Female Egg Research Articles

Hydration state does not affect selected body temperature during gravidity or gravidity duration in pythons (Antaresia childreni)

The embryonic development of many ectothermic species are highly sensitive to temperature and typically have a higher thermal optima than do most other physiological processes. Thus, female ectotherms often maintain a higher and more carefully controlled body temperature when she is supporting developing embryos (early development in oviparous species, throughout development in viviparous species). Considering the positive correlation between body temperature and evaporative water loss, this response could potentially exacerbate female water imbalance in water-limited environments, suggesting that female water balance and egg development may be in conflict. Using Children's pythons (Antaresia childreni), we hypothesized that water deprivation reduces thermophily during gravidity. We split reproductive females into two thermal treatments: those provided with a continuously available thermal gradient of 25–45 °C and those kept at a constant 31 °C. We also had seven non-reproductive females that were provided a thermal gradient. Within each thermal treatment group, we alternatingly assigned females to either have or not have water throughout gravidity. We found that reproduction increased female body temperature, but this increase was not affected by water regime. Reproduction also increased plasma osmolality, and lack of water during gravidity exacerbated this effect. We also found that thermal treatment, but not water regime, significantly influenced gravidity duration, with females given a thermogradient having a shorter gravidity duration, likely as a result of having a higher average body temperature than did the females provided constant heat. Finally, we found that females provided water throughout gravidity had greater clutch masses than did females without water. Further research is needed to improve scientific understanding of the interactions among water balance, body temperature, and various physiological performances.

An improved medium for in vitro studies of female reproduction and oviposition in Schistosoma japonicum

BackgroundSchistosomiasis is a disease primarily caused by eggs laid by pathogens called schistosomes. Among the schistosome species infecting humans, Schistosoma japonicum possesses the largest fecundity; each adult female produces an average of 3500 eggs per day. The lack of proper culture conditions supporting continuous oviposition in vitro has precluded detailed investigation of mechanisms regulating sexual maturation and egg production in Schistosoma japonicum.MethodsWe optimized in vitro culture conditions by replacing reagents that are part of the classical ABC169 medium. Fast Blue BB staining and 4′,6-diamidino-2-phenylindole (DAPI) labeling were applied to observe the sexual development status of the females. In vitro RNA interference (RNAi) technology was used to validate the capability of the modified medium. The detection of male β-alanyl-tryptamine (BATT) was conducted using liquid chromatography–mass spectrometry (LC–MS).ResultsBoth m-AB169 (1640) and AB169 (1640) media are capable of facilitating the sexual development of paired virgin female S. japonicum, as well as sustaining the mature reproductive organs and egg production of adult S. japonicum for at least 22 days in vitro. M-AB169 (1640) provided a more stable condition for supporting the sexual maturity of female S. japonicum, as evidenced by the consistent initiation of egg production compared with AB169 (1640). Through a comparative analysis of S. japonicum and S. mansoni in diverse media, we demonstrated that these closely related species display distinct demands for their sexual development and egg production, suggesting a potential influence of nutritional factors on the observed variations in host ranges among different schistosome species. Importantly, we successfully identified the presence of the pheromone β-alanyl-tryptamine (BATT) in S. japonicum, previously identified in S. mansoni, highlighting its conserved role in schistosome reproductive development. Through the employment of double-stranded RNA (dsRNA) treatment to silence two genes that are involved in either the male (gli1, glioma-associated oncogene homolog 1) or female (vf1, vitellogenic factor 1) side in male-induced female reproductive development of S. mansoni, we confirmed that the combination of m-AB169 (1640) and RNAi technology has the capacity to facilitate in vitro studies of S. japonicum’s reproductive and oviposition processes.ConclusionsWe developed a novel medium, m-AB169 (1640), that not only maintains the mature reproductive organs and continuous oviposition of adult female Schistosoma japonicum for up to 22 days but also supports the reproductive development and subsequent egg-laying of virgin females after pairing with male worms. This study provides a valuable in vitro platform for functional studies of the mechanisms underlying the fascinating biology of the female sexual development and egg production of S. japonicum, which may accelerate the development of new strategies targeting schistosome egg production.Graphical

Variation in Paramarteilia canceri infections in velvet crab Necora puber.

