镜湖花臂尾轮虫夏季种群内不同克隆的生活史特征

应用生命表统计学等方法对镜湖花臂尾轮虫夏季种群内4个在生化遗传特征上互不相同的克隆(克隆A、B、C和D)在4种温度(15℃、20℃、25℃和30℃)下的生活史特征及其对升高的温度的反应进行了比较研究。结果表明,温度对花臂尾轮虫存活率和繁殖率的影响在不同克隆间存在着差异。20℃和25℃下,4个克隆轮虫的世代时间和净生殖率均分别无显著的差异;20℃、25℃和30℃下,4个克隆轮虫的平均寿命和出生时的生命期望亦然。其余各温度下,4个克隆间轮虫的其他生命表参数均有显著的差异。20℃、25℃和30℃下,4个克隆轮虫所产后代中的混交雌体百分率间均具有显著的差异,且克隆C轮虫所产后代中的混交雌体百分率最高。15℃下,克隆D轮虫的个体适合度最高;25℃下,克隆A和B轮虫的个体适合度较高。4个克隆轮虫的生活史特征对升高的温度的反应也存在着差异。忽略温度的影响时,4克隆间,克隆D轮虫的世代时间、平均寿命和出生时的生命期望最短,净生殖率、种群内禀增长率和个体适合度均最低;克隆C轮虫所产后代中的混交雌体百分率最高。30℃下,4个克隆轮虫的种群内禀增长率存在着差异可能是不同基因型的轮虫克隆群在种群内所占的比例不同的重要原因;而它们的个体适合度相似则可能是不同基因型的轮虫克隆群在夏季镜湖中共存的主要原因之一。     

A true summer diapause induced by high temperatures in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Summer diapause in the cotton bollworm, Helicoverpa armigera (Hübner), which prolongs the pupal stage, particularly in males, is induced by high temperatures. In the laboratory, summer-diapausing pupae of H. armigera were induced at high temperatures (33-39 degrees C) with a photoperiod of LD8:16; winter-diapausing and non-diapausing pupae, cultured at 20 degrees C with a photoperiod of LD8:16 and at 27 degrees C, LD16:8, respectively, acted as a control. Retention time of eye spots, weight, and lipid and glycogen levels were compared. At high temperatures, both body weight and energy storage capacity were much higher in summer-diapausing pupae than in non-diapausing pupae reared at 33-39 degrees C. At temperatures (>33 degrees C) high enough to maintain summer diapause, the eye spots of summer-diapausing pupae did not move during the 30-day experiment. However, eye spots of summer-diapausing pupae placed at 30 degrees C began to move about 10 days after they were transferred, significantly later than in non-diapausing pupae reared at 33-39 degrees C or non-diapausing pupae reared at 27 degrees C, which initiated eye spot movement 2 days after pupation. The differences in retention time of eye spots between summer- and winter-diapausing pupae shows that winter diapause is more intense than summer diapause in this insect. The weight loss, and lipid and glycogen metabolism curves indicate that the summer-diapausing pupae's metabolism is very low. We conclude that summer diapause in the cotton bollworm is a true diapause and that the summer diapause enables the cotton bollworm to withstand the high temperatures of summer.     

卡拉麦里山有蹄类野生动物保护区野驴的夏季栖息地及种群数量

1982年7月航空调查了卡拉麦里山有蹄类野生动物保护区内野驴Equus hemionus hemionus Pallas的夏季栖息地及种群数量。见野驴358头,平均密度为每平方公里0.02头,多集中栖居在保护区的东北部。初步分析影响野驴夏季栖息地的因素是水、地形及人为干扰。     

Factors limiting the distribution ofDigitaria adscendens andEleusine indica on coastal sand dunes in Japan

Fate ofDigitaria adscendens andEleusine indica seedlings under field conditions and their responses to salt spray, drought and nutrients were experimentally investigated in order to evaluate the possible mechanisms controlling the different distributions of the two species in coastal sand dune areas. Salt spray produced no apparent positive effect on the growth or survival of both species. Seeds of each species germinated well in the field, although 80% ofE. indica seedlings died during a summer drought and surviving seedlings neither grew nor bore fruit. The mortality ofD. adscendens seedlings due to the drought was less than 10% and the survivors mostly bore fruit by the end of the growth season. No major difference in the sublethal water saturation deficit was noticed between the two species. However,D. adscendens individuals extended their roots into the deep sandy soil to a much greater extent in water-stressed conditions than in well watered conditions, whereasE. indica showed no such behavior. Additional watering in a dune environment did not help the growth ofE. indica seedlings, but additional nutrients had a markedly stimulatory effect.D. adscendens maintained its growth and fruition with much smaller amounts of nutrients thanE. indica. Soil nitrogen content at a site whereE. indica andD. adscendens were distributed sympatrically was higher than that at a site where onlyD. adscendens was present. Based on these findings, it is proposed thatE. indica seedlings are unable to become established because of their lower resistance to summer drought and the poor nutrient conditions present in a coastal rear sand dune habitat. Dedicated to Prof. emeritus Toshiro Saeki for his fruitful career in plant ecology.     

