In vivo measurement of pH and CO2 levels in the uterus of sows through the estrous cycle and after insemination.

The pH-CO2-HCO3- system is a ubiquitous biological regulator with important functional implications for reproduction. Knowledge of the physiological values of its components is relevant for reproductive biology and the optimization of Assisted Reproductive Technologies (ARTs). However, in situ measurements of these parameters in the uterus are scarce or null. This study describes a non-invasive method for in situ time-lapse recording of pH and CO2 within the uterus of non-anesthetized sows. Animals were at three different reproductive conditions, estrous with no insemination and two hours after insemination, and diestrous. From pH and CO2 data, HCO3- concentration was estimated. The non-invasive approach to the porcine uterus with novel optical probes allowed the obtaining of in situ physiological values of pH, CO2, and HCO3-. Variable oscillatory patterns of pH, CO2 and HCO3- were found independently of the estrous condition. Insemination did not immediately change the levels of uterine pH, CO2 (%) and HCO3- concentration, but all the values were affected by the estrous cycle decreasing significantly at diestrous condition. This study contributes to a better understanding of the in vivo regulation of the pH-CO2-HCO3- system in the uterus and may help to optimize the protocols of sperm treatment for in vitro fertilization.

Comparative studies of stenogamous behaviour in the mosquito Culex pipiens complex.

Understanding the processes of reproductive behaviour in mosquitoes is crucial for improving mating competitiveness and mating specificity for sterile insect release programmes. The Culex pipiens (Linneaus) (Diptera: Culicidae) forms pipiens and molestus (Forskål), two biotypes of the Cx. pipiens complex, are vectors for West Nile virus, St Louis encephalitis virus and lymphatic filariases. Hybridization of these biotypes is known to occur in nature, although form pipiens mates above ground in large spaces (eurygamy) and form molestus preferentially mates in small spaces (stenogamy) such as sewage tunnels. Hybridization may allow gene flow of biotype-specific characteristics that are crucial in the disease transmission cycle. The present study examined and compared mating behaviours, insemination rates, fecundity and fertility in parental and F1 hybrids between Cx. pipiens f. pipiens and Cx. pipiens f. molestus in conditions of stenogamy. Unique mating behaviour sequences were identified in Cx. pipiens f. molestus, including tapping, mounting, co-flying and copulation. Despite the considerably high insemination rates in hybrid crosses, fertility and fecundity rates were varied. This observation could suggest reproductive isolation in the hybrid zone. The study also documents a failure of heterospecific males to produce fertile eggs in Cx. pipiens f. pipiens females, which may be attributable to gametic incompatibilities and may represent an additional barrier to gene exchange.

Insemination, intrafollicular fertilization and development of the fertilization plug during gestation in Heterandria formosa (Poeciliidae).

The viviparous teleost Heterandria formosa is a remarkable species for its reproductive characters including: (a) the smallest oocyte in viviparous fish species; (b) a high level of matrotrophy with a complex placenta; and (c) the highest level of superfetation. Superfetation involves (d) the continuous development of oocytes and fertilization at the same time with embryos in gestation. The sequential fertilization of oocytes requires (e) storage of spermatozoa in the ovary. Among these characteristics, fertilization is of fundamental interest, specifically the intrafollicular fertilization of poeciliids, species that do not present micropyle, and the consequent formation of the fertilization plug, a structure developed at the periphery of the follicle where the entrance of spermatozoa occurs. Both processes intrafollicular fertilization and formation of the fertilization plug have been rarely described. There is only one study illustrating, the fertilization plug of H. formosa with a drawing. In the context of reproductive aspects of H. formosa, the goal of this study is to describe the morphology of the ovary during insemination, intrafollicular fertilization and development of the fertilization plug. After insemination, spermatozoa enter the ovary and occupy folds of the lamella near follicles of all stages of oogenesis, the delle, where the germinal epithelium establishes contact with the follicular epithelium. The results of the present study provide evidence that both epithelia open at the distal end of the delle, this morphological change allow that the spermatozoa to make contact with the zona pellucida of the oocyte. After fertilization, the delle becomes blocked by proliferation of cells of the germinal epithelium, to form the fertilization plug that persists throughout gestation. Abundant reticular fibers and blood vessels are seen around the fertilization plug. Persistence of the fertilization plug suggests that it could be the site where the juvenile will gain entrance to the ovarian lumen during birth.