Sustainable management of crustacean populations requires an understanding of the range of factors affecting different crustacean species. Recently, a high prevalence of a paramyxid parasite, Paramarteilia canceri, was reported in velvet crabs Necora puber in Ireland. Similar parasites have been known to cause mass mortalities in bivalves and, as velvet crabs are an important commercial species, these parasite infections are cause for concern. The main objective of this study was to examine variation in P. canceri infections in relation to host biology and season over a 2 yr period. In addition, we tested a range of host tissues and organs to gain more information on the host-parasite interaction. The parasite was present in all tissues and organs investigated, including the gonad and eggs of a berried female. Parasite prevalence was highest in the cuticular epithelium and hepatopancreas. Both annual and seasonal variation was found in parasite prevalence and parasite load. No difference was found in parasite prevalence or parasite load with either crab size or crab sex. Granulomas as a response to infection were significantly more abundant in infected velvet crab individuals. The results of this study provide important information on the host-parasite interaction between P. canceri and the velvet crab and highlight the importance of including parasite monitoring in the management of crustacean fisheries.

Linking weather conditions and winter tick abundance in moose

AbstractClimate change may modify species distribution to higher latitudes, resulting in potential changes of parasite diversity and transmission dynamics in areas where animals might not be locally adapted to these new parasite species. In addition, climate change may increase the frequency and severity of infestations of parasites that are already present in a region, by promoting the development and survival of infectious stages. Over the last decades, the number of moose (Alces americanus) infested by winter ticks (Dermacentor albipictus) has increased in eastern Canada, possibly because milder climatic conditions are increasing winter tick survival. Our main objective was to determine which meteorological variables are more likely to influence winter tick load on moose. We compiled several weather variables that may limit winter tick survival and explored which weather variables, or their interactions, influenced the winter tick load of 4,100 hunted moose from 2013 to 2019 in Québec, Canada along a latitudinal gradient. Winter tick load in fall decreased with the maximum number of consecutive days in spring with average daily temperatures below −15°C and with the number of consecutive days in summer with a relative humidity <80% when snowmelt in spring was earlier. These results suggest that cold temperatures and prolonged periods of low humidity, amplified by early snowmelt, limit the survival of adult female ticks and eggs, thus limiting their subsequent load on moose during the following fall. With climate change, precipitation increases and warm temperatures occur earlier in spring and are more frequent in summer. Our results suggest that climate change may have a positive long‐term influence on winter tick abundance in the environment and thereby increase winter tick load on moose, which could lead to a significant decrease in moose body condition and survival.

Host‐dependent larval migration and parasitism risk in a polyphagous moth

AbstractFemale herbivorous insects are expected to oviposit on the host plant providing the best performance of the offspring. However, in some insects the larvae are mobile and are not totally dependent on the mother's choice. They can change host plant when conditions for development or exposure to natural enemies vary between individual plants within a patch. Here we study larval migration and preference between two host plants, cotton and alfalfa, in the Egyptian leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). Previous studies have shown that although larval performance is better on cotton, females prefer to oviposit on alfalfa, and this preference corresponds to a higher survival of the eggs. In this study, S. littoralis larvae showed directed movement between host plants and were found to prefer alfalfa over cotton in field test in Egypt, as well as in laboratory selection of feeding site assays. To determine effects by natural enemies, the parasitism rates and various life‐history traits were measured for one larval parasitoid, Microplitis rufiventris Kokujev (Hymenoptera: Braconidae), on several host plants including cotton and clover (equivalent host plant to alfalfa). Overall, parasitism was higher on cotton and parasitoid performance (cocoon mass, adult longevity, and female egg load) was better on cotton compared to clover. This fact suggests an enemy‐free space on clover and alfalfa, as parasitism rate is higher on cotton, and the parasitoid performance is also better on cotton‐fed larvae.

