Regulation of the length of the fertile period in the domestic fowl by numbers of oviducal spermatozoa, as reflected by those trapped in laid eggs

The numbers of spermatozoa trapped in the vitelline membrane of laid eggs were counted after staining with the fluorochrome 2,4-diamidino-2-phenylindole. In a group of 24 hens inseminated with different numbers of spermatozoa to produce different lengths of fertile periods, the numbers of spermatozoa in successive eggs from each hen decreased logarithmically with respect to days following insemination. A relationship could be described between the numbers of spermatozoa per unit area of membrane of an egg and the probability of that egg being fertile. After insemination the number of spermatozoa on successively-laid eggs appears to become reduced until a critical value is reached, after which the hen will lay infertile eggs. By estimating the day on which the critical value was achieved, the actual length of the fertile period could be predicted. It is suggested that the numbers of spermatozoa trapped in the vitelline membrane of laid eggs represent those which surround the ovum at the time of fertilization.     

绿盲蝽成虫的产卵行为与习性

本文观察记录了绿盲蝽Apolygus lucorum(Meyer-Dür)雌性成虫的产卵行为,并研究了其产卵习性。结果发现,绿盲蝽卵主要产在植物组织中,单次产卵平均历时31.4 s;产卵主要在夜间进行,白天的产卵量仅占全天的6.6%。成虫交配后主要产可育卵,后期偶产不育卵;而未交配个体大部分能产不育卵。在25℃下,成虫从7日龄起开始产卵,16日龄前产卵量占总产卵量的48.9%;17～40日龄间产卵量约占40%。在棉株上,约65%卵分布在中部(第4到第7果枝),同时94.3%卵集中在叶柄、叶脉、蕾柄和铃柄上。     

Effect of host egg viability on reproduction and development of Trichogramma cacoeciae and T. principium (Hymenoptera: Trichogrammatidae)

A combination of a sterile insect technique, resulting in infertile eggs, and of an egg parasitoid, should provide better control of codling moth than either alone. Non-choice laboratory experiments were conducted with infertile and fertile codling moth eggs to evaluate the potential parasitism and reproduction of Trichogramma cacoeciae Marchal and T. principium Sug. et Sor. The tendency of T. cacoeciae females to attack infertile eggs was similar to that for fertile eggs, whereas T. principium showed a greater preference for infertile eggs than fertile eggs. The fertility status of the host did not affect the number of eggs that were parasitized but fewer F₁ progeny emerged from infertile eggs when parasitized than from fertile eggs. When T. cacoeciae and T. principium parasitized infertile host eggs their mean developmental time was prolonged but the viability and quality of parasitoid progeny was not influenced by the fertility status of the host eggs. The study demonstrates the compatibility of use of T. cacoeciae and T. principium in an integrated program employing the sterile insect technique for codling moth management.     

A reliable method for sexing unincubated bird eggs for studying primary sex ratio

In birds, offspring sex ratio manipulation by mothers is now well established with potentially important consequences for evolution and animal breeding. In most studies on primary sex ratio of birds, eggs are sexed after incubation by the use of PCR methods targeted to the sex-linked CHD1 genes. Sexing of unincubated eggs would be preferred, but as fertile and infertile blastodiscs cannot be distinguished macroscopically, errors could arise from PCR amplifications of parental DNA associated with the vitelline membrane of infertile eggs. In this study, we stained blastodiscs without the vitelline membrane with Hoechst 33342. This allowed unequivocal distinction between fertile and infertile blastodiscs. Fertile blastodiscs contained thousands of fluorescent nuclei, whereas no nuclei were seen in infertile eggs. In addition, after nucleic acid analysis, fertile blastodiscs yielded much stronger chromosomal DNA and CHD1-targeted PCR bands on agarose gels compared with infertile blastodiscs. These findings indicate that fertile blastodiscs contain much more embryonic DNA than parental DNA, allowing reliable sexing of the fertile eggs. The differences between fertile and infertile blastodiscs in chromosomal DNA and CHD1 PCR banding intensities alone could also be used to distinguish fertile from infertile eggs without using Hoechst staining. We conclude that identifying fertile blastodiscs either by Hoechst staining or by analyzing the yield of chromosomal DNA and CHD1-PCR products, combined with CHD1-targeted PCR amplification, presents an easy and reliable method to sex unincubated eggs.     

