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PubMed1992

Opposite influences of host anaemia on blood feeding rate and fecundity of mosquitoes.

We tested a theoretical model based on the physics of capillary flow and confirmed that anaemia accelerates blood intake in the yellow-fever mosquito, Aedes aegypti (L.). We also investigated the influence of anaemic blood on egg production of mosquitoes and found that it has a negative influence on fecundity. Based strictly on egg production and the physics of fluid intake, we propose that although anaemia associated with blood-borne parasites may be detrimental to mosquitoes that can engorge to repletion in one session, it may be beneficial to those interrupted before repletion because the greater quantity of the bloodmeal may compensate for its lower quality. Epidemiological consequences are discussed but require further inquiry.

Aedes↗
PubMed2002

Density-dependent fecundity and infective juvenile production in the entomopathogenic nematode, Heterorhabditis megidis.

The entomopathogenic nematode Heterorhabditis megidis may undergo several rounds of reproduction within a single host. Infective juveniles (IJs) are formed within each generation during a process referred to as endotokia matricida, which involves the progressive consumption of the parent hermaphrodite or female by the developing IJs prior to emergence from the host cadaver. The present study examines the extent to which within-host population dynamics exhibit density-dependent variation. Particular attention is paid to the effect of infection density on the relative production of IJs and 'normal', non-infective offspring within each generation and on the emergence of the IJs from the host. Fecundity was found to be negatively density dependent across generations. However, at high infection density the first generation hermaphrodites invested relatively more in IJs at the expense of producing non-infective offspring. It is suggested that this pattern resulted from an adaptive, phenotypically plastic allocation of reproductive investment between offspring types in response to increased competition. The F1 and F2 IJs were also shown to emerge from the host in relatively discrete pulses.

Animals↗
PubMed2004

Individual variation and effect of priming dose level on establishment, growth and fecundity of Cooperia oncophora in re-infected calves.

We investigated the effect of bovine anamnestic immunity on a range of parasitological variables. To this end, calves were primed with a single oral dose of 30000 or 100000 infective larvae (L3) of Cooperia oncophora, drenched with anthelmintic, maintained worm free in the following 2.5 months and subsequently re-infected with 100000 L3. Parasitological profiles of low, intermediate, and high responders were compared. The reduction in establishment of the worms was shown by a lower worm burden and increased percentage of fourth-stage (L4) larvae. Worm length and fecundity were similarly reduced by both priming doses but, the speed by which the effect occurred differed between animals primed with 30000 or 100000 L3. The difference in establishment between the responder types demonstrates that the ability of intermediate responders to mount a more effective and faster immune response compared to low responders is sustained after secondary infection.

Animals↗
PubMed2006

Stage-specific differences in fecundity over the life-cycle of two characterized isolates of the liver fluke, Fasciola hepatica.

The variability inherent in different isolates of Fasciola hepatica has been evident from reports in the literature but to date there has been no systematic examination of the relationship between these differences and the fecundity of the parasite. In this study we have attempted to remedy this situation by comparing the relative efficiencies with which 2 well-characterized isolates of the liver fluke (Oberon and Fairhurst) progress through both their definitive and intermediate hosts. We did not observe a reduction in fitness in the Oberon isolate which has been reported to be triclabendazole-resistant, compared to the triclabendazole-susceptible Fairhurst isolate, but considerable inter- and intra-isolate variability at different life-cycle stages was recorded. Thus the Oberon isolate gave 4-fold the number of cercariae when 100 snails were each challenged with a single miracidium and was more successful in establishing productive infections in rats. Fairhurst metacercariae excysted at a higher rate than those from the Oberon isolate and Fairhurst flukes produced 4-fold more eggs. The extent of the intra- and inter-isolate variability revealed in this work will provide a basis for the development of models of population dynamics aimed at predicting the response of the liver fluke to changing environmental conditions such as the use of anthelmintics or climatic change.

Adaptation, Physiological↗
PubMed1999

Influence of the trematode Aphalloïdes caelomicola Dollfus, Chabaud & Golvan, 1957 on the fecundity and survival of Pomatoschistus microps (Krøyer, 1838) (Teleostei: Gobiidae).

