Eggs In Autumn Research Articles

Determination of sex and gonad maturity in sturgeon (Acipenser gueldenstaedtii) using ultrasound technique

ABSTRACTThis study was conducted to investigate the sex and gonad stage of Russian sturgeons (Acipenser gueldenstaedtii) under natural water conditions in concrete ponds through the use of ultrasound technique. The ultrasound technique was effective in determining sturgeon gender. However, because the ultrasound showed that males were ready to produce viable sperm but females were not ready to produce eggs in autumn, it is clear that another ultrasound examination would be needed during the breeding season to identify females with mature eggs to ensure fertilization success.

Formation of long‐lasting galls by overwintered nymphs in the Japanese aphid Quadrartus yoshinomiyai (Hemiptera: Aphididae: Hormaphidinae)

AbstractThis paper examines the life history of a generation of galls created by the aphid Quadrartus yoshinomiyai (Hormaphidinae: Nipponaphidini) on its primary host plant, Distylium racemosum. First‐instar fundatrix nymphs of Q. yoshinomiyai initiated galls on stems of developing shoots in early April and incipient enclosed galls were found from later the same month. The galls lasted for up to 14 months, during which they grew to maturity, opened in early or mid‐April of the following year and dried up by the end of June. First‐instar fundatrix nymphs were found on winter buds, indicating that they hatched from eggs in autumn and overwintered as nymphs. These results suggest that Q. yoshinomiyai has a three‐year life cycle.

PROCJENA BROJNOSTI JAJA KUKURUZNE ZLATICE (DIABROTICA VIRGIFERA VIRGIFERA LECONTE) ZASNOVANA NA BROJNOSTIH ODRASLIH PRETHODNE GODINE

Abundance and mortality of Western corn rootworm eggs during the winter in the soil are the primary factor that determinates the potential damage of larvae on the maize roots in spring. The aim of investigation is to determine the relationship between the capture of western corn rootworm adults on baits and the estimated abundance of oviposited eggs in autumn and spring. Second aim was to describe the relationship between the estimated number of eggs in autumn and spring of next year to determine the ratio of mortality in the given circumstances. Data on the number of eggs in autumn and spring were analyzed by binominal estimate of the population number based on frequency of occurrence. Relationship between the estimated number of eggs in autumn and spring is described by linear regression model. There was a positive correlation between the data of captures of adult corn rootworm on baits and the estimated number of eggs in autumn and spring. Coefficient describes strong relationship. Linear model that describes winter mortality of eggs (y = 0,6505x – 512 586 (R² = 0,955*1) was set.

Variation in the hatching behaviour of Nematodirus battus: Polymorphic bet hedging?

Previous work on the transmission dynamics of Nematodirus battus, an important nematode parasite of farmed ruminants in temperate regions, suggests that it operates a bet-hedging strategy. Hatching of cold-sensitised eggs is concentrated in spring, while alternative hatching of non-cold-sensitised eggs in autumn mitigates the risk of poor conditions for hatching in spring or host absence during peak larval availability. Isolates from Scotland showed much less propensity to hatch without chilling than the previously characterised isolate from southern England. Nematodirus battus eggs from a hill farm in Scotland showed intermediate proportions of non-chilled hatching, perhaps related to unpredictability of climate at higher altitudes. Geographic polymorphism in larval behaviour appears to be present in the form of differing chilling requirements for egg hatching. Since bet-hedging through trait diversification is a plausible and demonstrated strategy for coping with environmental unpredictability, it is a likely target for adaptation to climate change. Predictions of disease epidemiology in a changing climate should incorporate parasite adaptation, but further theoretical and empirical characterisations of likely evolutionary responses are needed before this is possible for the most economically important systems.

Overwintering strategy of two weevils infesting three gorse species: When cold hardiness meets plant–insect interactions

The cold hardiness of two closely related weevil species, Exapion ulicis and E. lemovicinum was studied in relation to their life cycles. These two seed-eating weevils reproduce on Ulex plant species with different fruiting phenologies. E. ulicis lays eggs in spring and overwinters as an adult while E. lemovicinum lays eggs in autumn and overwinters as a larva. Adult weevils were collected in natural populations of Brittany (Western France) and characterized with morphological and molecular tools before experiments. We showed that both weevil species exhibited low supercooling points (SCPs) with mean seasonal values below −17 °C. Fresh mass, moisture content and sex were not correlated to supercooling ability. Weevils died upon freezing and the lower lethal temperatures (LLT) were within the range of SCP, indicating that both species are freezing intolerant. Comparison between species for SCP, LLT and survival to exposure at −8 °C in winter showed a higher cold resistance for E. ulicis than for E. lemovicinum. In addition, the seasonal evolution of cold hardiness differed depending on the species. These features suggest that response to cold of weevils is linked to their life cycles, and thus to the life history of their host plants.

