Egg Viability Research Articles

Isolation of Egg and Sperm Cells from Bauhinia blakeana

Isolated sperm cells and egg cells provide useful materials for the study of fertilization in higher plants, under controlled conditions, in the absence of somatic tissue. Viable egg cells from Bauhinia blakeana were isolated using enzymatic digestion and mechanical dissection. Ovules were digested with enzymes for 40–50 min and then transferred to a solution without enzymes for dissection. The three cells of the egg apparatus (i.e., the egg cell and two synergids) were released from a cut ovule by pushing the micropylar region of the ovule with a dissecting needle. Typically, 7–10 egg cells were isolated within 1 h. B. blakeana pollen is bicellular and contains only a vegetative and generative cell at anthesis. Sperm cells were isolated using an in vivo–in vitro method. The isolation of B. blakeana egg and sperm cells potentially provides a basis for in vitro fertilization of this woody dicotyledonous plant and materials for molecular biological investigations of fertilization mechanisms.

Opuntia ficus-indica cladode extract is an embryotoxic, larvicidal, and oviposition-deterrent agent for the diamondback moth, Plutella xylostella

The search for new compounds to control Plutella xylostella, the main pest of Brassica crops, has been stimulated by the environmental impact of the insecticides currently used and reports of resistant populations. This work evaluated the effects of a cladode extract from Opuntia ficus-indica (CE) on the survival and development of P. xylostella, as well as on its oviposition behavior. Additionally, the effects on the histological organization of the larval midgut, as well as digestive enzyme activities, were evaluated. CE contained flavonoids, cinnamic derivatives, terpenes, steroids, and reducing sugars. High-performance liquid chromatography analysis confirmed the presence of rutin and compounds containing aliphatic chains and aromatic rings in their structures. CE reduced the viability of eggs with an EC50 (concentration that reduces egg viability by 50%) at 5.37% (w/v) and killed larvae with an LC50 (concentration that kills 50% of larvae) at 7.75% (w/v). Histological analysis revealed several alterations in the midgut of larvae exposed to the extract, including the presence of spherites, cell nuclei expulsion, the disappearance of the peritrophic membrane, and an increase in the number of goblet cells. CE inhibited the in vitro activity of proteases from larvae midgut extracts. The extract also presented oviposition-deterrent activity. In conclusion, cladodes of O. ficus-indica are a source of compounds toxic to eggs and larvae of P. xylostella and are able to interfere with oviposition site choice. The results suggest potential of CE as a botanical insecticide, though field trials are needed to confirm activity.

Prey quantity affects development, survival and reproductive attributes of Coccinella transversalis Fabricius, 1781 under laboratory conditions

This study assessed development, survival and reproductive parameters of a ladybird beetle, Coccinella transversalis Fabricius, 1781 on different quantities (viz. scarce, optimum and abundant) of the bean aphid prey, Aphis craccivora under laboratory conditions (27 ±1°C; 65 ±5% relative humidity and 14 light: 10 dark hours photoperiod). The pre-oviposition period was the shortest (6.40 ±0.40 days) on abundant prey and longest (9.20±0.49 days) on scarce prey. The oviposition period significantly increased with increasing prey quantity, being longest (55.10 ±1.75 days) on abundant prey and shortest (38.50 ±2.14 days) on scarce prey. Lifetime fecundity and egg viability were recorded the highest (1604.10 ±45.61 eggs and 90.82 ±0.80%, respectively) on abundant diet and lowest (794.60 ±30.84 eggs and 82.72 ±0.67%, respectively) on scarce diet. Reproductive rate, reproductive time ratio, longevity of male and female were all highest, i.e. 29.20 ±0.61 egg/day, 3.70 ±0.26, 65.80 ±1days and 70.30 ±1.30 days, respectively on abundant diet. These parameters were lowest, i.e. 20.90 ±0.83 eggs/day, 1.95 ±0.16, 58.80 ±1.60 days and 56.20 ±1.75 respectively on scarce diet. Development was fastest on abundant prey followed by optimum and slowest on scarce prey. Percentage pupation, percent adult emergence, developmental rate, growth index and generation survival were all highest, i.e. 84.00 ±3.68%, 79.00 ±4.09%, 0.077 ±0.00 day-1, 3.50 ±0.19 day-1, 0.54 ±0.05, respectively when larvae were reared on abundant prey. The same parameters were lowest, i.e. 65.00 ±04.79%, 57.00 ±4.99%, 0.062 ±0.001 day-1, 10.46 ±0.11 day-1, 0.25 ±0.0, respectively on scarce prey. It may therefore be concluded that the availability of abundant prey enhances developmental and reproductive parameters of C. transversalis, and abundant diet of aphid prey may be used for better mass culture of ladybird beetles in laboratories for augmentative biological control of aphids.