Termination of incubation in doves: Influence of egg fertility and absence of mate

The present experiments examine the role of the eggs, the mate, and hormonal state in the termination of incubation by ring doves. Doves given either infertile eggs or newly laid fertile eggs at midincubation did not prolong incubation significantly beyond that observed in doves with hatching eggs. However, there was substantial lack of synchrony between mates in the experimental groups. Half the experimental females laid new eggs, often without interrupting incubation. To clarify the role of the mate in maintaining sitting, pairs were separated on Days 1, 5, or 10 of incubation. Initially birds in each group incubated alone throughout the day. The decline in sitting was more rapid in pairs which had been separated early in incubation. To explore the hormonal correlates of the termination of incubation, mates were separated on the 10th day of incubation and observed until they quit sitting. At this time, males showed substantial crop development. Females had little crop development and large preovulatory folliclels, indicating readiness to lay new eggs despite the absence of the male. We conclude that the termination of incubation by parent doves is delayed by the presence of the mate and this, in turn, prevents follicular development and recycling by the female. Cues from the offspring are important in synchronizing the behavior of the parents and also in preventing a new breeding cycle.     

Culture of naked quail (Coturnix coturnix japonica) ova in vitro for avian transgenesis: Culture from the single-cell stage to hatching with pH-adjusted chicken thick albumen

We first examined the pH change of the albumen of quail (Coturnix coturnix japonica) eggs before and after they were laid, as well as that of laid eggs. The pH rose rapidly after laying and continued to increase gradually in storage. Incubation at 37.5°C accelerated the increase in the pH of infertile eggs, while that of fertile eggs remained low during incubation. Referring to these results, we obtained a protocol for producing quail hatchlings by culture in vitro from naked ova. The naked ovum was filled with chicken (Gallus domesticus) thick albumen, the pH of which had been adjusted to 7.2–7.4. The ovum was cultured at 41.5°C in 20% CO₂ in air for the first 24 h. Then the embryo was moved to a surrogate quail egg shell that had been filled with non-pH-adjusted chicken thin albumen and cultured for a further 48 h in 100% air. The embryo was transferred again to a surrogate chicken egg shell and cultured under the same conditions until hatching. The culture yielded quail chicks with a hatchability of 19.4%. The method proposed here should be applicable to the production of transgenic birds.     

Observations on egg production by Toxocara pteropodis

Studies in juvenile Pteropus poliocephalus showed an average daily egg production by Toxocara pteropodis of 25,000 per female, with concentrations of up to 16,000 epg. regardless of whether eggs were fertile or infertile. Production commenced as early as 35 and as late as 48 days post-partum and rose to plateau average levels over about 10 days. For 23 days one bat passed infertile eggs which, over 2 days, were then replaced completely by fertile eggs. The implicit delay in maturation of a male nematode suggests that transmammary passage of larvae to suckling bats may persist for at least 3 weeks. Patency was terminated by the spontaneous expulsion of worms. If male worms were lost first, the egg output converted from fertile to 100% infertile within 48 h and the females were devoid of spermatozoa, suggesting that T. pteropodis copulate at least once daily. In prolonged infections, worm fecundity and egg fertility diminished, so that females with stored spermatozoa were producing mixtures of fertile and infertile eggs.     

Consequences of prenatal androgen exposure for the reproductive performance of female pheasants (Phasianus colchicus)

Maternal hormones in vertebrate eggs can mediate important forms of maternal effects. However, the function of hormone transfer to the eggs is still debated, especially because long-term fitness consequences have been little studied. We investigated the effect of prenatal exposure to physiologically elevated yolk testosterone (T) levels on reproduction of female pheasants (Phasianus colchicus) in captivity. We found that females hatching from T-injected eggs (T-females) had a lower egg-laying rate than controls, and their eggs were more frequently infertile than those laid by control females. There were no effects of prenatal maternal treatment on egg size and yolk T concentration, but eggs carrying a female embryo laid by T-females had smaller yolks than eggs with a male embryo, while there was no sex difference in yolk size among the eggs laid by control females. Progeny sex ratio was unaffected by maternal treatment. These findings suggest that the transfer of high androgen levels to the eggs by the mother is constrained by complex trade-offs between direct effects on her daughters' reproduction and by trans-generational differential consequences on male and female descendants.     