Sardine (Sardina pilchardus) egg abundance at station L4, Western English Channel, 1988-2008

Results from sampling for sardine (Sardina pilchardus) eggs at station L4 in the coastal WesternEnglish Channel over the period 1988–2008 are presented and discussed in relation to environ-mental conditions. As previously observed in this area, there is a summer spawning season (mid-March to early July) and one in the autumn (early September to mid-November). The historicaltrend for increasing autumn spawning has continued. The mean spawning temperatures were 12.6and 14.58C for the summer and autumn seasons, respectively. Temperature was negatively corre-lated with summer egg abundance and positively with autumn egg abundance. A negative corre-lation between egg abundance and the North Atlantic Oscillation index suggested a link betweenegg numbers and plankton production.

Introduction, Scenarios for Establishment and Seasonal Activity of Aedes albopictus in The Netherlands

The Asian tiger mosquito Aedes albopictus was detected for the first time in the Netherlands in the summer of 2005. Aedes albopictus is a competent vector of several human viral diseases, and therefore the recent appearance of the vector is a concern to local public health authorities. In 2006 and 2007, the mosquito was found repeatedly and regularly at Lucky bamboo import companies. To assess whether imported Ae. albopictus could establish to produce subsequent generations in the following years or whether the winter conditions in the Netherlands would prove too cold to allow overwintering of diapausing eggs, predictions were made using a Geographic Information Systems (GIS) model based on January average temperature and the annual precipitation recorded in 2006. Seasonal activity of overwintering Ae. albopictus was estimated for temperate strains based on the weekly average temperature and weekly photoperiod using spring egg hatching thresholds of 10.5 degrees C and 11.25 hours, and egg diapause and adult survival thresholds of 9.5 degrees C and 13.5 hours. The analyses indicate that the climate conditions in the Netherlands over the past 10 years were favorable to allow overwintering of diapausing eggs of temperate strains of Ae. albopictus, particularly in the western coastal region. This region was also the area where adult Ae. albopictus were intercepted inside and surrounding plant glasshouses. The estimated number of weeks elapsing between first egg hatching in spring and the production of diapausing eggs in autumn ranged between 17 and 22 weeks in 2006.

Trace elements in home-produced eggs in Belgium: Levels and spatiotemporal distribution

The purpose of this study was to evaluate the levels of arsenic, cadmium, lead, copper and zinc in home-produced eggs, soils and kitchen waste samples of private chicken owners in Belgium, and to determine spatiotemporal differences in trace element contents in eggs. Eggs were sampled in all provinces of Belgium in autumn 2006 and spring 2007. A total number of 59 private chicken owners participated in the study. Trace elements were determined by inductively coupled plasma-mass spectrometry except for mercury, which was determined by atomic absorption of mercury vapour. The mean fresh weight concentrations in eggs in autumn and spring respectively were < 8.0 and < 8.0 µg/kg for arsenic, 0.5 and < 0.5 µg/kg for cadmium, 116 and 74 µg/kg for lead, 0.43 and 0.52 mg/kg for copper, 20.3 and 19.2 mg/kg for zinc, and 3.15 and 4.44 µg/kg for mercury. Analysis of variance determined significant differences in some trace element concentrations in eggs among seasons and regions in Belgium. Average concentrations of arsenic, cadmium and mercury corresponded well with values measured in other countries, while copper and zinc concentrations were within the same order of magnitude as in other countries. Average lead concentrations were high compared to concentrations in eggs from other countries and correlated well with lead concentrations in soil, indicating that the soil is an important source. Other sources of trace elements in eggs might be home-grown vegetables and forage (grass and herbs), and indirectly, air pollution.

