Normal reference ranges for semen quality and their relations to fecundity

Several recent studies have shown that the fecundity of a man decreases progressively with sperm concentrations below 40 million spermatozoa per mL. Therefore, it is unfortunate that the new World Health Organization guidelines for semen analysis recommend lowering the lower cutoff value for normal sperm concentration from 20 to 15 million spermatozoa per mL. As a result large groups of subfertile men across the world may not receive appropriate andrological help in the future.

LABORATORY OBSERVATION ON SPAWNING,FECUNDITY AND LARVAL DEVELOPMENT OF AMPHIOXUS (BRANCHIOSTOMA BELCHERI TSINGTAUNESE)

Although amphioxus is widespread in temperate and tropical seas,its population is diminishing be-cause of environmental pollution.To keep the population of this evolutionarily important animal fromdiminishing,study on its reproduction and development is necessary.The main findings in this study onthe spawning and fecundity of the amphioxus reared in laboratory and its larval development are as fol-lows.1.Water temperature markedly affected the spawning.It spawned only when water temperature reached 21℃.2.Spawning of the amphioxus in laboratory was markedly extended.Initially,the amphioxus spawned at about 7:00 PM,but spawning time was postponed as spawning days went on.3.The number of eggs produced by a female ranged from 1400 to 12800,average of 5800.This al-so represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time.4.During the first few months of life of the amphioxus,its growth rate changed seasonally.Thegrowth rate in summer and fall was greater than that

Effects of ethanol extract of leaves of Helianthus annus on the fecundity of Wistar rats

Objective:To evaluate the effects of ethanol extract of leaves of Helianthus annus(H.annus) on the fecundity of Wistar rats.Methods:Forty(20 male and 20 female) Wistar rats,grouped into control,ethanol extract treated rats and untreated,were used for the study.Treated rats had 0.5 g/kg of ethanol extract orally for 2 weeks;control rats had 5%alcoholic water(solvent);and untreated rats had their normal feed and clean drinking water.Following treatment,the animals were sub-grouped into 5 mating groups to observe the coital frequency,pregnancy rate and average number of pups per group in pairs.Results:The results showed that coital frequency was unaffected by the extract treatment but pregnancy rate and number of pups per rat and per group were reduced significantly in groupsⅡ,ⅢandⅣcompared to those of groupⅠandⅤrats which were not treated with the ethanol extract of leaves of H.annus.Conclusions:The histodegenerative in the gonads reportedly induced by this ethanol extract in previous studies may be responsible for the reduced fecundity observed in treated adult rats.

Screening of Brown Planthopper Resistant miRNAs in Rice and Their Roles in Regulation of Brown Planthopper Fecundity

MicroRNAs(miRNAs)can participate in plant-insect interactions,which regulate plant defense networks.In this study,we analyzed the miRNA expression profiles of six rice varieties before and after brown planthopper(BPH)-feeding.We identified 45 differentially expressed miRNAs between BPH-susceptible and BPH-resistant rice varieties and 144 miRNAs that responded to BPH-feeding.Thus,miRNAs may be involved in multiple pathways regulating rice defense response against BPH.In addition,we found that the genetic history of rice varieties determined the regulation mode of the miRNA and affected the amounts,types,changing trends and response periods of miRNAs in response to BPH-feeding.To conclude,we scanned seven potential cross-kingdom miRNAs,of which miR5795 may target the vitellogenin gene in BPH,causing a 16.07%reduction in BPH oviposition.The results provide new miRNA information of rice-BPH interactions and BPH-resistant rice variety breeding.

Semen Analysis and Fecundity Association Among Women with Polycystic Ovary Syndrome Experiencing Ovulatory Dysfunction Treated by Ovulation Induction

