Egg Development Rates Research Articles

BIOLOGICAL VARIATION IN TWO ANOPHELES VESTITIPENNIS POPULATIONS WITH DIFFERENT FEEDING PREFERENCES IN SOUTHERN MEXICO

The lengths of gonotrophic cycle and egg development and survival rate were studied in Anopheles vestitipennis collected in horse and human-baited traps in southern Mexico. The gonotrophic cycle duration was estimated using cross-correlation analysis, whereas the survival rate was assessed using a vertical method. Daily changes of parity rates gave significant correlation indices at 3 and 4 days in the zoophilic and anthropophilic populations, respectively. The minimum time required to develop mature eggs after blood feeding was 54 and 60 h, and the survival rate was 0.93 and 0.88 in zoophilic and anthropophilic female mosquito populations, respectively. These biological differences provide additional support for the existence of subpopulations with distinctive feeding preferences within An. vestitipennis in southern Mexico.

Environmental effects on egg development and hatching success in Jordanella floridae, a species with parental care

Male flagfish Jordanella floridae provide parental care in the form of nest guarding, cleaning and fanning. Patterns of egg development, hatching success and disease in the absence of parental care across a range of physical environments that flagfish naturally experience were observed. Egg hatching success increased with salinity but was unaffected by temperature. Egg development rate, on the other hand, increased with temperature but was unaffected by salinity. Furthermore, disease (most likely fungus on the eggs) was the primary source of mortality. Thus, the results suggest that, in this species, parental care of the eggs can only significantly increase offspring fitness by reducing disease and that the value of care will overall be reduced in saline environments because eggs hatch readily there, in the absence of care.

Temperature-dependent development rates of plaice (Pleuronectes platessa L.) eggs from the Irish Sea

Experimentally derived temperature-dependent development rates for planktonic fish eggs are required for developing Individual Based Models (IBMs) of early life history stages and for estimating daily egg production in ichthyoplankton surveys. Development rates of Irish Sea plaice eggs were experimentally determined for temperatures between 4.5 and 12° C. Differences in development rates were apparent when these results were compared with literature data for eggs from North Sea parents. On average, plaice eggs from the Irish Sea developed more rapidly and hatched up to 2 days earlier compared with North Sea eggs incubated at the same temperature. In terms of parental effects, larger females tended to produce larger eggs but egg size decreased over successive batches from the same female within a year. Temperature-dependent egg development rates were influenced by egg size in a non-linear manner for eggs incubated at 6° C, but egg size had no effect at higher temperatures. Since most plaice eggs sampled from the Irish Sea during ichthyoplankton surveys in 1995 and 2000 were found in waters cooler than 8° C, such effects may modify egg development rates in the wild.

Comparison of reproductive capacity among univoltine, semivoltine, and re-emerged parent spruce beetles (Coleoptera: Scolytidae)

AbstractNew spruce beetle, Dendroctonus rufipennis (Kirby), adults of univoltine and semivoltine life cycles, as well as re-emerged parent beetles, were laboratory-tested for differences in reproductive capacity and brood characteristics. Parameters measured from the three groups include dry weight, lipid content, and egg production. Brood characteristics measured include egg length, development rates, and survival densities. Although there were some differences in dry weight and lipid content, females from the univoltine, semivoltine, and re-emerged parent groups did not greatly differ in egg production. Egg length was slightly smaller for eggs from univoltine parents, but other measured brood characteristics did not differ among the three parent groups, including the density of the surviving brood. In a field study, re-emerged parent beetles were determined to be flight capable. These findings imply that populations with univoltine broods will have higher growth rates than semivoltine populations. Consequently, the presence of univoltine broods, which is weather dependent, increases the risk of a beetle outbreak or can accelerate the rate of spruce mortality in an established outbreak. These results also indicate that re-emerged parent beetles can contribute substantially to brood production. Suppression strategies can be more effective if managers consider the ecological consequences of brood production from the three parent groups.

The combined effects of temperature and diet on development and survival of a crab spider , Misumenops tricuspidatus (Fabricius) (Araneae: Thomisidae)

