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901.
902.
Identification of sex pheromone components of the pea midge, Contarinia pisi (Diptera: Cecidomyiidae) 总被引:1,自引:0,他引:1
Ylva Hillbur Peter Anderson Heinrich Arn Marie Bengtsson Jan Löfqvist Anthony J. Biddle Olof Smitt Hans-Erik Högberg Ernst Plass Stephan Franke Wittko Francke 《Die Naturwissenschaften》1999,86(6):292-294
Three components in extract of pheromone glands of female pea midges, Contarinia pisi, were found to be active on male pea midge antennae by coupled gas chromatographic-electroantennographic detection. The EAD
active components were identified as 2-acetoxytridecane, (2S,11S)-diacetoxytridecane, and (2S,12S)-diacetoxytridecane. A blend of these compounds proved to be highly attractive to males in windtunnel experiments.
Received: 12 November 1998 / Accepted in revised form: 26 january 1999 相似文献
903.
The Science of Nature - 相似文献
904.
Jan H.A. Boerboom 《Agriculture, ecosystems & environment》1984,11(2):182-183
905.
Marta Heroldov Josef Bryja Jan Zejda Emil Tkadlec 《Agriculture, ecosystems & environment》2007,120(2-4):206-210
Small mammal communities were snaptrapped for six years in agricultural landscapes to establish their relationship to various crop habitats in southern Moravia, Czech Republic. The presence of 14 small mammals was documented; 77% of the community found in crops consisted of three rodents, namely Microtus arvalis, Apodemus microps and A. sylvaticus, whereas in woody habitats, 89% of the community was represented by Clethrionomys glareolus, Apodemus flavicollis and A. sylvaticus. In permanent habitats (windbreaks, small woods and fallow land), the community was more abundant and diversified. Among the crop fields, the lowest abundance was found in cereal fields whereas the lowest diversity was observed in alfalfa. Soil-cultivating practices affected abundances especially in sugar beat and maize. Seasonal variation in numbers was lowest in forest and fallow land. Species richness decreased from spring and summer to autumn and winter in annual crops (cereal, maize, sugar beet and other crops), increased in alfalfa and fallow land, and remained relatively stable in windbreaks and forests. Based on similarity indices, two groups of small mammal communities were identified: one for field crops and another for permanent habitats. The fallow land assemblages in spring and summer were more similar to field crop species assemblages and in autumn and winter to permanent habitats one. Trophic requirements of small mammals and the food supply available in the various habitats are discussed. 相似文献
906.
P.Monica Lind Anders Bergman Mats Olsson Jan rberg 《Ambio-人类环境杂志》2003,32(6):385-388
本文利用非侵入计算层析X射线摄影法(pQCT)研究了雄性波罗的海灰海豹(4~23岁龄)骨组织的矿物密度(mg/cm3).资料按照收集的年份分组.A组1850~1955年,有机氯(OCs)大量引入之前的时期;B组1965~1985年,OC污染十分严重的时期;C组1986~1997年,OCs浓度逐渐减小的时期.测量结果的复现性良好,变异系数(CV)为0.1%~2.1%.1986~1997年收集的标本中桡骨小梁的矿物密度比1965~1985年收集的标本的明显要高(p<0.05).1986~1997年收集的标本中,下颌骨的皮层骨矿物密度明显地低于1850~1955年收集的标本(p<0.05).这些结果表明小梁和皮层骨在一段时间内的不同响应.在OC污染非常严重的时期(1965~1985年),小梁骨矿物密度最低,而在1985~1997年收集的标本中,皮层骨密度最低,该时段是一个OC污染程度相当低的时期.有关这些效应背后的机制目前尚不知道.但是,可以假定这里涉及到OCs.由于目前缺乏有关研究个体中OCs残留水平的资料,因此不可能评估OCs在这方面的影响. 相似文献
907.
908.