ASSESSMENT OF SHELF LIFE AND BACTERIAL LOAD OF VIABLE EGGS OBTAINED AT THE POINT OF LAY FROM ROOM AND REFRIGERATOR STORAGE TEMPERATURES

It is well established that storing hatching eggs over a longer period of time affects its quality. The current study evaluated the impact of egg storage duration in-relation to two different temperature conditions (room and refrigerator) to determine the bacterial load and shelf life of viable eggs. One hundred and twenty eggs were used for this study, 60 were boiled and 60 were raw. Thirty of the boiled eggs were stored at room temperature and the other 30 eggs were kept in the refrigerator. Similarly, 30 raw eggs were each stored at room and optimal refrigeration temperatures for eggs (< 7 oC) respectively, while the egg weight, viability and sensory tests were performed daily on the eggs. However, the eggs kept in the refrigerator were viable for longer and relatively maintained higher physical appearance and sensory quality compared to eggs kept at room temperature. In the investigation of bacterial load, the total viable count ranged from 6.0× 103 to 11.9 × 103 coliform forming unit per millilitre (cfu/ml) and 1.0 × 103 to 6.5 × 103 cfu/ml for the boiled eggs kept at room and refrigeration temperatures (BRT and BFT) respectively. More so, the bacterial counts in raw eggs obtained at room and refrigerator storage ranged from 4.8 × 103 to 6.5 × 103 cfu/ml. Subsequently, the characterization and identification of bacterial isolates indicated the presence of Salmonella pullorum, Proteus mirabilis and Pseudomonas sp. The Salmonella pullorum was isolated from all the egg samples (BRT, BFT, RRT and RFT). The Proteus mirabilis was isolated from boiled eggs kept in both room and refrigerator temperatures (BRT and BFT) while Pseudomonas sp. was obtained only from raw eggs stored in the refrigerator (RFT). In addition, the boiled eggs at room temperature started deterioration on Day 9, while its counterpart in the refrigerator began spoilage or decrease in quality from Day 16. The weight of the viable eggs in relation to the non-viable ones was statistically significant (P < 0.05). The refrigeration of eggs increases its longevity while proper hygiene and adequate boiling of eggs reduces the risk of acquiring infections through bacterial contamination.

Histopathological, cytotoxicological, and genotoxic effects of the semi-synthetic compound dillapiole n-butyl ether in Balb/C mice

ABSTRACT Dillapiole n-butyl ether is a substance derived from dillapiole, which exhibits potential insecticidal effects on Aedes aegypti, the principal vector of the Dengue fever, Zika, and Chikungunya viruses, as well as Aedes albopictus, a vector of Dengue fever. As these mosquitoes are resistant to synthetic insecticides, dillapiole n-butyl ether may represent a valuable, plant-based alternative for their control. Dillapiole n-butyl ether has insecticidal and genotoxic effects on A. aegypti and A. albopictus, as shown by the reduction in clutch size and egg viability, and increased mortality rates, as well as a high frequency of micronuclei and chromosomal aberrations. However, the potential cytotoxic and genotoxic effects of this substance in mammals are still unknown. In Balb/C mice, structural changes were detected in hepatic, renal, and cardiac tissues, which were directly proportional to the concentration of the dose applied, in both genders. The induction of genotoxic, mutagenic, and cytotoxic effects was also observed at the highest concentrations (150 and 328 mg/kg). Further research will be necessary to better characterize the potential genotoxicity of this substance at lower concentrations, for the evaluation of the potential health risks related to its presence in environmental features, such as drinking water.