Plasma prolactin levels in incubating turkey hens during pipping of the eggs and after introduction of poults into the nest

Plasma levels of prolactin (Prl) associated with incubation and maternal behavior were compared in turkey hens allowed to incubate 10 fertile eggs (Group I, n = 9) or 10 infertile eggs (Group II, n = 7) in open nest boxes. At the end of the day that the first egg hatched, all unhatched eggs were removed from Group I hens and each hen was given 10 poults. At the end of the following day, infertile eggs were removed from Group II hens and each hen was given 10 poults. Although pipping of the eggs changed the incubation behavior of Group I hens, it had no effect on plasma Prl. Subsequent hatch of the eggs and/or presence of poults resulted, within 24 h, in a sharp fall in Prl levels, abandonment of the nests, and a shift to maternal behavior. Visual and auditory exposure to Group I poults had no effect on plasma Prl or incubation behavior of Group II hens incubating infertile eggs in adjacent pens. However, within 24 h after the infertile eggs were exchanged for newly hatched poults, Prl levels in Group II hens declined sharply and the hens abandoned the nests and showed maternal behavior similar to that observed in Group I hens. No significant relationships were found in either group between plasma Prl levels and quality of incubation or maternal behavior.     

Behavior of triatomines (Hemiptera: Reduviidae) vectors of Chagas' disease. III. Influence of the number of matings on the fecundity and fertility of Panstrongylus megistus (Burm., 1835) in the laboratory

A study of the effect of mating in the fecundity and fertility of females of P. megistus fed on pigeon blood every 14 days, was carried out in the laboratory. Two groups were constituted: I - females which mated only once; II - females which stayed always with the males. Only 56.7% of group I females laid fertile eggs, while as much as 90% of group II females laid fertile eggs. The duration of the fertile oviposition was greater in the females which stayed always with the males. Some females of this group were able to mate up to seven times throughout their life-span. This fact render useless sterile males in the control of these insects.     

Oviposition and development of the immature stages of Tomicus minor (Coleoptera, Scolytidae)

1 This paper describes the construction process of the brood gallery of Tomicus minor and its total length as well as the length of each arm, the fertile part where the female lays her eggs and also, the infertile part. >2 The presence of the parents during the process and their position in the brood gallery (arms or mating chamber) is studied and how it influences the number of eggs laid. Both the first brood galleries and those burrowed by the repenetrating females were observed. 3 The development and duration of the immature stages of the insect in the 3-year study period, from laying to the emergence of the young beetles from the F₁ generation, were also studied.     

How does the age of hoverfly females affect their reproduction?

In the present study, we observed the effect of age of Episyrphus balteatus DeGeer (Diptera, Syrphidae) females on their fecundity and fertility (number and percentage of fertile eggs). Eight newborn E. batteatus couples were placed in separated cages (30 cm x 30 cm x 60 cm) and the number of eggs laid and the egg viability were recorded daily during 45 days. E. balteatus females had a pre-oviposition period of 10 days before mating happened. The fecundity increased steadily from day 11 to day 16 with an average of 30 eggs a day. During the following days (from day 23 to day 45), we found that the optimal fecundity was observed every second day and that 70.47% of the eggs laid during the entire life of the females were fertile. We also found that the fertility decreased significantly when the females were older than 38 days. As result, the age of hoverfly females influence significantly on their reproduction, with suggesting that hoverfly females from 2 to 5 weeks old are important agents for biological control programs.     

Female Gryllus vocalis Field Crickets Gain Diminishing Returns from Increasing Numbers of Matings

Although female insects generally gain reproductive benefits from mating frequently, females do not mate unlimited numbers of times. This study asks whether the limit on female mating rate is imposed by trade‐offs between reproduction and survival. Female Gryllus vocalis were given the opportunity to mate 5, 10, or 15 times with novel males, and the effects on daily fecundity (egg production), fertility (proportion of eggs that were fertilized), and female post‐experimental longevity were measured. Females that mated 10 times laid more eggs and had a higher proportion of fertile eggs than females that mated 5 times. However, females that mated 15 times did not lay significantly more eggs or have a higher proportion of fertile eggs than females that mated 10 times. Although number of matings did not affect the date that females laid their last egg, mating more times was associated with a prolonged period of laying fertile eggs. Number of matings did not affect female post‐experimental longevity. Thus, there was no trade‐off between female reproductive effort and survival, even when females mated very large numbers of times. When females were allowed to mate ad libitum, the average number of times that females mated was greater than the number of times that confers maximal fitness. The lack of cost to mating explains why females might be willing to mate beyond the point of diminishing reproductive returns.     