Molecular and physiological analysis of Anopheles funestus swarms in Nchelenge, Zambia.

BACKGROUND: Anopheles funestus has been recognized as a major malaria vector in Africa for over 100 years, but knowledge on many aspects of the biology of this species is still lacking. Anopheles funestus, as with most other anophelines, mate through swarming. A key event that is crucial for the An. funestus male to mate is genitalia rotation. This involves the 135° to 180° rotation of claspers, which are tipped with claws. This physical change then enables the male to grasp the female during copulation. The aim of this investigation was to molecularly characterize wild An. funestus swarms from Zambia and examine the degree of genitalia rotation within the swarm. METHODS: Anopheles funestus swarms were collected from Nchelenge, northern Zambia, during dusk periods in May 2016. All the adults from the swarm were analysed morphologically and identified to species level using a multiplex PCR assay. Anopheles funestus s.s. specimens were molecularly characterized by restriction fragment length polymorphism type and Clade type assays. The different stages of genitalia rotation were examined in the adult males. RESULTS: A total of six swarms were observed during the study period and between 6 and 26 mosquitoes were caught from each swarm. Species analysis revealed that 90% of the males from the swarms were An. funestus s.s. MW-type, with 84% belonging to clade I compared to 14% clade II and 2% failed to amplify. Very few specimens (3.4%) were identified as Anopheles gambiae s.s. Eighty percent of the males from the swarm had complete genitalia rotation. CONCLUSIONS: This is the first time that An. funestus swarms have been molecularly identified to species level. Anopheles funestus swarms appear to be species-specific with no evidence of clade-type differentiation within these swarms. The An. funestus swarms consist mainly of males with fully rotated genitalia, which strongly suggests that swarming behaviour is triggered primarily when males have matured.

Effect of Sperm Morphology on Pregnancy Success via Intrauterine Insemination: A Systematic Review and Meta-Analysis.

PURPOSE: Men with abnormal sperm morphology are often counseled that natural conception and intrauterine insemination are ineffective, and in vitro fertilization is the only option. Our objective was to determine the effect of sperm morphology on the pregnancy success of intrauterine insemination. MATERIALS AND METHODS: We systematically searched for studies published prior to January 2017 that 1) reported ultrasound verified clinical pregnancies per intrauterine insemination cycle, 2) assessed sperm morphology using the Kruger strict criteria and 3) described morphology at the greater than 4% and 4% or less and/or the 1% or greater and less than 1% thresholds. In all studies mean female age was between 25 and 40 years and mean total motile sperm count was greater than 10 million. Estimates were pooled using random effects meta-analysis. RESULTS: Data were extracted from 20 observational studies involving a total of 41,018 cycles. When comparing men at the greater than 4% and 4% or less thresholds, the rate of ultrasound verified pregnancy per intrauterine insemination cycle was not statistically or clinically different (14.2% vs 12.1%, p = 0.06) and the risk difference was 3.0% (95% CI 1.4-4.6), indicating 3.0 additional pregnancies per 100 intrauterine insemination cycles. When comparing men at the 1% or greater and the less than 1% thresholds, there were no statistical or clinical differences in the rate of ultrasound verified pregnancy per cycle of intrauterine insemination (14.0% vs 13.9%, p = 0.97) or in the risk difference (1.6%, 95% CI -4.5-7.6). CONCLUSIONS: There appears to be no clinical difference in intrauterine insemination pregnancy success among men with normal and abnormal sperm morphology when accounting for total motile sperm count and female age. Abnormal sperm morphology alone should not exclude couples from attempting intrauterine insemination.

Fertility traits of Holstein, Brown Swiss, Simmental, and Alpine Grey cows are differently affected by herd productivity and milk yield of individual cows.