In this study,normal values of semen analysis were set for a general infertile population of couples among which most women had normal ovulation.The predictive capacity values of sperm quality,including concentration,motile count,progressive motile count,and morphology,are unclear for women with polycystic ovary syndrome(PCOS).A secondary analysis was conducted based on a randomized controlled trial investigating infertility among women with PCOS experiencing ovulatory disorder between 2011 and 2016 in China.A total of 1000 women received ovulation induction(acupuncture and clomiphene).We randomized the women with PCOS in 27 hospitals in China who received one of four interventions(acupuncture plus clomiphene,sham acupuncture plus clomiphene,acupuncture plus placebo,or sham acupuncture plus placebo).Semen analysis was performed for every male partner according to the World Health Organization(WHO)criteria.The outcomes included conception,clinical pregnancy,and live birth.Logistic regression was used to evaluate the predictive value of semen analysis among ovulatory women for conception,clinical pregnancy,and live birth.Among the 1000 couples,the number of couples who attained ovulation,conception,clinical pregnancy,and live birth were 780,320,235,and 205,respectively.Semen volume and motility were applied and used as prediction parameters for conception(area under the curve(AUC)of 0.62(95%confidence interval(CI),0.55–0.69)),clinical pregnancy(AUC of 0.67(95%CI:0.61–0.73)),and live birth(AUC of 0.57(95%CI:0.50–0.64)).No poor calibration was shown for these models in Hosmer–Lemeshow tests.The predictive capacity of semen analysis for treatment outcome in PCOS women with PCOS experiencing with ovulatory dysfunction is limited.

Fecundity and egg hatchability of Dastarcus helophoroides adults fed on different types of artificial diets

Both fecundities and egg hatchabilities were compared among three populations of Dastarcus helophoroides Fairmaire adults（Coleoptera： Bothrideridae） fed on three types of artificial diets（Diet of formula 1 composed of silkworm pupa powder, dried yeast powder,sucrose, peptone, egg yolk powder and poplar branch powder. Diet of formula 2 composed of silkworm pupa powder, dried yeast powder, sucrose, egg yolk powder,poplar branch powder, cricket powder, benzoic acid and distilled water. Diet of formula 3 composed of pine bark powder and Monochamus alternatus larva powder）. for90 days. The three diets showed no significant difference regarding the average number of eggs deposited by all D. helophoroides females（16622.3–23874.7）; the average number of eggs per female（1278.6–1836.5）; and the average number of eggs per female per day（14.2–20.4）.The number of eggs one cluster contained mainly（82.06–82.66 %） lied in 1–100 eggs, and the average number of eggs per cluster ranged from 61.7 to 63.1. In the first 10-day period, the number of eggs deposited by all females fed on formula 1 was significantly larger than that on formula 3. The eggs deposited in the last four 10-day periods were more than in the former five 10-day periods,on formula 3. There were no significant differences in hatchability of total eggs among the three artificial diets,and the average corrected egg hatchability ranged from82.85 to 84.78 %. No significant differences in the adult mortality and mean weight gain of D. helophoroides were found after feeding on three artificial diets. Our results suggest that D. helophoroides adults were not specialized on the diet, and the diet types might have little effect on fecundity and egg hatchability in D. helophoroides, as long as sufficient nutrition was supplied.

Effects of Exogenous Hormone on Fecundity of Sliv-er Fox

The paper aimed to study the effects of exogenous hormone on fecundity of silver fox. Vixens were timely injected with appropriate exogenous hormones at proper ratio to increase their ovulation and litter size, thereby improving the fecundity of silver fox. The average litter size in experimental group attained by 5.86 to 6.0 whelps, 1.61 - 1.75 whelps more than that in the control group. The hormone combination in the experimental group was high in performance/price ratio, which had no significant impact on fecundity of vixens in future.

Differential Aphid Colony Establishment in <i>Dolichos lablab</i>Varieties Correlated with Some Plant Specific Factors That Impact on Aphid Fecundity

Aphid establishes colony in the selective plant parts like vine, leaf petiole, leaflet, inflorescence, and tender fruit in Dolichos lablab Linn but not the entire plant. In this study, the aphid colony establishment in vine is focused to understand the differential resistance response between two varieties. At the early stage of aphid infestation, the aphid colony establishment was significantly different between two genotypes (p value = 0.00) and abbreviated as “resistant” variety that supported lower aphid proliferation (mean value = 48.2 ± 2.2) and “susceptible” variety that supported comparatively higher aphid proliferation (mean value = 215.5 ± 16.9). The total aphid number was significantly different between the two varieties, realized at the early infestation stage when both “antixenosis” and “antibiosis” defense mechanisms were working on. Some plant specific factors like vine diameter, wet/ dry weight ratio of vine, phloem sap pressure, the compactness of the vine, wet/dry weight ratio of leaflet, length of leaf petiole, diameter of leaflet vein were identified as modulating factors. The impact of resistant variety on aphid was also investigated for better understanding of aphid defense mechanism.

