Misplaced Pages

#21978

46-413: 230+, see text Trichogramma is a genus of minute polyphagous wasps that are endoparasitoids of insect eggs. Trichogramma is one of around 80 genera from the family Trichogrammatidae , with over 200 species worldwide. Although several groups of egg parasitoids are commonly employed for biological control throughout the world, Trichogramma spp. have been the most extensively studied. More than

92-440: A 10% survival rate, but the technique is not yet clinically available. With this technique, cryopreserved ovarian tissue could possibly be used to make oocytes that can directly undergo in vitro fertilization . By definition it means, to recapitulate mammalian oogenesis and producing fertilizable oocytes in vitro.it is a complex process involving several different cell types, precise follicular cell-oocyte reciprocal interactions,

138-453: A G-protein, Gs, also present in the oocyte membrane. Maintenance of meiotic arrest also depends on the presence of a multilayered complex of cells, known as a follicle, that surrounds the oocyte. Removal of the oocyte from the follicle causes meiosis to progress in the oocyte. The cells that comprise the follicle, known as granulosa cells, are connected to each other by proteins known as gap junctions, that allow small molecules to pass between

184-462: A cell whose primary function is to divide by the process of meiosis. However, although this process begins at prenatal age, it stops at prophase I . In late fetal life, all oocytes, still primary oocytes, have halted at this stage of development, called the dictyate . After menarche , these cells then continue to develop, although only a few do so every menstrual cycle . Meiosis I of ootidogenesis begins during embryonic development, but halts in

230-440: A consequence of meiosis. In vitro maturation ( IVM ) is the technique of letting ovarian follicles mature in vitro . It can potentially be performed before an IVF . In such cases, ovarian hyperstimulation is not essential. Rather, oocytes can mature outside the body prior to IVF. Hence, no (or at least a lower dose of) gonadotropins have to be injected in the body. Immature eggs have been grown until maturation in vitro at

276-444: A crowded environment. Zhang et al. 1979 finds 13 sensilla types on the antennae , eyes , mouthparts , wing , leg , and external genitalia of T. dendrolimi . This is considered to generalize to the entire genus, and there may be more still undiscovered. To locate host eggs, adult females use chemical and visual signals, such as egg shape and colour. After she finds a suitable egg, an experienced female attempts to determine if

322-570: A dependency on Wolbachia for core reproductive functions, such as oogenesis , so that eventually an infection is a requirement for successful reproduction. Finally, Wolbachia can influence gender determination in its hosts so that more females are successfully born. This results in a reversal in sexual selection , where females must compete for male mates, which has evolutionary implications as it exposes different phenotypes to natural selection. Trichogramma spp. have been used for control of lepidopteran pests for many years. They can be considered

368-811: A method of biological control of the Choristoneura fumiferana , a major pest of spruce and fir forests. Nine species of Trichogramma are produced commercially in insectaries around the world, with 30 countries releasing them. Trichogramma wasps are used for control on numerous crops and plants; these include cotton, sugarcane, vegetables, sugarbeets, orchards, and forests. Some of the pests controlled include cotton bollworm ( Helicoverpa armigera ), codling moth ( Cydia pomonella ), lightbrown apple moth ( Epiphyas postvittana ), and European corn borer ( Ostrinia nubilalis ). Trichogramma species vary in their host specificity. This can lead to nontarget hosts being parasitized. This, in turn, can cause problems by reducing

414-557: A result of meiosis I, the primary oocyte has now developed into the secondary oocyte . Immediately after meiosis I, the haploid secondary oocyte initiates meiosis II . However, this process is also halted at the metaphase II stage until fertilization , if such should ever occur. If the egg is not fertilized, it is disintegrated and released ( menstruation ) and the secondary oocyte does not complete meiosis II (and does not become an ovum ). When meiosis II has completed, an ootid and another polar body have now been created. The polar body

460-484: A thousand papers have been published on Trichogramma species, and they are the most used biological control agents in the world. Trichogramma spp. are also of interest in neuroscience research, having fewer than 10,000 neurons , approaching the theoretical lower limit of the size of an insect brain, yet exhibiting complex behaviors to sustain their lives. Trichogramma have highly developed chemosensory organs due to their need to discriminate host from nonhost in

506-445: A variety of nutrients and combinations of cytokines, and precise growth factors and hormones depending on the developmental stage. In 2016, two papers published by Morohaku et al. and Hikabe et al. reported in vitro procedures that appear to reproduce efficiently these conditions allowing for the production, completely in a dish, of a relatively large number of oocytes that are fertilizable and capable of giving rise to viable offspring in

