Effective Cumulative Temperature Research Articles

Thermal adaptations of embryos of six terrestrial hermit crab species

We evaluated the thermal adaptations of embryos of 6 terrestrial hermit crab species in the family Coenobitidae (genera Birgus and Coenobita): B. latro, C. brevimanus, C. cavipes, C. purpureus, C. rugosus, and C. violascens. Embryos of each species were cultured in vitro at 6 dif- ferent temperatures (18 to 34°C) in artificial seawater to avoid air desiccation; the lower threshold temperatures for embryonic development were estimated using heat summation theory equa- tions. Additionally, partial effective cumulative temperatures (> lower threshold temperature) until hatching were determined for ovigerous females of each species cultured in containers. The relationships between the embryonic growth index values (relative area of the embryonic body vs. total embryo surface) and effective cumulative temperatures were expressed using cubic equa- tions. Lower threshold temperature was estimated to be 12.7 to 14.5°C. The effective cumulative temperature and egg incubation period estimates from the appearance of the embryonic body to hatching were higher in B. latro and C. brevimanus, followed by C. rugosus, C. cavipes, and C. violascens, and lower in C. purpureus, suggesting that C. brevimanus may retain an ancestral thermal adaptation trait for embryos, as in B. latro, which is considered the most ancestral species in the coenobitid phylogeny. Egg size varied among species but did not affect the thermal adap- tations of embryos. The lower effective cumulative temperature and shorter egg incubation period may be advantageous to producing broods during the shorter summer breeding season in C. pur- pureus, which has the northern-most geographical distribution.

有効積算温度によるチャトゲコナジラミ成虫の発生ピーク日予測と年間発生世代数の推定

有効積算温度によるチャトゲコナジラミ成虫の発生ピーク日予測と年間発生世代数の推定

Simulating low and high streamflow driven by snowmelt in an insufficiently gauged alpine basin

Snowmelt and water infiltration are two important processes of the hydrological cycle in alpine basins where snowmelt water is a main contributor of streamflow. In insufficiently gauged basins, hydrologic modeling is a useful approach to understand the runoff formation process and to simulate streamflow. In this study, an existing hydrologic model based on the principles of system dynamics was modified by using the effective cumulative temperature (>0 °C) to calculate snowmelt rate, and the soil temperature to adjust the influence of the soil’s physical state on water infiltration. This modified model was used to simulate streamflows in the Kaidu River basin from 1982 to 2002, including normal, high, and low flows categorized by the Z index. Sensitivity analyses, visual inspection, and statistical measures were employed to evaluate the capability of the model to simulate various components of the streamflow. Results showed that the modified model was robust, and able to simulate the three categories of flows well. The model’s ability to reproduce streamflow in low-flow and normal-flow years was better than that in high-flow years. The model was also able to simulate the baseflow. Further, its ability to simulate spring-peak flow was much better than its ability to simulate the summer-peak flow. This study could provide useful information for water managers in determining water allocations as well as in managing water resources.

性フェロモンと有効積算温度を利用したカキのフジコナカイガラムシ（カメムシ目：コナカイガラ科）幼虫の発生時期予測

We investigated the possibility of predicting the emergence of first-generation young nymphs of the mealybug Planococcus kraunhiae (Kuwana) by using effective cumulative temperature, with peak sex pheromone trap captures as a base point. Seasonal yearly fluctuations in the number of sex pheromone trap captures in four persimmon fields in Japan (Shimane, Hiroshima, Gifu, and Fukuoka prefectures) indicated that Japanese mealybugs produce three to four generations in a year. The event of the first pheromone trap captures of wild mealybugs in the present study matched with those in our previous rearing experiments in Shimane Prefecture in 2007 and 2008 using male overwintering-generation nymphs raised in a ventilated case with a meteorological gauge (Stevenson screen). The actual timing of the first-generation nymph capture using band traps matched the estimated emergence time of the first-generation nymphs, which was calculated from the cumulative effective temperature starting from the pheromone trap capture time for the over-wintering adult male bugs. Therefore, setting pheromone trap capturing peak as a base point, prediction of occurrence of first-generation mealybug nymphs is considered possible, utilizing the effective cumulative temperature for persimmon.

