Entire Egg Research Articles

Nutritional characteristics of different types of eggs

Objective: To analyze 5 types of poultry eggs (chicken, turkey, ostrich, duck and quail) to compare their nutritional characteristics and sensory properties.
 Design/ Methodology/ Approach: A physical analysis was performed: weight of the entire egg (weight and proportion of the albumin, yolk and shell) length and width of the entire egg, shape index, shell color, and yolk color, nutritional (determination of raw fat, protein, dry matter and ashes) and in sensory adaptation (measured through hedonic testing of adaptability through the arrangement of nine points to an individualized quantity of 97). Different types of egg used: chicken, turkey, ostrich, duck and quail.
 Results: The egg containing the most amount of protein was that of the duck (13.02 ± 0.46 %), while the sample containing the lowest result was that of the ostrich (9.47 ± 0.27 %). The type of egg that contained the fattest level was the duck (10.31 ± 0.75 %); on the other hand, the type of egg that demonstrated the least amount of fat was that of the chicken egg (8.28 ± 0.39 %).
 Results/ Findings/ Conclusion: Even though some physical differences exist in all types of eggs, they are similar and there is minimal variation in terms of their nutritional value. Therefore, these different types of eggs can be applied for consumption as substitutes for chicken eggs and as an alternative source of protein.
 Limitations of the study/ Implications: Lack of previous research in regard to comparisons of the types of analyzed eggs.

Fusarium solani Species Complex (FSSC) in Nests of Hawksbill Turtles (Eretmochelys imbricata) with High Hatching Success in Melaka, Malaysia

Hatching failure is one of the threats to the declining sea turtle population. Sea turtle egg fusariosis, an emerging fungal disease, has been linked to lower hatching success in sea turtle nests. The disease is associated with the presence of members of the (Fusarium solani species complex (FSSC). Samples of cloacal mucus, nest sand, eggshells, and eggs were collected from seven hawksbill turtles and their corresponding nests at Melaka’s nesting beaches and hatchery site. FSSC was prevalent in the unhatched eggs (n = 32) from the seven study nests, colonising 96.9%. The remaining eggs from the study nests were found to have high hatching success, with a mean of 85.8 ± 10.5% (n = 7). It is unknown if the presence of FSSC contributed directly to embryonic mortality in this study. There are two possible roles of FSSC in sea turtle eggs: as a saprophyte or a primary pathogen. The presence of FSSC in the nest did not always compromise the hatching success of the entire egg clutch. FSSC was not detected in the sand samples of all nests, even though all nests contained Fusarium-colonised eggs. The concentration of FSSC in the sand might influence the infection rate of sea turtle eggs and their hatching success. Best practices for hatchery must be in place to achieve high hatching success for sea turtle conservation.

Repeatable randomness, invariant properties, and the design of biological signatures of identity.

What makes a perfect signature? Optimal signatures should be consistent within individuals and distinctive between individuals. In defense against avian brood parasitism, some host species have evolved "signatures" of identity on their eggs, comprising interindividual variation in color and pattern. Tawny-flanked prinia (Prinia subflava) egg signatures facilitate recognition and rejection of parasitic cuckoo finch (Anomalospiza imberbis) eggs. Here, we show that consistency and distinctiveness of patterns are negatively correlated in prinia eggs, perhaps because non-random, repeatable pattern generation mechanisms increase consistency but limit distinctiveness. We hypothesize that pattern properties which are repeatable within individuals but random between individuals ("invariant properties") allow hosts to circumvent this trade-off. To find invariant properties, we develop a method to quantify entire egg phenotypes from images taken from different perspectives. We find that marking scale (a fine-grained measure of size), but not marking orientation or position, is an invariant property in prinias. Hosts should therefore use differences in marking scale in egg recognition, but instead field experiments show that these differences do not predict rejection of conspecific eggs by prinias. Overall, we show that invariant properties allow consistency and distinctiveness to coexist, yet receiver behavior is not optimally tuned to make use of this information.

