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1.
不同寄主植物对云南紫胶虫自然种群的影响   总被引:7,自引:1,他引:6  
研究了云南紫胶虫(Kerria yunnanensis)在聚果榕、南岭黄檀、钝叶黄檀和偏叶榕上的发育、存活和繁殖情况.结果表明:在自然条件下,云南紫胶虫在钝叶黄檀上的种群初始密度最高,为181.17头·cm-2,聚果榕上最低,为145.27头·cm-2;雄虫占的比例以在南岭黄檀上最少,为0.19,偏叶榕和聚果榕上最多,为0.24;从幼虫到成虫的累积死亡率,南岭黄檀上最高,为90.03%,偏叶榕上最低,为87.05%;完成世代时间以在南岭黄檀上最长,为156 d,聚果榕上最短,为140 d;平均怀卵量以在南岭黄檀上最高,为536粒,聚果榕上最低,为345.86粒;虫体质量以在南岭黄檀上最大,为12.62 mg,偏叶榕上最小,为9.03 mg;世代净增值率以在南岭黄檀上最高,为48.51,聚果榕上最小,为32.79.综合比较4种不同寄主植物,南岭黄檀是云南紫胶虫夏季世代种群生长发育和繁殖最适宜的寄主.  相似文献   

2.
A panel of 18 rat x mouse somatic cell hybrid clones segregating individual rat chromosomes in different combinations was used to assign 23 biochemical loci to rat chromosomes. The chromosomal locations for these 23 loci were determined as follows: GOT1 on rat chromosome 1; HAGH on 2; ACP2, ADA, GANC, ITPA, and SORD on 3; LDHB on 4; PEPB on 7; GLB1 and HEXA on 8; IDH1 on 9; UMPH2 on 10; GUSB on 12; FH and PEPC on 13; PEPS on 14; ESD and NP on 15; DIA4 on 19; and PP on 20. In addition, ACP1 and GLO1 were reassigned to rat chromosomes 6 and 20, respectively. The chromosomal assignments of these loci extends the known syntenic homologies among rats, mice, and humans.  相似文献   

3.
Abstract The invasive Q biotype whitefly was first detected in the US on poinsettia in 2004 and is still not a pest outside of greenhouse environments in the US. To assess the potential for the establishment of the Q biotype on field crops, population cage experiments were conducted to compare the performance of a poinsettia‐derived Q population named P’06 on poinsettia and six field crops (alfalfa, tomato, melon, cotton, cowpea and cabbage). P’06 adults reared on poinsettia as nymphs laid eggs on all six field crops. Significantly more eggs were laid on alfalfa, tomato, melon and cotton than on cabbage, cowpea and poinsettia. These eggs hatched and the nymphs developed to adults on the six field crops. Relative to poinsettia, whitefly survival was similar on cowpea, alfalfa, tomato and cabbage, but significantly higher on cotton and melon. Moreover, P’06 had significantly shorter development times from egg to adult on cotton, melon, cowpea, tomato and alfalfa than they did on poinsettia. However, the F1 adults raised on the six field crops had significantly shorter lifespans and laid 11‐ to 18‐fold fewer eggs than did the F1 adults raised on poinsettia. Taken together, while P’06 may have some potential to establish on field crops, the shorter lifespans and extremely low fecundities of the F1 adults raised on the six field crops suggests that P’06 is incapable of rapidly adapting to them. Poor adaptation to field crops may explain, at least partially, why the Q biotype has not established in the US field system.  相似文献   

4.
Cells from pigmented retina of 8- to 9-day-old chick embryos were cultured under two different conditions: on noncoated (NS) or collagen-coated (CS) substrates. Although cells on CS seemed to start dividing 2 to 3 days earlier than those on NS, their early growth rates were basically similar. Cells on CS stopped growing after attaining confluency and formed a monolayer, while cells on NS continued to grow after confluency and overlapped each other. In early growth phase, cells on both substrates became depigmented. Cells became repigmented earlier on CS than on NS. The average melanin content of cells in confluent cultures on CS was two to three times higher than that of cells on NS. By Day 30 “lentoid bodies” were formed only in cultures on NS. Immunoelectrophoretic tests showed the presence of all crystallins (α-, β-, and δ) in cultures on NS but not in cultures on CS. It is concluded that a collagen substrate inhibits “transdifferentiation” of pigmented retinal cells into lens during cell culture.  相似文献   