Effect of temperature on life table parameters of Leptocybe invasa (Hymenoptera: Eulophidae)

AbstractLeptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) first described in 2004, is a new eucalyptus pest of global importance. A thorough understanding of pest biology is essential for development of a reliable pest population prediction system and management strategies, but little is known about this pest. Therefore, we quantified the development, fecundity, fertility, longevity, morphometrics (length, width, and hind tibia length of adults), and other life table parameters of L. invasa in relation to temperature and to provide an experimental basis for developing an overall wasp population model. The results showed that ranging from 20 to 32°C (five constant temperatures were 20, 23, 26, 29 and 32°C, respectively), the developmental period of immatures (egg to adult) was shortest at 29°C but longest at 20°C; the number of eggs per female in the oviduct and survival rate of immatures were greatest at 29°C but smallest at 32°C. The effect of temperature on morphometrics was more pronounced for females than males. When L. invasa was fed with a 40% honey solution, maximum longevity was at 23°C (9.0 days for females and 12.8 days for males). The intrinsic rate of natural increase (rm) was largest (0.0477) at 29°C, and the sex ratio of L. invasa was extremely female‐biased. The intrinsic rate of natural increase (rm) indicates that L. invasa population growth is likely to be greatest at 29°C. The developmental zero temperature (t) and the effective cumulative temperature (k) of egg, larva and pupa were 13.0, 19.7 and 17.1°C, and 128.1, 284.2 and 201.2°C, respectively. For L. invasa, 19.1°C (t) and 563.5°C (k) were indispensable for completing development from egg to adult. Therefore, farmers or managers of forests could predict the population dynamics of the wasp and adopt physical or chemical methods to control it according to the temperature.

The Relation between the Growth before Wintering and the Effective Cumulative Temperature after Seeding in the Winter Wheat Cultivar “Kitahonami”

The Relation between the Growth before Wintering and the Effective Cumulative Temperature after Seeding in the Winter Wheat Cultivar “Kitahonami”

Poaceae pollen in the air depending on the thermal conditions.

The relationship between the meteorological elements, especially the thermal conditions and the Poaceae pollen appearance in the air, were analysed as a basis to construct a useful model predicting the grass season start. Poaceae pollen concentrations were monitored in 1991–2012 in Kraków using the volumetric method. Cumulative temperature and effective cumulative temperature significantly influenced the season start in this period. The strongest correlation was seen as the sum of mean daily temperature amplitudes from April 1 to April 14, with mean daily temperature >15 °C and effective cumulative temperature >3 °C during that period. The proposed model, based on multiple regression, explained 57 % of variation of the Poaceae season starts in 1991–2010. When cumulative mean daily temperature increased by 10 °C, the season start was accelerated by 1 day. The input of the interaction between these two independent variables into the factor regression model caused the increase in goodness of model fitting. In 2011 the season started 5 days earlier in comparison with the predicted value, while in 2012 the season start was observed 2 days later compared to the predicted day. Depending on the value of mean daily temperature from March 18th to the 31st and the sum of mean daily temperature amplitudes from April 1st to the 14th, the grass pollen seasons were divided into five groups referring to the time of season start occurrence, whereby the early and moderate season starts were the most frequent in the studied period and they were especially related to mean daily temperature in the second half of March.