Plant phenology and seed predation: interactions between gorses and weevils in Brittany (France)

Abstract Exapion ulicis (Forster) and Exapion lemovicinum (Hoffmann) (Coleoptera: Curculionoidea: Apionidae) are seed predators of the three gorse species occurring in Brittany (France): Ulex europaeus L., Ulex gallii Planch., and Ulex minor Roth.(Fabaceae). Host‐plant phenology plays a major role in the relationship between apionid weevils and their gorse species, because larvae develop within gorse pods and adults have to wait for pod dehiscence to be released. We monitored flowering and fruiting phenology of gorse species, weevil reproductive behaviour, and egg‐laying patterns in six natural populations in the native area of these gorse species. At each site, U. europaeus, which flowers mainly in spring, was sympatric with one of two autumn flowering gorse species, U. gallii and U. minor. We noticed that E. ulicis laid eggs in spring and was restricted to U. europaeus whereas E. lemovicinum laid eggs in autumn and was restricted to the two autumn‐flowering species U. gallii and U. minor. Therefore, host specificity depended on gorse phenology, and not on geographic proximity. In addition, the infested pod content showed that E. ulicis laid several eggs per pod and suggested that females chose pods with the highest numbers of seeds. In contrast, E. lemovicinum laid a single egg per pod and showed no preference for pods with many seeds. Finally, the impact of seed predation by E. ulicis was higher than that of E. lemovicinum.

Doses of darkness control latitudinal differences in breeding date in the barnacle Semibalanus balanoides

This paper reports the first study of breeding in the boreo-arctic barnacle Semibalanus balanoides in which latitudinal variation in timing of egg mass hardening has been examined simultaneously over the geographical scale involved, thereby excluding temporal confounding of the data. The timing of autumn egg mass hardening on the middle shore was established in 2002 and 2003 at ten stations ranging latitudinally from Trondheim (63°24′N) to Plymouth (50°18′N). To assess variation at local scale (&lt;10 km), breeding was studied on three shores at each of two Irish locations (Cork and Galway). At Oban (Scotland) and Cork, the effect of shore height on timing of breeding was investigated. A strong influence of latitude and day length on timing of breeding was found in both 2002 and 2003. In both years, barnacles bred much earlier (when day length was longer) at high rather than low latitudes. No significant effect of environmental temperature or insolation on timing of breeding was detected. Shores no more than 10 km apart showed minimal difference in middle shore breeding date (&lt;4 days). However, upper shore barnacles bred significantly earlier (by 7–13 days) than middle shore animals. The data indicate that breeding is controlled by period of daily darkness, with high shore animals encountering longer effective ‘nights’ because of the opercular closure response to emersion (which will reduce light penetration to tissues). Predictions concerning the effects of global changes in climate and cloud cover on breeding and population distribution are made. It is suggested that increased cloud cover in the northern hemisphere is likely to induce earlier breeding, and possibly shift the present southern limit of Semibalanus southwards.

Cold tolerance in obligate and cyclical parthenogens of the peach‐potato aphid, Myzus persicae

Abstract. 1. Many aphids form mixed populations of cyclical and obligate parthenogens. This is puzzling, because all else being equal, obligate parthenogens should outcompete cyclical parthenogens due to the two‐fold cost of sex. Yet cyclical parthenogens produce frost‐resistant, diapausing eggs in autumn, while obligate parthenogens spend the winter as active stages. Frost resistance thus represents a short‐term advantage to sexual reproduction mediated by winter temperatures, which may promote this coexistence.2. Because obligate parthenogens overwinter as active stages, there may be selection for increased cold tolerance compared to cyclical parthenogens. This has the potential to gradually erode the advantage of sexually producing eggs.3. Four obligately and four cyclically parthenogenetic lines of Myzus persicae (Sulzer) (Hemiptera: Aphididae) were collected from each of two areas differing in winter severity, and their survival after exposure to a severe experimental frost (14 h at −9 °C), as well as their reproductive performance at a low (10 °C) and a high (20 °C) temperature were compared.4. There was significant variation among lines in survival after the experimental frost, but this variation was neither related to their reproductive mode, nor to their area of origin. Similarly, neither reproductive mode nor origin had a significant effect on reproductive performance, independent of temperature. The average slope of the response to variation in temperature was also similar for both reproductive modes, despite the fact that slopes differed significantly among lines.5. Within the limits of extrapolating from laboratory experiments, it is concluded that in M. persicae, the active stages of obligate parthenogens are not better adapted to cold temperatures than those of cyclical parthenogens.