Comparison of the eggshell mammillary microstructure of Galliformes and Anseriformes

AbstractIn free‐living species, the comparison of eggshell microstructure focus mainly on species representing extremely different reproductive strategies or with phylogenetically divergent taxa. The purpose of this study was to compare the microstructure of the mammillary layer in two bird orders (Galliformes and Anseriformes) representing phylogenetically close precocials, and to relate eggshell microstructure to female body weight and egg characteristics. The results showed significant differences between the studied orders. The mammillary layer in Galliformes had more knobs, and consequently, the percent coverage with them was higher than in Anseriformes. The size of individual knobs did not differ significantly between the orders. The obtained results are consistent with the reports that the ossification at the time of hatching is more advanced in Galliformes, so representatives of this order must resorb more calcium from the eggshell. Egg parameters and female body weight were correlated significantly negatively only with the number of knobs per mm2 for Anseriformes and, to a lesser extent, for Galliformes, but not with the coverage per cent of knobs or the size of individual knobs. Only for the three largest species, which lay proportionally larger eggs than the other species studied, the number of knobs per mm2 was significantly lower, but no difference was found in the per cent coverage of knobs. Our results showed that order was a stronger predictor of microstructure than species. Different ossification patterns of the embryonic skeletal system described in these two orders could be the explanation for the observed differences in eggshell microstructure; however, more research is needed.

Gamete sex and elevation affect genetically based variation for unreduced gamete production in a mixed-ploidy plant.

Unreduced gametes are the primary mechanism of neopolyploid formation. Their production in diploid populations is arguably maladaptive, but the magnitude and patterns of genetically based variation maintained in natural populations are poorly understood. We examined variation in male and female unreduced gamete production among plants from different elevations in fireweed, Chamerion angustifolium, grown in a common environment. Using seeds from three high-elevation and three low-elevation diploid populations in one study, and a single diploid population in another, we estimated realized rates of unreduced male (sperm) and female (egg) gamete production by reciprocally pollinating diploid and tetraploid plants and estimating the incidence of tetraploid seeds using flow cytometry. Unreduced gamete frequencies per plant were similar in the two studies (0.12% vs. 0.08%). High-elevation populations had a greater percentage of fruit with seeds from unreduced gametes, but a lower percentage of seeds per fruit than low-elevation populations. Female unreduced gamete frequencies differed among elevations, but male frequencies did not, and the gamete sexes were not correlated at the plant level. We conclude that genetically based variation for unreduced gametes is maintained within and among natural populations, despite their fitness disadvantages, suggesting that local selection may be ineffective at purging them under some conditions.

Hypothesis Explaining Development of Squamous Cell Carcinoma During Infection with Schistosoma Haematobium

Schistosome worms are blood-dwelling flukes that cause chronic infection in more than 200 million people and are thought to be responsible for 500,000 deaths annually. During infection with Schistosoma haematobium, eggs are deposited in the mucosa and submucosa of the bladder and lower ureters. Squamous cell carcinoma (SCC) of the bladder is a long-term sequela of chronic infection. The mechanisms underlying the association between S. haematobium and SCC of the bladder are largely unknown, with all reports to date exclusively demonstrating epidemiological evidence linking S. haematobium infection with SCC of the bladder. Scientists hypothesised that the parasite antigens might induce alterations in epithelial cells towards cancer. Scientists used Chinese Hamster Ovary (CHO) cells and treated the cells in culture with S. haematobium total antigen (Sh). Results showed increased proliferation, increased S-phase and decreased apoptosis, as well as down-regulation of tumor suppressor p27 and up-regulation of anti-apoptotic molecule Bcl-2 (Botelho et al., 2009). Angiogenesis is defined as the formation of new blood vessels from preexisting ones and is recognized as a key event in cell proliferation and carcinogenesis and spread of malignant lesions (Dematei et al., 2017). S. haematobium is classified as a Group 1 carcinogen by the World Health Organization’s International Agency for Research on Cancer (Hodderet al., 2000). Another factor that may play a major role in bladder carcinogenesis in schistosomiasis patients is the presence of continuous physical irritation and inflammation produced by Schistosoma eggs in the bladder mucosa. The adult S. haematobium worms inhabit the veins of the perivesical plexus, where the female lays eggs. Some eggs pass through the bladder mucosa and are excreted in the urine. Other eggs are trapped in the tissue. A chronic inflammatory reaction is initiated, with the invasion of histiocytes and other inflammatory cells into the bladder, the formation of granulomas and eventually fibrosis. In addition, the eruption of the eggs through the mucosa stimulates reparative urothelial hyperplasia and cell turnover (Rosin et al., 1994). In our article we try to explain possible mechanism of conversion normal cells into tumor cells from the position of karyogamic theory.