Monthly data collected during 1993 in the Vaccarès lagoon (Rhône Delta, France) were used to investigate the influence of the trematode Aphalloïdes coelomicola on the survival of the common goby Pomatoschistus microps, which acts both as second intermediate and definitive host. Prevalence of the parasite did not increase with fish size in either sex. Mean abundance and variance to mean abundance ratio gave evidence that the trematode could have an impact on host mortality. Gonad weight of parasitized females was reduced and the parasite seemed to provoke a gonadal regression above a certain parasitic biomass. Fecundity and egg diameters did not differ between parasitized and unparasitized females, we thus hypothesize that the energy content of eggs (composition in lipids and proteins) was probably modified as an adaptation to energy losses. Prevalence of infection in males compared to females and influence of the parasite on host survival and reproductive effort are discussed.

Analysis of Variance↗
PubMed2002

Mating and fecundity of Dermatophagoides farinae.

Studies of the life cycle of cultured Dermatophagoides farinae found that after an initial mating D. farinae females lived for 63.3+/-64.6 (SD) d after their egg production period ended (Arlian and Dippold 1996). The long period after cessation of egg production for D. farinae suggested D. farinae females could mate multiple times and produce eggs continuously for a longer period. The purpose of this study was to determine if female D. farinae could mate at least two times, and subsequently increase the production of viable eggs over a longer period of time compared to a single mating. Female D. farinae were randomly selected from thriving cultures and isolated in cages. When the females had ceased to lay eggs a male was added to the cage. Fifty-seven percent of the isolated females mated again and produced a second batch of viable eggs. In natural or culture populations, females have continuous availability of males. Therefore, in another experiment, females that emerged from the tritonymphal stages were continuously exposed to fresh males and fecundity and lengths of the reproductive and post reproductive periods were determined. These females had a 11 d longer reproductive period and produced 30.7% more eggs compared to females that only mated one time after they emerged from the tritonymphal stage. However, the post reproductive period was still long (58.6+/-11.4 [SE] d) the significance of which is not clear. In conclusion, this study revealed that D. farinae females are capable of more than one successful mating that results in increased egg production compared to that of a single mating. It is likely that females mate multiple times in natural and culture populations. It was observed that females actively attract males during the reproductive period but not afterward even though she continues to live a long time.

Animals↗
PubMed2002

Evolutionary adaptations to pre-eclampsia/eclampsia in humans: low fecundability rate, loss of oestrus, prohibitions of incest and systematic polyandry.

Gestational-hypertension/pre-eclampsia occurs in approximately 10% of human pregnancies. This persistent complication of pregnancy has been reported to occur more frequently in couples conceiving very shortly after the beginning of their sexual relationship and/or after a change in paternity. Primipaternity may be the leading cause of pre-eclampsia in women under 30 years of age when genetic susceptibility to cardio-vascular disease has not yet been expressed, especially in women before their twenties, who for the last 40,000 years have perhaps comprised the age group when the majority of parturients classified as Homo sapiens sapiens initiated their reproductive life. In terms of evolution, the prevalence of pre-eclampsia represents a distinct reproductive disadvantage in humans as compared with other mammals. Indeed, pre-eclampsia is a consequence of the defect of the normal human-specific deep endovascular invasion of the trophoblast. The large size of the human fetal brain imposing this deep trophoblastic invasion induced the need for major immunogenetic compromises in terms of paternal-maternal tissue tolerance. The price that mankind has had to pay to adapt to the pre-eclampsia risk is a low fecundability rate and therefore loss of oestrus, possibly a step in the deviation between apes and hominids. Further, pre-eclampsia risk may be a contributing factor leading to the rejection of systematic polyandry in human societies and have influenced prohibition of incest.

Adaptation, Biological↗
PubMed1983

Dynamics of an enzyme polymorphism in the isopod, Sphaeroma rugicauda (Leach). II. Sexual, gametic and fecundity selection.

