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1.
The thermal norms of egg development were studied in the ground beetles Amara communis, A. nitida, Carabus granulatus, Platynus assimilis, Poecilus versicolor, Pterostichus oblongopunctatus (spring breeding species), P. melanarius, and P. niger (autumn breeding species). The adults were collected in soil traps near Arkhangelsk, St. Petersburg, Moscow, and Bryansk in May–June. Females and males were kept in pairs at 20°C and 22 h light per day. The eggs laid by females were kept at constant temperatures (12, 14, 16, 18, 20, and 22 ± 0.1°C). The development time for each egg was determined accurate to 0.5 day. From the values of the individual development rate (a reciprocal of development time) at all the temperatures, the thermal constants for development were calculated: the coefficient of linear regression (CLR) of the development rate on temperature, the sum of degree-days, and the thermal threshold for development (TTD). The egg development time was found to vary significantly between the species, except for A. communis, A. nitida, and C. granulatus. The values of CLR (i.e., the slopes of the regression lines) and TTD varied rather distinctly between the species and populations that revealed differences in the thermal requirements for egg development. In the spring breeding species the mean egg development time was significantly shorter, and the CLR and TTD values were on average higher than those of the autumn breeding species. Intraspecific latitudinal variation of the development time and the thermal requirements for egg development was revealed. The eggs laid by beetles from the Arkhangelsk population developed faster than those of the same species from the southern populations at all experimental temperatures. These differences were not great but statistically significant. At the same time, the differences between the CLR and TTD values for the northern and southern populations of the same species were non-significant in most cases. Thus, the main ecophysiological adaptation of carabid beetles during their northward expansion was the shortening of development time within the entire range of favorable temperatures, while the CLR and TTD values only insignificantly changed.  相似文献   

2.
Development times of preimaginal stages and immature adult body mass of the dock leaf beetle Gastrophysa viridula from Bryansk (53°N, 34°E) were determined at six constant temperatures ranging from 16 to 26°C and at two photoperiods, 12L: 12D or 22L: 2D. The lower developmental threshold (LDT) and sum of degreedays (SDD) were calculated for eggs, larvae, and pupae; the values for the total preimaginal development were 7.9°C and 274.8 °C×d, respectively. The thermal reaction norms for preimaginal development were not affected by photoperiod, although the adult body mass was on average greater under short-day conditions. Our results confirm the previously published data on G. viridula concerning diapause induction by shorter daylengths, greater body mass under lower temperatures, and narrowing of the thermal optimum range during preimaginal development. The thermal reaction norms for larval development were shown to be the same in individuals that died during the pupal stage, and in those that successfully emerged as adults. Our results are more precise than the previous data on this species due to a larger sample size, careful control of rearing conditions, and the use of an alternative method for calculating LDT and SDD. In particular, a more accurate estimation of LDTs allowed us to demonstrate that rate isomorphy was violated in this species, contrary to what had been stated by Honěk and co-authors (2003).  相似文献   

3.
The study of sex ratio in larval populations in the urban mosquito Culex pipiens pipiens f. molestus inhabiting underground sites in St. Petersburg was carried out for the first time in 1997–2001, as part of monitoring of local populations of this mosquito in order to estimate its reproductive potential. Samples of the immature stages were regularly collected in the underground breeding places flooded with water with a varying degree of pollution in five city districts (altogether 27 samples, 14 251 larvae). Pupation was observed under laboratory conditions at 20°C for 6–46 days. The sex was determined at the pupal stage. In 19 samples collected in basements of dwelling houses the incidence of males widely varied from 40.2 to 65.6%, and the sex ratio (males: females), from 0.7: 1 to 1.9: 1. Medians defining the percentage of males in the populations in different basements during a certain period (from 3 to 11 months) were 57.5%, 47.0%, and 50.2%. The greatest incidence of males (the median being 62.2%) and sex ratio from 1.1: 1 to 3: 1 was observed in autumn in 1999–2001 in populations inhabiting the sewer pipe. Analysis of all the 27 samples showed that the males constituted on the average 54.5%, i.e., that is the sex ratio was close to the normal value of 1: 1. Such important population characteristics as normal sex ratio at the pupal stage and the high autogeny rate are indicative of high reproductive potential of the urban mosquito in St. Petersburg. The hydrotechnical (mostly drainage of basements) and special mosquito control measures are needed to decrease mosquito abundance and restrict their further dispersal within the city.  相似文献   