SECTION 10

#1732859137022

552-463: A very long time—months in mice, years in humans. Initially, the arrest is due to lack of sufficient cell cycle proteins to allow meiotic progression. However, as the oocyte grows, these proteins are synthesized, and meiotic arrest becomes dependent on cyclic AMP . The cyclic AMP is generated by the oocyte by adenylyl cyclase in the oocyte membrane. The adenylyl cyclase is kept active by a constitutively active G-protein-coupled receptor known as GPR3 and

598-405: A woman's life, the others will undergo atresia (degeneration). Two publications have challenged the belief that a finite number of oocytes are set around the time of birth generation in adult mammalian ovaries by putative germ cells in bone marrow and peripheral blood. The renewal of ovarian follicles from germline stem cells (originating from bone marrow and peripheral blood) has been reported in

644-446: Is always maintained, presents four phases: If, instead, there is fertilization, the uterine mucosa is modified to accommodate the fertilized egg, and the secretive phase is maintained. Both polar bodies disintegrate at the end of Meiosis II, leaving only the ootid, which then eventually undergoes maturation into a mature ovum. The function of forming polar bodies is to discard the extra haploid sets of chromosomes that have resulted as

690-402: Is an exception to the rule that generally only one product of female meiosis survives to maturity. In plants , oogenesis occurs inside the female gametophyte via mitosis . In many plants such as bryophytes , ferns , and gymnosperms , egg cells are formed in archegonia . In flowering plants , the female gametophyte has been reduced to an eight-celled embryo sac within the ovule inside

736-401: Is associated with depletion of ovarian reserves leading to menopause, but at a slower rate than in those with such mutations. Since older premenopausal women ordinarily have normal progeny, their capability for meiotic recombinational repair appears to be sufficient to prevent deterioration of their germline despite the reduction in ovarian reserve. DNA damages may arise in the germline during

782-438: Is maintained long enough for genetic divergence to occur and for a new species of asexual wasps to become reproductively isolated. Transmission of the bacterium through horizontal transfer has been observed within the same species and among different species of Trichogramma , including T. kaykai , T. deion, T. pretiosum, and T. atopovirilia ; however, limitations to transmission exist. In vitro successful horizontal transfer

828-486: Is predominately used in orchards. In Australia, T. carverae is used for biological control of light brown apple moth in vineyards. Though Australia has its own native Trichogramma species, not much work has been undertaken to use them commercially for biological control within Australia. Light brown apple moth is common throughout Australia and is polyphagous on more than 80 native and introduced species . The larvae cause

874-408: Is small in size. The ovarian cycle is divided into several phases: The uterine cycle occurs parallel to the ovarian cycle and is induced by estrogen and progesterone. The endometrium , formed by a monostratified cylindrical epithelium, with uterine glands (simple tubular), connective with a functional superficial layer (divided into a spongy layer, a compact layer, and a deeper basal layer, which

920-594: Is the most widely distributed species in North America. It is a more generalized parasitoid, able to parasitise a range of different species. It has been the focus of many research studies and has been successfully reared on 18 genera of Lepidoptera. T. pretiosum was introduced into Australia in the 1970s as part of the Ord River Irrigation Area IPM scheme. Trichogramma carverae is mainly used for light brown apple moth and codling moth control, and

966-484: Is uncommon within Trichogramma , which suggests that the density of Wolbachia must be relatively high inside of the hosts' ovaries. Cytoplasmic incompatibility of the host and bacterium can also be the source of this unsuccessful transfer in-vitro. These limitations in vitro suggest that in nature, horizontal transfer by parthenogenesis-inducing Wolbachia may be a difficult and rare phenomenon. However, when looking at

SECTION 20

#1732859137022

1012-619: Is widely adopted. In 2021 the National Trust in England embarked on a trial of using Trichogramma evanescens , which parasitises clothes moth eggs, in conjunction with pheromones to control common clothes moths , which cause serious damage to carpets, furniture, clothing and other wool and silk objects in historic buildings. The trial was abandoned in 2023; while the microwasps performed well at reducing moth populations in combination with pheromones, they were no better than pheromones alone. It

1058-527: The Drosophila of the parasitoid world, as they have been used for inundative releases and much understanding today comes from experiments with these wasps. Entomologists in the early 1900s began to rear Trichogramma spp. for biological control. T. minutum is one of the most commonly found species in Europe and was first mass reared in 1926 on eggs of Sitotroga cerealella . T. minutum has been investigated as

1104-1051: The United States National Museum . Currently, the number of Trichogramma species is over 200, but as of 1960, only some 40 species of Trichogramma had been described. Wolbachia is a widespread bacterial genus that infects insects' organs, most commonly the reproductive organs. Wolbachia has been observed to alter the host's reproductive success upon infection. Through a series of manipulations, Wolbachia- infected hosts transmit this intracellular bacterium to uninfected individuals. These manipulations include male killing (increasing ratio of infected females that can reproduce), feminization (males become fertile females), parthenogenesis , and cytoplasmic incompatibility . Horizontal transfer of parthenogenesis-inducing Wolbachia , which has been observed in Trichogramma wasps, causes infected females to asexually produce fertile females and nonfunctional males. The effects of this include potential speciation of Trichogramma , if Wolbachia