Life history traits and damage potential of an invasive pest Brontispa longissima (Coleoptera: Chrysomelidae) on Satakentia liukiuensis

AbstractThe coconut hispine beetle Brontispa longissima has been causing serious damage to the coconut palm Cocos nucifera in the Pacific, and Southeast and East Asia. This beetle also attacks Satakentia liukiuensis, an endemic palm on Ishigaki and Iriomote Islands, Japan. To assess the potential impact of B. longissima on S. liukiuensis, we examined the development period, survival rate, egg production and body size of B. longissima on S. liukiuensis at 22–31°C and consumption of S. liukiuensis leaf at 28°C. We also examined these life history traits on C. nucifera at 28°C to compare with those on S. liukiuensis. Brontispa longissima completed their development and reproduced on S. liukiuensis at 22–30°C. Linear regression analysis was used to estimate the effective cumulative temperature (k) as 891.2 degree‐days, and the lower developmental threshold as 13.3°C. On the basis of these values and monthly average temperatures on Ishigaki Island, it was estimated that B. longissima has four generations per year on the island. Satakentia liukiuensis was less suitable for B. longissima than C. nucifera in terms of immature survival, development time, resultant adult size and reproduction. The low quality of S. liukiuensis as a host‐plant may prevent the outbreak of B. longissima, which has not occurred yet on Ishigaki and Iriomote Islands.

Multivariate analysis of nitrogen content for rice at the heading stage using reflectance of airborne hyperspectral remote sensing

Airborne hyperspectral remote sensing was adapted to establish a general-purpose model for quantifying nitrogen content of rice plants at the heading stage using three years of data. There was a difference in dry mass and nitrogen concentration due to the difference in the accumulated daily radiation (ADR) and effective cumulative temperature (ECT). Because of these environmental differences, there was also a significant difference in nitrogen content among the three years. In the multiple linear regression (MLR) analysis, the accuracy (coefficient of determination: R 2, root mean square of error: RMSE and relative error: RE) of two-year models was better than that of single-year models as shown by R 2 ≥ 0.693, RMSE ≤ 1.405 g m −2 and RE ≤ 9.136%. The accuracy of the three-year model was R 2 = 0.893, RMSE = 1.092 g m −2 and RE = 8.550% with eight variables. When each model was verified using the other data, the range of RE for two-year models was similar or increased compared with that for single-year models. In the partial least square regression (PLSR) model for the validation, the accuracy of two-year models was also better than that of single-year models as R 2 ≥ 0.699, RMSE ≤ 1.611 g m −2 and RE ≤ 13.36%. The accuracy of the three-year model was R 2 = 0.837, RMSE = 1.401 g m −2 and RE = 11.23% with four latent variables. When each model was verified, the range of RE for two-year models was similar or decreased compared with that for single-year models. The similarities and differences of loading weights for each latent variable depending on hyperspectral reflectance might have affected the regression coefficients and the accuracy of each prediction model. The accuracy of the single-year MLR models was better than that of the single-year PLSR models. However, accuracy of the multi-year PLSR models was better than that of the multi-year MLR models. Therefore, PLSR model might be more suitable than MLR model to predict the nitrogen contents at the heading stage using the hyperspectral reflectance because PLSR models have more sensitive than MLR models for the inhomogeneous results. Although there were differences in the environmental variables (ADR and ECT), it is possible to establish a general-purpose prediction model for nitrogen content at the heading stage using airborne hyperspectral remote sensing.

Spatial distribution and temporal variation of the winter wheat late frost disaster in Henan, China