In the present study, the combined effects of temperature and diet on development and survival of a crab spider, Misumenops tricuspidatus (Fabricius) (Araneae: Thomisidae) in laboratory conditions were investigated. The experiments were carried out at five constant temperatures ranging from 15°C to 35°C on two kinds of diets, fruit flies ( Drosophila melanogaster) and a mixed diet of fruit flies and dung flies. It was found that development rate of eggs increased with successive temperature increments, reaching a maximum at 30°C, then declined at 32°C and that eggs survived well between 20°C and 30°C (>70%), but no eggs survived to hatching at 35°C regardless of whether the spiders were fed on single or mixed diet. Juveniles completed development on both diets at all constant temperatures tested, but survival was low at the extreme temperatures. Juvenile development times decreased over successive temperature increments up to 30°C, then increased at 32°C. Females developed faster than males. Diet also influenced development time, survival and number of moults to reach maturity. Juveniles raised on the mixed diet composed of fruit flies and dung flies developed faster, survived better, and required fewer moults to reach maturity than on a diet composed of only fruit flies. Plots of development rates (reciprocal of mean development times) and survival rates (expressed as percentages) against constant temperatures indicated that M. tricuspidatus is well adapted to low temperatures, but detrimentally affected by high temperatures. Using linear regression, the lower development threshold (LDT) and the sum of effective temperatures (SET) for all life stages of M. tricuspidatus on each diet were estimated. LDT and SET varied among developmental stages and between diets.

A new ageing method for eggs of fish species with daily spawning synchronicity

A new method for ageing staged eggs of fish is presented. The method is intended for species that show spawning synchronicity and for which the egg phase can be classified into development stages, each of which lasts less than a day, such as sardines and anchovies. It combines biological information on the daily frequency of spawning and egg development rates, via a probabilistic resampling method. A general methodology that allows the use of models of daily spawning frequency and egg development as a function of temperature is provided and applied to sardine egg data from three surveys in northern Spain. Unlike previous ageing methods, the proposed method allows for the variability of egg ages in a way that reflects the extent of the assumed daily spawning period, and estimates of the uncertainty in the stage-to-age conversion can be obtained. These estimates of uncertainty can be incorporated into subsequent analyses that involve age as a covariate, such as in the daily egg production method (DEPM), thus allowing more reliable estimates of the variance of egg production.

A simulation model for environmental population densities, survival rates and prevalence of Boophilus decoloratus (Acari: ixodidae) using remotely sensed environmental information

A simulation model for the African tick Boophilus decoloratus is presented. This model is based on the use of a dynamic life table that is driven by abiotic variables (temperature and vegetation status) remotely sensed (AVHRR sensor of the NOAA series of satellites) over time. The model incorporates temperature-dependent rates of egg production and development, climate-driven density-independent mortality rates, and density-dependent regulation of on-host stages. The model successfully describes both the seasonality and annual variation in the numbers of questing larvae and engorging females observed in eight sites throughout sub-Saharan Africa. Climate data from 1983 to 1999 in 10-day intervals are used as the basic input for modelling the dynamic patterns of activity at four different sites in Africa and to understand how abiotic factors can modulate the long-term life cycle of B. decoloratus.

Experimental evidence for a demographic cline in Panstrongylus megistus populations.

The population biology of three populations of Panstrongylus megistus was compared to determine possible influence on the behaviour and epidemiological importance of this species. The results demonstrated differences in terms of egg eclosion time, nymphal mortality and development rates, and feeding and defaecation rates. These differences appeared to follow a geographical cline, primarily reflecting different degrees of adaptation to domestic habitats.

Effects of temperature on the development and fecundity of Diaperasticus erythrocephala Olivier (Dermaptera: Forficulidae)

The developmental, oviposition, and mortality rates for the polyphagous earwig Diaperasticus eryihrocephala Olivier feeding on pollen and Ephestia kuehniella Zeller eggs were measured at constant temperatures of 18, 25 and 32 °C. The developmental period for D. erythrocephala required 533 degree-days (DD) above a threshold of 6.7 °C. Egg and larval development rates increased with increasing temperature, with the shortest developmental period being recorded at 32 °C. However, egg and larval mortality and larval malformation rates were significantly higher at 32 than at 25 and 18 °C. Over a period of 60 days, females laid an average of 26.5 eggs at 25 °C and none at 18 °C. Based on the results obtained, it is concluded that of the three temperatures, 25 °C is the most suitable for the laboratory mass rearing of D. erythrocephala.

Interaction of photoperiod and temperature in the regulation of prediapause development in the spotted tentiform leafminer (Lepidoptera: Gracillariidae)

The spotted tentiform leafminer, Phyllonorycter blancardella (F.), overwinters in a photoperiodically induced state of pupal diapause. The critical day length (50% of leafminers enter diapause) for P. blancardella from latitudes of about 42–44°N in southwestern Ontario was 14.25 h at an average August temperature (Environment Canada 1993) of 20°C (Trimble 1994). The development time of actively growing larvae decreased with increased temperature, whereas the development time of diapause-destined larvae was not affected by temperature at the critical day length, suggesting a strong interaction between photoperiod and temperature in the regulation of prediapause development (Trimble 1994). This paper describes the interaction of photoperiod and temperature in the regulation of the rate of egg and larval development of diapausedestined leafminers in the laboratory and in semi-natural conditions.