1150-801: The Wolbachia -host associations, the Trichogramma-Wolbachia form a monophyletic group based on several Wolbachia -specific genes, which may be explained by horizontal transfer of Wolbachia between different species. Therefore, although interspecific horizontal transfer of Wolbachia is limited in vitro , it is likely to occur quite frequently in nature and is not well understood yet. The effects of Wolbachia in Trichogramma have several evolutionary implications. Commonly, uninfected wasps are unable to breed with infected wasps. Many generations of reproductive isolation of these different groups may result in speciation. In addition, some hosts can evolve with

1196-428: The diplotene stage of prophase I until puberty. The mouse oocyte in the dictyate (prolonged diplotene) stage actively repairs DNA damage, whereas DNA repair is not detectable in the pre-dictyate ( leptotene , zygotene and pachytene ) stages of meiosis. For those primary oocytes that continue to develop in each menstrual cycle, however, synapsis occurs and tetrads form, enabling chromosomal crossover to occur. As

1242-451: The ovary of the flower. Oogenesis occurs within the embryo sac and leads to the formation of a single egg cell per ovule. In ascaris , the oocyte does not even begin meiosis until the sperm touches it, in contrast to mammals, where meiosis is completed in the estrus cycle. In female Drosophila flies, genetic recombination occurs during meiosis . This recombination is associated with formation of DNA double-strand breaks and

1288-532: The aid of spindle -coordinating centrosomes . The creation of oogonia traditionally does not belong to oogenesis proper, but, instead, to the common process of gametogenesis , which, in the female human, begins with the processes of folliculogenesis , oocytogenesis, and ootidogenesis . Oogonia enter meiosis during embryonic development, becoming oocytes. Meiosis begins with DNA replication and meiotic crossing over. It then stops in early prophase. Mammalian oocytes are maintained in meiotic prophase arrest for

1334-409: The aim to optimize the characteristics of ovarian tissue culture systems and to better support the three main phases: 1) activation of primordial follicles; 2) isolation and culture of growing preantral follicles; 3) removal from the follicle environment and maturation of oocyte cumulus complexes. While complete oocyte in vitro development has been achieved in mouse, with the production of live offspring,

1380-492: The amount of parasitism of the target host, and depending on the rate of parasitism, nontarget effects could be significant on nontarget host populations. Research is being done on the use of Trichogramma wasps to control populations of spruce bud moth ( Zeiraphera canadensis ) , which damages white spruce trees. Trichogramma began to be seriously used in the 1990s in China. Since then some applications have fallen out of use due to

1426-434: The basis of reference for subsequent descriptions of species. The original specimens, however, were lost. Riley also described a second species in 1879 as Trichogramma pretiosum , but these specimens were also lost. To correct these errors, entomologists returned to the areas where Riley originally found the species and obtained neotype specimens of T. minutum and T. pretiosum . These specimens are now preserved properly in

Trichogramma - Misplaced Pages Continue

1472-432: The cells. The granulosa cells produce a small molecule, cyclic GMP , that diffuses into the oocyte through the gap junctions. In the oocyte, cyclic GMP prevents the breakdown of cyclic AMP by the phosphodiesterase PDE3, and thus maintains meiotic arrest. The cyclic GMP is produced by the guanylyl cyclase NPR2. As follicles grow, they acquire receptors for luteinizing hormone, a pituitary hormone that reinitiates meiosis in

1518-456: The decades long period in humans between early oocytogenesis and the stage of meiosis in which homologous chromosomes are effectively paired ( dictyate stage). It has been suggested that such DNA damages may be removed, in large part, by mechanisms dependent on chromosome pairing, such as homologous recombination. Some algae and the oomycetes produce eggs in oogonia . In the brown alga Fucus , all four egg cells survive oogenesis, which

1564-421: The egg has previously been parasitized, using her ovipositor and antennal drumming (tapping on the egg surface). Females also use antennal drumming to determine the size and quality of the target egg, which determines the number of eggs the female will insert. A single female can parasitize up to 10 host eggs a day. Trichogramma wasps are small and very uniform in structure, which causes difficulty in identifying

1610-753: The first part of oogenesis starts in the germinal epithelium , which gives rise to the development of ovarian follicles , the functional unit of the ovary . Oogenesis consists of several sub-processes: oocytogenesis , ootidogenesis , and finally maturation to form an ovum (oogenesis proper). Folliculogenesis is a separate sub-process that accompanies and supports all three oogenetic sub-processes. Oogonium —(Oocytogenesis)—> Primary Oocyte —(Meiosis I)—> First Polar body (Discarded afterward) + Secondary oocyte —(Meiosis II)—> Second Polar Body (Discarded afterward) + Ovum Oocyte meiosis, important to all animal life cycles yet unlike all other instances of animal cell division, occurs completely without