Growth and Morphological Differences between the Sexes and Female Fecundity of Ocadia sinensis

In this study, artificially hatched Ocadia sinensis individuals were cultured for 60 months, to record the growth and development process and investigate the morphological characteristics between the sexes and individual fecundity of O. sinensis. Results showed that the main morphological differences between male and female individuals are concentrated in secondary sexual characteristics ： female turtle individuals have flat or slightly prominent sternites, short tails, short length from anal pore to sternite trailing edge; male turtle individuals have concave sternites, relatively stout tails, large length from anal pore to sternite trailing edge. There were significant differences in the growth of male and female individuals, in the first 12 months, female individuals grew faster than male individuals, with greater carapace length, carapace width and weight, but the differences between male and female individuals were not significant; in the late stage, the growth rate of female individuals was much higher than that of male individuals; by the end of the experiment, the average weight of female individuals was 3.86 times of that of male individuals. Regression analysis of female fecundity showed that the clutch size of O. sinensis had significant regression relationship with carapace length and weight, the fertility of female individuals was improved with the increasing size （ carapace length and weight）.

Sex Hormones Changes in Blood and Their Effect on Fecundity of African Catfish(Clarias gariepinus Burchell,1822)after Being Injected with Different Doses of Human Chorionic Gonadotropin(HCG)Hormone

This study was conducted to investigate the effect of different doses injection of human chorionic gonadotropin(HCG)hormone on fecundity and serum sex hormones(FSH,LH,estrogen(E2),progesterone(P4),testosterone(T))of African catfish(Clarias gariepinus).African catfish spawners were intermuscularly injected with different doses of HCG(500,1500,3000,6000 IU/kg female),and group is not injected as a control;males were injected at half the female dose.The results showed that,fish group injected by 6000 IU HCG/kg female had the highest gonadsomatic index,absolute fecundity and relative fecundity,while,the lowest value of absolute fecundity and relative fecundity were recorded with 500 IU HCG/kg female.The group injected with the highest amount of HCG(6000 IU/kg female)recorded the lowest value from egg diameter,while the highest egg diameter was observed in 500 IU HCG/kg female.In females,the group injected with 6000 IU HCG/kg female reflected the lowest level of FSH and the highest level of LH and the highest level of P4 compared to other treatments.Level of T recorded the highest level with 1500 IU HCG/kg female.The control group reflected the highest level of FSH and E2,while the control group reflected the lowest level of T and P4 level.In males,serum FSH,LH,P4 and E2 in male groups injected with HCG were relatively higher than those recorded in the control group.The highest level of T was recorded in treatment injected with the highest dose of HCG and decreased in other treatments until recorded the lowest level of T in the control group.It was observed,HCG hormone has successfully and accelerate induced spawning in African catfish(Clarias gariepinus)and increased in reproductive performance with the increase in HCG dosage and as compared to group not injected.

Spawning induction and fecundity of commercial native fish species from the São Francisco River basin,Brazil,under hatchery conditions

In order to exploit native fish species for aquaculture, basic parameters of artificial reproducetion and estimates of reproductive potential for this fish must be determined to improve hatchery success. We analyze seven Brazilian commercial fish. Spawning was induced using the hypophysation method, with injection of crude carp pituitary extract (CCPE). Characiformes species signaled the spawning time with behavioral alterations (usually circular movements). The time of oocyte extrusion varied from 5.3 ± 0.3 h in Salminus franciscanus to 8.6 ± 0.1 h in Prochilodus argenteus after the second CCPE injection. The greatest diameter of a vitellogenic oocyte was registered for P. argenteus (873.9 ± 122.2 μm) and the smallest was for Pimelodus maculates (465.4 ± 36.3 μm). The diameter of vitellogenic oocytes was very similar among species belonging to the same family. The highest ROI values were registered for Prochilodus costatus(27.0 ± 3.5 μm) and P. argenteus (23.4 ± 3.7 μm), while the lowest values were found in Pseudoplatystoma corruscans (4.6 ± 0.9 μm) and P. maculatus (6.0 ± 1.3 μm). Absolute fecundity (number of oocytes released at spawning) was lowest in P. maculatus and highest in P. corruscans. Relative fecundity (RF) presented a high correlation (r = 0.98 to 0.99) with gonad weight, indicating high efficiency of spawning. The RF also presented a high correlation with body weight (r = 0.88 to 0.97) and total length (r = 0.86 to 0.92). The highest RF was registered for Leporinus obtusidens, and the lowest was for P. corruscans. Released fecundity had a negative correlation with the diameter of vitellogenic oocytes and with the height of the follicular cells, and a positive correlation with the thickness of the zona pelucida. These results indicate that the species studied herein are suitable candidates for aquaculture due to their reproductive and zootechnical characteristics.