The estuarine isopod Sphaeroma rugicauda (Leach) exhibits a diallelic polymorphism at the locus coding for the enzyme Pgi. An investigation carried out during the animal's breeding season (June-July) in 1979 and 1980 indicated that the animals were mating at random. It also showed the s/s-homozygote females to be the earliest to release offspring and to be the most fecund of the three genotypes (f/f, f/s and s/s). Further, data from the wild population in 1980 and laboratory experiments indicated that male s-gametes were selected against in s/s females, resulting in offspring ratio distortions in f/s (male) X s/s (female) crosses, in favour of heterozygotes. The net effect of these selective pressures did not, however, significantly alter the genotype frequencies (found in the offspring) from expected values.

Animals↗
PubMed1993

The ovine Booroola fecundity gene (FecB) is linked to markers from a region of human chromosome 4q.

The autosomal Booroola fecundity gene (FecB) mutation in sheep increases ovulation rate and litter size, with associated effects on ovarian physiology and hormone profiles. Analysis of segregation in twelve families (379 female progeny) identified linkage between the mutation, two microsatellite markers (OarAE101 and OarHH55, Zmax > 9.0) and epidermal growth factor (EGF) from human chromosome 4q25 (Zmax > 3.0). The marker OarAE101 was linked to secreted phosphoprotein 1 (SPP1, which maps to chromosome 4q21-23 in man) in the test pedigrees and independent families (Zmax > 9.7). The identification of linkage between the FecB mutation and markers from human chromosome 4q is an important step towards further understanding the control of ovulation rates in mammals.

Animals↗
PubMed1999

Wolbachia infection in the terrestrial isopod oniscus asellus: sex ratio distortion and effect on fecundity

Maternally inherited Wolbachia bacteria are widespread in arthropods where they are responsible for various reproductive alterations. In terrestrial isopods (woodlice), Wolbachia may induce feminization or cytoplasmic incompatibility (CI), but their effect remains unknown in most host species. To increase our understanding of host/symbiont interactions in terrestrial isopods, the effect of Wolbachia was investigated in the oniscidean Oniscus asellus, mainly to discriminate between feminization and CI. The Wolbachia infection was not linked with a CI phenomenon, but females infected with Wolbachia produced female-biased broods compared with uninfected females. The fecundity of infected females was slightly lower than that of uninfected, but the number of young at the adult stage was similar between the two female categories. The experimental transfer of the symbiont into uninfected strains showed that Wolbachia was responsible for the feminization of a number of genetic males. In female-biased broods, Wolbachia were vertically transmitted to around 88% of the offspring, but the transmission rate was lower in the few male-biased progenies. The feminizing activity of these symbionts was not systematic, as many phenotypic males were infected. These results contrasted with what is known in another woodlouse species, and indicated that feminization has evolved in different ways in terrestrial isopods.

Journal Article↗
PubMed2001

Fecundity and offspring ploidy in matings among diploid, triploid and tetraploid Chamerion angustifolium (Onagraceae): consequences for tetraploid establishment.

Models of polyploid evolution indicate that tetraploids are more likely to establish within diploid populations when they are formed recurrently through the union of unreduced (n=2n) gametes. To account for the coexistence of diploids and tetraploids in populations of Chamerion angustifolium, diploid, triploid and tetraploid plants were crossed in all possible combinations and fecundity and ploidy using flow cytometry of the resulting progeny were measured. Combined with previous data on cytotype fitness, these data were used in a simulation to examine the impact of unreduced gametes on tetraploid evolution. Seed set per fruit was highest in 2x x 2x crosses (69%), intermediate in 4x x 4x, 2x x 4x and 3x x 4x crosses (range, 11-35%) and lowest in 3x x 2x and 3x x 3x crosses (range, 1-10%). Offspring were diploid (94%) or triploid (6%) in 2x x 2x crosses, diploid (17.5%), triploid (56%) or tetraploid (26.5%) in 3x x 2x crosses, and triploid (53%) and tetraploid (44%) in all others (4x x 4x, 3x x 4x, 2x x 4x), indicating that some gametes are unreduced, particularly in triploids. Forty-two percent of offspring, from three different crosses, had DNA contents greater than tetraploids. Computer simulations based on these results showed that unreduced gamete formation via triploids in C. angustifolium can promote the coexistence of diploids and tetraploids, but, due to law triploid fitness, is insufficient to overcome tetraploid minority disadvantage.