Milk yield has a strong effect on fertility, but it may vary across different herds and individual cows. Therefore, the aim of this study was to assess the effects of breed and its interaction with level of milk production at the herd level (Herd-L) and at a cow-within-herd level (Cow-L) on fertility traits in dairy cattle. Data were gathered from Holstein (n = 17,688), Brown Swiss (n = 32,697), Simmental (n = 27,791), and Alpine Grey (n = 13,689) cows in northeastern Italy. The analysis was based on records from the first 3 lactations in the years 2011 to 2014. A mixed model was fitted to establish milk production levels of the various herds (Herd-L) and individual cows (Cow-L) using milk as a response variable. The interval fertility traits were interval from calving to first service, interval from first service to conception, and number of days open. The success traits were nonreturn rate at 56 d after first service, pregnancy rate at first service, and the number of inseminations. The interval from calving to first service, interval from first service to conception, and number of days open were analyzed using a Cox's proportional hazards model. The nonreturn rate at 56 d after first service, pregnancy rate at first service, and the number of inseminations were analyzed using logistic regression. There was a strong interaction between breed and productivity class at both Herd-L and Cow-L on all traits. The effects of herd and cow productivity differed from each other and differed among breeds. The dual-purpose Simmental and Alpine Grey breeds had better fertility than the specialized Holstein and Brown Swiss dairy cows; this difference is only partly attributable to different milk yields. Greater herd productivity can result in higher fertility in cows, whereas higher milk yield of individual cows within a herd results in lower fertility. These effects at both Herd-L and Cow-L are curvilinear and are stronger in dual-purpose breeds, which was more evident from low to intermediate milk yield levels than from central to high productivity classes. Disentangling the effects of milk productivity on fertility at Herd-L and Cow-L and taking the nonlinearity of response into account could lead to better modeling of populations within breed. It could also help with management-for example, in precision dairy farming of dairy and dual-purpose cattle. Moreover, assessing the fertility of various breeds and their different responses to herd and individual productivity levels could be useful in devising more profitable crossbreeding programs in different dairy systems.

Complexity, adaptations and variations in the secondary insemination system of female Dermanyssina mites (Acari: Anactinothrichida: Gamasida): the case of Afrocypholaelaps africana.

Gamasine mites, mainly of the taxon Dermanyssina, possess a secondarily evolved insemination system (sperm access system), of which there are two, generally recognized, structurally different types, the laelapid- and the phytoseiid-type. The ultrastructure of the female sperm access system in Afrocypholaelaps africana is described. It consists of paired insemination pores, opening between the bases of legs three and four, and paired cuticle-lined tubules that converge into a large, sack-like spermatheca, remarkably cuticle-lined as well. The entire spermatheca and part of the tubules are embedded in a peculiar syncytial tissue where numerous sperm cells are present. The general organization of this insemination system is of the laelapid-type. However, it presents striking structural differences, compared with the systems described in Varroa destructor and Hattena cometis, the other gamasine mites having a laelapid-type system studied ultrastructurally until now. The functional morphology, complexity and variations of the sperm access system in Dermanyssina are discussed and correlated with the evolutionary biology of the group.

Genetic analysis of the rates of conception using a longitudinal threshold model with random regression in dairy crossbreeding within a tropical environment.

This study was designed to: (i) estimate genetic parameters and breeding values for conception rates (CR) using the repeatability threshold model (RP-THM) and random regression threshold models (RR-THM); and (ii) compare covariance functions for modeling the additive genetic (AG) and permanent environmental (PE) effects in the RR-THM. The CR was defined as the outcome of an insemination. A data set of 130 592 first-lactation insemination records of 55 789 Thai dairy cows, calving between 1996 and 2011, was used in the analyses. All models included fixed effects of year × month of insemination, breed × day in milk to insemination class and age at calving. The random effects consisted of herd × year interaction, service sire, PE, AG and residual. Variance components were estimated using a Bayesian method via Gibbs sampling. Heritability estimates of CR ranged from 0.032 to 0.067, 0.037 to 0.165 and 0.045 to 0.218 for RR-THM with the second, third and fourth-order of Legendre polynomials, respectively. The heritability estimated from RP-THM was 0.056. Model comparisons based on goodness of fit, predictive abilities, predicted service results of animal, and pattern of genetic parameter estimates, indicated that the model which fit the desired outcome of insemination was the RR-THM with two regression coefficients.

Machine learning algorithms for the prediction of conception success to a given insemination in lactating dairy cows.