Bioecology of the millet head miner, Heliocheilus albipunctella De Joannis (Lepidoptera : Noctuidae) in the Sahelian zone of Burkina Faso

Pearl millet, Pennisetum glaucum (L.) R.Br., main cereal crop in the Sahelian zone of Burkina Faso, is attacked by the millet head miner, Heliocheilus albipunctella De Joannis (Lepidoptera: Noctuidae) which causes considerable damage. Previous studies on this pest have been conducted on ecology, biology and biological control. However, knowledge of some bioecological parameters of H. albipunctella remains to be elucidated. This is necessary in order to strengthen existing control strategies for more effective control of the pest. Thus, the work carried out for two consecutive years in 2015 and 2016 showed that the proportion of adults captured in light traps was four females for one male. The rate of gravid females was between 73 and 100%, whether they were fed by honey solution or fasting. In addition, no adults of H. albipunctella were captured in the dry season. To ensure their progeny, females prefer lay eggs on 1/3 extension and fully expanded panicles. They have a lifespan of 4 days and live longer than males. The average egg hatch rate was more than 89% with a survival rate for stage 1 (L1) larvae ranging from 41 to 88% on millet panicles depending on the number of L1 present on the millet panicle. In farmers' fields, the damage caused by MHM is important with more than 40% of panicles destroyed. In addition, no female lays eggs on a panicle that has previously received eggs from another female. The implications of these results for control strategies against this pest are discussed.

The adaptive skill of pest dysdercus koenigii fabricius (hemiptera, pyrrhocoridae),and their destruction on the plant Abelmoschus esculenta, at Ramgarh (Jharkhand, India).

The insect Dysdercus koenigii Fabricus (Hymenoptera,pyrrhocoridae) is a polyphagus serious vegetable pest. Its adaptation with change in climatic temperature and humidity makes it the omnipresent, it is commonly called as Red Cotton bug. Adults have more climatic tolerance than nymphs and eggs. In extreme cold the eggs hatched to nymph and nymph to adult in short duration,during this period adult hides under the old fallen decaying leaves on the soil, in the cracks or crevices. In the spring the female lays eggs on the moist ground under the old decaying leaves, in the cracks or in the crevices. The incubation period for eggs completed and tiny nymphs appear, after 5 moults nymph transform into adults. In hot season the life cycle was variable, in the scarcity of host plant pest migrate to or bridging to other cultivated plant and continue its life cycle but its most likely host plant is cotton plant. The experimental place Ramgarh is a district town located at atlatitude: 23.380 N and longitude 85.340E. Moderate temperature, more humidity and dense greenary make it one of the most attractive district. Nature puts all the workmanship to create this place and reinforced all its beauty to it. It is surrounded on three sides by hills and open at one side by planes .The slop of the hills, variety of soils, plants and animals make it a natural resource of biodiversity. It is a niche for various kinds of animal and insect (Upadhyay2023). The experimental pest Dysdercus koenigii. Fabricius (Hemiptera, pyrrhocoridae) was also observed in the crop field of Ramgarh. The farmers cultivate vegetable plant Abelmos chus esculentus in mass level and experimental pest like to feeds the soft leaves and pods of host plants decline the quality of product and reduce quantity. During extreme cold months egg and nymph transform into adult is adapted to tolerate cold better and spend their life to enter under the decaying fallen leaves ,in the cracks or in the crevices .In extreme hot season its life cycle become variable, rising in temperature and humidity varies its life cycle. Prevention from this bug is very difficult; no natural enemies are better known, but control of pest population by some synthetic chemicals are advised to the farmers to spray. Endosulphan 2% dust, Malathion and Fenitrothion are widely used insecticides to control the bug population. . KEYWORDS :Nature, Biodiversity, adaptation, variable, quantity population, synthetic chemical.

Differences in the reproductive output and larval survival of Rocky Mountain wood ticks (Dermacentor andersoni) and American dog ticks (Dermacentor variabilis) from prairie populations near their northern distributional limits in western Canada.

