for decrease of the mean granuloma surface in the liver. Individual anti-Sm28GST IgG antibodies were apparently unrelated to levels of immunity, but there was partial evidence that cytophilic IgE might play a role in the immune mechanisms affecting worm viability, but not fecundity. In the mouse model, Sm28GST vaccination resulted in a lower hatching ability of tissue eggs recovered from immunized mice whereas passive transfer of specific anti-Sm28GST T-lymphocytes, one day before infection, significantly reduced the number of eggs in the liver of mice. We propose that different protocols of immunization with a recombinant molecule can impede Schistosoma mansoni worm viability and fecundity, but can also affect miracidium physiology, with important consequences for disease transmission and granuloma-derived pathology.

Animals↗

PubMedDate not supplied

The sperm penetration test (P-test) can predict fecundability in the male partner from infertile couples.

Three hundred and twenty-one consecutive couples were investigated for infertility at Hvidovre University Hospital in the period from November 1977 to June 1985. The male partners were evaluated in two ways: the classical semen analysis, and the ability of sperm to penetrate fresh hen egg white, the P-test. A Cox regression analysis was used to describe the relation between these variables and fecundability, i.e. the time required to conceive. Four of thirteen variables--the number of morphologically normal spermatozoa, the number of motile spermatozoa, the P-test, and the man's age--each have significant relation to the fecundability. However, when covariation is considered, only the P-test and the man's age possess significant prognostic information, whereas the variables of the classical semen analysis do not. This indicates that the P-test may replace the classical semen analysis when trying to predict individual pregnancy probabilities. Finally, the P-test and the man's age are combined to form a prognostic index which predicts the fecundability of the male partner in the individual infertile couple.

Adult↗

PubMed1989

Hypergravity and ageing in Drosophila melanogaster. 1. Fecundity.

In Drosophila melanogaster daily fecundity has been recorded throughout life of flies kept at various gravity levels (1-5 g). Hypergravity (HG) did not decrease total fecundity but modified its expression during life. The 1 g group could be opposed to the various HG groups, i.e. a clear regression of the various fecundity items on the HG level could not be disclosed. Results are discussed in relation with Pearl's rate of living theory.

Aging↗

PubMed1987

Lack of demonstrable density-dependent fecundity of schistosomiasis mansoni: analyses of Egyptian quantitative human autopsies.

Conflicting interpretations regarding the fecundity of schistosomes infecting human beings have arisen and are, in part, due to the inability to directly measure the parameters. The inability to experimentally manipulate human beings necessitates the use of surrogate variables, i.e., number of eggs per gram of feces, as an indicator of worm burden. This study reanalyzes data from quantitative autopsies performed in Egypt by Cheever and colleagues on individuals with active Schistosoma mansoni infections. Exploratory regression analysis of the relationship of female worms recovered to eggs/g of feces and of female worms to eggs retained in host tissues suggests a linear relationship in both cases. Over the observed range of female worms recovered from an individual human being, the estimated worm fecundity, as measured by the number of eggs either in feces or retained in tissues per female worm, is not significantly different from a constant value. Hence, density-dependent fecundity of S. mansoni in the human host, as suggested by others, is not demonstrated in these data.

Adolescent↗

PubMed1975

[Fecundity and embryonal mortality of four inbred strains of mice, BALB/c, B10.CW, A/Sn, CC57W and their hybrids].

The object of this investigation was the potential fecundity of four inbred strains of mice, viz. BALB/c, B10.SW, CC57W, A/Sn and of their different hybrid combinations. The inbred strains studied had different normal ovulation numbers varying from 9,2 to 11,9 and different death-rate of embryos before (10,99-39,49%) and after (9,05-22,47%) the implantation. The numbers of live embryos per female in the strains A/Sn, B10.CW and CC57W were practically equal to one another, but significantly larger than in the strain BALB/c. Interlinear crosses resulted in a considerable decrease of the total embryonic death-rate, while the normal ovulation number did not undergo any changes. The number of live embryos in simple hybrids did not differ significantly from that in the maternal inbred strains. Therefore the heterozygosity of embryos did not affect significantly the potential fecundity of females. The number of surviving embryos per female increased in the cross between the simple hybrids (BALB/cXB10.CW) X (CC57WXA/Sn) to 8,9 +/- 0,37. This heterosis was the result of the total death-rate of embryos down to 14,89%. As it is shown by the comparison of the potential fecundity of pregnant females carrying homo- and heterozygous embryos to that of pregnant hybrid females, the rate of survival of embryos depends more on the genotype of the mother, than on that of the embryos.