5.
Abstract:  Effects of feeding history on feeding responses of western cherry fruit fly, Rhagoletis indifferens Curran, to the commercial protein baits GF-120 and Nulure were determined in the laboratory. Flies were kept on 5% sucrose alone or yeast extract and sucrose (Y + S) for 3–7 or 14–16 days and exposed to 24-h-old GF-120 or Nulure drops on artificial leaves. Numbers and durations of feeding events on leaves and durations of non-feeding events were recorded over 1-h periods. Experiments were also conducted to determine effects of Y + S feeding sequences on responses to Nulure, of starvation after sucrose or Y + S feeding on responses to Nulure, and of feeding history on mortality after exposure to GF-120 and Nulure. Protein-deprived flies consistently fed more times on GF-120 and Nulure than protein-fed flies and fed longer. One day of exposure to Y + S or 16 h of starvation after exposure to sucrose caused greater feeding on Nulure than 7 days of exposure to Y + S or 16 h of starvation after exposure to Y + S. Durations of non-feeding events on leaves with sucrose or bait were similar in protein-deprived and -fed flies. Responses of 4- to 6-day-old flies kept on sucrose to 0- and 24-h-old GF-120 or Nulure were similar. More flies kept on sucrose were paralysed or dead at 6–32 h after exposure to GF-120 or Nulure with spinosad than flies kept on Y + S. Results show that complete or long periods of protein deprivation and starvation after sucrose feeding increased feeding responses to GF-120 and Nulure. The general lack of differences in durations of non-feeding events on leaves with sucrose or GF-120 or Nulure in protein-deprived and -fed flies suggests that most protein-deprived flies found baits through chance encounters following normal movement.  相似文献   

6.
Selection for ability of soybean cyst nematode (SCN), Heterodera glycines, to reproduce on soybeans with different sources of resistance divides some SCN race 4 field populations into two distinct subpopulations. These subpopulations reproduce well on ''Bedford'' and plant introduction (PI) 88788 or PI 89772 and PI 90763 but not on both pairs of soybean lines. The ability of these subpopulations to reproduce on the four soybean lines was reversed by changing the soybean line used as a host during a second cycle of selection. When SCN populations previously selected for reproduction on Bedford and PI 88788 were selected for their ability to reproduce on D72-8927 and J74-88, the ability of these populations to reproduce on Bedford and PI 88788 decreased significantly and their ability to reproduce on PI 89772 and PI 90763 increased significantly. Conversely, when SCN populations, previously selected for reproduction on P189772 and P190763, were selected for their ability to reproduce on Bedford, the reproduction of these populations on Bedford increased significantly and reproduction on PI 89772 and PI 90763 decreased significantly. Selection for ability of a SCN race 4 field population to reproduce on soybean lines derived from SCN race 4 resistant PIs resulted in the same division of the field population into two distinct subpopulations. These data substantiate earlier proposals to rotate cultivars with different genes for SCN resistance as a means of managing SCN populations.  相似文献   

7.
The distribution and succession of epiphytic and other associated lichens on blackthorn (Prunus spinosa) growing on the shingle at Dungeness is described. Some 33 epiphytic species, which exhibited a range of ecological strategies from pioneer to late colonizers, were recorded. Both the rate of change of status (age) of blackthorns and the progress of lichen colonization seemed to depend on whether the bushes were growing directly on shingle or on adjacent alluvial soil; both processes seeming to be more rapid on the former substratum. Terricolous lichens, of which 18 were recorded, generally appeared late in the succession and mostly amongst bushes growing on shingle. Rabbits often invaded the blackthorns, especially those on alluvium, and probably contributed to the lack of terrestrial lichens under these bushes. Blackthorns growing on shingle tended to be more prostrate in form than those on alluvium. 1996 The British Lichen Society  相似文献   

8.
Linear growth was studied in 20 children suffering from Still''s disease on various treatment regimens, and their ability to secrete growth hormone and cortisol was investigated. Growth recovered on reducing daily corticosteroid therapy or on changing to an alternative regimen. Retardation of growth was not due to an absolute inability to secrete growth hormone. Basal plasma cortisol levels and the plasma cortisol response to hypoglycaemia were reduced in patients on daily steroid therapy, but patients on alternate-day prednisone did not differ significantly in this respect from those on non-steroid regimens. Those on alternate-day corticotrophin showed preservation of the circadian rhythm but a subnormal response to hypoglycaemia.  相似文献   

9.
It is widely known that many upland-breeding shorebirds tend to nest on plateaus but to date no studies have put forward explanations for this phenomenon. We examined the effect of slope and habitat on the distribution of ground-nesting golden plover Pluvialis apricaria at two study sites in County Durham, U.K. Golden plovers showed strong selection for nesting on flat ground. Habitat significantly affected nest-site location on one study site (heather burnt within the past 2 years was favoured and older stands of heather were avoided) but not on the other. Fifty-nine per cent of all nests failed. We attributed 95% of all losses to predation. Seventy-five per cent of nests, in which the predator was identified, were taken by ground predators, mainly stoats Mustela erminea . Nests on flat ground had significantly higher rates of survival than those on slopes. Nest survival did not vary significantly with habitat type nor with vegetation height or density around the nest. Neither habitat type, vegetation height nor vegetation density around nests differed between nests on slopes and on flat ground. In addition, individuals that nested on flat ground tended to have less black on their underparts (a suggested indicator of dominance). We suggest that birds nesting on slopes are less efficient at avoiding nest predation than those nesting on the flat. The nature or degree of a bird's response to a predator may be related to the efficiency of individual anti-predator responses and/or to visibility from the nest. This study cannot differentiate between these two explanations. We encourage further work to investigate differences in behaviour between individuals nesting on slopes and those on flat ground.  相似文献   

