| In this paper,the temperature that Carposina sasakii experiences had been simulated as the following:the diurnal temperature changes during the process of diapause induction and the average temperature changes in different diapause stages during the overwintering period.And environmental temperatures during the late winter and early spring also were investigated.Then we estimated the effects of the environment temperatures on the diapause overwintering and post-diapause development in the context of climate warming.The main conclusions were as follows:(1)The temperature during the process of diapause induction had effects on relevant physiological indices of diapause larvae in C.sasakii.The super cooling point(SCP)and freezing point(FP)increased with the increase of daily high temperature,The performance was inconsistent under different temperatures.For example,SCP rose from-23.23±0.60 C to-22.21±1.42 C with the daily temperature rising from 26 C to 30 C when the night temperature was 22 C.But FP was the lowest-13.29±0.83 C at daily temperature 28 C and the highest-10.92±0.56 C at daily temperature 30 C and SCP and FP increased significantly with the increase of night low temperature from 18 C to 20 C,especially at daily high temperature of 26 C and 30 C.For example,SCP rose from-21.77±1.67 C to-20.35±2.34 C with the night temperature rising from 18 C to 22 C when the daily temperature was 26 C.FP rose from-12.9±0.73 C to-9.44±0.77 C.The water content increased with the increase of day high temperature,from 42.08±4.49%to 46.76±6.06%at night temperature 20 C;and increased with the increase of night temperature,from 40.27±3.37%to 43.80±1.78%at daily temperature 30 C.The fat content varied with the temperature changes.The content of small molecule sugar alcohols varied with the temperature changes.The changes of these metabolites were affected by the diapause development and the temperature changes.The dynamic changes of these metabolites might be related to the cold tolerance of C.sasakii.(2)The overwintering time of C.sasakii is relatively longer,generally 5?8 months.And its overwintering period can be divided into three stages:pre-diapause,diapause and post-diapause.The effects of temperature patterns of different stages on the overwintering success of C.sasakii were studied indoors.It was found that the larval development rate increased with the increase of temperature during its pre-diapause,and the finding was that the larvae showed its shortest ingress time and heaviest weight at the highest temperature,up to 30.5±8.2 mg,which was significantly different from other temperatures;the survival rate of larvae decreased with the increase of pre-diapause temperature,dropped from 77.62±1.14%to 34.90±12.10%.The survival rate of the larvae increased with the increase of diapause temperature.The survival rates of larvae at 0 C and at 4 C(respectively 64.66±3.19%and 69.22±1.47%)were significantly higher than those at-8 C during diapause period(49.80±1.19%).The survival rate of larvae decreased first and then increased with the increase of post-diapause temperature.But the overall survival rate of the larvae decreased.The maximum survival rate was 78.06±1.07%at 22 C.The survival rate of the larvae was only 61.94±1.48%when the temperature increased to 30 C.The survival rate of larvae increased from 50.58±0.29%at 24 C to 62.57±1.52%at 28 C with the increase of the temperature of the whole year.The results showed that the temperature changes at different stages of diapause were closely related to the success of overwintering.(3)Temperatures had effects on the biological characteristics of C.sasakii at different over-wintering stages.The unearthed peak of overwintering larvae dropped with the pre-diapause temperature increasing.The duration of unearthed larvae was shortened by 10 days at 26 C than at 20 C and 6 days at 28 C than at 26 C.Diapause temperature had no significant effect on unearthing of larvae,the emergence rate of adult,the longevity of adult and oviposition amount.The emergence rate of adults increased from 38.77±2.34%to 57.35±4.59%with the increase of temperature from-8 C to 4 C.when the post-diapause temperature rose,the unearthed time of C.sasakii was advanced,9 days at 30 C earlier than at 28 C,10 days at 28 C earlier than at 26 C,6 days at 26 C earlier than at 24 C,the unearthed time was the same at 24 C and at 22 C;the unearthed peak dropped,the emergence rate of adults decreased from 59.79±1.71%to 38.92±2.26%;the longevity of the adults was shortened from 7.5310.26 d at 22 C to 3.47±0.21 d at 30 C;the reproductive capacity decreased from 81.64±1.90 grains/female at 22 C to 40.00±2.25 grains/female at 30 C.The unearthed date of overwintering larvae became more centralized with temperature rising in the whole year,which narrowed the dispersity of the population,advanced the adult emergence,the emergence time at 28 C was 7 days earlier than that at 26 C,9 days at 26 C earlier than that at 24 C,shortened adult longevity,the longevity of adults was 4.93±0·12 d at 24 C and only 3.77±0.38 d at 28 C.The male and female were unable to copulate and the reproductive capacity decreased from 86.78 ± 1.83 grains/female at 24 C to 32.39±2.37 grains/female at 26 C.Overall,the greatest influence on population dynamics was the pre-diapause temperature,the post-diapause temperature and the whole year temperature.(4)The correlation between soil temperature fluctuation at depth of 5 cm and the post-diapause development of C.sasakii during late winter and early spring was studied(late December to mid-April).By removing outdoor larval samples over this period,results showed that with the delay of sampling time,the cold tolerance of overwintering larvae gradually lost.The daily minimum temperature and average temperature were significantly correlated with the unearthed time and cold tolerance of C.sasakii.With the increase of temperature,the cold tolerance dropped and the unearthed time is shortened.There was a correlation between the freeze-resistant protectant and the supercooling point(SCP)of larvae,which began to decrease in late December,but only a weak correlation with the survival rate of cold stress during the post-diapause.These findings suggested that diapause stage and soil temperature should be taken into account when field dynamics of soil-dwelling overwintering insects were predicted based on degree day accumulation models. |
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