The ability to accurately predict the conception outcome for a future mating would be of considerable benefit for producers in deciding what mating plan (i.e., expensive semen or less expensive semen) to implement for a given cow. The objective of the present study was to use herd- and cow-level factors to predict the likelihood of conception success to a given insemination (i.e., conception outcome not including embryo loss); of particular interest in the present study was the usefulness of milk mid-infrared (MIR) spectral data in augmenting the accuracy of the prediction model. A total of 4,341 insemination records with conception outcome information from 2,874 lactations on 1,789 cows from 7 research herds for the years 2009 to 2014 were available. The data set was separated into a calibration data set and a validation data set using either of 2 approaches: (1) the calibration data set contained records from all 7 farms for the years 2009 to 2011, inclusive, and the validation data set included data from the 7 farms for the years 2012 to 2014, inclusive, or (2) the calibration data set contained records from 5 farms for all 6 yr and the validation data set contained information from the other 2 farms for all 6 yr. The prediction models were developed with 8 different machine learning algorithms in the calibration data set using standard 10-times 10-fold cross-validation and also by evaluating in the validation data set. The area under curve (AUC) for the receiver operating curve varied from 0.487 to 0.675 across the different algorithms and scenarios investigated. Logistic regression was generally the best-performing algorithm. The AUC was generally inferior for the external validation data sets compared with the calibration data sets. The inclusion of milk MIR in the prediction model generally did not improve the accuracy of prediction. Despite the fair AUC for predicting conception outcome under the different scenarios investigated, the model provided a reasonable prediction of the likelihood of conception success when the high predicted probability instances were considered; a conception rate of 85% was evident in the top 10% of inseminations ranked on predicted probability of conception success in the validation data set.

Asymmetric Mating Interference between Two Related Mosquito Species: Aedes (Stegomyia) albopictus and Aedes (Stegomyia) cretinus.

Aedes (Stegomyia) albopictus (Skuse) and Aedes (Stegomyia) cretinus Edwards are closely related mosquito species with common morphological features and bio-ecological similarities. Recent mosquito surveillance in Athens, Greece, showed that they are sympatric mosquito species, with Ae. albopictus [corrected] developing quite higher population densities than Ae. cretinus [corrected] . The potential of mating interference between these species was investigated by reciprocal and homologous mating experiments in cages under laboratory conditions. In non-choice interspecific crosses (groups of males and females) females of both species produced sterile eggs. Insemination rate was 58% for Ae. cretinus females and only 1% for Ae. albopictus [corrected] females. Aedes albopictus males were sexually aggressive and inseminated Ae. cretinus females (31%) in choice experiments, where males of one species had access to mate with females of both species. Whereas, interspecific mating of Ae. albopictus [corrected] females with Ae. cretinus males in the co-occurrence of Ae. cretinus females was weaker (4%). Aedes cretinus females from non-choice crossing with Ae. albopictus [corrected] or Ae. cretinus males were paired individually with conspecific males. The percentage of fertile Ae. cretinus females was 17.5% when had encaged before with Ae. albopictus [corrected] males, compared to 100% when Ae. cretinus [corrected] females were encaged with conspecific males only. Probable ecological consequences of asymmetric mating between these ecologically homologous species in nature are discussed.

Free fatty acid levels in fluid of dominant follicles at the preferred insemination time in dairy cows are not affected by early postpartum fatty acid stress.

The fertility of high-yielding dairy cows has declined during the last 3 decades, in association with a more profound negative energy balance (NEB) during the early weeks postpartum. One feature of this NEB is a marked elevation in circulating free fatty acid (FFA) concentrations. During the early postpartum period (≤ d 42), circulatory FFA levels were measured weekly, and progesterone concentrations and the diameter of the dominant follicles were determined thrice weekly. Retrospectively, cows that ovulated within 35 d postpartum were grouped as "normal ovulating" cows (n = 5), and the others were grouped as "delayed ovulating" cows (n = 5). In both groups, high total FFA levels (>500 µM) were evident immediately postpartum. Interestingly, cows with delayed ovulation had higher plasma FFA concentrations in the first weeks postpartum compared with normal ovulating cows. In both cow groups, FFA decreased to control levels of non-NEB cows within 3 wk postpartum. The FFA compositions and concentrations in fluids from the dominant follicles of postpartum cows were not different between the normal and delayed ovulating cows when measured at potential insemination points: d 55, 80, and 105 postpartum. Interestingly, the concentration of monounsaturated oleic acid was higher and that of saturated stearic acid lower in follicular fluids of both groups compared with that in blood. The level of FFA in follicular fluid was correlated with the ratio of 17ß-estradiol (E2) to progesterone (P4) in follicular fluid, with a relatively high level of unsaturated FFA in follicles with a low E2:P4 ratio. Taken together, these results indicate that a more severe NEB early postpartum is related to a delay in the first postpartum ovulation and does not affect FFA composition in follicular fluid at the preferred insemination time. The high FFA level in dominant follicles with a low E2:P4 ratio may be due to a different FFA metabolism in these follicles. The diagnostic value of this observation for selective screening of dominant follicles needs further investigation.

