Production Of Mature Eggs Research Articles

Influence of larval and adult diets on the maturation of male and female reproductive organs of the avian vampire fly, Philornis downsi (Diptera: Muscidae)

AbstractThe invasive avian vampire fly, Philornis downsi, Dodge and Aitken (Diptera: Muscidae) is a threat to the long‐term conservation of Darwin's finches and other landbirds in the Galapagos Islands. Adult flies feed on fermented fruit, but their larvae are obligate parasites that feed on, and often cause the mortality of, the developing nestlings. Various techniques for the control of this parasite are currently under study, but the inability to rear flies in captivity has slowed progress. To help understand the reproductive behaviour of P. downsi, in this study, we measured the reproductive organs of male and female flies to determine the age flies mature physiologically, as well as the influence of the larval and adult diets on this process. Both females and males reared from larvae that had developed in the wild on live birds reached physiological maturity at 6 days; in the males, this was associated with increased pigmentation of the testes and the presence of free sperm, and in the females, mature eggs. Females reared in the laboratory on an artificial diet produced mature eggs at 6 days. However, the ovaries of laboratory‐reared females were statistically smaller than those of wild females, suggesting that egg production was affected by larval diet. Physiological maturity was delayed in laboratory‐reared males, taking twice as long. The testes of these males had more unpigmented areas and deformities indicating that the artificial larval diet was insufficient. Enrichment of the adult diet could help compensate for this. The addition of methoprene (M) to the diet was found to have a positive effect on the sexual development of the flies. In females, a diet of sugar + yeast hydrolysate (YH) in a 3:1 ratio combined with M favoured the development of larger ovaries and the production of mature eggs at an earlier age (3 days). In the case of males, a diet with YH increased testis size and M accelerated the growth of testis length even when males were fed only with sugar and without YH. Additional studies are recommended for improving the diets for mass‐rearing this highly harmful fly.

Survivors of Climate Driven Abalone Mass Mortality Exhibit Declines in Health and Reproduction Following Kelp Forest Collapse

Marine ecosystems are vulnerable to climate driven events such as marine heatwaves yet we have a poor understanding of whether they will collapse or recover. Kelp forests are known to be susceptible, and there has been a rise in sea urchin barrens around the world. When temperatures increase so do physiological demands while food resources decline, tightening metabolic constraints. In this case study, we examine red abalone (Haliotis rufescens) looking at sublethal impacts and their prospects for recovery within kelp forests that have shifted to sea urchin barrens. Abalone are a recreationally fished species that once thrived in northern California’s bull kelp forests but have recently suffered mass mortalities since the 2014–2016 marine heatwave. Quantitative data exist on the health and reproduction of abalone both prior to and after the collapse. The survivors of the mass mortality show a 2-year lag in body and gonad condition indices. After the lag, body and gonad indexes decreased substantially, as did the relationship between shell length and body weight. Production of mature eggs per female declined by 99% (p< 0.001), and the number of eggs per gram of female body weight (2,984/g) declined to near zero (9/g). The number of males with sperm was reduced by 33%, and the sperm abundance score was reduced by 28% (p= 0.414). We observed that these reductions were for mature eggs and sperm while immature eggs and spermatids were still present in large numbers. In the lab, after reintroduction of kelp, weight gains were quickly lost following a second starvation period. This example illustrates how climate-driven declines in foundation species can suppress recovery of the system by impacting body condition and future reproduction of surviving individuals. Given the poor reproductive potential of the remaining abalone in northern California, coupled with ongoing mortality and low kelp abundances, we discuss the need to maintain the fishing moratorium and implement active abalone restoration measures. For fished species, such as abalone, this additional hurdle to recovery imposed by changes in climate is critical to understand and incorporate into resource management and restoration.