The effects of temperature and relative humidity (RH) on female reproductive output, egg development and larval survival were determined for Rocky Mountain wood ticks (Dermacentor andersoni) from a prairie population (Chin Lakes, Alberta, Canada) near the northern distribution limit of this species. The responses of D. andersoni eggs and unfed larvae to different temperature (25 or 32°C) and RH (35, 55, 75, 85 or 95%) regimes were compared to our previously published data (Diyes et al. 2021) for a northern prairie population of American dog ticks (Dermacentor variabilis). Oviposition by D. andersoni females took 21-30 days at 25°C and 95% RH compared to 10-21 days for D. variabilis. The number of eggs laid by female ticks was strongly dependent on their engorgement weight, and D. andersoni females produced more eggs than D. variabilis females of an equivalent body weight. Eggs of D. andersoni took less time to develop at 32°C than 25°C with ≥ 85% RH, and hatched faster than those of D. variabilis. Larval survival times declined as temperature increased and RH decreased, but D. andersoni survived longer at 32°C and ≤ 75% RH than D. variabilis. The interspecific differences in responses to the same temperature and humidity regimes indicate that D. andersoni is xerophilic, whereas D. variabilis is hydrophilic. Hence, 'prairie' populations of the Rocky Mountain wood tick occur in the drier grassland ecoregions but are absent in Aspen Parklands Ecoregion which is located to the north and east of the distributional range of D. andersoni.

Variation in Copepod Morphological and Life History Traits along a Vertical Gradient of Freshwater Habitats

Understanding trait selection factors is vital for decoding the processes shaping species’ assemblages. However, trait-based studies in freshwater crustacean copepod assemblages are scarce, especially in groundwater environments. We explored how environmental filtering influences functional traits in copepod assemblages across four freshwater habitats (an alluvial aquifer, a hyporheic zone, a stream benthic zone and a lake littoral) along a depth gradient. Each habitat had distinct environmental templates based on light, temperature and dissolved oxygen. We analysed 4898 individuals from 43 copepod species and examined 12 morphological and life history traits. The results revealed significant differences in copepod traits among habitats, notably in ovigerous female biomass, egg biomass and ovigerous female percentages. Furthermore, despite some statistical uncertainty, notable differences were also observed in the number of juveniles, male-to-female abundance ratios and overall biomass. No significant differences were observed in juvenile biomass, egg characteristics, body size dimorphism or juvenile-to-adult ratios among habitats. The trait variations offer insights into copepod-mediated ecosystem services, particularly carbon recycling. To gain a deeper understanding of copepod adaptations to environmental features and anthropogenic changes, future research should consider additional functional traits, such as locomotion and feeding habits.

Spawning interactions between hatchery‐reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in high‐altitude tropical streams, Kenya

AbstractRainbow trout (Oncorhynchus mykiss) is among the most widely translocated fish species in the world. The current study evaluated the spawning interactions between naturalized and wild rainbow trout from two high‐altitude second‐order streams, in Kenya. Data on total length, weight, condition factor, fecundity, fertilization, egg diameter and fry survival were collected on spawning rainbow trout between March and December 2021. Length–weight relationship showed parabolic equations as W = 0.0144L2.900, W = 0.0069L3.0285 and W = 0.00027L3.175 for wild fish stock, hatchery‐reared and wild × hatchery‐reared rainbow trout, respectively. Total fecundity differed significantly among the hatchery‐reared, wild fish and the cross of the two (p < 0.05). The fertilization rate showed significant differences (p < 0.05), with no discernable difference observed between the hatchery‐reared and crossed (wild × hatchery‐reared). There was a positive correlation among the total fecundity to female egg weight, female body weight, fertilization rate and eyed egg survival in all the populations. Relative fecundity was significantly different among the three groups of fish (p < 0.05), but the differences between the hatchery and the crossed (wild × hatchery‐reared) fish showed no significant differences. We recommend the use of crossed (wild × hatchery‐reared) populations for fry production for use in aquaculture as they presented the highest fecundity and gave the best outcome of fry with high survival.

Response of Mouse Ovaries to Stimulation witch ihe FSH-SU-PER Drug

Hormonal preparation of female egg donors is one of the first stages in obtaining genetically modified animals by microinjected zygote transplantation. A large number of embryos synchronized in development can be obtained by a superovulation procedure based on treating female animals with gonadotropins. As a rule, drugs from different manufacturers differ markedly in terms of their efficacy. In the context of sanctions imposed on the Russian Federation, attention should be paid to domestic hormonal drugs, thus substantiating their objective assessment. It was shown that different batches of the FSH-SUPER drug, used mainly for hormonal treatment of farm animals, differed in stimulating effect on superovulation in female mice. At the same time, the efficacy of this drug surpassed that of Follimag (Mosagrogen, Russia).