No evidence of conpopulation sperm precedence between allopatric populations of house mice.

Investigations into the evolution of reproductive barriers have traditionally focused on closely related species, and the prevalence of conspecific sperm precedence. The effectiveness of conspecific sperm precedence at limiting gene exchange between species suggests that gametic isolation is an important component of reproductive isolation. However, there is a paucity of tests for evidence of sperm precedence during the earlier stages of divergence, for example among isolated populations. Here, we sourced individuals from two allopatric populations of house mice (Mus domesticus) and performed competitive in vitro fertilisation assays to test for conpopulation sperm precedence specifically at the gametic level. We found that ova population origin did not influence the outcome of the sperm competitions, and thus provide no evidence of conpopulation or heteropopulation sperm precedence. Instead, we found that males from a population that had evolved under a high level of postcopulatory sexual selection consistently outcompeted males from a population that had evolved under a relatively lower level of postcopulatory sexual selection. We standardised the number of motile sperm of each competitor across the replicate assays. Our data therefore show that competitive fertilizing success was directly attributable to differences in sperm fertilizing competence.

Postcopulatory sexual selection generates speciation phenotypes in Drosophila.

BACKGROUND: Identifying traits that reproductively isolate species, and the selective forces underlying their divergence, is a central goal of evolutionary biology and speciation research. There is growing recognition that postcopulatory sexual selection, which can drive rapid diversification of interacting ejaculate and female reproductive tract traits that mediate sperm competition, may be an engine of speciation. Conspecific sperm precedence (CSP) is a taxonomically widespread form of reproductive isolation, but the selective causes and divergent traits responsible for CSP are poorly understood. RESULTS: To test the hypothesis that postcopulatory sexual selection can generate reproductive isolation, we expressed GFP or RFP in sperm heads of recently diverged sister species, Drosophila simulans and D. mauritiana, to enable detailed resolution of species-specific sperm precedence mechanisms. Between-species divergence in sperm competition traits and mechanisms prompted six a priori predictions regarding mechanisms of CSP and degree of cross asymmetry in reproductive isolation. We resolved four distinct mechanisms of CSP that were highly consistent with predictions. These comprise interactions between multiple sex-specific traits, including two independent mechanisms by which females exert sophisticated control over sperm fate to favor the conspecific male. CONCLUSIONS: Our results confirm that reproductive isolation can quickly arise from diversifying (allopatric) postcopulatory sexual selection. This experimental approach to "speciation phenotypes" illustrates how knowledge of sperm precedence mechanisms can be used to predict the mechanisms and extent of reproductive isolation between populations and species.

Time of insemination culture and outcomes of in vitro fertilization: a systematic review and meta-analysis.

BACKGROUND Conflicting results have been reported regarding the technique of brief insemination used in IVF. The aim of this meta-analysis was to determine if better clinical outcomes of IVF are associated with a brief co-incubation of gametes than with a standard overnight co-incubation. METHODS A computerized search was conducted of the published literature of four databases, using search terms related to gamete, time of co-incubation and outcome measure. Eligible studies compared outcomes of IVF with a brief co-incubation of gametes to that of a control group of standard insemination and reported rates of live birth (primary outcome), normal fertilization, polyspermy, good quality embryos, implantation, clinical pregnancy or ongoing pregnancy (secondary outcomes). A total of 11 studies were included in the meta-analysis. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for the data. Statistical heterogeneity was tested using Cochran Q and I² values. RESULTS Brief co-incubation of gametes was associated with significantly higher rates of clinical pregnancy (RR: 1.84, 95% CI: 1.24-2.73) and ongoing pregnancy (RR: 1.73, 95% CI: 1.27-2.33) than standard insemination. Brief co-incubation of gametes was associated also with a significantly higher rate of implantation (RR: 1.80, 95% CI: 1.43-2.26) than standard insemination. However, the rates of normal fertilization (RR: 0.98, 95% CI: 0.93-1.02), good quality embryos (RR: 1.24, 95% CI: 1.0-1.53) and polyspermy (RR: 0.84, 95% CI: 0.7-1.01) were not significantly different with brief co-incubation of gametes compared with standard insemination. CONCLUSIONS Reduced gamete exposure time may be associated with beneficial outcomes. Drawbacks inherent to the quality of several studies limit the quality of the available evidence. Adequately powered randomized controlled studies need to be performed to evaluate the efficacy of brief insemination.