Jill Man-Ying Chiu Vengatesen Thiyagarajan Jan A. Pechenik Oi-Shing Hung Pei-Yuan Qian 《Marine Biology》2007,151(4):1417-1431
Larvae of the slipper limpet Crepidula onyx metamorphose in response to marine biofilms. In this study, we investigated how the percentage of larval metamorphosis in
this species was affected by biofilms that differed in certain attributes. To manipulate bacterial and diatom cell densities
and community composition, we developed biofilms in the laboratory (1) at different temperatures (16, 23 and 30°C) and salinities
(20, 27 and 34‰), (2) with or without addition of antibiotics, and (3) in the light or in the dark. We also allowed biofilms
to develop at three field sites with different prevailing environmental conditions so as to generate biofilms with different,
but natural, attributes. Bacterial and diatom community composition in biofilms were determined using a DNA fingerprinting
technique and microscopic examination, respectively. The effects of biofilms on metamorphosis were investigated in laboratory
assays. The percentage of larval metamorphosis correlated with bacterial and diatom cell densities in only one of the three
experiments conducted, but was substantially affected by differences in bacterial and diatom community composition in all
three experiments. It also appears that metamorphosis of C. onyx depends on the simultaneous presence of both bacterial and diatom communities in biofilms. 相似文献
909.
Dietary separation between two blennies and the Pacific gregory in northern Taiwan: evidence from stomach content and stable isotope analyses 总被引:1,自引:0,他引:1
Cheng-Tze Ho Shuh-Ji Kao Chang-Feng Dai Hwey-Lian Hsieh Fuh-Kwo Shiah Rong-Quen Jan 《Marine Biology》2007,151(2):729-736
Two blennies, Ecsenius lineatus Klausewitz and Ecsenius namiyei (Jordan and Evermann), and a cohabiting territorial damselfish, the Pacific gregory, Stegastes fasciolatus (Ogilby), were collected from shallow reefs in northern Taiwan between September and November 2004, and in October 2005 for
stomach content and δ
13C and δ
15N analyses in an effort to study how extensively their food sources overlapped and to delineate the pattern of cohabiting
interactions. These analyses showed differences in food use between the Ecsenius blennies and S. fasciolatus. However, there were inconsistencies. Epiphytic algae were their major food items of E. namiyei and E. lineatus. Macroalgae were rarely taken. Nevertheless, δ
13C and δ
15N signatures suggested that E. namiyei and E. lineatus might have assimilated mainly macroalgae-derived detritus instead of epiphytic algae. In contrast, macroalgae were the major
food items of S. fasciolatus, followed by epiphytic algae. Differences in both δ
13C and 15N values indicated that for S. fasciolatus, algae (both macroalgae and epiphytic algae) might not be as important as the stomach contents showed. Instead, polychaetes
were possibly its major food source. Differences between stomach contents and evidence from the separation of stable isotope
signatures between blennies and the Pacific gregory indicate that some of the interspecific interactions derived from exploitative
competition may have been alleviated. Moreover, their widespread territory overlap is possibly a sign of mutualism: S. fasciolatus allows territory sharing, while Ecsenius blennies, in return, clean up the algal mat by removing sand and detritus. 相似文献
910.
Jan Lindström Tim Coulson Loeske Kruuk Mads C. Forchhammer Dave W. Coltman Tim Clutton-Brock 《Behavioral ecology and sociobiology》2002,52(1):25-30
We studied the effects of ecological variables on the birth sex ratio of Soay sheep (Ovis aries) lambs on the island of Hirta, in the St Kilda archipelago, Scotland. Both individual- and population-level models were constructed. In the individual-based model, only population size was significantly associated with the sex of a lamb, with the probability of giving birth to a male lamb being positively associated with population size. However, this model explained a very small proportion of the variance in birth sex ratio. A multiple regression analysis of the annual population birth sex ratio also showed a slight increase in the proportion of males born in years following high autumn population density, but this result was not statistically significant. Population growth rate, Julian birthday, litter size, mother's age and weight, and the weather conditions during the gestation and neonatal period did not explain significant variation in the birth sex ratio. 相似文献