The effect of the chelated form of trace elements in diet on weight gain, production traits, egg specific gravity, immune system, blood parameters, liver enzymes, and progesterone hormone in Ross 308 broiler breeder chickens

This experiment was conducted in order to investigate the effect of the chelated form of trace elements in diet on the production traits, immunity, and blood parameters of Ross 308 broiler breeder chickens. Treatments included Treatment 1 (Negative control): Mn, Se, Cu, Fe and Zn provided as non-chelated form; Treatment 2 (Positive control): Mn, Se, Cu, Fe and Zn provided as chelated form; Treatment 3: Mn, Se, Cu, Fe and Zn provided as 50% chelated form and 50% non-chelated form; Treatment 4: Zn provided as chelated form; Treatment 5: Cu provided as chelated form; Treatment 6: Fe provided as chelated form; Treatment 7: Mn provided as chelated form; Treatment 8: Se provided as chelated form. The results showed that over the entire production period egg production and egg mass were affected by the experimental treatments (p < 0.05) and that the highest levels were observed in treatments 2 and 3. The chelated form of trace elements had a significant effect, increasing the number of settable eggs and decreasing the unsettable eggs over the entire production period (p < 0.05). Average egg weight over the entire period was not significantly changed (p > 0.05). The highest percentage of 2-yolk, thin shell, broken and small eggs was observed in 61st week of age significantly (p < 0.05). The experimental treatments had a significant effect on the immunity and the antibody titre against Newcastle disease showed a significant increase in treatments 2 and 8 (p < 0.05). The concentration of glucose, triglyceride, progesterone, AST and ALT were affected by the experimental treatments (p < 0.05). In conclusion, the use of a basic diet containing Zn, Fe, Cu, Se and Mn in the chelated form or the use of a basic diet containing mineral elements of Zn, Fe, Cu, Se and Mn with 50% non-chelated form and 50% in the chelated form improves the performance of production traits, immunity and blood parameters of Ross 308 broiler breeder chickens. Highlights Chelated form of trace elements in the diet led to improvement in productive traits, immune response and blood parameters compared to the mineral form Basic diet containing mineral elements of Zn, Fe, Cu, Se, and Mn, 50% in the non-chelated form and 50% in the chelated form led to a significant improvement in egg production, egg mass, egg weight and egg specific gravity Chelated form of trace elements in the diet led to a decrease in the number of abnormal eggs including double-yolk, thin shell, broken, deformed, and small eggs

Taking care of the enemy: egg predation by the Darwin wasp Tromatobia sp. (Ichneumonidae) on the cobweb spider Chrysso compressa (Araneae, Theridiidae)

Some wasp species use spiders as food resources, overcoming several anti-predator barriers that are exerted by spiders. Tromatobia ichneumonid wasps are spider egg predators that usually attack Araneidae species, although there are few records of predation on Clubionidae, Philodromidae, Linyphiidae, Tetragnathidae, and Theridiidae spiders. Here, we describe the interaction between Tromatobia sp. and Chrysso compressa, a subsocial theridiid spider that exhibits extended maternal care, in the Atlantic Forest of southeastern Brazil. We observed that the larva of Tromatobia sp. develop inside the egg sacs of C. compressa, preying on the entire egg mass and building cocoons that change the color and morphology of the egg sacs. Despite these structural modifications, we registered an adult female of C. compressa guarding and caring for the cocoons (attacked egg sac) of the predators as if they were offspring (non-attacked egg sac). To the best of our knowledge, this study represents the first record of Tromatobia preying on Chrysso eggs.

IVF bovine oocyte classification and selection.