Unlike Zika, Chikungunya virus interferes in the viability of Aedes aegypti eggs, regardless of females\u2019 age

Chikungunya and Zika are arboviruses transmitted by the mosquito Aedes aegypti. Mosquito fecundity and egg viability are important parameters of vectorial capacity. Here we aim to understand, comparatively, the effects of Chikungunya virus (CHIKV) and Zika virus (ZIKV) infections on the fecundity and fertility of young and old Aedes aegypti females. Using artificial infection blood feeding experiments we observed that both CHIKV and ZIKV do not alter the number of eggs laid when compared to uninfected females, although the egg fertility significantly decreases in both young and old CHIKV-infected females. There is an upward trend of null females (infertile females) from 2.1% in young to 6.8% in old ZIKV-infected females. Together, our data revealed that CHIKV and ZIKV affects differently Ae. aegypti physiology, that may be related to different viral spread in nature.

Reproductive interference between Aedes albopictus and Aedes flavopictus at a place of their origin.

Aedes (Stegomyia) albopictus and Aedes (Stegomyia) flavopictus are related species that have overlapping distributions from southern to central Japan. To understand how they interact, we studied reproductive interference between them, particularly focusing on the body size difference between the mating pair. Here, we examined the effects of conspecific, heterospecific and double mating (i.e. heterospecific mating followed by conspecific mating) on copulation duration, egg production and hatchability of eggs using mosquitoes that varied in body size. Females mated only with heterospecific males produced few viable eggs, indicating that post-mating isolation is almost complete. When mated with heterospecific males before conspecific mating, the production of viable eggs was lower than when mated only with conspecific males, revealing the occurrence of reproductive interference. The degree of reproductive interference was larger in Ae. flavopictus than in Ae. albopictus when the female size was small but did not differ between them when the female size was large. Aedes albopictus females appear to be able to distinguish Ae. flavopictus males from conspecific males and larger females are more successful in the rejection of heterospecific males. On the other hand, Ae. flavopictus were not able to discriminate between conspecific and heterospecific males.

Air-drying bed as an alternative treatment for UASB sludge under tropical conditions

Abstract This study investigated the behaviour of pathogens and microbial indicators during dewatering of sludge from an upflow anaerobic sludge blanket (UASB) reactor treating real domestic wastewater under tropical conditions. The sludge was dewatered in air-drying beds during wet and dry seasons and was monitored for 90 days. Culture-based methods, direct microscopy identification and quantitative polymerase chain reaction assays, were used to evaluate pathogenic and microbiological indicator microorganisms in the sludge. Thermotolerant coliforms and coliphages (somatic and male F-specific) were monitored as bacterial and viral indicators, respectively. Pathogenic organisms monitored included Salmonella spp., Salmonella Typhimurium, Salmonella Enteritidis, pathogenic Escherichia coli strains (intimin-coding genes), Campylobacter jejuni, Cryptosporidium spp., adenovirus, and viable helminths eggs. Results revealed that microbial indicators did not show a significant variation between the dry and wet seasons, as it was verified for some pathogens. During the 90 days of sludge dewatering, the air-drying bed was able to remove microbial indicators and the pathogenic organisms E. coli, S. Typhimurium, and Cryptosporidium spp. (when present). Pathogenic C. jejuni, S. Enteriditis, and adenovirus decreased 0.5–1.7, 0.3–0.4, and 2.6–4.8 log units, respectively. These results highlight the potential of air-drying beds as a simple and low-cost process for sludge dewatering and hygienisation.

Lake sturgeon (Acipenser fulvescens) spawn in the St. Marys River Rapids, Michigan