Transcriptome profiling of the Plutella xylostella (Lepidoptera: Plutellidae) ovary reveals genes involved in oogenesis

BackgroundAs a specialized organ, the insect ovary performs valuable functions by ensuring fecundity and population survival. Oogenesis is the complex physiological process resulting in the production of mature eggs, which are involved in epigenetic programming, germ cell behavior, cell cycle regulation, etc. Identification of the genes involved in ovary development and oogenesis is critical to better understand the reproductive biology and screening for the potential molecular targets in Plutella xylostella, a worldwide destructive pest of economically major crops. ResultsBased on transcriptome sequencing, a total of 7.88Gb clean nucleotides was obtained, with 19,934 genes and 1861 new transcripts being identified. Expression profiling indicated that 61.7% of the genes were expressed (FPKM≥1) in the P. xylostella ovary. GO annotation showed that the pathways of multicellular organism reproduction and multicellular organism reproduction process, as well as gamete generation and chorion were significantly enriched. Processes that were most likely relevant to reproduction included the spliceosome, ubiquitin mediated proteolysis, endocytosis, PI3K-Akt signaling pathway, insulin signaling pathway, cAMP signaling pathway, and focal adhesion were identified in the top 20 ‘highly represented’ KEGG pathways. Functional genes involved in oogenesis were further analyzed and validated by qRT-PCR to show their potential predominant roles in P. xylostella reproduction. ConclusionsOur newly developed P. xylostella ovary transcriptome provides an overview of the gene expression profiling in this specialized tissue and the functional gene network closely related to the ovary development and oogenesis. This is the first genome-wide transcriptome dataset of P. xylostella ovary that includes a subset of functionally activated genes. This global approach will be the basis for further studies on molecular mechanisms of P. xylostella reproduction aimed at screening potential molecular targets for integrated pest management.

Retrospective Evaluation of the Effects of Human Disturbance and Goldfish Introduction on Endangered Pahrump Poolfish

Life history data for Pahrump poolfish (Empetrichthys latos latos) collected from 1937 to 1975 were organized and analyzed to improve our understanding of changes caused by human habitat disruption and introduced goldfish (Carassius auratus) at Manse Spring, Nevada. Pahrump poolfish twice demonstrated their ability to recover numerically from a population crash. The first crash followed a November 1961 introduction of a few goldfish and sub- sequent removal of vegetation by local ranch children intent on turning Manse Spring into a swimming hole. The sec- ond crash followed another major habitat disturbance resulting from an unsuccessful attempt to eradicate goldfish in July 1967. Each crash (1962-1963 and 1967-1968) reduced the poolfish population to fewer than 50 adults and was fol- lowed by a population recovery to more than 1000. Following the first habitat disruption, changes in poolfish population structure and poolfish diet were observed. These changes caused an increased mortality rate, resulting in disappearance or decline in relative abundance of larger poolfish size classes with a commensurate reduction in production of mature eggs by the population. We detected no additional changes in life history characteristics that could be associated with the second population crash and recovery. We concluded that removal of vegetation in the summer of 1962 and the more extreme habitat disruption and fish handling in June-July 1967 were human-induced pulse disturbances resulting in poolfish population crashes. We also concluded that the changes in poolfish life history characteristics resulted princi- pally from press disturbances attributable to goldfish.

Adult diet and male-female contact effects on female reproductive potential in Mexican fruit fly (Anastrepha ludens Loew) (Diptera tephritidae).

Wild strains of fruit flies (Diptera: Tephritidae) placed into laboratory rearing conditions are subjected to selection pressures caused by the diet, cages, density of flies, and other factors. Selection that changes mating behavior of the strain may result in less effective males released in sterile insect programs. Tests were performed to examine the effects of protein in diet and adult interactions on egg production and mating during sexual maturation of the Mexican fruit fly (Anastrepha ludens Loew) in laboratory cages. Flies were offspring of wild flies collected from Chiapas or Nuevo Leon, Mexico, and reared on Valencia oranges. Experiments demonstrated effects of yeast hydrolysate protein in adult diet and pairing with males on production of mature and immature eggs, numbers of females producing eggs, and mating with females aged 15 d. Addition of protein to 4% fructose in the adult diet approximately tripled mature egg production in females maintained for the total maturation period with an equal number of males. Females that matured without males produced approximately 33% more-mature eggs when fed protein than those fed no protein. Total egg production of females matured without males and fed sugar only or sugar with protein was more than twice that of females matured with males. Tests to examine the effects of male and female diet separately on female egg production showed slightly higher egg production in females fed protein, or females paired with males fed protein, but these differences were not significant. The most definitive effects were that combining wild strain females and males in cages during maturation reduced egg production. This effect was greatest when flies were not fed protein.