Phenotypic plasticity and development of cold-season insects (Coleoptera: Leiodidae) and their response to climatic change

Cold-season beetles, Catops nigricans Spence, Choleva agilis Illiger and Choleva elongata Payk., i.e. beetles which start to lay eggs in autumn, which are active during the winter in the adult stage and develop from the egg stage to the adult stage mainly during the winter months, were collected from various locations in north-western Europe and reared in the laboratory at varying temperatures and photoperiods.Reproduction of all species started in autumn and continued during the winter months. Highest reproductive and survival rates occurred at low temperatures and within a small thermal window ranging from 5° to 10°C: The fitness of individuals decreased at higher and lower temperatures. The lower thermal threshold for all developmental stages was in the range from -5°C to +2°C. The metabolisms of the species were independent of temperature in both dormant and non-dormant stages and were elevated in the low temperature range in comparison to other species which show a temperature-dependent reaction pattern.Optimal dates for reproduction were determined by the duration of an obligatory adult summer diapause. In C. nigricans, which favours the litter layer of deciduous forests, this duration was fine-tuned by exogenic factors, such as photoperiod and temperature. In contrast, the soil-inhabiting species Ch. elongata showed a homeostatic response pattern, independent of temperature and photoperiod. Heritability (h2) of the duration of diapause was approximately 0.26 in C. nigricans, less pronounced in Ch. agilis (ca. 0.12) and not evident in the subterranean species Ch. elongata.All three species compensated for the vagaries of climate through bet-hedging tactics. Bet-hedging is so pervasive that a recent substantial increase in temperature seems to have a negligible effect on the distribution pattern of all three species. Based on life-history data it is conceivable that both soil-inhabiting Choleva species, which require a relatively low thermal sum for their development, were already present in western Europe during the sub-arctic conditions when ice shields reached their maximum extension during glacial periods by shifting their activity from the cold to the warm season. The Atlantic fringe north of the Pyrenees, where the climate was not cold enough for permafrost during glacial stages, was probably the only refuge where Ch. elongata might have survived. In contrast, the Mediterranean region should have been the northernmost refuge for C. nigricans during glacial periods. This species has relatively high day-degree requirements (= 1150 d°) for individual development when compared to both Choleva species (= 700 d°).

Eggs in autumn: responses to declining incubation temperatures by the eggs of montane lizards

Facultative hatching in response to environmental cues may increase the viability of offspring, if the cue that stimulates hatching also predicts the negative consequences of delayed emergence. Declining incubation temperatures might provide such a cue for montane lizards, because eggs that fail to hatch before winter will perish in the nest. I tested this idea by incubating eggs of an alpine scincid lizard (Bassiana duperreyi) in the laboratory. For the first half of the incubation period the eggs were kept at nest temperatures typical of those experienced in summer in the field (daily cycle of 18 ± 7.5°C). I then transferred eggs at weekly intervals into cooler regimes (either 15 ± 7.5°C; or with daytime temperatures unchanged but dropping to 0°C overnight). Contrary to prediction, the eggs did not hatch early. However, transfer to lower temperatures caused only a relatively short delay in hatching, because of a virtual temperature-independence of developmental rates late (but not early) in incubation. Decreasing incubation temperatures also modified hatchling running speeds and post-hatching growth rates, even if the thermal decrease occurred only shortly before the usual time of hatching. These processes plausibly affect hatchling fitness in cold-climate reptiles, and might be adaptations to montane habitats. Alternatively, they may prove to be widespread in other (warmer-climate) reptile taxa, in which case no adaptive hypothesis need be proposed. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 76, 71–77.

Eggs in autumn: responses to declining incubation temperatures by the eggs of montane lizards

Eggs in autumn: responses to declining incubation temperatures by the eggs of montane lizards

カマキリタマゴカツオブシムシ第１世代成虫の越冬と産卵時期

Adults of the first generation of the dermestid beetle, Thaumaglossa rufocapillata emerging from hatched egg cases of Tenodera spp. mantises in autumn, were reared under semi-natural conditions. Some adults fed on 10% honey overwintered and survived until next summer. Females laid eggs in autumn, and resumed egg laying in spring. They are considered to have the potential to overwinter as adults, although no adult of this dermestid has been collected in winter in mainland Japan. In contrast, no female overwintered when reared without food and water, or when feeding was stopped in mid-November. The results indicate that adult longevity of the first generation of this dermestid is limited, not by low temperatures in winter, but by food supply.