The current technology for in vitro fertilization (IVF) has a long history of merely 40 years. The addition of all live births from either fresh or frozen oocytes transferred from a single oocyte collection is known as the IVF productivity rate. The ability to select the best quality eggs is the key to minimizing the number of oocytes generated, procedural cycles for potential failed attempts, and lowering cost and maximize efficiencies. The current standard for egg selection is based on defined morphological criteria. Technicians usually look for an identifiable pattern such as cytoplasm, perivitelline space, zona pellucida, size, etc. Concomitantly oocyte is also screened using genetic analysis that enhances selectivity. However, the same selection procedure is not possible for oocytes. It also has been shown that eggs with similar morphology performance might have drastically different metabolism. Here we proposed a solution where we focus on developing advanced non-invasive imaging methods to map the energy metabolism of oocytes using fluorescent lifetime imaging (FLIM). Combining multiphoton excitation, hyperspectral imaging, and machine learning approach to minimize instrumenting costs, minimize laser exposure to the bovine oocyte, and maximize predictably results for oocyte selection whether fresh or frozen. Hyperspectral imaging (HI) offers the capability of collecting intensity of autofluorescence signals from the oocytes with less laser exposure minimizing the risk of photo-toxicity. Using the phasor approach to HI enables the use of multiparametric analysis of the emission in the range of 350-500 nm range (in the range of emission of metabolic cofactors in oocytes). Complete profiling of the entire egg in three-dimensional space shows its morphological and metabolic features is then generated, showing significant differences for super-stimulation with follicle stimulating hormone, in-vitro maturation, IVF, and in-vitro culture produced oocytes.

Influence of the calcium and nutrient content of the prelay diet on egg production, egg quality, and tibiae mineralization of brown egg-laying hens from 16 to 63 wk of age

The influence of the Ca and nutrient content of the diet fed from 16 to 19 wk of age, on egg production, egg quality, and tibiae mineralization, was studied in brown egg-laying hens from 16 to 63 wk of age. The experimental design was completely randomized with 4 prelay diets organized as a 2×2 factorial with 2 levels of Ca (2.5 vs. 3.8%) and 2 standardized ileal digestible Lys (g/kg) to AMEn (Mcal/kg) ratios (DLys:ME; 2.84 vs. 3.13) as main effects. From 20 to 63 wk of age, all hens received a common diet with 2.75 Mcal AMEn/kg, 0.75% DLys, and 3.8% Ca. Each treatment was replicated 18 times and the experimental unit was a cage with 10 hens. Hen production and egg quality traits were measured by period (4 wk), feeding phase (prelay and lay), and cumulatively (16-63 wk of age) and tibiae mineralization was measured at 63 wk of age. During the prelay phase, an increase in Ca delayed egg production (P=0.065), reduced feed intake (P < 0.05), and increased BW gain (P < 0.01) and percentage of shell of the egg (P < 0.05). An increase in the DLys:ME ratio increased feed intake (P < 0.01) and reduced egg size (P < 0.01). Nutrient content of the prelay diets did not affect hen production during the lay phase, except egg weight that increased (P < 0.05) in hens previously fed the low DLys:ME ratio. Eggshell quality (weight, percentage, strength, and thickness) in this phase was better (P < 0.05) in hens previously fed 3.8% Ca. Cumulatively (16-63 wk of age), hens fed the high Ca prelay diets had better shell quality but tibiae mineralization was not affected. In conclusion, an increase in Ca content of the prelay diet from 2.5 to 3.8% improved shell quality for the entire egg cycle without showing any negative effect on hen production.

Oral tolerance induction protocol to egg white – A report of three pediatric cases

Food allergies are the main cause of anaphylaxis in children. Cow’s milk and egg white are the most common agents and elimination diets are considered the current strategy for their management. Many children can tolerate increasing amounts of the known allergen, and thus, oral tolerance induction protocols seem to be a promising approach. The authors present a protocol drawn up in a pediatric allergic diseases’ outpatient clinic, at a level II hospital, with the aim of egg white oral tolerance induction. During the protocol there is an increase in the amount of egg white offered to children, at the end, tolerance is tested with the ingestion of an entire egg. The protocol was performed in three children with anaphylaxis to egg white. Two children completed the protocol successfully. Oral tolerance to egg white allows a less restrictive diet and improves the quality of life of the patients and their caregivers.