Does dispersal affect the reproductive physiology of the sweet potato whitefly,Bemisia tabaci?

Abstract.The reproductive physiology of sweet potato whiteflies,Bemisia tabaci(Gennadius) (Homoptera: Aleyrodidae), was examined after their dispersal from cotton fields. Of particular interest was the synthesis of vitellogenins and the production of mature eggs. Whiteflies that dispersed out of fields, and were flying at ≈ 0.1 m above the soil surface, exhibited a reproductive physiology that was not significantly different from whiteflies that remained in cotton fields. However,B. tabacicaught at 2.1 m above the ground matured eggs at a significantly lower rate. It appears these latter whiteflies exhibit a physiology that indicates a reallocation of nutrient and energy resources in support of movement.

Changes in the ovary of the Gulf killifish, Fundulus grandis (Baird and Girard), during seasonal and semilunar spawning cycles

Annual and semilunar ovarian cycles were examined in a wild population of Gulf killifish, Fundulus grandis, from the Alabama (U.S.A.) coast of the Gulf of Mexico. Production of mature eggs was first observed in late February, with the main breeding season beginning by mid‐March and extending into August. The season was punctuated by shorter, typically semilunar, cycles of spawning activity and gamete development that became more pronounced as the season progressed. In September any remaining ovulated eggs and oocytes past the intermediate‐cortical alveolus stage underwent atresia, suggesting that the latter may be the final gonadotropin‐ independent stage of oocyte development in F. grandis. Seasonal proliferation of primary growth phase and cortical alveolus oocytes occurred in late autumn and early winter (October‐January). Vitellogenic oocytes first appeared in early February at the start of a month of intense and rapid vitellogenic oocyte growth prior to the March onset of a new breeding season.

Factors influencing the fecundity of Moniliformis moniliformis (Acanthocephala): constant diet and varied dose

Aspects of the reproductive performance of Moniliformis moniliformis were investigated in rats allowed to feed ad libitum on a purified diet containing 1% (w/w) fructose as an energy source for the worms. The rats were infected with either 10, 20, 40 or 80 cystacanths each with the intention of investigating density‐dependent effects on worm fecundity. The establishment of the worms in the gut was independent of dose, but survival, growth and reproductive performance generally were shown to be related to the infective dose given to the rats. The effects could not be related to the absolute numbers of worms present in the small intestine at post‐mortem examination. In general, some unidentified regulatory process appeared to operate to create severe density‐dependence in survival so that surviving parasites were not present in numbers expected to generate competition. Attainment of sexual maturity, growth and the production of mature eggs by worms from rats given doses of 80 cystacanths each were delayed compared with worms from rats given the other doses, but eventually the performance of the high‐dose worms caught up. Worms attached more anteriorly in the small intestine grew bigger and produced more mature eggs. Possible mechanisms responsible for the observed effects are discussed.

Factors influencing the fecundity of Moniliformis moniliformis (Acanthocephala): constant dose and varied diet

The reproductive performance, including survival, growth and mature egg production, of Moniliformis moniliformis was studied experimentally during primary infections in rats given 10 cystacanths each. Four isoenergetic purified diets containing either 1, 3, 6 or 12% fructose (w/w) were used and the amounts of fructose in the intestinal lumen of rats fed on these diets were measured. It was concluded that, while dietary composition had no effect on parasite establishment, there were associations between diet and the survival, growth and fecundity of the parasite. The host diet containing 3% fructose was considered to be more favourable for the worms than the others; 12% fructose was associated with a curtailment of survival time without any compensatory production of eggs. Female worms from rats fed on diets containing 3 or 6% fructose grew larger, and consistently carried more ovaries and produced more eggs than those from rats fed on the 1% fructose diet. It was concluded that these and other findings might be mediated not only through the amount of available fructose in the intestine for worm metabolism, but also by the responses of the host's intestinal physiology to the varying concentrations of fructose in the diet.