The winter wheat late frost disaster (WFD) occurs mainly in the Yellow and Huaihe River area, of which Henan Province covers the most part. Henan is the major area of wheat production in China, but it is severely hit by the WFD. In this study, we construct a WFD index based on the minimum temperature and the winter wheat development period (WDP). The WFD degrees and days at 30 agrometeorological stations in Henan Province during the period of 1981–2004 are calculated. For the large-scale temporal variation analysis of WFD, the 24-yr WDP observation series is relatively short, so it is expanded by using the relation between the turning green date of winter wheat and the 5-day running mean temperature and that between the stem elongation phase and the effective cumulative temperature above a critical value of 2.5°C. The WFD data are also expanded for the last 50 years and are analyzed by using the empirical orthogonal function (EOF) and the Morlet wavelet methods. Characteristics in the spatial distribution and temporal variation of WFD are revealed. The results show that the frequency of WFD is generally high, exceeding 40% in parts of Henan, and exhibits a rising trend in the period of 1970–1990. The variation trend of WFD degrees is similar to that of WFD days, and the areas with higher WFD degrees coincide the areas with more WFD days. Moreover, the WFD degree has a greater impact on the winter wheat yield than the WFD days. The areas with high WFD degrees lie in the southeast and southwest of Henan, and the areas with low WFD degrees lie in the south of the Huaihe River and parts of western Henan. Temporal variations of the first and second EOF modes of the WFD degree display 16- and quasi-22-yr periodicities, respectively. The areas of high (low) WFD frequency are distributed in the northern Henan and the southwest border of Henan (the northeast Henan and the middle part of southwest Henan). The temporal variation of the first (second) EOF mode of WFD days exhibits a periodicity (periodicities) of quasi-4 yr (quasi-3 and quasi-6-7 yr).

큰이십팔점박이무당벌레(Henosepilachna vigintioctomaculata (Motschulsky))의 생태적 특성 및 강릉지역 발생소장

큰이십팔점박이무당벌레(Henosepilachna vigintioctomaculata (Motschulsky))의 강릉지역 발생소장과 발육단계별 감자잎 섭식량 및 온도별(10, 15, 20, 25, <TEX>$30^{\circ}C$</TEX>) 발육소요기간을 조사하였다. 큰이십팔점박이무당벌레는 연 3회, 즉 5월 하순, 6월 하순 및 8월 하순에 발생하였으며, 특히 5월 하순부터 7월 중순까지 높은 밀도로 발생하여 감자 식물체를 집중적으로 가해하였다. 발육단계별 감자잎 섭식량은 유충의 영기가 진전될수록 많았으며, 4령 유충기에 가장 많은 섭식량을 보였다. 큰이십팔점박이무당벌레 부화율과 우화율은 각각 <TEX>$10^{\circ}C$</TEX> 및 <TEX>$30^{\circ}C$</TEX>에서는 매우 낮았고 <TEX>$20{\sim}23^{\circ}C$</TEX>에서 가장 높았다. 알에서 성충으로 우화되기까지 발육단계별 생육기간은 온도가 증가함에 따라 감소하였는데, <TEX>$10^{\circ}C$</TEX>에서 90일 정도로 매우 느렸으며 <TEX>$20^{\circ}C$</TEX>에서는 40여일, <TEX>$25^{\circ}C$</TEX>에서는 25일이 소요되었다. 또한 발육영점온도와 유효적산온도는 알에 대해서 <TEX>$7.3^{\circ}C$</TEX>와 83.3 DD, 유충에 대해서 <TEX>$5.2^{\circ}C$</TEX>와 294.1 DD, 번데기에 대해서 <TEX>$6.2^{\circ}C$</TEX>와 97.1 DD이었다. The seasonal fluctuation of the large 28-spotted lady beetle, Henosepilachna vigintioctomaculata (Motschulsky), was observed in potato fields of Gangneung region, Gangwondo Province. The effects of their leaf consumption over a 24 hour period and developmental periods by different temperatures were investigated, and then the developmental threshold (DT) and effective cumulative temperature (ET) of each stage were calculated. Various developmental stages of H. vigintioctomaculata were captured in the fields from May to September, with three peaks in late May, late June, and late August. Leaf consumption by larval stages increased with the development of instar. The 4th instar larvae consumed potato leaves much more than other stages. Egg hatchability and emergence rate of H. vigintioctomaculata were lower at <TEX>$10^{\circ}C$</TEX> and <TEX>$30^{\circ}C$</TEX>, but higher at around <TEX>$20{\sim}23^{\circ}C$</TEX>. The developmental periods of each stage became shorter as temperature increased; 90 days at <TEX>$10^{\circ}C$</TEX>, 40 days at <TEX>$20^{\circ}C$</TEX> and 25 days at <TEX>$25^{\circ}C$</TEX>. Base on developmental velocity to temperature, calculated DT and ET were <TEX>$7.3^{\circ}C$</TEX> and 83.