Early Life of the Mink Frog (Rana septentrionalis): From Fertilization to Metamorphosis

Mink Frogs (Rana septentrionalis) are a unique ranid species restricted to Canada and the northern edge of the United States, from northern Minnesota to northern Maine. They are a member of the Aquarana clade that includes Green Frogs (R. clamitans), American Bullfrogs (R. catesbeiana), and four other species. Despite being relatively common where present, the biology of this species has been poorly studied and little in particular is known about its breeding and development from fertilization through overwintering as larvae. Critically, the species' representation in museum collections is limited in general, but particularly at early life stages. Here we report on our initial efforts to describe larval Mink Frog development by inducing breeding of wild-caught adults in the laboratory, then sampling tadpoles from fertilization until the subsequent spring. Specimens, including tissue samples, adult specimens of both sexes, an entire laboratory-induced egg mass, and a captive-bred larval series are available in the Yale Peabody Museum of Natural History. Our approach here demonstrates that Mink Frogs can be captive bred for use in laboratory experiments, and our work provides a novel larval series from egg mass to metamorphosis for this secretive, understudied species.

Assessment of Environmental Impacts from Different Perspectives-Case Study of Egg Value Chain System in Serbia.

The environmental performance of various aspects of animal origin food supply chains has been the focus of research in recent years, and has provided useful information. However, there were no studies that covered the entire egg supply chain from different perspectives. The aim of this study was to analyze the majority of environmental impacts in the table egg supply chain comprising of three subsystems: farms, retail outlets and households, with quantification of each individual subsystem and the entire supply chain. All data were gathered from 30 farms, 50 retail stores and 300 households in Serbia. In parallel, the perception and ranking of environmental impacts along the supply chain were also evaluated. Finally, the quality function deployment for the environment was used to determine the degree of correlation between the set of environmental requirements and the identified environmental impacts. Results revealed that the greatest environmental impacts come from the production of feed for laying hens and the use of natural resources, and they contribute the most to the pollution of each individual environmental indicator. Additionally, the results show the differences in the environmental impacts of each individual subsystem and identify opportunities to mitigate them through the optimization of animal feed, energy consumption and household food waste management. The overall perspective of the egg supply chain points to climate change effects as the most important. The differences in the perceptions of environmental impacts along the entire egg supply chain suggest the need for promotion of mitigation strategies to all stakeholders that would encourage them to achieve sustainable development goals.

Macrobiotus hupingensis, a New Tardigrade Species in the Macrobiotus pallarii Complex from China.

In this paper we describe Macrobiotus hupingensis, a new tardigrade species of the Macrobiotus pallarii complex from southern China. We used the traditional morphology-based taxonomic analysis, supported by detailed morphometrics, light microscopy imaging, scanning electron microscopy, and analysis of four genetic markers (18S rRNA, 28S rRNA, COI and ITS-2). Macrobiotus hupingensis sp. nov. is characterized by eggs with large, conical processes, each surrounded by six (only sometimes five) hexagonal areolae. Based on the morphological characters of the animals (two macroplacoids, one microplacoid, porous curicle, Y-shaped claws) as well as genetic data, we demonstrate the new species to be a member of the M. pallarii complex. However, it differs specifically from M. pallarii, M. pseudopallarii, and M. ripperi mainly by the absence of sparse granulation between legs III and IV. It also differs from M. margoae mostly by the presence of meshes within the entire egg process wall. Finally, the new species can be easily distinguished from M. caymanensis by the presence of granulation visible in light microscopy in all legs.

Quality perception throughout the table egg supply chain

Purpose:This research shows how the perception of quality differs through the table egg chain and highlights the main quality characteristics for each studied chain participant (farm, retail, consumer).Design/methodology/approach:Observing the change in perception starts from the farm, through retail to the end consumer using the customer–supplier interaction, while looking back from the consumer to the farm, the application of the quality function deployment (QFD) was used. The study included 30 farms, 50 retail stores, 1,000 customers and 300 households.Findings:The farm–retail comparison highlights the type of production as the dominant factor affecting egg quality for both of these participants, followed by hen diet and the type of laying hen hybrid from the farmer's point of view, while retail focuses on packaging and egg damage. Egg quality aspects from the retail–household perspective emphasize the shell appearance and the origin of the eggs, while shelf life and egg class are equally important characteristics for both participants. The application of the QFD throughout the entire egg chain emphasizes quality vs price as the most important characteristic.Originality/value:This study could serve to food policy makers as an introduction to further research and production orientation in relation to the set of quality requirements associated with the egg supply chain.