The St. Marys River connects Lake Superior to Lake Huron, comprising the international border between Michigan, United States, and Ontario, Canada. This Great Lakes connecting channel naturally encompasses various habitats including lakes, wetlands, islands, tributaries, side channels, and main channels. The St. Marys River Rapids are shallow rock areas with high flow velocities (>1 m/s) in the upper river adjacent to the navigation locks and electric power generating stations, while the Little Rapids are shallow, recently restored rocky areas with lower velocities located about 7 km downstream. The St. Marys River Rapids provide important spawning habitat for several native and introduced fishes, but spawning by lake sturgeon (Acipenser fulvescens) was not previously documented. We sampled for lake sturgeon eggs and larvae in both locations during June and July 2018–2019 using weekly benthic egg mat lifts and overnight D-frame larval fish drift nets. Viable lake sturgeon eggs (11 in 2018, 45 in 2019) were collected in the tailrace of a hydroelectric power facility adjacent to the St. Marys River Rapids. Larval lake sturgeon (21 in 2018, 1 in 2019) were collected in the same area as the eggs. Neither lake sturgeon eggs nor larvae were collected at Little Rapids in either year. Our results are the first documentation of successful lake sturgeon spawning and larval drift in the upper St. Marys River. While our observations showed spawning in a human-made tailrace area, the fate of larvae produced here is unknown and warrants further research.

Reproduction of Atlantic bluefin tuna

AbstractThe reproductive success of fish populations depends on their reproductive potential and offspring survival to maturity. The reproductive potential affects recruitment and hence populations’ resilience and productivity. Extensive research carried out throughout the current century has improved our understanding of the reproductive biology of the Atlantic bluefin tuna (ABFT), Thunnus thynnus. Yet, crucial questions still remain unresolved. This paper examines key factors that drive ABFT reproductive performance (maturity, spawning frequency, fecundity, sex ratio, spawning habitat). Some reproductive variables (spawning at age, spawning omission, egg and offspring viability, parental effect) remain poorly investigated due to the enormous challenge of implementing the required research across the distribution range and over time. These fundamental traits of the reproductive life history, however, provide valuable information to fish stock assessment models and hence require further attention. There is a major debate as to the extent of similarity in reproductive traits between eastern and western ABFT stocks. Both stocks have been considered to display differing maturity schedules, which would result in different spawning rates and reproductive outputs. Yet, similarities have been found in major reproductive aspects suggesting that discrepancies between stocks may not be as broad as often assumed. Though substantial, the information acquired on ABFT reproduction over the years is still incomplete for adequately advising fisheries management. The present report provides a synthesis of the existing information on the reproductive biology of ABFT. It also identifies major research needs and analyses future research actions towards bridging current gaps in ABFT reproduction science.

Screening test of Diatomaceous Earth as an alternative control method for Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) eggs

The sugarcane borer Diatraea saccharalis is a pest that causes damage to sugarcane fields. The female lays imbricated egg masses on the leave. They cause the greatest damage as larvae, and thus, control before egg hatching is desired to prevent the development of this pest and avoid damage to the plant. Diatomaceous Earth, or diatomite, is inert dust with insecticidal properties. In this work, we aimed to test the activity of Diatomaceous Earth on viable eggs of D. saccharalis as a potential alternative control method for sugarcane borer. D. saccharalis eggs 1 day after oviposition were immersed in a Diatomaceous Earth solution (10% - w/v) for 5, 10, or 15 min and observed every 24 h for 216 h of analysis. During the first 72 h, there were no changes observed in egg morphology, which maintained an oval shape, pale yellow in color. After 96 h, chorion striations were observed in the treatments with 10 and 15 min of exposure and were not present in the chorion controls eggs. Differences between embryo's number it was observed after 96h in the 15 min treatment when compared with the untreated eggs control. Besides that, control larvae completely hatched in 192 h and the treatment with 10 min and 15 min not shown completely hatching suggesting a delay in the embryonic development of the D. saccharalis larvae. Overall, our study is the first report of the application of D. saccharalis eggs, and we believe that Diatomaceous Earth could be a potential tool for the control of Diatraea eggs, however, thorough investigations are required to elucidate the action of this powder on Diatraea and would be an alternative method to interrupt the biological cycle of the pest.