1656-691: The goal of obtaining oocytes of sufficient quality to support embryo development has not been completely reached into higher mammals despite decades of effort. BRCA1 and ATM proteins are employed in repair of DNA double-strand break during meiosis . These proteins appear to have a critical role in resisting ovarian aging . However, homologous recombinational repair of DNA double-strand breaks mediated by BRCA1 and ATM weakens with age in oocytes of humans and other species. Women with BRCA1 mutations have lower ovarian reserves and experience earlier menopause than women without these mutations. Even in woman without specific BRCA1 mutations, ovarian aging

1702-497: The male process of spermatogenesis, where gametocytes are continuously created. In other words, primary oocytes reach their maximum development at ~20 weeks of gestational age, when approximately seven million primary oocytes have been created; however, at birth, this number has already been reduced to approximately 1-2 million per ovary. At puberty, the number of oocytes decreases even more to reach about 60,000 to 80,000 per ovary, and only about 500 mature oocytes will be produced during

1748-494: The most damage, especially to grape berries, as their feeding provides sites for bunch rot to occur. Losses in the crops can amount up to $ 2000/ha in one season. It is very predominant in areas such as the Yarra Valley . Insecticide use is not a choice method for most growers, who prefer a more natural means of controlling pests. As a result, Trichogramma wasps were considered a good candidate for biological control, even more so as

1794-691: The moth larvae are difficult to control with insecticide. Moreover, light brown apple moths are relatively vulnerable to egg parasitism, with their eggs being laid in masses of 20–50 on the upper surfaces of basal leaves in grapevines. List of Trichogramma species Polyphagous Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.132 via cp1112 cp1112, Varnish XID 394891337 Upstream caches: cp1112 int Error: 429, Too Many Requests at Fri, 29 Nov 2024 05:45:37 GMT Oogenesis In mammals ,

1840-414: The mouse. This technique can be mainly benefited in cancer patients where in today's condition their ovarian tissue is cryopreserved for preservation of fertility. Alternatively to the autologous transplantation, the development of culture systems that support oocyte development from the primordial follicle stage represent a valid strategy to restore fertility. Over time, many studies have been conducted with

1886-531: The oocyte and causes ovulation of a fertilizable egg. Luteinizing hormone acts on receptors in the outer layers of granulosa cells of the follicle, causing a decrease in cyclic GMP in the granulosa cells. Because the granulosa cells and oocyte are connected by gap junctions, cyclic GMP also decreases in the oocyte, causing meiosis to resume. Meiosis then proceeds to second metaphase, where it pauses again until fertilization. Luteinizing hormone also stimulates gene expression leading to ovulation. Oogenesis starts with

Trichogramma - Misplaced Pages Continue

1932-434: The postnatal mouse ovary. In contrast, DNA clock measurements do not indicate ongoing oogenesis during human females' lifetimes. Thus, further experiments are required to determine the true dynamics of small follicle formation. The succeeding phase of ootidogenesis occurs when the primary oocyte develops into an ootid . This is achieved by the process of meiosis. In fact, a primary oocyte is, by its biological definition,

1978-437: The process of developing primary oocytes, which occurs via the transformation of oogonia into primary [oocyte]s, a process called oocytogenesis . From one single oogonium, only one mature oocyte will rise, with 3 other cells called polar bodies. Oocytogenesis is complete either before or shortly after birth. It is commonly believed that, when oocytogenesis is complete, no additional primary oocytes are created, in contrast to

2024-399: The rise of Bt crops because Bt is also toxic to the parasitoid. Future expansion of Bt in China is expected, and this threatens some uses of Trichogramma , however for some crops/pests it remains the better option and so is expected to continue instead of expanded Bt in those applications. Trichogramma will be especially necessary for resistance management if Bt maize/ Bt corn

2070-460: The separate species. As females are all relatively similar, taxonomists rely upon examination of males to tell the different species apart, using features of their antennae and genitalia. The first description of a Trichogramma species was in North America in 1871, by Charles V. Riley. He described the tiny wasps that emerged from eggs of the viceroy butterfly as Trichogramma minutum . In taxonomy , original specimens are very important, as they are

2116-493: Was suspected that the high interiors may not have been suitable and the Trust may continue to use the wasps in smaller stores or where they can be sited close to a known infestation source. The most commonly used species for biological control are T. atopovirilia , T. brevicapillum , T. deion , T. exiguum , T. fuentesi , T. minutum , T. nubilale , T. platneri , T. pretiosum , and T. thalense . T. pretiosum

#21978