Duration times of the immature stages of Cacopsylla pyri L. (Hom., Psyllidae), estimated under field conditions, and their relationship to ambient temperature

The duration of the immature stages of Cacopsylla pyri L. was studied under field conditions by artificially infesting pear branches on several dates during the year. The duration of the egg stage decreased from winter to summer, as the season progresses and temperature rises, and slightly increased in September. It ranged from 27.4 to 6.7 days. The same trend was observed in the duration of the first three larval stages (L1−3) which ranged from 18.8 to 10.3 days. For eggs deposited during the period February–August the duration of the last two larval stages (L4−5) ranged from 17.5 to 12.1 days. However, the duration of L4−5 developed from eggs deposited in September and which give rise to winter‐form adults were the longest observed. The rate of egg development was related to average ambient temperature with a highly significant linear relationship. This relationship indicates that the egg stage requires a constant number of 158.9 (SD = 5.0) of day‐degrees above an average temperature of 2.31°C to complete development. The rate of development both of L1−3 and L4−5 were related to average ambient temperature with curvilinear relationships. These relationships indicate a proportional increase in the developmental rate as temperature rises between 10–22°C. At the higher average temperatures that occurred in the summer experiments (24–27°C) the acceleration of development of L1−3 is reduced and the developmental rate of L4−5 decreases. The developmental rates of L4−5 developed from eggs deposited in September did not follow the established relationship with temperature and they were lower than those in the other periods of the year with the same average temperature.

Ascaris suum: seasonal egg development rates in a Saskatchewan pig barn

This study investigated the effects of seasonal temperature variations on the rate of development to infectivity of Ascaris suum eggs under western Canadian climatic conditions. Flasks containing a suspension of A. suum eggs were placed inside a pig barn located near Saskatoon, Saskatchewan, Canada, at monthly intervals from July 1997 to July 1998. Eggs from each flask were monitored weekly for development to the infective larval stage. Infectivity of eggs was confirmed using a mouse bioassay. Development to the infective stage took three to four weeks in summer when in-barn temperatures were similar to the external ambient temperature. Fall, winter and early spring egg development took longer as in-barn temperatures were cooler. Mid-winter egg development took as long as 11–12 weeks. The in-barn mean temperature during this period was approximately 17°C, close to the development threshold of A. suum eggs. These data are discussed in relation to similar studies from northern Europe and to potential control measures.

Interaction of rearing temperature and maternal influence on egg development rates and larval size at hatch in yellowtail flounder (Pleuronectes ferrugineus)

We assessed the extent to which temperature interacts with maternal contributions to egg size to affect development time and size of yellowtail flounder (Pleuronectes ferrugineus) larvae at hatch. Maternal effects contributed significantly to differences in egg sizes produced by four females. Eggs from each female were incubated at five temperatures. Development time was most significantly affected by temperature, and female effects were minimal. However, the variance in development time within a population was significantly affected by an interaction between female and temperature effects. Average length at hatch varied significantly among temperatures and females, as did the variance in hatching length within a population. Variance in hatching length explained by maternal effects peaked at intermediate temperatures (~38% explained variance at 7°C), while variance explained by covariation with development time increased linearly with temperature, explaining ~40% variance at 13°C. Overall, the nonadditive interaction between maternal contributions and the environment suggests that female effects must be considered over the entire range of environmental conditions experienced by their progeny. In addition, our results support the idea that it is inappropriate to quantify female effects among eggs and extrapolate these differences to larvae.

Interaction of rearing temperature and maternal influence on egg development rates and larval size at hatch in yellowtail flounder (<i>Pleuronectes ferrugineus</i>)

Interaction of rearing temperature and maternal influence on egg development rates and larval size at hatch in yellowtail flounder (<i>Pleuronectes ferrugineus</i>)

Embryo development and reproductive cycle in the snow crab, Chionoecetes opilio (Crustacea: Majidae), in the southern Gulf of St. Lawrence, Canada

Embryonic stages and egg-incubation durations were compared between female snow crabs, Chionoecetes opilio, in captivity and from the wild. In the southern Gulf of St. Lawrence the incubation time is 24-27 months. There are two prolonged periods of embryo development: (1) stages 3 and 4 (cleavage and blastula, gastrula) last for at least 6 months between May and January following egg extrusion, and (2) stages 11 and 12 (eye-pigment formation, chromatophore formation) last for 3-4 months between October and January of the following year. Water temperature plays an important role in determining the egg-development rate. Embryo development takes 12-13.5 months (365-410 days) when females are kept at a higher temperature (1.8-3.8°C) than that of the normal habitat (-1 to +1°C). Ovigerous females usually inhabit depths of 40-100 m, which is the cold intermediate water in the southern Gulf of St. Lawrence (year-round temperature and salinity -1 to +1°C and 32-33‰, respectively). However, ovigerous females are also observed at depths of 100-300 m in the Laurentian Channel, where the year-round water temperature is 3-5°C. For ovigerous females that do not migrate to the deeper, warmer waters, the duration of embryo development is 2 years, whereas females that inhabit deeper waters develop their embryos over a 1-year cycle. The reproductive potential and abundance of females with 1- and 2-year embryo-development cycles in the southern Gulf of St. Lawrence are unknown.