DETEKSI RESIDU ANTIBIOTIK PADA TELUR AYAM LAYER DI PETERNAKAN AYAM LAYER DI SESAOT LOMBOK BARAT

Eggs are a source of animal protein that is cheap and easy to obtain by the community besides having a good taste and also eggs have complete nutrition. However, one of the problems that can harm consumers when consuming chicken eggs is the presence of antibiotic residues that offer antibiotics that are not right or not according to the procedure. cause residues in large amounts and cause side effects, which are very detrimental in terms of health, such as the most important allergies and can even cause resistance. This study aims to see no antibiotic residue in the layers of chicken eggs from layer chicken farms in Sesaot Narmada, West Lombok. The results of testing samples from 10 samples of layer chicken eggs Layer chicken farms in sesaot Narmada West Lombok which were tested using the Bioassay Screening Test method showed negative results containing antibiotic residues. Negative results after testing the antibiotic residues in the entire sample Layer chicken eggs in layer chiken pruttny in the village of Sesaot farms, Narmada district, West Lombok Regency, showed negative results. Negative results in every event with no inhibition zone formed around the disc paper containing the layer chicken egg sample and only the inhibition zone formed on the positive control disc paper on the Bioassay Screening Test tester. of the four classes of antibiotics including macrolides, aminoglycosides, Tetracycline and penicillin.

Non-destructive evaluation of the volumes of egg shell and interior: Theoretical approach

Describing the properties of table eggs requires the development of methods enabling to look inside the egg without destroying it, suggesting a thorough theoretical study including the formulation of theoretical aspects of this advanced egg-related research area. For this purpose, we developed a mathematical assay for computing the volumes of shell and interior of a chicken egg using, as input data, its main external geometric dimensions (length, maximum breadth, and the value of its shift from the centre of the horizontal axis) as well as the thickness of the shell. The shell volume can be determined as the product of the average thickness by the surface area estimated along the midline of shell section. We obtained theoretical dependences of the midline-based estimate of surface area on the values of the average shell thickness and the outer surface area of the egg. Since the volume of egg interior, in addition to the volumes of the entire egg and shell, is also affected by air cell volume, we derived theoretical formulae for computing this indicator. To calculate it, in addition to the values of the basic geometric dimensions of the egg, data on the diameter of the air cell or its height should be used, which is quite simple to measure with conventional measuring instruments like an ovoscope. • A formula for eggshell volume was defined using shell surface area and thickness. • Geometrical parameters of egg and air cell were good predictors of air cell volume. • A formula for recalculation of the volume of egg interior was deduced.

Synthesis of Hydroxyapatite Crystals From Egg Shells

The aim of the review is to raise awareness to synthesise hydroxyapatite (HAp) crystals from eggshells. The development of hydroxyapatite crystals shows a systematic approach towards the development in various biomedical applications. The economic approach of the synthesis of crystalline hydroxyapatite crystals from the eggshells is done using ultrasound assisted technology. The study demonstrates the use of biowastes such as egg shells which is a promising technique to develop hydroxyapatite crystals due to its mechanical and osteogenic properties. The hydroxyapatite crystals are synthesised using biowastes such as egg shells which are rich in calcium and ammonium dihydrogen phosphate. This is a viable substitute for bone regeneration and orthodontic appliances due to its properties such as fracture toughness, mechanical strength, elastic modulus, osteoconductivity, bioactivity and differentiation. These minerals are similar to the inorganic content of the bone and are used widely for complete or partial bone augmentation, filling bone and teeth. They are used as coatings in orthopaedics and dental implants. The organic components of the matrix of the egg shells are mainly composed of mucopolysaccharides, proteins, mainly composed of chondroitin sulphate A and B, glucosamine, galactosamine, galactose, mannose, fructose and sialic acid. They are widely used as the matrix fibres have a strong influence on the mechanical strength of the entire egg shells. These crystals are characterised for bone tissue engineering due to the following properties such as biocompatibility, bioactivity and other mechanical properties without getting rejected by the immune system.