The etiological agent of cytoplasmic incompatibility in Culex pipiens

All individuals of Culex pipiens (wide sense) which have been examined were infected with Wolbachia pipientis. Larvae reared in tetracycline were freed of these symbiotes and remained free (aposymbiotic) in future generations. When males were freed of their symbiotes, they no longer displayed incompatibility. Aposymbiotic males were compatible with all females, whether infected or not. Aposymbiotic females, on the other hand, laid fertile eggs after mating with aposymbiotic males, but not after mating with normal males. Most eggs laid by aposymbiotic females after mating with normal males showed no development at all, even though the females had been inseminated.     

Behavior of triatomines (Hemiptera:Reduviidae) vectors of Chagas' disease. IV. Fecundity, fertility and longevity of Panstrongylus megistus (Burm., 1835) pairs and virgin females starved under laboratory conditions

A laboratory study was conducted on the fecundity, fertility and life span of Panstrongylus megistus pairs and on the fecundity and life span of P. megistus virgin females submitted to starvation after the last moulting. Of the mated females, 22.2% laid eggs, 4.4% of which were fertile. Females resisted starvation more than males. Of the starved virgin females, only 10% laid eggs, with a low egg-laying rate (0.47) per female. Resistance to starvation was lower in virgin than in mated females.     

CLUTCH-SIZE, INCUBATION AND HATCHING SUCCESS IN THE HOUSE SPARROW AND TREE SPARROW PASSER SPP. AT OXFORD

Clutch-size, incubation and hatching success were studied in P. domesticus and P. montanus in 1961 and 1963–64 at Oxford. The most frequent clutch-size was four eggs in P. domesticus and five eggs in P. montanus . With one exception, colonies of P. domesticus showed no significant annual or local variations in its mean clutch-size; in P. montanus , however, there were significant annual variations in the mean clutch-size. Both species showed a seasonal increase followed by a decrease in their mean clutch-sizes.
Partial incubation occurred during the laying period of the clutch; sufficient incubation for continuous development of the embryo was apparently achieved when the last egg had been laid in clutches of two and three eggs in P. domesticus and in clutches of four eggs in P. montanus , but when the penultimate egg had been laid in larger clutches of both species. On average, hatching in P. domesticus occurred more or less synchronously in all eggs in clutches of two and three eggs, and in all eggs except the last one laid in larger clutches; the last egg in the larger clutches hatched up to a day after the others. It is suggested that this pattern of hatching was brought about by the pattern of incubation during the laying period.
P. domesticus had a lower hatching success than P. montanus , probably because fewer of its eggs were fertile.     

Apoptosis as a possible mechanism of infertility in Echinococcus granulosus hydatid cysts

Echinococcus granulosus is a parasitic cestode causing hydatidosis in intermediate hosts (human and herbivorous). Most symptoms of the disease occur by the pressure exerted on viscera by cysts that are formed upon ingestion of the parasite eggs excreted by definitive hosts (canines). Protoscoleces, the developmental form of the parasite infective to definitive hosts, are formed in the germinal nucleated layer of fertile hydatid cysts. For unknown reasons, some cysts are unable to produce protoscoleces (infertile hydatid cysts). In this study, analysis of DNA fragmentation using TUNEL and agarose gel electrophoresis showed higher levels of apoptosis in infertile cysts as compared to fertile cysts. Additionally, caspase 3 was detected both in fertile and infertile cysts; the activity of this enzyme was found to be higher in infertile cysts. We conclude that apoptosis may be involved in hydatid cyst infertility. This is the first report on the presence of programmed cell death in E. granulosus.     