Genetic and Phenotypic Consequences of Local Transitions between Sexual and Parthenogenetic Reproduction in the Wild.

AbstractTransitions from sexual to asexual reproduction have occurred in numerous lineages, but it remains unclear why asexual populations rarely persist. In facultatively parthenogenetic animals, all-female populations can arise when males are absent or become extinct, and such populations could help to understand the genetic and phenotypic changes that occur in the initial stages of transitions to asexuality. We investigated a naturally occurring spatial mosaic of mixed-sex and all-female populations of the facultatively parthenogenetic Australian phasmid Megacrania batesii. Analysis of single-nucleotide polymorphisms indicated multiple independent transitions between reproductive modes. All-female populations had much lower heterozygosity and allelic diversity than mixed-sex populations, but we found few consistent differences in fitness-related traits between population types. All-female populations exhibited more frequent and severe deformities in their (flight-incapable) wings but did not show higher rates of appendage loss. All-female populations also harbored more ectoparasites in swamp (but not beach) habitats. Reproductive mode explained little variation in female body size, fecundity, or egg hatch rate. Our results suggest that transitions to parthenogenetic reproduction can lead to dramatic genetic changes with little immediate effect on performance. All-female M. batesii populations appear to consist of high-fitness genotypes that might be able to thrive for many generations in relatively constant and benign environments but could be vulnerable to environmental challenges, such as increased parasite abundance.

Study of the embryonic period of female crayfish egg development in different species

Freshwater crayfish farming is a promising area of production in the food market. This aquaculture industry is currently gaining popularity around the world, but given the high consumer demand, it requires modernisation. The efficiency of aquaculture production is based on the introduction of innovative methods into production processes, which are based on knowledge of biological characteristics, including reproductive capacity and the embryonic period of caviar development. The study aims to assess the reproductive quality of females and determine the incubation period of caviar, its quantity, weight, and survival rate. The study presents the results of research on the reproductive qualities and embryonic period of crayfish eggs of four species (Cherax quadricarinatus, Procambarus clarkii, Procambarus fallax forma virginalis, Cherax destructor) kept in separate closed water supply tanks at an optimal planting density of 4 individuals per 0.45 m2 . Studies have shown that the colour range of caviar and the duration of the incubation period for its maturation varies among different crayfish species. Thus, the first stage of incubation was the shortest and ranged from 2.80 (Florida crayfish) to 3.55 (destructor crayfish) days, while the second stage lasted the longest – from 13.17 to 15.80 days for Australian and broad-toed crayfish, respectively. Based on the analysis of the physiological characteristics of the female crayfish micropopulation, they were divided into quality categories, considering the following indicators: female weight, egg weight, total number of eggs, and number of eggs per 1 g of female. Females of the Australian red snapper of the excellent category was the best among all species in terms of live weight (63.0±0.67 g), egg weight (5.0±0.05 g) and total number of eggs (376.8±16.34 pcs.), the lowest similar indicators were in the marble species (16.8±0.15 g, 1.6±0.03 g, 124.5±2.66 pcs.), respectively. In terms of the number of eggs per 1 g of female weight, Florida crayfish prevailed (7.8±0.19). Instead, the destructor crayfish had intermediate results in these characteristics. The study results can be used in the economic activities of enterprises producing aquatic organisms

Increased offspring provisioning by large female fish and consequences for reproductive efficiency.

Contemporary fisheries research and management have highlighted the need to protect size and age structures of fish populations. Many studies particularly emphasize a disproportionate contribution of populations' largest, oldest female fish to population-level recruitment through maternal effects: non-genetic effects of females on performance of their offspring including through energetic provisioning of eggs. Our study synthesized the effects of increasing female size on offspring performance using a meta-analysis approach. In a stepwise fashion, we conducted three separate meta-analyses to estimate the broad-scale patterns of maternal effects in fish. We synthesized relationships between female size and egg size, egg size and offspring size, and egg size and offspring survival. We tested maternal effects across numerous taxonomic orders and system types including freshwater, diadromous, and saltwater species. We also compared the effects of increasing egg size on offspring performance at different experimental durations. These three meta-analyses all supported the paradigm that larger females render individual benefits to offspring performance. However, females have finite gonadal energy and space for egg provisioning and must trade off between egg size and fecundity. For the largest females to contribute disproportionately to population recruitment (relative to their gonadal investment), they must utilize their gonadal investment more efficiently than their smaller conspecifics. Using example studies in published literature, we demonstrated how established maternal effects on egg provisioning do not necessarily support greater reproductive efficiency in larger females. Therefore, while larger females do produce larger eggs, which promote offspring growth and survival, we concluded these benefits may not always outweigh relative fecundity costs of larger eggs.