Computer Simulation↗
PubMed2001

Comparative fecundity and survival rates of phlebotomus papatasi sandflies membrane fed on blood from eight mammal species.

Female sandflies, Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae), were fed via chicken membrane on heparinized blood from eight species of mammal (human, horse, cow, pig, dog, rabbit, guinea-pig, hamster) and their reproductive success rates were compared. No appreciable differences between those fed on human and animal blood were detected with respect to the proportion of flies that fed successfully, mortality-rate within 24h, number of eggs laid per blood-fed female or egg viability. When mass-rearing sandflies for research purposes, membrane-feeding avoids practical difficulties encountered if sandflies are allowed to feed on live hosts (i.e. anaesthesia, distress from handling and postfeeding inflammation) and reduction of sandfly fecundity due to host antibody interference. Use of animal blood also eliminates risks of accidental transmission of human blood-borne pathogens, e.g. hepatitis B and human immunodeficiency virus (HIV), and is less expensive than maintenance of animals and their preparation for sandfly feeding.

Animals↗
PubMed2002

Genetic parentage assessment in the crayfish Orconectes placidus, a high-fecundity invertebrate with extended maternal brood care.

Microsatellite data have recently been introduced in the context of genetic maternity and paternity assignments in high-fecundity fish species with single-parent-tended broods. Here we extend such analyses to an aquatic invertebrate, the crayfish Orconectes placidus, in which gravid females carry large numbers of offspring. Genetic parentage analyses of more than 900 progeny from 15 wild crayfish broods revealed that gravid females were invariably the exclusive dams of the offspring they tended (i.e. there was no allomaternal care), and that most of the females had mated with multiple (usually two) males who contributed sometimes highly skewed numbers of offspring to a brood. Within any multiply sired brood, the unhatched eggs (or the hatched juveniles) from different fathers were randomly distributed across the mother's brood space. All of these genetic findings are discussed in the light of observations on the mating behaviours and reproductive biology of crayfish.

Animals↗
PubMed2001

Vaccination with neutrophil inhibitory factor reduces the fecundity of the hookworm Ancylostoma ceylanicum.

Neutrophil inhibitory factor (NIF), a protein isolated from hookworms of the genus Ancylostoma, inhibits CD11b/18-dependent leucocyte function, binding to the I domain of CD11b. Historically, NIF was serendipitously isolated from whole worm extracts during a search for novel antihaemostatic agents, and little is known of its source or biological significance to the parasite. NIF has also been identified as a possible hookworm vaccine candidate. Ancylostoma ceylanicum recombinant NIF, expressed in its active form in Pichia pastoris, was purified and its functional activity confirmed using neutrophil adhesion assays and confirmatory immunoassay. Recombinant NIF was subsequently used in vaccination trials in the A. ceylanicum-hamster model system for human hookworm infection. Vaccinated and challenged animals were not protected in terms of worm burden or haematocrit values, despite the presence of high levels of specific antibody against NIF. However, adult worms resident in vaccinated animals showed a significant reduction in fecundity (85.8% by day 21 postinfection), indicating a degree of protection against subsequent transmission by vaccination. These data indicate that targeted vaccination with recombinant subunit material, derived from a known and effective immune suppressant secreted by the parasite, may offer partial protection against the transmission of hookworm infection. Furthermore, we can also report that a biological activity characteristic of NIF is detectable in the secretions of A. ceylanicum using two complementary bioassays. Complete neutralization of this secreted activity by vaccination in combination with other vaccine candidates may result in improved protection against A. ceylanicum infection.

Ancylostoma↗
PubMedDate not supplied

Developmental flexibility and the effect of social environment on fertility and fecundity in parthenogenetic reproduction.

One specialized environment that can influence development arises in the context of social interactions, including the environment contributed by a sexual partner during sexual reproduction. It is often difficult, however, to separate out the effect of mating (fertilization) from the effect of social environment. In the study reported here we examine the effect of social environment mediated by a pheromonal signal on the fertility and fecundity of the facultatively parthenogenetic cockroach Nauphoeta cinerea. By examining parthenogenetically reproducing females, we isolate the effects of social environment in the absence of mating or fertilization. Females exposed to male odors are more likely to produce parthenogenetic offspring. Further, increased exposure to the male pheromone increases the number of offspring produced. Variation in timing of reproduction is also dependent on the male. Thus, social environments are a mechanism by which males contribute to the development of their offspring, resulting in variation in development. This study illustrates the potential evolutionary importance of social environments in development, because a requirement for male-contributed environments may be a constraint to evolving asexual reproduction from a sexually reproducing species.