Identification of a fatty acid synthase gene(FAS1)from Laodelphax striatellus planthoppers contributing to fecundity

Fatty acid synthase (FAS) is a multifunctional enzyme that plays an important role in the formation of fatty acids. The fatty acids take part in many processes, such as cell signaling and energy metabolism, and in insects they are important in both cuticular hydrocarbon (CHC) formation and reproduction. Here we characterized the sequence structure and function of an FAS from the small brown planthopper (SBPH), Laodelphax striatellus. The full-length open reading frame (ORF) sequence of LsFAS1 was 7122 bp, encoding a predicted protein of 2373 amino acid residues. There were 7 functional domains in the LsFAS1 protein sequence. Gene expression screening by real-time quantitative polymerase chain reaction (RT-qPCR) showed that LsFAS1 was expressed in all developmental stages. Relative expression was highest at the 4th-instar and female adult stages. Among different tissues, the expression level of LsFAS1 in the ovary was the highest. Phylogenetic analysis showed that LsFAS1 clustered in a clade with 2 FASs from Nilaparvata lugens. Furthermore, these 3 FASs are related to cockroach BgFAS and locust LmFAS. After RNA interference-mediated knock-down, most treated insects died at eclosion. In addition, the lifespan of dsFAS1-treated female adults was shorter than that of the dsGFP-injected control, and offspring production decreased. Also, the expression of vitellogenin (Vg) and vitellogenin receptor (VgR) genes decreased. Virgin females dissected at days 2 and 4 post-eclosion showed many matured oocytes in planthoppers treated with dsGFP but not with dsFAS1. These data highlight the importance of LsFAS1 in SBPH, including a role in reproduction.

Reproductive biology of Hemitripterus villosus in the Bohai Strait,China

To understand the reproductive biology of Hemitripterus villosus in the Bohai Strait,and fill the key knowledge gap in verifying reproductive seasonality and documenting gonadotropin dependent reproductive cycle of this species,a year-round detail study was conducted for the first time.In total,263 individuals were randomly sampled off the coasts of the Bohai Strait.Results show that and the overall female-to-male ratio(1.35:1)did not differ significantly from the 1:1 sex ratio.The length and weight relationship for females and males were regressed,depicting an isometric growth for both sexes.Four reproductive phases of the complete gonadotropin dependent reproductive cycle in both sexes were identified.The monthly variations in the gonadosomatic and hepatosomatic indexes for both sexes further indicated that this species spawns a single batch of eggs per year and the peak spawning period is from October to December.The average diameter of eggs ranged from 2.10 to 3.57 mm.The length at first sexual maturity was 224.87 mm for females and 241.26 mm for males.Significant positive relationships between absolute fecundity and fish size,and also gonadal weight were observed.H.villosus from the Bohai Strait exhibited smaller body size,smaller egg diameter,lower gonadosomatic index,lower absolute fecundity,and higher population extinction risk than the other populations’studied previously.Our findings contribute to understanding the status of this isolated westernmost population,and we emphasize that more efficient protection measures for the species and control measures are urgently required to improve the coastal environment in the Bohai Strait.