Inter-population mating success in Australian dengue vector mosquitoes: effects of laboratory colonization and implications for the spread of transgenics.

Variability between Aedes aegypti populations in north Queensland, Australia, has the potential to impact the successful implementation of new population replacement mosquito releases for dengue control. Four Ae. aegypti colonies originating from different locations (Cairns, Mareeba, Innisfail, and Charters Towers), along with one F1 field-derived population from Cairns, were inter-crossed to determine any incompatibilities in copulation, insemination, and production of viable offspring. Greater copulation and insemination rates were observed when males recently introduced from the wild ('Cairns-Wild' population) were mated with long-term laboratory females. Egg viability rates for all crosses ranged from 90.2-98.2%, with no significant differences observed between crosses. Greater egg production was seen in some populations, and when corrected for wing-length, egg production was greatest in a Mareeba x Innisfail cross (19.55 eggs/mm wing length) and lowest for the Charters Towers intra-population cross (14.35 eggs/mm). Additionally, behavioral differences were observed between laboratory and wild mosquitoes from the Cairns location, suggesting possible laboratory conditioning. Finally, despite controlled larval rearing conditions, size differences between populations existed with Charters Towers mosquitoes consistently smaller than the other populations. The spread of genes or bacterial symbionts between these populations is unlikely to be hindered by pre-existing reproductive barriers.

In vitro fertilization versus conversion to intrauterine insemination in the setting of three or fewer follicles: how should patients proceed when follicular response falls short of expectation?

OBJECTIVE: To determine whether in vitro fertilization (IVF) cycles with suboptimal response should be converted to intrauterine insemination (IUI) or proceed to oocyte retrieval (OR). DESIGN: Retrospective cohort. SETTING: Academic medical center. PATIENT(S): All patients initiating IVF from January 2004 through December 2011. INTERVENTION(S): OR versus conversion to IUI. MAIN OUTCOME MEASURE(S): A total of 1,098 patients were identified whose IVF cycles were characterized by recruitment of three or fewer follicles, excluding patients with bilateral tubal disease or severe male factor. Cycles with three follicles were defined as those with three follicles ≥ 14 mm with no fourth follicle ≥ 10 mm. Cycles with two or fewer follicles were similarly defined. Outcomes were compared for patients proceeding with OR (n = 624) versus converting to IUI (n = 474). Age-adjusted relative risks for pregnancy were calculated, stratifying for number of follicles. RESULT(S): The likelihood of retrieving at least one mature oocyte (82.9% vs. 94.8% vs. 96.2%), having at least one zygote (61.9% vs. 76.8% vs. 84.2%), and undergoing transfer (57.1% vs. 73.0% vs. 83.3%) increased significantly with increasing follicle number. Patients with three or fewer follicles were 2.6 times more likely to achieve a live birth with IVF versus IUI (9.3% vs. 3.4%). This benefit was only apparent when at least two follicles were present. No benefit was gained by performing OR in the setting of one follicle. CONCLUSION(S): IVF compared with IUI presents superior pregnancy rates in the setting of two or more follicles. Assisted reproduction programs may benefit their patients by pursuing IVF in this scenario.