Novaluron prevents oogenesis and oviposition by inducing ultrastructural changes in ovarian tissue of young adult Lygus lineolaris.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), has emerged as a major pest of cotton, Gossypium hirsutum L, in the mid-southern USA. In the early 1990s L. lineolaris populations developed resistance to several classes of conventional insecticides, increasing the need for insecticides with alternative modes of action such as insect growth regulators (IGRs) for integrated pest management (IPM). The benzoylphenyl urea (BPU) class of IGRs acts by disrupting the growth and development of immature stages of insects, but little is known about its impact on adult stages. The effect of novaluron (Diamond™ 0.83EC), a BPU with known chitin synthesis inhibitor activity, was investigated on adult females of L. lineolaris. Treatment of 1-day-old adults with 600 ppm of novaluron in the diet prevented oviposition, while treatment of older females had no impact on oviposition. Oral novaluron exposure of adults of all ages reduced the viability of eggs laid. Novaluron treatment caused ultrastructural changes in the ovaries of 1-day-old adults (48 h post exposure), distorting the follicular epithelial cell architecture of developing oocytes. Additionally, novaluron treatment decreased the chitin content in ovarian tissue. Our results suggest that chitin or chitin-like components in the developing ovaries of adult L. lineolaris are a target of IGRs such as novaluron, but its activity is specific to a critical time during development. This enhances our understanding of the effects of BPUs on adult insects and could lead to incorporation of IGRs in IPM for controlling adult insect pest populations in the field. © 2020 Society of Chemical Industry.

Increase in egg resistance to desiccation in springtails correlates with blastodermal cuticle formation: Eco-evolutionary implications for insect terrestrialization.

Land colonization was a major event in the history of life. Among animals, insects exerted a staggering terrestrialization success, due to traits usually associated with postembryonic life stages, while the egg stage has been largely overlooked in comparative studies. In many insects, after blastoderm differentiation, the extraembryonic serosal tissue wraps the embryo and synthesizes the serosal cuticle, an extracellular matrix that lies beneath the eggshell and protects the egg against water loss. In contrast, in noninsect hexapods such as springtails (Collembola) the early blastodermal cells synthesize a blastodermal cuticle. Here, we investigate the relationship between blastodermal cuticle formation and egg resistance to desiccation in the springtails Orchesella cincta and Folsomia candida, two species with different oviposition environments and developmental rates. The blastodermal cuticle becomes externally visible in O. cincta and F. candida at 22% and 29% of embryogenesis, respectively. To contextualize, we describe the stages of springtail embryogenesis, exemplified by F. candida. Our physiological assays then showed that blastodermal cuticle formation coincides with an increase in egg viability in a dry environment, significantly contributing to hatching success. However, protection differs between species: while O. cincta eggs survive at least 2 hr outside a humid environment, the survival period recorded for F. candida eggs is only 15 min, which correlates with this species' requirement for humid microhabitats. We suggest that the formation of this cuticle protects the eggs, constituting an ancestral trait among hexapods that predated and facilitated the process of terrestrialization that occurred during insect evolution.

Performance of Trichograma spp in small tomato borer (Neoleucinodes elegantalis Guenée): Pest management with egg parasitoid

The tomato is a crop of great importance for Brazilian agriculture. Among the most damaging pests, the small tomato borer, Neoleucinodes elegantalis Guenée (Lepidoptera: Crambiadae) has caused great losses, since they directly reach the fruits to be commercialized, being used for its handling a large volume of insecticides. In this way, the use of alternative techniques that help in the management of this pest becomes of great importance. Among them, the use of the egg parasitoid Trichogramma spp. has been promising. Thus, the present study aimed to evaluate the performance of Trichogramma species and/or strains in N. elegantalis by selection of strains. The selection was made based on four lineages maintained in the Nucleus of Scientific and Technological Development in Phytosanitary Management of Pests (NUDEMAFI), being three strains of the species T. pretiosum and one of T. galloi species. The parameters evaluated were percentage of parasitized eggs, egg viability, number of individuals per eggs, sex ratio and number of Trichogramma spp. to be released. The T. galloi (T. g1) showed the best parameters for selection of the strain. Estimating the optimal number of T. g1 in eggs of small-fruit-borer was 82 individuals per egg parasitoid. Therefore, this strain was selected for the management of the small tomato-borer, whose eggs presented favorable physicochemical characteristics for the development of the parasitoid.

VisEgg: a robust phenotyping tool to assess rainbow trout egg features and viability.