Characteristics, abundance and fertility of orphan eggs of the Lesser Rhea ( Pterocnemia-Rhea-pennata pennata ): implications for conservation

The Lesser Rhea (Pterocnemia-Rhea-pennata pennata) has a complex reproductive system that combines polygyny with sequential polyandry, in which males build the nest, fully incubate the eggs and care for the young. As occurs with the Greater Rhea (Rhea americana), Lesser Rhea females sporadically lay eggs outside the nest (‘orphan’ eggs), which are not incubated and thus fail to hatch. We have examined the orphan eggs of Lesser Rhea over two separate breeding seasons to determine their abundance and fertility status. During 2004 and 2005, weekly ground searches for orphan eggs were conducted in a wild population of Lesser Rhea in northwestern Patagonia, Argentina. During these searches the total number of nests, eggs in each nest and orphan eggs laid outside the nests was recorded. Orphan eggs represented approximately 7% of the total eggs laid in a breeding season. Six fresh orphan eggs were artificially incubated, four of them being fertile. Orphan eggs seemed to have two origins: some were laid near deserted nests in the early to mid-reproductive season; others were probably laid by first-time breeders and were found later in the reproductive season. Given the near-threatened status of the Lesser Rhea, harvesting and artificial incubation of orphan eggs, which otherwise would be unproductive, may contribute significantly to the conservation of this species, i.e., ‘recovered’ birds could be used for reintroduction or reinforcement of wild Lesser Rhea populations.     

圆唇散白蚁雌性补充生殖蚁不同发育阶段表皮长链碳氢化合物的变化

【目的】确定圆唇散白蚁 Reticulitermes labralis 补充生殖蚁不同发育阶段表皮长链碳氢化合物(cuticular long-chained hydrocarbons, CHCs) 的变化。【方法】人工隔离巢群饲养圆唇散白蚁 R. labralis,观测其翅芽型补充生殖蚁的分化时间和补充生殖蚁数量趋于稳定的时间,并采用气质联用仪(GC-MS)对补充生殖蚁不同发育阶段的表皮长链碳氢化合物变化趋势进行分析。【结果】随着补充生殖蚁的出现,每一巢群会逐渐形成稳定数量的具有生殖能力的生殖蚁。若蚁在分化为补充生殖蚁的第8天时,43.3%的组补充生殖蚁数量趋于稳定,第16天时83.3%的组趋于稳定,第25天时93.3%的组趋于稳定,36 d后100%的组趋于稳定。通过补充生殖蚁不同发育阶段中CHCs各峰面积与若蚁阶段相应峰峰面积的比值随发育阶段的变化趋势分析发现,在卵中没有检测到的保留时间为38.52 min的化合物在补充生殖蚁产7~8粒卵时峰面积比值是若蚁阶段的14.14倍;在卵中检测到的保留时间为35.50和39.21 min的峰面积比值在补充生殖蚁开始产卵后显著升高。【结论】CHCs不能用来区分有无生殖能力的补充生殖蚁个体,但可以很好地用来区分补充生殖蚁个体与尚未转化为生殖蚁的若蚁个体;保留时间为38.52 min的化合物是补充生殖蚁的特有物质;保留时间为35.50和39.21 min的化合物可作为补充生殖蚁已经产卵的标志。     

Factors affecting captive whooping crane egg fertility: A retrospective analysis

The whooping crane (Grus americana) has been managed in captivity since the 1960s following a substantial genetic bottleneck in the wild population. Through major ex situ conservation efforts, there are 158 whooping cranes managed in North American institutions and chicks are released annually into the wild. Current reintroduction goals for the whooping crane however, are impeded by poor reproduction within the ex situ population, in part because of low egg fertility. Development of improved management techniques to overcome low egg fertility requires a better understanding of factors that influence egg fertility. We collected data for eggs laid at Patuxent Wildlife Research Center from 2005–2014 (n = 438 eggs; n = 23 pairs). We constructed 5 sets of generalized linear mixed-models, with a Bernoulli-distributed response variable (fertile or infertile), to address the effects of egg-specific variables (month laid, sequence, and clutch order of the egg), life-history events of the male and female (age, rearing method, wing condition, age at first pairing, age at current pairing, and female age at first laying), pair-specific characteristics (kinship, years paired, chick-rearing experience, and previous pairings), and captive management decisions (inclusion in the artificial insemination program and pair experience chick-rearing) on the probability of egg fertility. Our results indicate that female-specific factors (especially age, age at current pairing, and wing status) and pair-specific factors of kinship, chick-rearing experience, copulation, and inclusion in the artificial insemination program influenced fertile egg production. Specifically, the younger a female is when paired with her current social mate, the higher probability that her eggs will be fertile. Furthermore, high kinship reduced fertility, whereas chick-rearing experience and artificial insemination of females with a donor male other than her social mate increased fertility. Further research on mate selection and reproductive mechanisms is needed to better understand egg laying and egg fertility in the whooping crane. © 2019 The Wildlife Society.