Removal Of Eggs Research Articles

Success of Delayed Translocation of Loggerhead Turtle Nests

ABSTRACT Sea turtle embryo mortality in natural nests due to environmental and anthropogenic factors can be very high. To increase hatching success of these endangered species, nest translocation to hatcheries immediately after egg‐laying is a common management tool. To test the viability of delayed translocation, we moved 50 loggerhead sea turtle (Caretta caretta) nests to a beach hatchery after various times (0–96 hr) after egg‐laying at Boavista Island (Republic of Cabo Verde, western Africa). We transported eggs in a rigid plastic container, being careful to maintain their original vertical orientation. Delayed translocation times of 0 hours, 12 hours, 24 hours, 84 hours, or 96 hours after egg‐laying did not have any effect on hatching success, incubation period, or hatchling size and mass. Delayed translocation slightly increased the duration of the translocation process because of extra precautions taken (e.g., maintaining axial orientation, protecting eggs from mechanical shocks). We conclude that delayed nest translocation can be done in a safe and effective way, thereby increasing the efficiency of the whole monitoring program. Finally, delayed translocation, accompanied by an evaluation of fertility, would seem to permit the removal of undeveloped eggs and to facilitate their subsequent exploitation by local communities without affecting turtle nesting success.

Impacts of Water Quality and Hand‐Picking of Dead Eggs on the Survival of Brown Trout and Atlantic Salmon Eggs

AbstractThe effect of water source and removal of dead eggs by hand on egg survival of brown trout Salmo trutta and Atlantic salmon S. salar was studied experimentally in a hatchery trial, which started from fertilization in October and lasted until egg eye‐up in early March; no antifungal chemical treatments were used. The experimental treatments were water source (surface water, filtered surface water, or groundwater), species, and hand‐picking of dead eggs (used, not used); we used four replicates per treatment, resulting in 48 batches. Incubation of eggs in groundwater yielded higher egg survival to eye‐up than incubation in surface water or filtered surface water. Hand‐picking of dead eggs enhanced survival of eggs incubated in surface water but not those incubated in groundwater. The best combination for egg survival in both species was the use of groundwater incubation without hand‐picking of dead eggs.

Helminth eggs inactivation efficiency by faecal sludge dewatering and co-composting in tropical climates

This study investigates helminth eggs removal and inactivation efficiency in a treatment process combining faecal sludge (FS) dewatering and subsequent co-composting with organic solid waste as a function of windrow turning frequency. Fresh public toilet sludge and septage mixed at a 1:2 ratio were dewatered on a drying bed. Biosolids with initial loads of 25–83 helminth eggs/g total solids (TS) were mixed with solid waste as bulking material for co-composting at a 1:2 volume ratio. Two replicate sets of compost heaps were mounted in parallel and turned at different frequencies during the active composting period: (i) once every 3 days and (ii) once every 10 days. Turning frequency had no effect on helminth eggs removal efficiency. In both setups, helminth eggs were reduced to <1 viable egg/g TS, thereby complying with the WHO guidelines 2006 for the safe reuse of FS.

The impact of spraying frames of honey bee eggs with four aqueous solutions on egg removal

The impact of spraying frames of honey bee eggs with four aqueous solutions on egg removal

Nestmate recognition for eggs in the honeybee (Apis mellifera L.)

Colony integrity is fundamental to social insects and is threatened by the reproduction of non-nestmates. Therefore, discrimination between eggs derived from nestmates and non-nestmates would constitute an adaptation to prevent exploitation of the entire cooperative group by unrelated individuals. The removal of nestmate and non-nestmate queen and worker-laid eggs was evaluated in honeybees using colonies of Apis mellifera capensis to test female and of A. m. scutellata to test male eggs. The data show that honeybees can distinguish between nestmate and non-nestmate eggs of both sexes. Moreover, non-nestmate female queen-laid eggs were removed significantly faster than nestmate female worker-laid eggs in A. m. capensis, indicating that nestmate recognition cues can override caste-specific ones. While the experimental manipulation accounts for 37.2% (A. m. scutellata) or 1.6% (A. m. capensis) of variance in relation to egg removal, nestmate recognition explains 33.3% for male eggs (A. m. scutellata) and 60.6% for female eggs (A. m. capensis), which is almost twice as high as the impact of caste (16.7% A. m. scutellata; 25% A. m. capensis). Our data show a stronger effect of nestmate recognition on egg removal in the honeybee, suggesting that cues other than caste-specific ones (viability/kin) can dominate egg removal behavior. In light of intraspecific social parasitism, preventing the reproduction of unrelated individuals (group selection) rather than preferring queens’ eggs (kin selection) appears to be the driving force behind the evolution of egg removal behavior in honeybees.