Sexual Dimorphism and Female Reproductive Characteristics in the Hainan Water Skink(Tropidophorus hainanus)from Hainan,South China

We studied sexual dimorphism in body size and shape and female reproductive characteristics in the Hainan Water Skink(Tropidophorus hainanus)from Hainan,South China.In our sample the largest female and male were 61.1 and 55.2 mm snout-vent length(SVL),respectively.The mean SVL was larger in adult females(52.0 mm)than in adult males(48.3 mm).Juveniles were sexually dimorphic in head length but not in other examined morphological variables.Adult males were longer in head length and shorter in abdomen length and fore-limb length than adult females of the same SVL.Ontogenetic shifts in sexual dimorphism in body shape were evident,as revealed by the fact that morphological differences between the sexes were more pronounced in adults than in juveniles.Females produced a single litter of 3–6 offspring per season from early August to early September.Litter size,litter mass and offspring(neonate)mass were positively related to female SVL.Neonate mass was independent of relative fecundity.From the above findings we draw three main conclusions.First,females are the larger sex in T.hainanus,and sexual dimorphism in body shape is more pronounced in adults than in juveniles.Second,larger female T.hainanus produce more and larger offspring and thus heavier litters than smaller ones.Third,the offspring size-number trade-off does is not evident in T.hainanus.

Identification of a sugar gustatory receptor and its effect on fecundity of the brown planthopper Nilaparvata lugens

In insects, the gustatory system plays a crucial role in multiple physiological behaviors, including feeding, toxin avoidance, courtship, mating and oviposition. Gustatory stimuli from the environment are recognized by gustatory receptors. To date, little is known about the function of gustatory receptors in agricultural pest insects. In this study, we cloned a sugar gustatory receptor gene, N/Gr11, from the brown planthopper (BPH), Nilaparvata lugens (Stal), a serious pest of rice in Asia;we then identified its ligands, namely, fructose, galactose and arabinose, by calcium imaging assay. After injection of N/Gr11 doublestranded RNA, we found that the number of eggs laid by BPH decreased. Moreover, we found that N/Gr11 inhibited the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and promoted the phosphorylation of protein kinase B (AKT). These findings demonstrated that N/Gr11 could accelerate the fecundity of BPH through AMPK- and AKT-mediated signaling pathways. This is the first report to indicate that a gustatory receptor modulates the fecundity of insects and that the receptor could be a potential target for pest control.

FoxO directly regulates the expression of TOR/S6K and vitellogenin to modulate the fecundity of the brown planthopper

As a conserved transcription factor,FoxO plays a crucial role in multiple physiological processes in vivo,including stress resistance,longevity,growth and reproduction.Previous studies on FoxO have focused on human,mouse,Drosophila melanogaster and Caenorhabditis elegans,while there are few reports on agricultural pests and little is known about how FoxO modulates insect fecundity.In Asia,the brown planthopper(BPH)Nilaparvata lugens(St?l)is one of the most serious pests in rice production and high fecundity is the basis of the outbreak of BPH.Here,using the genome-wide ChIP-seq of NlFoxO in BPH,we found that NlFoxO binds to the promoters of ribosomal protein S6 kinase(NlS6K)and serine/threonine-protein kinase mTOR(NlTOR)and increases their expression levels.We also found that NlFoxO directly binds to the exon of vitellogenin(NlVg)and has a specific inhibitory effect on its expression.In addition,the number of eggs laid and their hatching rate decreased significantly after injection of NlFoxO double-stranded RNA into BPH adults.Our findings provide direct evidence that FoxO modulates insect fecundity through binding to the promoters of NlS6K,NlTOR and the exon of NlVg and affecting their gene expression in the Vg network.

Effects of delayed mating on the fecundity, fertility and longevity of females of diamondback moth, Plutella xylostella

The effects of delayed mating on the copulation duration, female fertility, fecundity, egg fertility, longevity and the number days alive after mating of females of diamondback moth （DBM）, Plutella xylostella, were studied. When male mating was delayed, the female fertility, fecundity, egg fertility, longevity and number days alive after mating of DBM decreased, and there was a negative correlation between the age of the moth with those variables except copulation duration. When female mating was delayed, the female fertility, fecundity, percent egg fertility and number days alive after mating of DBM also decreased, but the longevity increased, which also showed a negative relationship between the age of the moth with the variables except copulation duration and longevity. When both males and females delayed mating, the female fertility and fecundity decreased; egg fertility was affected marginally, and the longevity of females increased. The moth age was negatively correlated with those variables.