4.
Regulation of growth and development by photoperiod was studied in a population of the speckled wood butterfly, Purarge aegeria L. (Lepidoptera: Satyrinae), from southern Sweden. Individuals were reared in a range of photoperiodic regimes (9L. to 22L) and temperatures (13°C to 21° C). Plasticity was found for important life-history traits- generation time, growth rate and final weight and seasonal regulation of development in response to photoperiod was found to occur at two levels. Purarge aegeria hibernates as a third instar larva or in the pupal stage, cantering one of four major developmental pathways in response to photoperiod: (1) direct development in both the larval and pupal stages, (2) pupal winter diapause with or (3) without a preceding larval summer diapause, or (4) larval winter diapause. In addition to this high-level regulation of individual development, larval growth rate and pupal development rate also appear to be finally regulated by photoperiod within each major pathway. As photoperiods decreased from 22 h to 17 h at 17° C, growth rate among directly developing larvae increased progressively, as was the case for larva? developing according to a univoltine life cycle from 17 h to 14 h. At two photoperiods, 13 h and 16 h (corresponding to shifts between major pathways), both larval and pupal development were extremely variable with the fastest individuals developing directly and the slowest developing with a diapause. This indicates a gradual nature of diapause itself, suggesting that the two level may not he fundamentally different.  相似文献   

5.
Replicated lines of Drosophila melanogaster were allowed to evolve in population cage culture at 16.5° C or 25° C for five years. Their larval and pupal development times, larval growth rates, larval critical weights for pupariation and pre-adult survival rates were then measured at both temperatures. Pre-adult survival showed evidence of adaptation of the lines to their thermal selection regimes, with each set of lines showing superior survival when tested at the temperature at which they had been evolving. Pupal periods were similar for all lines when growing at 16.5° C but, at 25° C, the low temperature lines had the longer pupal periods. Irrespective of experimental temperature, low temperature lines grew faster and had shorter larval development periods than the high temperature lines. Larval critical weights for pupariation were higher in the low temperature lines at the low experimental temperature, and higher in the high temperature lines at the higher experimental temperature. The correlations between these traits induced by thermal evolution were in general different from or opposite to the genetic correlations found within a single temperature.  相似文献   

6.
Open field experiments with the blowfly, Calliphora vicina originating from the environs of St. Petersburg showed that the correlation between the rate of its preimaginal development under the natural conditions and the mean daily temperature could be very closely approximated by linear regression. The sum of effective temperatures required for development from the egg to the puparium constituted ca 140 degree-days and from the egg to the adult, ca 320 degree-days with the lower thresholds of 5.8 and 4.8°C, respectively. The minimum duration of development (6–8 days from the egg to the puparium and 16–20 days from the egg to the adult) was recorded during the period of the highest mean temperatures (22–23°C) from July 8 to August 15 of 2010 and 2011. The rate of development under natural thermorhythms was not siggnificantly different from that under the laboratory conditions at constant temperatures from 12 to 23°C.  相似文献   

7.
Temperature (25, 22, 16, and 12°C) and salinity (32–14‰) effects on the development of the low-boreal holothurianEupentacta fraudatrix were investigated. By studying the desalination resistance of adult holothurians,E. fraudatrix was shown to be a stenohaline species. The lower salinity limit at which both the larvae and adults survived was 22‰. Fertilization and development to the stage of free-swimming blastula occurred at the bottom. Embryogenesis, a critical stage of development, was successfully completed at a salinity of 32–26‰ and temperature of 22–16°C. The fertilization and development of a free-swimming blastula proved to be most resistant to temperature changes. The blastulae that developed at lowered temperatures (16–12°C) were capable of further development and settling at the same temperatures, which is likely associated with the peculiarities of the species range. If the early development proceeded at a higher temperature (22°C), the larvae failed to adapt to and perished from sharp temperature decreases at later stages of development. Thus, the lecithotrophic larva and a short period of larval development in the pelagial larvae (3–3.5 days from fertilization to settlement) ofE. fraudatrix are caused by the stenohalinity and environmental conditions of the species and, in turn, contribute to the fact that the young animals settle in the vicinity of their parents.  相似文献   

8.
The temperature tolerances of embryonic and early larval development stages of Tripneustes gratilla were investigated from 13-34°C under laboratory conditions. Zygotes showed unequal cleavage at 13°C, whereas cleavage did not occurred at 34°C. Hatching was observed between 16–31°C with maximum hatching rates observed at 22–29°C. The lower and higher temperature limits for embryonic development were approximately 22°C and 29°C, respectively. Outside of this temperature range, embryos showed abnormality at different incubation times. Early larvae of this species have the ability to survive the higher temperature limit for short periods of time. Prism and 2 arm pluteus larvae survived at temperatures between 30 and 33°C, whereas 4 arm pluteus larvae survived at temperatures between 30 and 36°C for 2 h. These results suggest that the larval temperature tolerance capability of T. gratilla is stage dependent. These findings are important for understanding the life history strategy of this sea urchin in the shallow open water environment.  相似文献   