Effects of Shiny CowbirdMolothrus bonariensisparasitism on different components of House WrenTroglodytes aedonreproductive success

Avian brood parasites, including cuckoos and cowbirds, have multiple negative effects on their hosts. We analysed the effects of Shiny CowbirdMolothrus bonariensisparasitism on different components (e.g. egg losses, hatching success, chick survival and nest abandonment) of House WrenTroglodytes aedonreproductive success. We also conducted an experiment to discriminate between two mechanisms that may reduce hatching success in parasitized clutches: lower efficiency of incubation due to the increase in clutch volume and disruption of host incubation by the early hatching of Cowbirds. Egg puncturing by Shiny Cowbirds reduced host clutch size at hatching by 10–20%, and parasitized nests had a decrease in hatching success of 40–80%. Egg losses and hatching failures were positively associated with the intensity of parasitism. Brood reduction was greater in parasitized nests, but the growth rate of the chicks that fledged was similar to that in unparasitized nests. The combined effects of egg losses, hatching failures and brood reduction decreased the number of fledged chicks by 80%. In addition, egg puncturing increased the likelihood of nest abandonment by Wrens. Experimental data showed that hatching failures occurred when there was a combination of: (1) an increase in the volume of the clutch by the addition of the Cowbird egg without removal of host eggs, and (2) the addition of the Cowbird egg before the onset of incubation. This was relatively common in House Wren nests, as Cowbirds generally parasitize before the onset of incubation. Our results indicate that Shiny Cowbird parasitism imposes a major impact on House Wrens, as it affects all components of the Wren's reproductive success.

“Selfish worker policing” controls reproduction in a Temnothorax ant

Animal societies, including those of humans, are under constant threat by selfish individuals, who attempt to enforce their own interests at the cost of the group. In the societies of bees, wasps, and ants, such individual selfishness can be prevented by “policing,” whereby workers or queens impede the reproduction of other individuals by aggression, immobilization, or egg eating. In this study, we report on a particular kind of reproduction control in the ant Temnothorax unifasciatus, which can be considered as a selfish act itself. We experimentally induced workers to lay eggs by dividing several colonies into two halves, one with and one without a queen. In queenless colonies, workers established rank orders by aggression and several top-ranking workers started to reproduce. Upon reunification, egg-laying workers mostly stopped behaving aggressively. They were neither attacked by the queen nor by random workers, but instead received infrequent, nondestructive, targeted aggression from a few workers, most of which became fertile when the queen was later removed. The introduction of differentially stained worker-laid and queen-laid eggs in queenright fragments did not lead to a selective removal of worker-laid eggs. Hence, there appears to be no collective worker policing in T. unifasciatus. Instead, reproduction appears to be controlled mostly through a few attacks from high-ranking workers, which, in this way, might attempt to selfishly increase their chances of future reproduction.

The impact of spraying frames of honey bee eggs with four aqueous solutions on egg removal

The impact of spraying frames of honey bee eggs with four aqueous solutions on egg removal

Reassessing the Cowbird Threat

AbstractThe demographic significance of parasitism by Brown-headed Cowbirds (Molothrus ater; hereafter “cowbirds”) has been debated for years, because manipulative studies are few and mathematical models of cowbird-host systems have not led to tests of their predictions. We combine results from a cowbird- removal experiment (Smith et al. 2002, 2003) with a stochastic simulation model that we developed, to reassess the effect of cowbirds on the annual reproductive success (ARS) and nesting success in Song Sparrows (Melospiza melodia). Our model followed the breeding success of individual Song Sparrow nests and extrapolated to output variables including ARS, nest survival, and parasitism rates. We parameterized the model with field data from cowbird control sites (i.e., cowbirds not manipulated) and found that output variables matched those observed. We used the reduced parasitism rates observed on cowbird-removal sites, reran the model, and compared output with observed values. On removal sites, ARS was greater than predicted by the model, which indicates that the model failed to account for some biological phenomenon that occurred when cowbirds were in the system. To assess what this phenomenon might be, we conducted further analyses that indicated that cowbirds may facilitate nest predation by “conventional” predators. Using elasticity analyses, we show that cowbirds have their largest effect on ARS through egg removal and that conventional predators are more important than cowbirds in directly affecting nest survival rates. We report that to assess the effect of cowbirds on nest survival, researchers must avoid using the common technique of comparing survival rates of parasitized and unparasitized nests within populations.Réévaluation de la Menace du Vacher