Genotype-environment interaction effects on reproductive performance in Tribolium castaneum

Three lines of Tribolium castaneum were raised totally on a yeast-free or yeast-supplemented diet, or raised to pupation on a yeast-free diet and then on a yeast-supplemented diet, and vice versa, to study the effects of genotype x environment interaction and diet changes after pupation on reproduction.Feeding the yeast-supplemented diet generally resulted in earlier sexual maturation, heavier adult weights and higher egg production. The diets had no effects on larval viability. Changes in diet after pupation had no effects on age at sexual maturity or adult weight. Egg production was determined largely by the environment just prior to and during egg laying. However, egg production on the yeast-free diet was influenced by the pre-pupation diet.There was significant line x environment interaction effects on age at sexual maturity, mature egg production and adult weight (P<0.01). There was also a sire x environment effect on egg production (P<0.05).

アカイエカに血液の諸成分などをあたえたさいの産卵状況の検討

Under natural condition ovarial developments followed by oviposition of a mosquito is usually affected only sucking blood of host animals. In the present study, observations were made to see whether the blood, some of its components served to mosquitoes as liquids soaked in cotton layers might effect in producing the eggs, and such artificial breeding method might be used for maintaining laboratory colony of Culex pipiens form fatigans for which absence of autogeny had been checked for more than 20 generation. In a comparative observation on the efficiency of ingestion of the blood served by different methods, the mosquito was found to engorge either of the three routes, defibrinated bovine whole blood coated with chicken membrane, that soaked in cotton layer in a petri dish, or through biting on a laboratory mouse fixed in wire-screen cage, with the rates to the total mosquitoes of 94.0%, 85.7% and 72.3% respectively. However, the rates of reproduction as calculated by dividing the total numbers of eggs deposited by the number of females tested were 36.8, 37.9 and 98.8, and the above two artificial feeding methods were found to be less than half in the efficiency of reproduction than through natural bite on animals. Results of dissections of mosquitoes which ingested the blood soaked in cotton have shown that it is usually taken into dorsal or ventral diverticles of oesophagus but later transffered into the midgut, and that no peritrophic membrane is formed like after natural bite on animals. Many of the mosquitoes thus fed artificially were found to discharge the blood without fully utilizing it as the nutrient. However, developments of yolk in ovarian follicles as well as production of mature eggs were affected when the blood meal was served repeatedly for several days at least in a part of the mosquitoes tested. Further experiments were made to see which of the blood component was effective to induce maturation of the eggs when fed by the above method. Out of 25 mosquitoes tested for each lot oviposition was seen only in 8 females engorged with bonine whole blood with the average egg number of 80.8, and all of the others fed once by saline suspension of blood corpuscles, serum, purified hemoglobin or sugar solution failed to produce mature eggs. However, in another experiment in which hemoglobin was fed cotinuously for successive days, a part of females which ingested it for more than three times were found to produce small numbers of eggs. A similar experiment was made with hemolysed blood, the rates of the number of the oviposited mosquitoes to the number of the blood ingested mosquitoes were lower than the none hemolysed blood, but were no significant difference in the egg number. The whole blood obtained from chicken, cattle, horse, rabbit and mouse was all effective to induce egg production through the artificial ingestions, and no significant difference were seen in the rate of ingestions as well as the rate of reproductions by blood source. The course of blood digestions in the midgut and the development of ovaries after the artificial ingestion was carefully checked daily following Sella's classification proposed for Anopheles. However, the blood fed by the abnormal route was often discharged from the anus or often caused death of the mosquitoes probably due to an intoxication, thus cousing irregular results. The addition of 1, 000 unit percent of pencilline and 250mg percent of streptomycine to the blood were found to be effective to reduce the mortality and to increase the reproduction rates. In a similar experiment made with an autogenuous colony or molestus-form of Culex pipiens complex, the ingestion of blood or its components did not cause any significant increase in its first batch of autogenous egg production. The more oviposition was not seen in the groupes that did not engorge blood meal after the autogeny, and in this strain of the molestus-form