9.
The combined effects of temperatures of 14, 17, 20, 22, and 25°C and salinities of 36–12‰ on embryos and larvae of the sand dollar Scaphechinus mirabilis was studied. Embryonic development is the most sensitive stage in the early ontogenesis of S. mirabilis. It is completed at a temperature of 14–20°C in a salinity range of 36–24‰ and at temperature of 22°C to 26‰. The fertilization proceeds in wider ranges of temperature and salinity. Among the swimming larvae, blastulae showed the greatest resistance to variations of these environmental factors. All the larvae survived at a temperature of 14–22°C and a salinity of 36–20‰, and more than 70% of them at 18‰. The pluteus I is the most vulnerable stage; probably this is related to the formation of the larval skeleton and transition to phytoplankton feeding. The survival of larvae at the age of 20 days was 100% at 14–22° C and a salinity of 36–24‰, most of them survived at 14–20°C and a salinity 18‰. The temperature 25 ° C is the most damaging for early development of S. mirabilis. The duration of development of that species lasts 28.5–29 days at 20°C and a salinity of 32.2–32.6‰. At 20 and 22°C, the larvae settled and completed metamorphosis more quickly if sand from the parental habitat was present. The larvae did not settle during the experiment (14 days) at 14 ° C and in the absence of sand.  相似文献   

10.
Rising sea temperatures may potentially affect the dispersive larval phase of sessile marine invertebrates with consequences for the viability of adult populations. This study demonstrated that the planktonic larvae of Rhopaloeides odorabile, a common Great Barrier Reef sponge, survived and metamorphosed when exposed to temperatures up to 9°C above the annual maximum (~29°C). Planktonic larval duration of 54 h, at ambient temperatures (~28°C), were reduced to 18 h for larvae exposed to elevated temperatures (32–36°C). Moreover, at ambient temperatures larvae began metamorphosing after 12 h, but at 32–36°C this reduced to only 2 h. Larvae survived and could still metamorphose at temperatures as high as 38°C, but were no longer functional at 40°C. These results imply that predicted increases in sea surface temperature may reduce planktonic larval duration and dispersal capabilities, thereby contributing to population subdivision of the species.  相似文献   

11.
At a time when global climate changes are forcing life to adapt to a warming and salinity-changing environment, it is essential to understand how future changes in ocean chemistry will affect species. This study evaluates the combined effects of temperature and salinity on survival and development of Upogebia pusilla larvae. Combinations were made from three temperatures (18, 23, and 28°C) and three salinities (15, 25, and 35). Survival, larval duration and megalopa size were compared between treatments. U. pusilla larvae developed optimally in the highest salinity (35) and higher temperatures (23–28°C). Low salinities and temperatures did not support larval survival and development, with salinity being the main restricting factor for survival, while temperature affected mainly the duration of the larval stages. Larvae at higher temperatures (23–28°C) presented a higher development rate but no differences were found in megalopa size.  相似文献   

12.
The problem of cryptic species in Diacyclops bicuspidatus was examined using interpopulation crosses of four populations collected from a: (1) permanent flood lake in Kiev, Ukraine, (2) temporary pool in Kiev, (3) permanent pond in St. Petersburg, Russia (1200 km to north from Kiev) and (4) lake in Crimea (1100 km south of Kiev). The only interpopulation crosses to exhibit fertility were those between the St. Petersburg population and each of the two Kiev populations. The crosses between the Kiev and Crimea populations, between the St. Petersburg and Crimea populations, and between the two Kiev populations were sterile, as evidenced by either nonviable eggs, empty egg membranes or incomplete copulations. The F1 hybrids resulting from the St. Petersburg permanent pond X Kiev flood lake cross were fertile and produced mature F2 offspring. Some data on development times of parental and hybrid lines are presented. The St. Petersburg parental line showed development times almost twice as long as those of the Kiev flood lake population when reared at 10 °C and 20 °C in the laboratory. The F1 offspring of the cross between St. Petersburg females and Kiev floodlake males showed similar development times to females of the St. Petersburg parental lines at both temperatures. The F2 hybrids also showed development times that approximated those of the St. Petersburg parental line. These crossbreeding studies suggest the presence of cryptic species in the D. bicuspidatus inhabiting ecologically different populations in many parts of its large holarctic range.  相似文献   