Multiple decrement life tables of Cephus cinctus Norton (Hymenoptera: Cephidae) across a set of barley cultivars: The importance of plant defense versus cannibalism.

Accurately estimating cause-specific mortality for immature insect herbivores is usually difficult. The insects are exposed to abiotic and biotic mortality factors, causing cadavers to simply disappear before cause of mortality can be recorded. Also, insect herbivores are often highly mobile on hosts, making it difficult to follow patterns for individuals through time. In contrast, the wheat stem sawfly, Cephus cinctus Norton, spends its entire egg, larval, and pupal period inside a host stem. Therefore, with periodic sampling stage-specific causes of mortality can be ascertained. Consequently, we examined C. cinctus mortality in eight barley, Hordeum vulgare L., cultivars in two locations in Montana from 2016 to 2018 by collecting stem samples from stem elongation to crop maturity at weekly intervals, and collecting overwintered barley stubs the following spring and summer from the same plots. If larvae were present, we examined larval status—dead or alive—and categorized dead individuals into one of 5 mortality categories: plant defense, cannibalism, parasitism, pathogens, and unknown factors. We used multiple decrement life tables to estimate cause-specific mortality and irreplaceable mortality (the proportion of mortality from a given cause that cannot be replaced by other causes of mortality). Plant defense (antibiosis) caused 85.7 ± 3.6%, cannibalism (governed by antixenosis) caused 70.1 ± 7.6%, parasitism caused 13.8 ± 5.9%, unknown factors caused 38.5 ± 7.6%, and pathogens caused 14.7 ± 8.5% mortality in the presence of all causes of mortality. Similarly, irreplaceable mortality due to plant defense was 22.3 ± 6.4%, cannibalism was 29.1± 4.2%, unknown factors was 6.2 ± 1.8%, pathogens was 0.9 ± 0.5%, and parasitism was 1. 5 ± 0. 6%. Antibiosis traits primarily killed newly emerged larvae, while other traits supported more favorable oviposition decisions by females, increasing mortality by obligate cannibalism. Our results suggest that breeding barley for resistance to C. cinctus targeting both categories of traits (antibiosis and antixenosis) is a highly valuable tactic for management of this important pest.

Effect of Precipitation and Temperature on Larval Survival of Cephus cinctus (Hymenoptera: Cephidae) in Barley Cultivars.

Host plant traits strongly affect survivorship of insect herbivores, and host suitability is especially important for the wheat stem sawfly, Cephus cinctus Norton, which spends its entire egg, larval, and pupal periods in a single stem. Measuring larval survival inside stems from egg hatch through diapause-mediated dormancy is a potential measure of population size for the next year but is also useful in assessing effects of growing season precipitation and temperature. Larval growth is synchronized with host plant growth, and the larva cannot switch hosts. Thus, incorporating plant physiological time, as growing degree days (GDD), may yield a better prediction of larval survival. Therefore, we assessed wheat stem sawfly survival from early larval growth to the beginning of autumnal diapause in barley cultivars selected from across feed, forage, and two- or six-row malt groups. Field experiments were conducted in Gallatin and Chouteau counties, Montana, in 2016 and 2017. We used Kaplan-Meier estimation to assess larval survival among cultivars. We found that the survival of pre-diapause larvae was greatest in 'Hockett' (36.5%) and lowest in 'Celebration' (15.4%). Precipitation and temperature during the growing season affected temporal patterns for larval survival across study sites. Adjusting survivorship curves using site-specific GDD accumulation allowed cultivar-specific survivorship to be estimated more precisely for each site, despite differing environmental influences. Our findings suggest that measuring wheat stem sawfly survival across barley cultivars and standardizing by site-specific GDDs may provide better recommendations on barley cultivars that impede wheat stem sawfly population growth and reduce economic losses.