Adaptation to climate change through dispersal and inherited timing in an avian migrant.

Many organisms fail to adjust their phenology sufficiently to climate change. Studies have concentrated on adaptive responses within localities, but little is known about how latitudinal dispersal enhances evolutionary potential. Rapid adaptation is expected if dispersers from lower latitudes have improved synchrony to northern conditions, thereby gain fitness and introduce genotypes on which selection acts. Here we provide experimental evidence that dispersal in an avian migrant enables rapid evolutionary adaptation. We translocated Dutch female pied flycatchers (Ficedula hypoleuca) and eggs to Sweden, where breeding phenology is ~15 days later. Translocated females bred earlier, and their fitness was 2.5 times higher than local Swedish flycatchers. We show that between-population variation in timing traits is highly heritable, and hence immigration of southern genotypes promotes the necessary evolutionary response. We conclude that studies on adaptation to large-scale environmental change should not just focus on plasticity and evolution based on standing genetic variation but should also include phenotype-habitat matching through dispersal as a viable route to adjust.

Phenotypic plasticity in an egg parasitoid affects olfactory response to odors from the plant–host complex

Female egg parasitoids must optimize their ability to find a suitable host for reproduction in a limited foraging time. Odorant cues associated with the plant–host complex play an essential role in guiding females toward the host. However, parasitoid response is not always identical within the same genotype, and it could be influenced by the environment. This phenotypic plasticity affects parasitoid behavior and morphology and is directly linked to rearing conditions. Yet, how plasticity influences olfactory responses of egg parasitoids toward plant–host odors is largely unexplored. Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) is an effective biocontrol agent of the invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). Laboratory no-choice and choice tests showed T. japonicus potential to develop in eggs of non-target Pentatomidae. In Y-tube olfactometer we evaluated the olfactory responses of T. japonicus reared on different hosts toward plant–host derived volatiles associated with H. halys and two other stink bug species. Parasitoids reared on the main host H. halys positively responded only to odors from V. faba–H. halys complex. When reared on alternative hosts, T. japonicus was smaller and did not exhibit attraction to any stimuli, although egg load was only partially affected. Host-induced phenotypic plasticity should be considered when evaluating parasitoids for classical biological control.

OXIDATIVE STRESS IN OVARIES OF FEMALE WISTAR RATS EXPOSED TO GEOPHAGIC CLAY (EKO)

The impacts of geophagy on reproductive health, especially the ovaries remain unexplored. The reproductive health of individuals (mostly pregnant women) may be impacted, by exposure to geophagic clay, as there is evidence to substantiate the presence of some contaminants in the studied geophagic clay. The ovary which is the site of production of female egg cells, in the female reproductive system can give useful information on the reproductive effects of this practice in exposed organisms. In this study, thirty-six (36) healthy adult female rats of the Wistar strain, were placed in six (6) groups, of six (6) animals each (A-F) and administered geophagic clay orally with gavage, for forty-two (42) days. Group (A) which served as the control group received feed and distilled water only. Groups (B-F) were administered (250, 500, 1000, 1500, and 2000) mg/kg bw geophagic clay dissolved in distilled water. Markers of oxidative stress were assessed. Histopathological examinations were also carried out on the ovaries. Comparison of the results obtained, by matching control group with the treatment groups, revealed that oxidative stress markers [superoxide dismutase (SOD) and malondialdehyde (MDA)] were elevated significantly (p < 0.05) mostly in the groups administered high doses (1000-2000 mg/kg bw) of geophagic clay. There was a marked depletion (p < 0.05) in reduced glutathione (GSH) level (2000 mg/kg bw). Histopathological examination of the ovaries revealed slight alterations in the anatomic features predominantly in the group administered the highest dose (2000 mg/kg bw). This finding infers possible toxicity in the ovaries especially when geophagic clay is consumed in high concentrations. This implies that geophagic clay may cause a redox imbalance in the ovary, altering female reproductive function, especially when consumed in high doses.