Lipophorin receptor regulates the cuticular hydrocarbon accumulation and adult fecundity of the pea aphid Acyrthosiphon pisum

Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle.Lipophorin loads and transports lipids,including hydrocarbons,from one tissue to another.In some insects,the lipophorin receptor(LpR),which binds to lipophorin and accepts its lipid cargo,is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes.However,it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown.We herein present the results of our molecular characterization,phylogenetic analysis,and functional annotation of the pea aphid(Acyrthosiphon pisum)LpR gene(ApLpR).This gene was transcribed throughout the A.pisum life cycle,but especially during the embryonic stage and in the abdominal cuticle.Furthermore,we optimized the RHA interference(RNAi)parameters by determining the ideal dose and duration for gene silencing in the pea aphid.We observed that the RNAi-based ApLpR suppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity.Additionally,a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress,with decreased survival rates under simulated drought conditions.Moreover,ApLpR expression levels significantly increased in response to the desiccation treatment.These results confirm that ApLpR is involved in transporting hydrocarbons and protecting aphids from desiccation stress.Furthermore,this gene is vital for aphid reproduction.Therefore,the ApLpR gene of A.pisum may be a novel RNAi target relevant for insect pest management.

Evaluation of Darwin＇s fecundity advantage hypothesis in Parthenium beetle, Zygogramma bicolorata

In the Parthenium beetle, Zygogramma bicolorata Pallister （Coleoptera： Chrysomelidae）, variation in body size exists between and within the sexes. The females are larger than the males. Darwin （1874） proposed the fecundity advantage hypothesis, that is, large-sized females produce more progeny, with subsequent studies supporting, as well as, refuting the hypothesis. Thus, in order to evaluate whether this hypothesis stands in Z. bicolorata we performed experiments to investigate the role of body size in influencing： （i） assortative mating; （ii） reproductive attributes; and （iii） growth, development and survival of offspring. It is the first attempt in this beetle. We found that size influenced assortative mating, reproductive output and offspring fitness. Larger males and females were preferred as mates over smaller ones. The pairs, having larger adults as mates, had higher fecundity, while the egg viability was influenced by the male size only. The offspring of larger parents had fast development and higher survival, indicating thereby possible better nutrient allotment by the female and supply of accessory gland proteins by the male in addition to better quality of genes.

Praziquantel decreases fecundity in Schistosoma mansoni adult worms that survive treatment:evidence from a laboratory life-history trade-offs selection study

Background:Mass drug administration of praziquantel is the World Health Organization’s endorsed control strategy for schistosomiasis.A decade of annual treatments across sub-Saharan Africa has resulted in significant reductions of infection prevalence and intensity levels,although‘hotspots’remain.Repeated drug treatments place strong selective pressures on parasites,which may affect life-history traits that impact transmission dynamics.Understanding drug treatment responses and the evolution of such traits can help inform on how to minimise the risk of drug resistance developing,maximise sustainable control programme success,and improve diagnostic protocols.Methods:We performed a four-generation Schistosoma mansoni praziquantel selection experiment in mice and snails.We used three S.mansoni lines:a praziquantel-resistant isolate(R),a praziquantel-susceptible isolate(S),and a coinfected line(RS),under three treatment regimens:untreated,25 mg/kg praziquantel,or 50 mg/kg praziquantel.Lifehistory traits,including parasite adult-worm establishment,survival,reproduction(fecundity),and associated morbidity,were recorded in mice across all four generations.Predictor variables were tested in a series of generalized linear mixed effects models to determine which factors had a significant influence on parasite life-history traits in definitive hosts under different selection regimes.Results:Praziquantel pressure significantly reduced adult-worm burdens across all generations and isolates,including within R-lines.However,previous drug treatment resulted in an increase in adult-worm establishment with increasing generation from P1 to F3.The highest worm numbers were in the co-infected RS line.Praziquantel treatment decreased adult-worm burden,but had a larger negative impact on the mean daily number of miracidia,a proxy for fecundity,across all three parasite isolates.Conclusions:Our predicted cost of resistance was not supported by the traits we measured within the murine host.We did not find evidence for negative adult worm density-dependent effects on fecundity.In contrast,of the adult worms that survived treatment,even low doses of praziquantel significantly reduced adult-worm fecundity.Such reductions in worm fecundity post treatment suggest that egg-based measures of drug efficacy,such as Kato-Katz,may overestimate the short-term effect of praziquantel on adult-worm burdens.These findings have important implications for S.mansoni transmission control,diagnostic protocols,and the potential for undetected selection toward drug resistance.