Self-pressurised rapid freezing, a time-efficient and affordable cryo-fixation method for ultrastructural observations on unhatched cyst nematodes

Summary Ultrastructural analysis of the early development of nematodes is hampered by the impermeability of the eggshell to most commonly used fixatives. High-pressure freezing (HPF), a physical cryo-fixation method, facilitates a fast rate of fixation, and by using this method the issue of the uneven delivery of fixative is circumvented. Although HPF results in a superior preservation of the fine structure, the equipment costs impede a wider application of this method. Self-pressurised rapid freezing (SPRF) is an alternative low-cost cryo-fixation method, and its usefulness was evaluated in an ultrastructural study of the eggshell and the cuticle of unhatched second-stage juveniles (J2) of Globodera rostochiensis and Heterodera schachtii. A comparison with conventional (chemical) fixation demonstrates that SPRF fixation results in a remarkably well-preserved ultrastructure of the entire egg including both the eggshell and the cellular details of the unhatched J2. Therefore, SPRF fixation is proposed as an affordable, relatively easy-to-use and time-efficient technique to study the ultrastructure of unhatched J2 and eggs of nematodes.

Oomycete parasites in freshwater copepods of Patagonia: effects on survival and recruitment.

Copepods are hosts to various oomycete parasite species, but the effects of pathogens on copepod populations have rarely been studied. This study aimed to characterize oomycete infection in the freshwater copepod Parabroteas sarsi in a temporary pond in Patagonia (Argentina). A complete hydroperiod was monitored, evaluating environmental variables as influencing factors in the oomycete infections. Laboratory experiments were performed to evaluate the susceptibility of infected copepods to consumption by predators. Although 5 species of copepods were present in the pond, only ovigerous P. sarsi females were parasitized by oomycetes. Two species of oomycetes were always found together: Aphanomyces ovidestruens and Pythium flevoense. Infections were detected at water temperatures >20°C, with a positive relationship between temperature and parasite prevalence. Infection occurred after a decrease in large filter-feeder densities. The pathogens were not lethal to P. sarsi females in the short-term, but did produce mortality of entire egg sacs, thus negatively impacting subsequent recruitment. Mean prevalence of infection in females was 53%, reaching 83% in December. Females have the capacity to release an infected egg sac and generate a new one in a few days. This infection does not affect the susceptibility of P. sarsi to the predator Notonecta vereertbruggheni. The decrease in female abundance registered towards the end of the hydroperiod could be related to a combination of factors that may have a differential effect on female survival, such as increasing temperature, the energy cost of egg sac development and carrying and oomycete infection.

Cannibalism of Egg and Neonate Larvae by Late Stage Conspecifics of Anopheles gambiae (Diptera: Culicidae): Implications for Ovipositional Studies.

Laboratory experiments intended to test the effects of a purported ovipositional deterrent pheromone of Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) led instead to the finding that egg cannibalism by fourth-instar larvae explained the 'deterrent effect' rather than chemical signals from larvae. Virtually no eggs were counted from cups containing fourth-instar larvae, after oviposition. Numbers of eggs from cups containing younger, conspecific larvae, or pupae did not differ significantly from water only control. Video recording of larval behavior revealed that fourth-instar larvae consumed entire eggs in one continuous ingestive bout. Egg output in the presence of fourth-instar larvae with their mouthparts sealed was similar to the larvae-absent treatment, but nearly 100-fold greater than that counted in the presence of fourth-instar larvae that could eat freely. Thus, the huge egg reduction in eggs counted in the presence of fourth-instar larvae was due to egg cannibalism, not because presence of these larvae deterred oviposition as has been reported in previous studies. Third and especially fourth-instar larvae also cannibalized newly hatched first-instar larvae. Artificial food availability did not eliminate but did reduce cannibalism during first several hours of exposure. The rate at which fourth-instar larvae consumed conspecifics rose significantly and linearly with prey density, generating a non-plateauing, type I functional response curve. These results clearly show that care must be taken such that mosquito ovipositional experiments are not confounded by presence of cannibalizing larvae.