Animals↗

PubMed1975

[Fecundity and embryonal mortality of four inbred mouse lines, BALB/c, B10.CW, A/Sn, CC57W and their hybrids].

The object of this investigation was the potential fecundity of four inbred strains of mice, viz. BALB/c, B10.SW, CC57W, A/Sn and of their different hybrid combinations. The inbred strains studied had different normal ovulation numbers varying from 9,2 to 11,9 and different death-rate of embryos before (10,99-39,49%) and after A/Sn, B10.CW and CC57W were practically equal to one another, but significantly larger than in the strain BALB/c. Interlinear crosses resulted in a considerable decrease of the total embryonic death rate, while the normal ovulation number did not undergo any changes. The number of live embryos in simple hybrids did not differ significantly from that in the maternal inbred strains. Therefore the heterozygosity of embryos did not affect significantly the potential fecundity of females. The number of surviving embryos per female increased in the cross between the simple hybrids (BALB/cXB10.CW)X(CC57WXA/Sn) to 8.9 +/- 0,37. This heterosis was the result of the total death-rate of embryos down to 14,89%. As it is shown by the comparison of the potential fecundity of pregnant females carrying homo- and heterozygous embryos to that of pregnant hybrid females, the rate of survival of embryos depends more on the genotype of the mother, than on that of the embryos.

Animals↗

PubMed1991

[Biology of Triatoma infestans populations: fluctuations of fecundity and mortality].

Fecundity and mortality in population of insects is relevant to the epidemiology of insect transmitted diseases. These variables were studied for T. infestans during 5 years under constant conditions of temperature, relative humidity, light periods and individual density. Mean fecundity was 0.96 +/- 0.69 eggs/female-week, range 0 to 4. Minima were observed in april and maxima in october and november. Mean mortality of intermediate forms was 0.058 +/- 0.031/individual-week, range 0.009 to 0.135, similar for females and males. Minima for mortality were observed in june and july, maxima from november to march. Fluctuations of fecundity are attributed to endogenous cyclic changes related to mating and egg laying. Possible explanations for fluctuations in mortality include the action of infectious agents. The secondary mortality cycle may be related to delayed effect of population density or to differential mortality of cohorts born under different environmental conditions.

Animals↗

PubMed1991

Fecundity of gastrointestinal trichostrongylid nematodes of sheep in the field.

Twenty-two Dorset Rambouillet lambs were moved to contaminated pasture on Apr 1, 1987. At regular intervals thereafter, pairs of lambs were withdrawn and euthanatized. Gastrointestinal parasites in the abomasum, small intestine, cecum, and large intestine were removed and counted. The last pair of lambs was euthanatized 8 months after original placement on the contaminated pasture. Fecal samples were taken at 3- to 4-week intervals throughout the grazing season and the fecal egg counts were used to estimate parasite fecundity (output of eggs per female parasite per day). The principal parasite genera found included Haemonchus spp, Trichostrongylus spp, and Nematodirus spp. In each of the genera examined, parasite fecundity remained the same irrespective of the intensity or duration of infection. Estimated average fecundities (eggs/female/day) were as follows: Haemonchus contortus, 6,582; Trichostrongylus spp, 262; Nematodirus spp, 40; and Oesophagostomum venulosum, 11,098.

Abomasum↗

PubMed1991

Adjunctive leuprolide therapy does not improve cycle fecundity in controlled ovarian hyperstimulation and intrauterine insemination of subfertile women.