Integrating remote sensing and GIS for prediction of rice protein contents

In this study, protein content (PC) of brown rice before harvest was established by remote sensing (RS) and analyzed to select the key management factors that cause variation of PC using a GIS database. The possibility of finding out the key management factors using GreenNDVI was tested by combining RS and a GIS database. The study site was located at Yagi basin (Japan) and PC for seven districts (85 fields) in 2006 and nine districts (73 fields) in 2007 was investigated by a rice grain taste analyzer. There was spatial variability between districts and temporal variability within the same fields. PC was predicted by the average of GreenNDVI at sampling points (Point GreenNDVI) and in the field (Field GreenNDVI). The accuracy of the Point GreenNDVI model (r 2 > 0.424, RMSE < 0.256%) was better than for the Field GreenNDVI model (r 2 > 0.250, RMSE < 0.298%). A general-purpose model (r 2 = 0.392, RMSE = 0.255%) was established using 2 years data. In the GIS database, PC was separated into two parts to compare the difference in PC between the upper (mean + 0.5SD) and lower (mean − 0.5SD) parts. Differences in PC were significant depending on the effective cumulative temperature (ECT) from transplanting to harvest (Factor 4) in 2007 but not in 2006. Because of the difference in ECT depending on vegetation term (from transplanting to sampling), PC was separated into two groups based on the mean value of ECT as the upper (UMECT) and lower (LMECT) groups. In 2007, there were significant differences in PC at LMECT group between upper and lower parts depending on the ECT from transplanting to last top-dressing (Factor 2), the amount of nitrogen fertilizer at top-dressing (Factor 3) and Factor 4. When the farmers would have changed their field management, it would have been possible to decrease protein contents. Using the combination of RS and GIS in 2006, it was possible to select the key management factor by the difference in the Field GreenNDVI.

Developmental Parameters and Photoperiodism in Trigonotylus tenuis (Reuter) (Heteroptera: Miridae)

Developmental parameters and photoperiodism in Trigonotylus tenuis (Reuter) (Heteroptera: Miridae) were examined using wheat seedlings as food. The thermal threshold and effective cumulative temperature were 12.5°C and 91.9 day-degrees in the egg stage, 12.7°C and 155.8 day-degrees in the nymphal stage, and 11.7°C and 49.7 day-degrees in the preoviposition stage. Mean longevity of female and male adults at 25°C was 18.4 and 22.8 days, respectively, and a female adult laid 203 eggs on average. A temperature-dependent long-day photoperiodic response was observed in the maternal induction of egg diapause. At 17.5, 20 and 22.5°C, females showed a clear response to the photoperiod with a critical daylength of around 12.5 h/day; females reared under short-day conditions laid diapause eggs whereas those reared under long-day conditions laid nondiapause eggs. At higher temperatures (25, 27.5 and 30°C), however, females responded little to the photoperiod, irrespective of which they laid a high percentage of nondiapause eggs. Based on comparisons with T. caelestialium, a species closely related to T. tenuis, this photoperiodism is considered to be an adaptation to southern climates.