Evaluation of Formalin and Hydrogen Peroxide Treatment Regimes on Rainbow Trout Eyed Eggs

AbstractThis study examined the use of antifungal chemicals at nonstandard treatment concentrations or treatment intervals during the incubation of eyed eggs of rainbow trout Oncorhynchus mykiss until hatch in vertically stacked incubation trays. Daily chemical treatments of 500, 1,000, and 1,667 mg of commercial formalin (containing 37% formaldehyde)/L for 15 min and a nonchemical, dead‐egg‐removal control were included in three trials. The second and third trials added a true control (no antifungal measures) and the third trial also incorporated a treatment of formalin at 1,667 mg/L for 15 min every other day. In these three trials, formalin at 1,000 or 1,667 mg/L daily or 1,667 mg/L every other day significantly improved egg survival to hatch relative to the other treatments and completely controlled fungal growth. A fourth trial evaluated treatments of formalin at 750 mg/L for 15 min daily or every other day, hydrogen peroxide at 500 mg/L for 15 min daily or every other day, and control groups for both treatments. Egg survival to hatch was significantly different among the treatments; the daily 750‐mg/L formalin treatment produced the greatest number of hatched fry, followed by the treatment with 750 mg/L formalin every other day, the dead‐egg‐removal control, and daily hydrogen peroxide treatment. Survival in the every‐other‐day hydrogen peroxide treatment and the true control could only be estimated because of extreme fungal growth, and was substantially less than the other treatments. Only daily 750 mg/L formalin treatments and dead egg removal completely controlled fungal growth. To adequately control fungus and maximize egg survival, either daily 15‐min treatments of formalin at concentrations of at least 750 mg/L or every‐other‐day treatments of formalin at 1,667 mg/L are recommended.

Maternal clutch reduction in the pied flycatcherFicedula hypoleuca: an undescribed clutch size adjustment mechanism

During eight years of study of a population of pied flycatchersFicedula hypoleucabreeding in central Spain, we observed throughout incubation 22 cases of intact eggs being placed on the nest rim and clearly outside of the nest bowl and remaining there, with consequent embryo mortality. We assume that the removal of eggs had been performed by the incubating female. There is no evidence that pied flycatcher parents can detect embryo mortality and eject unhatchable eggs. Maternal egg ejection constitutes a direct mechanism of clutch size adjustment during incubation and before hatching of any young of the brood. This adjustment of clutch size happened when the mean and minimum temperature of the day before ejection were especially low. Also, clutch‐reducing females were significantly more prone to show moult‐breeding overlap than other females, suggesting a lower disposition to invest in reproduction. Clutch‐reducing females were also frequently older than four years and had indications of a lower immunocompetence than females not ejecting eggs. Our results support the hypothesis that adverse conditions can elicit parental family size adjustment at every stage of reproduction without the need to depend on mechanisms of sibling competition.