Problems arising from controlled ovarian hyperstimulation for intrauterine insemination, such as premature luteinization and asynchronous ovarian follicular development, are identical to those encountered with controlled ovarian hyperstimulation for in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT). It has been suggested that the adjunctive use of GnRH agonists for controlled ovarian hyperstimulation improves the efficiency of GIFT and IVF cycles. We hypothesized that adjunctive use of leuprolide acetate, a GnRH agonist, would have a similarly beneficial effect on cycle quality and cycle fecundity in subfertile women treated with controlled ovarian hyperstimulation and intrauterine insemination. We randomly assigned the first cycle of controlled ovarian hyperstimulation and intrauterine insemination for each of 97 subfertile women to include either human menopausal gonadotropins (hMGs) alone or hMGs following midluteal pre-treatment with leuprolide. If a pregnancy did not occur in the first cycle, the woman was given the other treatment in the second cycle. Although the cycles that included leuprolide required a larger amount of hMGs and more days of stimulation per cycle, the mean estradiol concentrations and numbers of follicles were not different. Despite prevention of premature luteinization with leuprolide, the cycle fecundity was not different between groups (0.11 with adjunctive leuprolide treatment and 0.22 with hMGs alone). We conclude that in unselected subfertile patients, the adjunctive use of leuprolide for controlled ovarian hyperstimulation and intrauterine insemination does not improve cycle fecundity compared with treatment cycles that do not include adjunctive leuprolide therapy.

Adult↗

PubMed1990

The possible influence of male worm age on the fecundity of Moniliformis moniliformis (Acanthocephala) in laboratory rats.

During the course of a primary infection of Moniliformis moniliformis in rats, involving an experimentally structured population of worms derived from infective doses of 10 male and 10 female cystacanths per rat, the fecundity of the female worms appeared to be influenced by the age of the males. The experimental design ensured that all the female worms were 35 days old when fecundity was assessed. On average, the number of eggs in females recovered from rats containing 28-day-old males was 20,930 +/- 2,143, that from rats containing 35-day-old males was 7,434 +/- 937, and that from 42-day-old males was 14,396 +/- 1,704; these values were found to be significantly different (least significant difference, P less than or equal to 0.01). The results suggest that the variable age of the worms would be likely to favor fecundity in naturally occurring infections.

Acanthocephala↗

PubMed1988

Control of fertility and fecundity of sheep by means of hormonal manipulation.

The results of four experiments are presented in summary form. The data are considered in relationship to the improvement of the fecundity and fertility of the Australian ewe breeding flock. In the first, three commonly used methods of oestrous synchronization were examined and showed differences that are attributed to the different patterns of hormonal changes associated with the methods demonstrated. The second experiment looked at the use of active immunization against testosterone and concluded that this method can improve fecundity but not fertility. The third experiment, a group of five trials, studied the use of progestagen sponges and PMSG in anoestrous ewes as a means of inducing normal fertility. The extensive data produced in this experiment allowed the relationships between ovulation rate and fertility and between fertility and prolificacy (fecundity) to be examined. Fertility appeared greatest when the mean flock ovulation rate was about 2.5. At this ovulation rate prolificacy was also improved and a high proportion of twins were produced. We concluded that high fertility and low prolificacy (i.e. of 1.00) are an unlikely combination. In the final experiment the effect of post-mating hormonal supplementation on fertility was examined and a number of earlier reports were confirmed by showing that fertility can be improved with supplementary progesterone between days 10 and 25 post-mating. The effect appears to be modified by hormonal and nutritional factors.

Animals↗

PubMed1988

Size of inoculum dose regulates in part worm burdens, fecundity, and lengths in ovine Haemonchus contortus infections.

Density-dependent factors frequently have been shown to regulate population parameters of free-living and parasitic helminths. To test the effects of various infection levels of Haemonchus contortus on fecundity and worm size, lambs were inoculated with 3,000, 10,000, and 30,000 infective larvae. Daily eggs per gram (epg) and daily total fecal production per lamb were monitored continuously. Worms were collected from abomasa on 6, 15, 22, and 30 days postinfection (PI). Female worms were smaller on each day in the high-dose group when compared to female worms from the low-dose group; males in the high-dose group were smaller from days 15 through 30 PI. The high- and medium-dose groups had higher mortality rates on day 30 PI, and fecundity (eggs/female/day) was 78% lower. Daily epg and daily total eggs/lamb/day were lower in the high-dose group. Fecundity and worm size were correlated with the log-transformed dose level but not with adult worm number. Early parasite and/or host responses apparently exert long-term negative effects on growth and reproduction relative to the size of the establishing population of H. contortus.

Abomasum↗