Effects of Egg Size, Laying Order and Larval Density on Performance of Epirrita autumnata (Lep., Geometridae)

Size of successively laid eggs decreased in the egg clutch of Epirrita autumnata. The laying order of the eggs in autumn had a significant effect on the development of the eggs the following spring; larvae from the first-laid eggs hatched first. First-hatched larvae grew slightly larger than the ones that hatched last. Pupal mass, total number of eggs laid, number of fertile eggs, and proportion of unfertilized eggs did not differ among siblings originating from the different parts of the female's egg clutch. Rearing larvae solitarily or in groups did not differentially affect the performance of individuals originating from successively laid egg groups. Larger, earlier laid eggs of E. autumnata did not perform better than smaller, later laid eggs

Local variation in overwintering stages ofPanonychus akitanus Ehara (Acarina: Tetranychidae)

The overwintering behaviour ofPanonychus akitanus Ehara was compared in a population (Sapporo) overwintering as the egg and the adult female and in a population (Tomakomai) overwintering in the egg stage only. In both populations, winter eggs were larger in size and darker in colour than summer eggs, and females laying winter eggs showed clear differences in body colour and behaviour from summer females. Both populations produced winter eggs in response to short photoperiods, and the critical photoperiod was between 13.0 and 13.5 h in the Sapporo population and between 13.5 and 14.0 h in the Tomakomai population. The hatchability of winter eggs of the Sapporo population collected from the field began to increase in November, and that of the Tomakomai population in December. In the Sapporo population, a 40-day or more exposure to 5°C promoted hatching of winter eggs, and a 50-day exposure of females which had previously laid some winter eggs to 5°C induced the production of summer eggs. Females of the Sapporo population laid winter eggs in autumn, and then themselves overwintered as well, and produced summer eggs in the following spring. These females were called winter-habit females.

Analysis of gene action in the control of body conformation and egg weight in the chicken.

The CH and IA inbred lines and crosses between them up to the S3 and sibbed backcross generations are used to analyse the genetic control of shank length and body conformation (1500 cocks and 1626 pullets) and egg weight in the autumn (854 pullets) and spring (670 hens). Hatch effects are demonstrated for shank lengths and autumn egg weight. After adjustment for hatch effects, the genes controlling shank lengths and autumn egg weight are found to be associated with the genes for large size in the CH line. But association is less complete for spring egg weight, and such genes as might control the two derived measures of body conformation, an allometric index of plumpness and the modular difference between right and left shanks, show almost complete dispersion. In the main analyses, by least squares equation of generation means to parameters for various genetic and maternal effects, the modular difference between shank lengths is not demonstrably heritable. Autumn egg weight shows only additive and dominant effects, the latter appearing more important. The remaining characters are best fitted by a model including interaction between pairs of linked loci. Maternal and sex-linked effects are shown for shank lengths. But shank lengths and plumpness in females are controlled primarily by duplicate gene interaction. In the less satisfactory analyses of spring egg weight and male plumpness, complementary gene interaction is indicated.

The life‐cycle of the Wolf spider Pardosa lugubris in Holland

Pardosa lugubris in Scotland has a 2‐year life‐cycle. In Holland the situation is less clear‐cut: spiderlings emerging from the summer egg sac can reach sexual maturity by the following spring. These spiders, with a 1‐year life‐cycle, have one instar fewer than the Scottish spiders. The Dutch spiderlings from the autumn egg sac, like the Scottish spiders, have a 2‐year life‐cycle and have the same number of instars as the Scottish spiders.The shorter life‐cycle of some of the Dutch spiders is probably due to the fact that summer temperatures are higher in Holland than in Scotland. It is suggested that the length of the life‐cycle may be an important factor in spider distribution and that this may account for the relative scarcity of large spider species in high latitudes.

Aspects of the ecology and energetics of the egg sac parasites of the wolf spider Pardosa lugubris (Walckenaer).

The egg sacs of the wolf spider Pardosa lugubris are parasitised by two ichneumonid wasps, namely Gelis micrurus and Hidryta sordidus. The parasites are bivoltine, the first generation parasitising the summer egg sac of P. lugubris and the second generation parasitising, and overwintering in, the autumn egg sac. Parasitised egg sacs have a characteristic appearance.The degree of egg sac parasitism was 9.8% and 6.9% for the two egg sac batches in 1965 and 2.9% and 34.8% for those of 1966. The degree of parasitism varies from area to area as does the percentage parasitism attributable to the two species.The gross growth efficiency for Hidryta from the first egg sac is 31.2% and from the second 16.2%. 3.0% in 1965 and 4.3% in 1966, of the annual yield from P. lugubris to predators and parasites, goes to the egg sac parasites. This represents reductions in recruitment of 9.1% in 1965 and 10.9% in 1966.