PARENTS BENEFIT FROM EATING OFFSPRING: DENSITY-DEPENDENT EGG SURVIVORSHIP COMPENSATES FOR FILIAL CANNIBALISM

Abstract Why should animals knowingly consume their own young? It is difficult to imagine many circumstances in which eating one's own young (i.e., filial cannibalism) actually increases an individual's fitness; however, filial cannibalism commonly co-occurs with parental care in fishes. The evolutionary significance of filial cannibalism remains unclear. The most commonly accepted explanation is that filial cannibalism is a mechanism by which caring males gain energy or nutrients that they reinvest into future reproduction, thereby increasing net reproductive success. There is mixed support for this hypothesis and, at best, it can only explain filial cannibalism in some species. A recent alternative hypothesis suggests that filial cannibalism improves the survivorship of remaining eggs by increasing oxygen availability, and thus increases current reproductive success. This theory has received little attention as of yet. We evaluated the hypothesis of oxygen-mediated filial cannibalism in the sand goby by examining the effect of oxygen and egg density on the occurrence of filial cannibalism, evaluating the effects of partial clutch cannibalism on the survivorship of remaining eggs, and comparing potential costs and benefits of filial cannibalism related to the net number of eggs surviving. Indeed, we found that oxygen level and egg density affected the occurrence of cannibalism and that simulated partial clutch cannibalism improved survivorship of the remaining eggs. Additionally, because increased egg survivorship, stemming from partial egg removal, compensated for the cost of cannibalism (i.e., number of eggs removed) at a range of cannibalism levels, filial cannibalism potentially results in no net losses in reproductive success. However, oxygen did not affect egg survivorship. Thus, we suggest a more general hypothesis of filial cannibalism mediated by density-dependent egg survivorship.

Developing Methods for Harvesting Rosy Red Fathead Minnow Eggs

AbstractWe evaluated the effectiveness of different types of spawning substrates in retaining the eggs of rosy red fathead minnow Pimephales promelas, the potential substrate preference of the fish, and the effectiveness of different concentrations of sodium sulfite for detaching eggs from substrates without affecting egg survival. Egg adherence was determined by placing replicate sections of four types of conveyor belt material of varying roughness into a pool stocked with fathead minnow. A screened tray was suspended below each substrate to catch the eggs that did not adhere. Substrate preference was evaluated by following a similar protocol, but only three males were stocked (equal to the number of replicates of each substrate). To test the efficacy of sodium sulfite in removing eggs, substrates with eggs were placed in 0.0, 1.5, and 3.0% solutions and uniformly agitated. The effect of exposure time and egg age was tested by exposing eggs to a 1.5% solution of sodium sulfite for 0 (control), 5, 10, 15, 20, 25, and 30 min. The two rougher substrates retained a significantly greater percentage of eggs than the two smoother ones (72–77% versus 34–39%). Nest locations near the water inlet and air stones were preferred regardless of substrate type. The 1.5% sodium sulfite solution was as effective as the 3.0% solution in removing eggs from substrates. There were no significant differences in hatching rate or percentage of atypical fry resulting from exposure of eggs to 1.5% sodium sulfite for up to 30 min. An egg harvesting system consisting of placing a rough or textured substrate in well‐aerated locations and subsequent egg removal with sodium sulfite appears to be feasible, although economic questions remain.

The ectoparasitic wasp Eulophus pennicornis (Hymenoptera: Eulophidae) uses instar-specific endocrine disruption strategies to suppress the development of its host Lacanobia oleracea (Lepidoptera: Noctuidae)

To successfully complete its development, the gregarious ectoparasitoid Eulophus pennicornis must inhibit the moult of its host, Lacanobia oleracea. In the present study, we examined the possibility that moult- and metamorphosis-associated endocrine events may be disrupted in caterpillars parasitized as newly moulted last (sixth) instars. Juvenile hormone (JH) titres on days 2 and 5 of the final stadium were significantly higher (>100 fold) in parasitized than in non-parasitized hosts, in which JH was essentially absent. Elevated JH levels were associated with reduced haemolymph JH esterase (JHE) activity (down by ⩽99.8%) and enhanced in vitro JH biosynthesis by the corpora allata (CA) (up to 4.5 fold). Wasp adults and/or larvae, in which we measured high levels of JH III (up to 2.7 ng/g), but little or no JH I or JH II, were not seen as likely sources of JH in parasitized hosts, in which we found mostly JH I and JH II. In addition, removal of parasitoid eggs or larvae after oviposition did not prevent the rise in JH titres seen in parasitoid-laden hosts, suggesting that wasp venom may be responsible for the observed hormonal dysfunction. Host haemolymph 20-hydroxyecdysone (20-E) levels were largely unaffected by parasitism during the final stadium although they were observed to increase earlier and decrease more rapidly in parasitized insects. We compare these results with those reported earlier for L. oleracea larvae parasitized by E. pennicornis as penultimate (fifth) instars, which display significantly depressed 20-E titres relative to control larvae. We conclude that E. pennicornis employs host endocrine-disruption strategies that differ according to whether the host is parasitized as a penultimate or final-stadium larva.