Determinação da dose inseminante e embriogênese na fertilização artificial de tambaqui (Colossoma macropomum) / Determination of insemination dose and embryonic development in the artificial fertilization of tambaqui (Colossoma macropomum)

Determinou-se a dose inseminante para fertilização artificial e descreveu-se o desenvolvimento embrionário de tambaqui (Colossoma macropomum). Os gametas foram coletados de reprodutores induzidos hormonalmente. Foi realizada fertilização artificial nas proporções de espermatozoides/ovócito de D1-50.666; D2-75.999; D3-101.332; D4-126.665; D5-151.998. O desenvolvimento embrionário foi acompanhado por meio de observações periódicas em estereoscópio até a eclosão dos ovos. Na fase de fechamento do blastóporo foi calculada a taxa de fertilização nas diferentes doses inseminantes. A porcentagem de fertilização aumentou de forma linear segundo a equação Ŷ =0,050 + 0,00000773X (R²=97,5), atingindo um platô em 84% na proporção de 102.486 espermatozoides/ovócito. Os embriões apresentaram segmentação meroblástica discoidal, típica de ovos telolécitos, com eclosão ocorrendo aos 357 horas-grau após a fertilização. Conclui-se que o desenvolvimento embrionário de tambaqui obedece ao esperado para peixes com ovos telolécitos e recomenda-se o uso da dose inseminante de aproximadamente 100.000 espermatozoides/ovócito na rotina de fertilização artificial dessa espécie.

The objective of this research was to determine the insemination dose for artificial fertilization and describe the embryonic development of tambaqui (Colossoma macropomun). The gametes were collected from induced breeding hormonally. An artificial fertilization was performed with different sperm/oocyte ratios of D1-50666, D2-75999, D3-101 332, 126 665-D4, D5-151 998 sperm/oocyte. Embryonic development was monitored through periodic stereoscopic observations until hatching. When embryos reached the blastopore closure stage, the rate of fertilization in different insemination doses was calculated. A regression equation was estimated to determine the ideal proportion of the gametes. The fertilization rate increased linearly according to the equation Ŷ = 0.050 + 0.00000773 X (R² = 97.5), up to the proportion of 102.486 spermatozoa/oocyte, and, from this point, the fertilization rate was maintained at 84%. The embryonic development of tambaqui was meroblastic discoidal, as expected from telolecithal eggs and we recommend the use of the insemination dose of approximately 100.000 sperm/oocyte in the artificial fertilization of tambaqui.

Male accessory gland substances from Aedes albopictus affect the locomotor activity of Aedes aegypti females.

Dengue is one of the world's most important mosquito-borne diseases and is usually transmitted by one of two vector species: Aedes aegypti or Aedes albopictus . These two diurnal mosquitoes are frequently found coexisting in similar habitats, enabling interactions between adults, such as cross-mating. The objective of this study was to assess cross-mating between Ae. aegypti females and Ae. albopictus males under artificial conditions and evaluate the locomotor activity of Ae. aegypti virgin females injected with male accessory gland (MAG) homogenates to infer the physiological and behavioural responses to interspecific mating. After seven days of exposure, 3.3-16% of Ae. aegypti females mated with Ae. albopictus males. Virgin Ae. aegypti females injected with conspecific and heterospecific MAGs showed a general decrease in locomotor activity compared to controls and were refractory to mating with conspecific males. The reduction in diurnal locomotor activity induced by injections of conspecific or heterospecific MAGs is consistent with regulation of female reproductive activities by male substances, which are capable of sterilising female Ae. aegypti through satyrisation by Ae. albopictus.

Male accessory gland substances from Aedes albopictus affect the locomotor activity of Aedes aegypti females

Dengue is one of the world’s most important mosquito-borne diseases and is usually transmitted by one of two vector species: Aedes aegypti or Aedes albopictus . These two diurnal mosquitoes are frequently found coexisting in similar habitats, enabling interactions between adults, such as cross-mating. The objective of this study was to assess cross-mating between Ae. aegypti females and Ae. albopictus males under artificial conditions and evaluate the locomotor activity of Ae. aegypti virgin females injected with male accessory gland (MAG) homogenates to infer the physiological and behavioural responses to interspecific mating. After seven days of exposure, 3.3-16% of Ae. aegypti females mated with Ae. albopictus males. Virgin Ae. aegypti females injected with conspecific and heterospecific MAGs showed a general decrease in locomotor activity compared to controls and were refractory to mating with conspecific males. The reduction in diurnal locomotor activity induced by injections of conspecific or heterospecific MAGs is consistent with regulation of female reproductive activities by male substances, which are capable of sterilising female Ae. aegypti through satyrisation by Ae. albopictus .