13.
This study investigated the effect of temperature on the development and overwintering capacity of the pupal parasitoid, Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae), a candidate classical biological control agent against leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae) in Canada. It was estimated that 256.4 day-degrees, above a lower threshold temperature of 7.3°C, were required for D. pulchellus to complete development, from egg to adult eclosion. Laboratory and field experiments on the immature and mature parasitoids indicated that D. pulchellus overwinters primarily, if not exclusively, in the adult stage. Only adults were able to survive an entire winter under natural outdoor conditions in central Europe. Immature parasitoids developing inside their pupal hosts were capable of withstanding short periods of temperatures as low as −5°C or −10°C, but even much higher temperatures were lethal if sustained for several weeks. Among adults, females demonstrated greater cold hardiness than males. The LTime50 at −12°C, simulating winter temperatures without snow cover, was 4–5 and 6–7 days for males and females, respectively. The LTime50 at −4°C, simulating winter temperatures beneath an insulating snow layer, was 1–2 and 2–3 weeks for males and females, respectively, with maximum survival of eight weeks. It is likely that survival would be even greater in a natural environment where the parasitoids could select optimal overwintering sites and have the option to feed when temperatures rise enough to permit activity. Based on these results, D. pulchellus is expected to survive winters in the targeted release areas of Ontario and Quebec.  相似文献   

14.
Biomass (CHN), respiration rate and food uptake were estimated for the larval development ofElminius modestus at three temperatures (12, 18, 24°C). Mean values of dry weight, elemental composition and energy equivalents increased exponentially with the development from nauplius II to VI. Dry weight, elemental composition and energy content exhibited the highest values at 18°C. Respiration rates increased with the larval stages expressed by a power function, but increased logarithmically with the dry weight of the larvae. The cypris larvae showed a reduced respiration rate compared with nauplius VI. The ingestion rate was measured at a concentration of 100 cells ofSkeletonema costatum μl−1. At 12 and 18°C ingestion rates increased exponentially and at 24°C by a logarithmic function. The fittings were used to estimate the energy budget ofE. modestus during larval development. The energy content of the larvae increased during the development from nauplius II to VI by a factor of 21 at 12°C, 25 at 24°C and 31 at 18°C. The estimated energy content of the freshly metamorphosed barnacle is 100 mJ (12°C), 130 mJ (24°C) and 150 mJ (18°C). The assimilation- (A/I) and gross growth efficiencies (K1) increased strongly during the development from nauplius II to VI (A/I: 6–14% in nauplius II to 50–90% in nauplius VI; K1: 4% in nauplius II to 75% in nauplius VI). The net growth efficiency (K2) showed a relatively constant level ranging between 57 and 83%.  相似文献   

15.
Eggs, larvae, pupae and adults of the large narcissus fly (Merodon equestris) were reared at a series of constant temperatures between 9–24°C. Egg development required from 37 days at 9°C to 7 days at 21.5°C. The low-temperature threshold for development was 6.7°C. Larvae reared at 1424°C were fully-grown after 18 weeks, but it took much longer for such insects to pupate, and adult flies emerged only after about 45 weeks of development. Large narcissus flies enter diapause during the larval stage and overwinter as fully-fed larvae, forming pupae in the following spring. Post-winter pupation and pupal development took from 169 days at 10°C to 36 days at 21.5°C. Of this, pupal development required from 91 days at 10°C to 19 days at 21.5°C. The low-temperature threshold for post-winter pupation and pupal development was 7.1°C, and for pupal development alone, 7.2°C. Females maintained at or below 19°C laid few eggs, whereas some females kept at or above 21.5°C laid more than 100 eggs (mean 69 ± 36). Approximately 50% of females maintained at or above 21.5°C laid less than 10 eggs during their lifetime. The mean egg-laying time was 6 to 9 days. Although temperatures at or below 19°C inhibited mating, once a female had mated, such temperatures did not prevent oviposition.  相似文献   

16.
The duration of Drosophila melanogaster larval and pupal periods was measured in laboratory thermal lines and in populations collected along a latitudinal transect in eastern Australia. In replicated laboratory lines kept for 9 years at 16.5° C or 25° C the duration of larval development had continued to diverge compared with 4 and 5 years previously, with more rapid larval development, and hence reduced total duration of pre-adult development, in the low temperature lines at both experimental temperatures. After 4 years of separate evolution, lines derived from the 25° C lines and subsequently cultured at 29° C showed no evidence of significant divergence in the duration of any part of the pre-adult period. The geographic populations showed a decrease in the duration of larval development, and hence of the total pre-adult period, with increasing latitude. In both laboratory and field populations, evolution at lower temperature was associated with more rapid larval development to a larger adult body size, the opposite genetic correlation between these traits to that found within a single temperature. The indications are that lower temperatures may be permissive of more efficient growth in D. melanogaster. It will be important to discover if evolution in response to temperature induces similar correlations in other ectotherms.  相似文献   