Antioxidant protection and plasma carotenoids of incubating great tits ( Parus major L.) in relation to health state and breeding conditions

Carotenoids are biologically active pigments, which are important for animals due to their dual role in health maintenance and ornamental signalling. In adult birds, immunostimulatory properties of carotenoids have been repeatedly demonstrated while much less is known about the importance of carotenoids as antioxidants. We studied the relationships between plasma carotenoid levels, as well as total antioxidant protection, and various hemato-serological health state indices in female great tits ( Parus major L.), incubating their second clutches in two contrasting (coniferous and deciduous) habitats in southwest Estonia. To manipulate reproductive effort, four eggs were removed from half of the clutches during laying to stimulate females to lay additional eggs. However, egg removal had no effect on the final number of eggs laid. Plasma carotenoid levels increased seasonally in parallel with caterpillar food availability. However, no between-habitat differences in carotenoid levels, total antioxidant capacity, or indices of health state could be found despite the apparently better feeding conditions in the coniferous habitat. No correlation was detected between plasma carotenoid levels and measures of total antioxidant capacity, which suggests that at least for the adult birds feeding on naturally carotenoid-rich diet, antioxidant function of carotenoids is not of primary importance. A strong non-linear association between the measures of antioxidant protection and leukocytic markers of inflammation was found, which suggests that measures of total antioxidant capacity deserve further attention in ecophysiological studies as potential indicators of immunopathology.

Nest desertion by a cowbird host: an antiparasite behavior or a response to egg loss?

Natural selection can favor songbirds that desert nests containing eggs of the parasitic brown-headed cowbird (Molothrus ater). However, the high variability in desertion of parasitized nests within species is perplexing in light of the typically high costs of parasitism. Because nest desertion can also be a response to partial clutch predation, we first asked if Bell’s vireos (Vireo bellii) deserted nests in response to the presence of cowbird eggs (antiparasite response hypothesis) or to egg removal by predators and female cowbirds (egg predation hypothesis). Second, we asked whether variation in nest desertion was due to intrinsic differences among individuals or to variation in nest contents. We monitored a large number of nests (n ¼ 494) and performed a clutch manipulation experiment to test these hypotheses. The number of vireo eggs that remained in a nest was a strong predictor of desertion both within and among pairs. Neither the presence of a single cowbird egg, which leads to nest failure for this host, nor the number of cowbird eggs received in a vireo nest influenced nest desertion. Furthermore, vireos did not desert experimental nests when we immediately exchanged cowbird eggs for vireo eggs but deserted if we removed vireo eggs and replaced them with cowbird eggs the following morning. Desertion of parasitized nests by Bell’s vireos can be almost entirely explained as a response to partial or complete clutch loss and does not appear to have been altered by selection from brood parasitism. Key words: Bell’s vireo, brown-headed cowbird, egg predation, evolutionary lag, host‐parasite coevolution, Molothrus ater, Vireo bellii. [Behav Ecol]

The role of forensic geoscience in wildlife crime detection

The increase in both automation and precision in the analysis of geological materials has had significant impact upon forensic investigations in the last 10 years. There is however, a fundamental philosophical difference between forensic and geological enquiry. This paper presents the results of forensic geoscientific investigations of three cases of wildlife crime. Two cases involve the analysis of soils recovered after incidents of illegal badger baiting in the United Kingdom. The third case involves the illegal importation of Eleonora's Falcon ( Falco eleonorae) into the United Kingdom from the Mediterranean. All three cases utilise the analysis of soils by a variety of physical, chemical and biological techniques. These involve mineral and grain size analyses, cation and anion compositions, pH, organic content and pollen analysis. The independent analysis undertaken by specialists in each of these three main fields conclude firstly, that there is a significant similarity between sediments taken at the crime site at both badger setts and with sediments recovered from various spades, shovels and clothing belonging to suspects and secondly, that the soils analysed associated with the removal of the falcon eggs in the Mediterranean contained characteristics similar in many respects to the soils of the breeding areas of F. eleonorae on the cliffs of Mallorca. The use of these independent techniques in wildlife crime detection has great potential given the ubiquitous nature of soils and sediments found in association with wildlife sites.