낙지 (Octopus minor)의 산란과 부화

We investigated the reproductive behavior of Octopus minor, order Octopoda, class Cephalopoda under laboratory conditions. Each mature female octopus was kept in an aquarium with a plastic tube for shelter, and one mature male was introduced for the purpose of copulation. Before spawning, the female coated the roof of the shelter with a light-green material, upon which it then fixed its eggs one by one. This spawning behavior lasted 1 to 3 days. Fertilized females spawned 54 eggs on average, ranging from 21 to 112 eggs at 72 to 98 days after copulation. The attached eggs were 18.1-19.0 mm in length, 5.0-6.1 mm in width, and 0.30-0.38 g in weight. The mother octopods did not feed; they attended to the eggs by using their arms to rub the egg surfaces and used their funnel to blow sediments off of the eggs. At water temperatures of <TEX>$20.9-21.5^{\circ}C$</TEX>, the fertilized eggs hatched within 73 to 90 days after being spawned. The effective cumulative water temperature was <TEX>$1,569-1,892^{\circ}C$</TEX>. At the end of incubation, the body weight of the mother octopods was reduced to approximately 56% of the initial weight, and most mother octopods died soon after the young hatched.

Nitrogen mineralization processes of soils from natural saline-alkalined wetlands, Xianghai National Nature Reserve, China

Nitrogen mineralization was evaluated using a 12-wk anaerobic incubation at 30°C in two wetland soils located in Xianghai National Nature Reserve, China. The Erbaifangzi wetland is an open wetland because it hydrologically connected to the surrounding ecosystem, whereas the Fulaowenpao wetland is a closed wetland, which is not hydrologically connected. Nitrogen mineralization was fitted to an effective cumulative temperature model. Nitrogen mineralization increased gradually with increases in the cumulative temperature and decreased with depth in the soil profile. Nitrogen mineralization was positively correlated with total N (TN) or soil organic matter (SOM), but not with soil pH. Basal N mineralization was found to be greater in the Fulaowenpao wetland (0 .314g N m-2 d-1) than the Erbaifangzi wetland (0.230 g N m-2 d-1). Key words: Saline-alkalined wetland; marsh soils; nitrogen mineralization; anaerobic incubation; the effective cumulative temperature model

Annual variations in pollen deposition and meteorological conditions on the fell Aakenustunturi in northern Finland: Potential for using fossil pollen as a climate proxy

Annual variation in meteorological parameters (7 years) and pollen deposition (6 years) for 4 sites on a transect across an altitudinal timberline on Aakenus, a fell in northern Finland were monitored, in order to see how pollen production, as reflected by pollen deposition (grains cm year), is related to climate conditions. Wind direction and wind speed before and after estimated flowering time were determined. These indicated that, within the forest and at the physiognomic forest line, pollen deposition is primarily from plants growing within the forested area on the fell and that the contribution of windblown pollen from further south is minimal. Pollen deposition can, therefore, be taken as equivalent to pollen production. Simple linear correlation coefficients between pollen deposition and one-month and two-week mean temperature, effective temperature sums and cumulative effective temperature sums for the current and previous summers were calculated. For Pinus sylvestris the quantity of pollen deposited is affected by July mean temperature, July effective temperature sum and total effective temperature sum, for the year previous to pollen emission. Pollen deposition of Betula pubescens and Picea abies is also affected by thermal factors but of different time periods (Betula of early June and Picea of early July), but always of the year previous to flowering. However, the correlation is not as strong as for Pinus. The results suggest that annual fossil Pinus pollen quantities, if calculated from peat and/or lake sediments, are a potential climate proxy. They also demonstrate that it is possible to use temperature parameters of the current year to make forecasts of the intensity of flowering and pollen production in the following year.

QTL analysis of seed dormancy in rice (Oryza sativa L.)

Effective cumulative temperature (ECT) after heading would be a more reasonable parameter for seed sampling of pre-harvest sprouting/seed dormancy (SD) tests in segregating populations than the days after flowering. SD is an important agronomic trait associated with grain yielding, eating quality and seed quality. To identify genomic regions affecting SD at different grain-filling temperatures, and to further examine the association between SD and ECT during grain-filling, 127 double haploid (DH) lines derived from a cross between ZYQ8 (indica)/JX17 (japonica) by anther culture were analyzed. The quantitative trait loci (QTLs) and their digenic epistasis for SD were identified using a molecular linkage map of this population. A total of four putative QTLs for SD (qSD-3, qSD-5, 6 and 11) were detected on chromosomes 3, 5, 6 and 11, together explaining 41.4% of the phenotypic variation. Nine pairs of digenic epistatic loci were associated with SD on all but chromosome 9, and their contributions to phenotypic variation varied from 2.87%–8.73%. The SD QTL on chromosome 3 was identical to the QTLs found in other mapping populations with different genetic backgrounds, which could be a desirable candidate for gene cloning and marker-assisted selection in rice breeding.