Population fluctuations and natural mortalities of the pine-moth,Dendrolimus spectabilis

Annual changes in the population of the pine-moth, Dendrolimus spectabilisButler , were studied in Kashima district. The insect completes two generations in one year, and the adult emerges in early summer and again in autumn. The insect population showed fairly drastic fluctuations in the past years, and a conspicuous peak was recorded in three times, in 1950, 1955 and 1961. It was noted in each of those three years that a great number of adults of the summer generation emerged in autumn. The main reason for this great abundance of the insect population seemed to be high survival rate of the young larvae in summer. It was suggested that the climate in July had powerful influence upon the survival f thos e young larvae. The effects of natural enemies were usually the greatest on the egg population of the pine-moth in either generation. Much greater number of insects in the overwintering generation was destroyed by parasites and diseases than in the summer generation. Finally, a rapid increase of the insect population in autumn was considered to be caused by a combined effect of climatic conditions and of natural enemies.     

黑龙滩水库夏季不同水位对鱼产量及浮游生物的影响

水位变动对鱼产量及浮游生物群落结构有着重要影响。本文通过对黑龙滩水库１３年（１９８０—１９９２）水位落差（夏季水位）、年降雨量、５—９月降雨量,年入库流量与鱼产量的关系进行了回归分析,其中鱼产量（Ｙ）与水位落差（Ｘ）呈显著的负相关：Ｙ＝２５．９８－１．３３Ｘ,（ｒ＝－０．７１１３）。对该水库夏季不同水位时浮游生物种类组成,现存量及生物多样性指数进行了分析比较,发现夏季高水位时（１９９２年６月）浮游生物个体小型化,生物量减少,浮游植物多样性增加。根据营养级差串联效应理论（Ｃａｓｃａｄｉｎｇｔｒｏｐｈｉｃｉｎｔｅｒａｃｔｉｏｎ）,可能与鱼的摄食压力有关。     

Selection for an optimal monovoltine life cycle in an unpredictable environment. Studies on the beetleCatops nigricans Spence (Col., Catopidae)

Summary Catops nigricans reproduces in the autumn. Pre-imaginal development is temperature-dependent and takes place during the winter, followed by aestivation in the early adult stage. This summer diapause is obligatory and temperature independent. It synchronizes the monovoltine life cycle with the annual cycle. In three populations collected near Kiel (54°22′ N, 10°6′ E), K?ln (50°54′ N, 7°6′ E), and Paris (49°25′ N, 2°20′ E), pre-imaginal development slowed and the duration of summer diapause decreased with increasing latitude. Synchronization of the critical breeding interval with the appropriate environmental conditions was achieved through temperature- and photoperiod-dependent sensitivity of ovipositing adults, through different thermal thresholds in eggs, larvae, and pupae, and through sensitivity to photoperiod in third-instars larvae.C. nigricans copes with the unpredictability of climatic conditions in different ways. The local populations have evolved a mean diapause length which probably adjusts the life cycle in most years to the optimal date for reproduction. The mean diapause length was 77 days for Kiel, 98 days for K?ln and 138 days for Paris at 10°C, short-day (=SD).C. nigricans also spreads the risk by varying diapause length. Amongthe progeny of single females the range of diapause duration covered about 70% of the total range of the whole population. The oviposition rate of females confined to subterranean life was the same as females confined to subterranean life was the same as in those living under the influence of a varying photoperiod.C. nigricans should therefore be able to live both in the litter layer of forests and also in the nests and galleries of small mammals.     

双季稻区稻水象甲一代成虫的滞育

对浙江省双季稻区稻水象甲（ＬｉｓｏｒｈｏｐｔｒｕｓｏｒｙｚｏｐｈｉｌｕｓＫｕｓｃｈｅｌ）夏季种群的研究表明,光照和温度可排除在一代成虫夏季滞育的诱导因子之外,而不同的食料条件是引发滞育的主导因素．在自然状态下,即使是强迫滞留,早稻田内的一代成虫也不转入正常发育,但取食稻秧能使新羽一代成虫和稻田内外处于生殖滞育状态的一代成虫的卵巢正常发育,并能解除已进入夏蛰的一代成虫的生殖滞育;同时,不论是新羽成虫还是夏蛰成虫,取食稻秧后卵巢和飞行肌同时发育;若这种食料条件能持续下去,则飞行肌消解而卵巢发育产卵．     

一级生产水平下冬小麦,夏玉米的生产模拟

通过模拟计算得到一级生产水平下冬小麦和夏玉米的累积干物质动态曲线 .两年的计算结果和实测值都比较吻合 .研究表明 ,在黄淮海平原 ,可以把亩产吨粮作为冬小麦 夏玉米一年两茬平作粮田达到一级生产水平的指标 .若用中熟夏玉米套作代替早熟夏玉米平作 ,籽粒的年产量可增加一成 .通过对不同叶面积指数下干物质产量的模拟计算 ,得到一年两茬平作的干物质产量最大可达 46t·hm- 2 ,籽粒产量 1 9.1t·hm- 2 .