Effect of high-pressure hot water washing treatment on fruit quality, insects, and disease in apples and pears: Part IV: Use of silicone-based materials and mechanical methods to eliminate surface arthropod eggs

The presence of surface arthropods on commercially processed apples and pears poses a problem when these fruits are exported to countries where there are either limits on the numbers of eggs or a total quarantine restriction against these pests. Removal of mite and other arthropod eggs, such as European red mite (ERM) and codling moth (CM) eggs, may be enhanced by the use of a surface cleaning system, such as a hot water, high-pressure spray. Even if organosilicones, like Silwet L-77, have been used to kill spider mites, it was unclear if these chemicals could also facilitate the removal of arthropod eggs from the surface of fruit. In the present study, high-pressure washing process was highly effective in removing CM and ERM eggs at pressures as low as 400 kPa, resulting in greater than 60% removal of ERM eggs and 90% of CM eggs. High-pressure washing was the most important factor in removal of codling moth and European red mite eggs than organosilicone dips or hot water sprays.

PARENTAL BEHAVIOR IN ANGUID LIZARDS

Abstract Among 21 species for which information is available (out of ca. 100 extant species), three diploglossines, five gerrhonotines, and six anguines attend their eggs during incubation, implying that parental behavior might be synapomorphic for the more inclusive clade Anguidae. A captive Gerrhonotus infernalis attended her clutch for 62 days, occasionally left it to feed and defecate, and did not pursue prey in the presence of her neonates. Viviparous Barisia imbricata, Elgaria coerulea, and Mesaspis moreleti consume extraembryonic debris and sometimes assist with birth; viviparous M. monticolus and Diploglossus fasciatus (mode of reproduction unknown) likely attend their neonates; and parental behavior is perhaps absent in viviparous Anguis fragilis and Ophiodes. Meager circumstantial evidence suggests that chemical cues influence those activities in anguids, and that thermoregulation, defense of eggs and/or young, and hygienic removal of spoiled eggs or birth debris are among the ecological advanta...

EFFECTS OF EGG BATH AND DAILY REMOVAL OF DEAD EGGS ON HATCHING SUCCESS AND PRODUCTION OF STAGE 2 JUVENILES DURING ARTIFICIAL INCUBATION IN NOBLE CRAYFISH (ASTACUS ASTACUS L.)

The effects of egg bath (iodine-detergent preparation) and daily removal of dead eggs on hatching success and production of juveniles in stage 2 were investigated during a short (sixteen days) artificial incubation (AI) of noble crayfish eggs. At the beginning of AI, eggs were in phase XII (pulsating heart appearance) and were incubated in 18 polyethylene 1liter jars (100 eggs/jar, egg density 4.5 eggs.cm-2 ). Six different treatments were tested during AI: – C: control group without removal of dead eggs and egg bath; – R: daily removal of dead eggs without egg bath; – R-LB: daily removal of dead eggs, low frequency of egg bath (once every five days); – R-FB: daily removal of dead eggs, frequent egg bath (once every three days); – LB: without removal of dead eggs, with low frequency of egg bath; – FB: without removal of dead eggs, with frequent egg bath. Egg bath was performed by iodine-detergent preparation Jodisol (dose 2 ml.l-1 and exposition time 2 minutes). Results showed a better hatching rate after removing dead eggs rather than using the egg bath. Three treatments (R; R-LB; R-FB) showed significantly better survival rates in stage 1 (86.3 ± 5.4%) and 2 (84.2 ± 5.4%) than control (74.3 ± 0.9% and 73.3 ± 0.5%, respectively). Two treatments (LB, FB) showed no statistically different survival rate in stage 1 and 2 (82.5 ± 5.5 and 80.7 ± 5.3%, respectively) than the other treatments. After AI, juveniles from all treatments were reared under controlled conditions. At the end of rearing period, juveniles reached a survival rate of 64.1 ± 0.5% with mean body length of 22.0 ± 1.6 mm and mean body weight of 266.0 ± 50.9 mg. Negative effects of AI on growth and survival of juveniles were not evidenced.