Possible existence of a common temperature and a common duration of development among members of a taxonomic group of arthropods that underwent spaciational adaptation to temperature.

The parameters in the law of total effective temperature, the developmental zero temperature (t) and the effective cumulative temperature (k), were estimated in several species or strains of the family Tenebrionidae. It was shown that the relationship between t and k is linear; k decreases with increasing t. Similar relationships were noted among members of the genus Periplaneta in the family Blattidae, the genus Aedes in the family Culicidae, the family Pyralidae, the family Aphididae and the family Tetranychidae. Based on analysis among groups of orders or higher categories, several researchers have found a similar relationship. The current study on a family or a genus revealed a more rigorous linearity. However, the focus of this study was the linear relationship itself and it was discovered that the t-k relationships of members within each taxonomic group of arthropods determines a common temperature (Tc) and a common duration of development (Dc). This phenomenon was mathematically deducible as a consequence of the t-k linear relation. Biologically, Tc and Dc are probably the optimum temperature and duration of development, respectively, that a group of organisms possess in common.

Laboratory Studies on the Influence of Temperature on the Reproductive Potential of Artemia sinica Cai (Crustacea: Anostraca) from Yanchi Saltlake, China

ABSTRACT The effects of temperature on population characteristics of Artemia sinica Cai from Yanchi Saltlake, Shanxi province, China, were studied in the laboratory at a salinity of 60%&0ihel0;. The developmental stages and generation time were dramatically shortened with increasing water temperature between 16°C and 34°C. Hatching and survival rates decreased rapidly above 30°C. The optimum temperature for reproduction and population growth was 26–28°C. The threshold temperatures for hatching of eggs and development of larvae were 9.07°C and 11.00°C, respectively. The effective cumulative temperature for a generation (time x temperature required from hatching to death) was 458.4±39.6 C degree-days. Based on field monitoring, Yanchi Saltlake provides favorable annual conditions of 2884.1 C degree-days, which would support an estimated 6.3±0.5 A. sinica generations per year. The intrinsic and finite rates of population increase were both increased with adapted water temperature. Extrapolating this data to Yanchi Saltlake, the period from the middle of May to September (second to fifth A. sinica generations) would be the most productive, with a generation time of < 42 d, a population doubling time of < 15 d, a finite rate of increase of > 1.0 d−1, and an intrinsic rate of natural increase of > 0.04 d−1.

Effect of temperature on the development of Aedes aegypti and Aedes albopictus

Three strains of Aedes aegypti and 3 strains of Ae. albopictus of laboratory colonies were reared in different temperatures to compare their development in the immature stage (larval and pupal periods). The duration of developmental times of Ae. aegypti strains averaged 31.0-32.0 days at 15℃, 13.9-16.6 days at 20℃, 10.2-11.8 days at 25℃ and 7.4-8.2 days at 30℃. The developmental zero was 8.2-10.6℃ and the effective cumulative temperature was 145-176 days degree. For Ae. albopictus the duration of developmental times averaged 12.6-15.1 days at 20℃, 10.0-11.7 days at 25℃ and 7.6-8.4 days at 30℃. The developmental zero was 4.2-8.2℃ and the effective cumulative temperature was 166-214 days degree. Male adults emerged 0.2-1.0 days faster than females due to a difference in the duration of the 4th-instar larval period. Aedes aegypti that easily breeds in urban environment could be re-established if introduced in Japan.