Analysis of Variance↗
PubMed2001

Anti-mosquito midgut antibodies block development of Plasmodium falciparum and Plasmodium vivax in multiple species of Anopheles mosquitoes and reduce vector fecundity and survivorship.

The mosquito midgut plays a central role in the sporogonic development of malaria parasites. We have found that polyclonal sera, produced against mosquito midguts, blocked the passage of Plasmodium falciparum ookinetes across the midgut, leading to a significant reduction of infections in mosquitoes. Anti-midgut mAbs were produced that display broad-spectrum activity, blocking parasite development of both P. falciparum and Plasmodium vivax parasites in five different species of mosquitoes. In addition to their parasite transmission-blocking activity, these mAbs also reduced mosquito survivorship and fecundity. These results reveal that mosquito midgut-based antibodies have the potential to reduce malaria transmission in a synergistic manner by lowering both vector competence, through transmission-blocking effects on parasite development, and vector abundance, by decreasing mosquito survivorship and egg laying capacity. Because the intervention can block transmission of different malaria parasite species in various species of mosquitoes, vaccines against such midgut receptors may block malaria transmission worldwide.

Animals↗
PubMedDate not supplied

Viability and fecundity of human semen specimens cryostored and transported at 5 degrees C using the Bio-Tranz shipping.

This study was designed to assess the viability and fecundity of semen stored at 5 degrees C for 24 hours using the Bio-Tranz shipping system. Semen specimens were assessed for motility and sperm membrane integrity at the time of collection and 24 hours after storage in the Bio-Tranz. In group 1 (n = 61), specimens were diluted in TYB, processed and used for intrauterine insemination (IUI), leaving an aliquot for storage for 24 hours in the Bio-Tranz. In group 2 (n = 67), specimens were diluted in TYB, stored for 24 hours in the Bio-Tranz and then processed and used for IUI. In both groups, the total motile sperm used for IUI was similar and the women that underwent IUI were standardized for ovulation prediction and time of insemination. The overall sperm characteristics between the two groups were within normal range. Significant decreases were noted in sperm motility and membrane integrity in both groups after storage. Similar pregnancy rates were obtained between the two patient populations. The use of the Bio-Tranz shipper is extremely convenient for patients requiring semen evaluation, cryostorage or IUI and other assisted reproductive technologies.

Adult↗
PubMed2003

Recruitment density can determine adult morphology and fecundity in the barnacle, Semibalanus balanoides.

Although consequences of the settlement preference of larvae have been well documented, the consequence of these settlement choices on subsequent mortality, morphology and fecundity has been little studied. The aim of this study was to determine the relationship between recruit and adult density and to determine the effect of recruitment on adult morphology and egg tissue mass. This study follows 48,718 barnacles (Semibalanus balanoides) from recruitment at the end of the settling season to reproductively mature adults at a field site in the Clyde Sea (UK). Overall survivorship of the recruits to adulthood was 8.5%, although survivorship was up to 42% on low density settlement panels. In low density colonies (< 10 recruits cm-2), recruitment density was related to adult density (P < 0.001), whereas no relationship was found for higher density colonies. A shell morphology index measured at adulthood was related to recruitment density for low density recruited colonies (P < 0.001) but not high density colonies. Using ANCOVA, variations between the colonies in shell and egg tissue mass were not explained by mass of somatic tissue. However, egg mass was explained by recruitment density (P < 0.01). These results show that adult density is not a reliable indicator of the previous population density of the colony. Moreover, there are marked differences in population development between colonies with high and low recruit densities in terms of impact upon shell morphology and egg production. The dynamics that operate between recruits at the end of the settlement season and sexually mature adults to create the patterns elucidated in this paper, and other literature, remain unclear.

Animals↗