Assessing female fish reproductive success requires a thorough evaluation of egg characteristics, including egg number, size, and variability as well as egg developmental potential through the monitoring of embryo survival after fertilization. While embryonic success relies, at least in part, on paternal contribution, some parameters are strictly related to egg characteristics, one of the main ones being the viability of the egg when released into the water at spawning. It is however not necessarily possible, at least in salmonid fish that lay nontransparent eggs, to separate the different causes of egg/embryo failure. In this context, our aim was (i) to develop a simple and rapid system to capture images of rainbow trout eggs combined with computerized processing of these images to perform a fully automatic individual characterization of egg features including number and size (ii) to estimate unfertilized egg viability through the monitoring of the percentage of eggs that will not survive to water hydration. To evaluate the VisEgg system, unfertilized eggs (approximatively 400 eggs per batch) originating from 105 different females were hydrated in water. After 24 h, a picture of the eggs was obtained using a dedicated shooting system consisting of a light source and a digital single-lens reflex (SLR) camera. An image processing algorithm was developed to allow the automatic detection and separation of the eggs and to perform automatic measurements of egg number and individual egg size. The presence of white egg was used as an indirect measure of egg integrity, the "whitening" being the result of water entry into the egg through the vitelline membrane. These white eggs were therefore considered nonviable, as a result of their lack of physical integrity. Fertilization assays were performed in parallel using a subsample of the same egg batch. Embryonic development was monitored and hatching rate was calculated. A significant correlation between white egg percentage after hydration and hatching rate was observed (Spearman coefficient = -0.557, p < 0.001), in consistency with the fact that nonviable egg will not allow successful embryonic development. In contrast, the percentage of eggs that do not successfully hatch includes egg/embryo failures of different nature including reduced egg viability. Using the VisEgg, we were able to quantify the lack of viability of the eggs separately from the different other events that may occur during fertilization and incubation. the VisEgg is a convenient and reliable tool to obtain individual measures on trout eggs. It can be used to assess not only egg size and egg number but also unfertilized egg viability before fertilization.

Efficacy of bioactive compounds and their association with different cowpea cultivars against their major stored pest.

Stored grain insects are controlled with fumigant insecticides which can select resistant insect populations and cause environmental and applicator contamination. Thus, resistant cultivars and chemical constituents of essential oils are an alternative to the almost exclusive use of these insecticides. The effects of the combination of cowpea cultivars Vigna unguiculata (L.) Walp. with chemical constituents of essential oils against Callosobruchus maculatus were determined. Four cowpea cultivars: BRS Tracuateua, BR 17 Gurgueia, Epace 10 and Sempre Verde (insect rearing) untreated were used in the experiments and combined with chemical constituents of essential oil: eugenol, geraniol and trans-anethole. The biological parameters observed were: total egg number and eggs per grain, egg viability (%), insects emerged and insects per grain, immature stage viability (%), instantaneous rate of growth (ri), insect dry weight (mg), grain weight loss (%) and egg-adult period. When comparing all biological parameters, the cultivars BRS Tracuateua and BR 17 Gurgueia were harmful to C. maculatus. In the toxicity tests, the results showed that LC30 and LC50 of the chemical constituents ranged from 54.77 to 103.48 ppm and 60.99 to 125.18 ppm, respectively. In most of the biological parameters, LC50 had adverse effects significantly higher than LC30 and BR 17 Gurgueia treated were harmful to C. maculatus. Overall, the findings showed that BR 17 Gurgueia combined with eugenol and geraniol more significantly affected the biological parameters of C. maculatus than when associated with trans-anethole, reducing egg number, insects emerged and egg viability. © 2020 Society of Chemical Industry.

Impact of female mating status and female familiarity with remating interval on the reproductive success of Propylea dissecta (Mulsant) (Coleoptera: Coccinellidae)

Abstract Remating rate is a fundamental parameter that acts on disease transmission, sexual dimorphism, and the rate of evolution of species. Recent studies have indicated that sperm production can be costly. It is thus likely that males may tailor their sperm expenditure according to female mating status and the remating interval between successive matings. In this study, we investigated the effects of male remating interval, female mating status and familiarity of females in the ladybird beetle Propylea dissecta (Mulsant). Ten-day-old adults were allowed to mate and, post disengagement, these adults were exposed to second mating opportunities, either immediately after the first mating, or 6, 18 or 24 h later. To assess the effect of female mating status, the males were subjected to mating with virgin and mated females. Similarly, for assessing the effects of female familiarity, males were subjected to mating with either familiar or unfamiliar females. With increasing remating interval individuals mated for longer, resulting in higher fecundity. Percent egg viability increased with increased remating interval and was highest at 24 h. Mated and unfamiliar females were found to be more fecund than virgin females. Mated females produced a higher number of viable eggs than virgins, suggesting that multiple mating and promiscuity are essential for maximizing the reproductive success of both sexes.