Egg size, fecundity, and development rate of two introduced New Zealand chinook salmon (Oncorhynchus tshawytscha) populations

Interpopulation differences in several adult phenotypic traits suggest that New Zealand (NZ) chinook salmon (Oncorhynchus tshawytscha) are evolving into distinct populations. To further investigate this hypothesis, we compared egg sizes, fecundities, and early development rates of chinook from two NZ streams. The two NZ study populations differed in size-adjusted egg weight and gonadosomatic index, but not in size-adjusted fecundity. Egg weight, fecundity, and gonadosomatic index values for both NZ populations were different than values for chinook from Battle Creek, California, the population regarded as the ancestral NZ stock. In contrast, there was little evidence of divergence in juvenile development. Time to hatching did not differ between the two NZ study populations and heritability estimates were small with large standard errors. Evidence of a small difference in alevin growth rate may have represented an effect of yolk conversion mechanics related to egg size. Despite the similarity in development rates under shared conditions, modeling based on temperature records suggests that emergence dates in the two NZ streams may differ by 4-6 weeks, yielding significant phenotypic differences.

Life-history parameters of different biotypes ofBemisia tabaci(Hemiptera: Aleyrodidae) in relation to temperature and host plant: a selective review

AbstractLife-history parameters of different biotypes of the whiteflyBemisia tabaci(Gennadius) species complex were reviewed. This included the B-biotype ofB. tabaci, identified asB. argentifolii(Bellows & Perring). Comparisons were made among different biotypes on cotton, among host plants for biotype B and among the whitefly speciesB. tabaciandTrialeurodes vaporariorum(Westwood), the greenhouse whitefly. The biotype identification of different populations ofB. tabaciwas summarized in a table. Biotypes discussed were A, B, Indian and biotypes of the Old World group. Temperature dependent relationships were estimated for egg development rate, development rate from egg to adult, immature mortality, adult longevity, sex-ratio, pre-oviposition period and fecundity. The fitted curves will be used as input for a simulation model of the population dynamics ofB. tabaciin a greenhouse when parasitoids are released. The model makes it possible to evaluate the integrated effect of different life-history parameters and behavioural parameters of parasitoids on whitefly population levels in a greenhouse.

Egg size, fecundity, and development rate of two introduced New Zealand chinook salmon (<i>Oncorhynchus tshawytscha</i>) populations

Egg size, fecundity, and development rate of two introduced New Zealand chinook salmon (<i>Oncorhynchus tshawytscha</i>) populations

Direct positive effect of invertebrate predators on birth rate in Daphnia studied with a new method of birth rate analysis

Three natural Daphnia populations in which the previously established impact of invertebrate predators on the death rate (but not on the birth rate) were investigated. Two other cladoceran populations primarily affected by food were used for comparison. The effect of predators on the per capita birth rate of Daphnia was detected by decomposing changes in birth rate into components dependent on changes in egg development rate, mean clutch size, and proportion of adults and then comparing them. This method revealed short‐term changes in the proportion of adults, which dominated changes in birth rate. The effect can be attributed to size‐selective feeding of the invertebrate planktivores that normally prey on young daphnids, and it did not occur in food‐dependent cladocerans. Invertebrate predation pressure tends to increase the per capita birth rate of Daphnia, which may provide a mechanism that stabilizes prey.

Factors affectingLocusta migratoria migratorioidesegg development and survival in the Lake Chad basin outbreak area

Abstract Environmental factors affecting egg development and survival in Locusta migratoria migratorioides (Reiche and Farimaire) (Orthoptera: Acrididae) were examined for four seasons in three soil habitats in the Chad basin outbreak area. During the early rainy season eggs survived in sandy habitats only; the survival rate was 29.2%. The fastest rate of egg development occurred in this season, as indicated by an incubation period of 9.5 days, which coincided with the highest air temperature (29.8–36–2°C) in the area. The lowest development rate occurred during the harmattan when incubation lasted 24 days in clay, the only suitable soil for egg survival (11.4%) during the season. The slow rate of development coincided with the lowest air temperatures, which ranged from 19.2 to 25.6°C. During the main rainy season eggs survived in all the three habitats and the development rates were intermediate to those in the two seasons already mentioned. Incubation lasted 13.6 days in sand, 16.0 days in sandy‐clay lo...