17.
Larvae of an estuarine grapsid crabChasmagnathus granulata Dana 1851, from temperate and subtropical regions of South America, were reared in seawater (32/%.) at five different constant temperatures (12, 15, 18, 21, 24 °C). Complete larval development from hatching (Zoea I) to metamorphosis (Crab I) occurred in a range from 15 to 24 °C. Highest survival (60% to the first juvenile stage) was observed at 18 °C, while all larvae reared at 12 °C died before metamorphosis. The duration of development (D) decreased with increasing temperature (T). This relationship is described for all larval stages as a power function (linear regressions after logarithmic transformation of bothD andT). The temperature-dependence of the instantaneous developmental rate (D −1) is compared among larval stages and temperatures using the Q10 coefficient (van't Hoff's equation). Through all four zoeal stages, this index tends to increase during development and to decrease with increasingT (comparing ranges 12–18, 15–21, 18–24 °C). In the Megalopa, low Q10 values were found in the range from 15 to 24 °C. In another series of experiments, larvae were reared at constant 18 °C, and their dry weight (W) and respiratory response to changes inT were measured in all successive stages during the intermoult period (stage C) of the moulting cycle. Both individual and weight-specific respiration (R, QO 2) increased exponentially with increasingT. At each temperature,R increased significantly during growth and development through successive larval stages. No significantly differentQO 2 values were found in the first three zoeal stages, while a significant decrease with increasingW occurred in the Zoea IV and Megalopa. As in the temperature-dependence ofD, the respiratory response to changes in temperature (Q10) depends on both the temperature range and the developmental stage, however, with different patterns. In the zoeal stages, the respiratory Q10 was minimum (1.7–2.2) at low temperatures (12–18 °C), but maximum (2.2–3.0) at 18–24 °C. The Megalopa, in contrast, showed a stronger metabolic response in the lower than in the upper temperature range (Q10=2.8 and 1.7, respectively). We interpret this pattern as an adaptation to a sequence of temperature conditions that should typically be encountered byC. granulata larvae during their ontogenetic migrations: hatching in and subsequent export from shallow estuarine lagoons, zoeal development in coastal marine waters, which are on average cooler, return in the Megalopa stage to warm lagoons. We thus propose that high metabolic sensitivity to changes in temperature may serve as a signal stimulating larval migration, so that the zoeae should tend to leave warm estuaries and lagoons, whereas the Megalopa should avoid remaining in the cooler marine waters and initiate its migration to wards shallow coastal lagoons.  相似文献   

18.
Isolates ofStypocaulon scoparium Kütz. were collected from the Gulf of St. Lawrence, Canada and compared in culture to isolates collected from the Atlantic and Mediterranean coasts of Europe. The Canadian isolates grew at temperatures ranging from −2° C up to 22° C, with maximum rates of growth at 10–15° C; in trials lasting 3 months they survived the lowest temperatures but died at 22 or 25° C. In contrast, for the European isolates, maximum growth occurred between 10 and 27° C, and they died only after several months at 30 or 33° C. At the low end of the temperature range, European plants suffered damage or died at 5° C. Only the northernmost isolate, from Brittany, could both survive at 0° C and remain undamaged at 5° C in short days. All European isolates died at −2° C. Geographic distributions and the different thermal responses suggest that the eastern and western Atlantic populations are two different entities, the European plants being possibly of Tethyan origin, and the Canadian plants being possibly of north Pacific origin. The former would then have occupied the north Atlantic for thelongest time, which may partly explain the occurrence of ecotypic variation among these isolates.  相似文献   

19.
20.
Field experiments conducted in the environs of St. Petersburg (Russia) with a local population of Calliphora vicina showed that induction of larval diapause under natural conditions was significantly dependent on day lengths and temperature. The maternal photoperiodic response had a distinct threshold: the first diapausing larvae hatched from the eggs laid in the middle of August when the day length was 16 h; at shorter photoperiods, the fraction of diapausing larvae depended only on temperature. At the mean temperature of 16°C, larval diapause was rarely recorded; at 12–13°C, about 50% of the larvae entered diapause; at 7–9°C, nearly all the larvae entered diapause. These results of the field experiments agree well with the parameters of photoperiodic and thermal responses studied in the laboratory at constant temperatures and photoperiods.  相似文献   

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