An Insight into the Potential Parasitological Effect ofSchistosoma mansoniAntigens in Infected Mice: Prophylactic Role of Cercarial Antigen

Schistosomiasis is a multifactorial disease that includes environmental, behavioral, parasitic, vector, and host factors. This study aimed to assess the protective effect of single and polyvalent antigens from cercarial antigen preparations (CAPs), soluble worm antigen preparations (SWAPs), and soluble egg antigens (SEAs) which were used as candidate vaccines in an experimental model of Schistosoma mansoni-infected mice. The efficiency of the antigens was tested by determining their effects on fecal egg count, egg viability analysis, and tissue egg counts. Histological and morphometric analyses of granulomas in liver and intestine tissues were performed. In the present study, all immunized groups showed a significant reduction in the average fecal egg count and tissue egg load compared with infected mice. The most substantial reduction in fecal egg count was observed in the combined vaccinated group (23.23 ± 3.2). The group vaccinated with CAP before infection showed the highest reduction in tissue egg load (liver and intestine: 85.22 and 91.70%, respectively). Immunized animals showed a highly significant reduction in the numbers of hepatic granulomas compared with the infected non-immunized group. In conclusion, combining these different antigens (CAP, SWAP, and SEA) augments the protective immunity compared with other immunized groups.

Survival of lizard eggs varies with microhabitat in the presence of an invertebrate nest predator

The risk of nest depredation is influenced by numerous factors, including predator density, environmental conditions of the nesting landscape, and nesting behaviors of mothers. Many reptiles choose nest microhabitats that facilitate embryonic development, but little is known about how the risk of nest depredation in different habitats influences egg survival and nesting behavior. To address this knowledge gap, we quantified predator–prey relationships between square-back marsh crabs (Armases cinereum) and eggs of the brown anole lizard (Anolis sagrei). Our experiments aimed to answer the following questions: (1) are marsh crabs a predator of brown anole eggs, (2) does egg depredation differ among microhabitat types, and (3) how does crab density affect egg survival? We placed viable eggs in three different microhabitats used by nesting females (open area, palm frond, leaf litter), and manipulated the placement of the eggs as either buried or not buried. We also manipulated crab density in a field experiment. Our experiments confirmed square-back marsh crabs as egg predators, and eggs in the leaf litter or eggs buried were the least likely to be depredated. Additionally, eggs in leaf litter and under palm fronds escaped depredation longer than those in the open. Increased crab density also raised the risk of depredation for eggs placed under palm fronds or in open habitats. These results suggest that selection of nest sites by female brown anoles can influence offspring survival in the presence of marsh crabs, and the importance of nest site microhabitat choice may vary with predator density.

Integrative taxonomy of the willow cyst nematode, Heterodera salixophila Kirjanova, 1969, a new record of the Humuli group from Iran

Summary Whilst investigating plant-parasitic nematodes in Urmia City, West Azerbaijan, Iran, soil samples were collected from the rhizosphere of willow trees (Salix babylonica) known to have a population of cyst nematodes. Morphological, numerical and molecular approaches revealed that this population represented the willow cyst nematode, Heterodera salixophila, the first report of this species from Iran. Reproduction of the nematode on S. babylonica was confirmed by inoculating 5000 viable eggs and second-stage juveniles (J2) per kg soil on 2-year-old seedlings of S. babylonica grown in pots containing sterilised soil and incubated under glasshouse conditions. Principal Component Analysis (PCA) and hierarchical cluster analysis of morphometric characters of J2 and vulval plates of species within the Humuli group supported the separation of H. salixophila from other species in this group. In the ITS-rRNA phylogenetic tree, the Iranian population of H. salixophila formed a cluster with two other populations of the species from Belgium and Ukraine, while in the D2-D3 expansion segments of the 28S rRNA tree, it grouped with a population from Belgium as a basal clade in the Humuli group.