10.
There is ample evidence for ecological responses to recent climate change. Most studies to date have concentrated on the effects of climate change on individuals and species, with particular emphasis on the effects on phenology and physiology of organisms as well as changes in the distribution and range shifts of species. However, responses by individual species to climate change are not isolated; they are connected through interactions with others at the same or adjacent trophic levels. Also from this more complex perspective, recent case studies have emphasized evidence on the effects of climate change on biotic interactions and ecosystem services. This review highlights the ‘knowns’ but also ‘unknowns’ resulting from recent climate impact studies and reveals limitations of (linear) extrapolations from recent climate-induced responses of species to expected trends and magnitudes of future climate change. Hence, there is need not only to continue to focus on the impacts of climate change on the actors in ecological networks but also and more intensively to focus on the linkages between them, and to acknowledge that biotic interactions and feedback processes lead to highly complex, nonlinear and sometimes abrupt responses.  相似文献   

11.
Premature rise of progesterone during the late follicular phase in stimulated IVF cycles is a frequent event and its effect on the endometrial receptivity and on the ART (Assisted Reproductive Technique) – outcome has become a matter of intense debate and research. An emerging body of evidence demonstrates that premature progesterone rise does have a negative impact on the outcome of the ART-success. Until now, the exact cause of progesterone elevation is not fully clear, however lately published studies points to the fact, that premature progesterone elevation might be caused by enhanced FSH stimulation. The impact of elevated peripheral progesterone levels seems to be mainly on the endometrium and the window of implantation, leading to an asynchrony between the endometrium and the developing embryo. Hence, new data show additional an influence on the embryo quality. This review aims to summarize the up-to-date knowledge on the causes of premature progesterone rise during hormonal stimulation, on its influence on endometrial receptivity and embryo quality, on the impact on pregnancy and live birth rates as well as on the possible strategies to prevent this event or to deal with premature progesterone elevation in case it could not be avoided.  相似文献   

12.
目的:鼠伤寒沙门菌在多种表面形成的生物膜对其致病性和引起食物中毒等方面起着重要作用,本研究探讨鼠伤寒沙门菌pStSR100质粒对细菌在不同材质表面生物膜形成的影响。方法:用LB(Luria-Bertani,LB)培养基和TSB(Tryptose Soya Broth,TSB)培养基分别将携带pStSR100质粒的野生株在96孔板与放置无菌小圆玻片的24孔板中静态培养48 h,用结晶紫半定量法确定生物膜形成的适宜培养基。将野生株与消除质粒的突变株,用结晶紫半定量法和激光共聚焦显微镜(Confocal Laser scanning microscopy,CLSM)观察其在聚苯乙烯培养板和小圆玻片表面形成生物膜的差异。结果:用LB培养时细菌生物膜的形成能力高于用TSB培养,LB培养基更适宜生物膜形成;结晶紫半定量法结果表明野生株比突变株在小圆玻片表面形成生物膜的能力明显增强,而在聚苯乙烯培养板表面两者则无明显差异;CLSM观察发现,野生株在小圆玻片表面形成融合成片的大克隆,突变株仅形成较小克隆。结论:鼠伤寒沙门菌pStSR100质粒能促进该菌在亲水性材质表面生物膜的形成,但其对该菌在疏水性材质表面生物膜的形成未见明显影响,这一新发现为进一步研究鼠伤寒沙门菌生物膜形成的调控机制,研制抗感染材料提供了理论和实验依据。  相似文献   

13.
二化螟水稻种群与茭白种群光周期反应的比较   总被引:2,自引:0,他引:2  
本文报道了用水稻和茭白分别饲养二化螟水稻种群和茭白种群的光周期反应。光周期反应曲线显示,用水稻饲养茭白种群或用茭白饲养水稻种群,无论是在短光照还是在长光照条件下,绝大多数幼虫被诱导进入滞育,丧失了各自原有的光周期反应特性,表明这两个种群已分化到仅适应其本身寄主的程度。用水稻饲养的茭白种群仅有5%~6%的个体化蛹,且其幼虫期较用茭白饲养的延长了15~18天;而用茭白饲养的水稻种群有30%~40%的个体化蛹,其幼虫期与水稻饲养的仅相差3~8天。茭白种群用水稻饲养时32日龄幼虫体重仅为茭白饲养的53.1%,而水稻种群用水稻饲养时32日龄幼虫体重为茭白饲养的79.5%。这些结果表明,茭白种群不适应取食水稻,而水稻种群对取食茭白则有一定的适应能力。根据这些结果,我们认为:(1)这两个种群已出现种下分化的迹象;(2)茭白种植不会对水稻田二化螟的发生产生大的影响。  相似文献   

14.
孙建财  刘任涛  王真  田颖 《生态学报》2024,44(14):6405-6415
放牧是草地管理和利用的主要方式,对草地生物多样性及其生态系统结构与功能产生深刻影响。土壤动物作为草地生态系统的重要组成部分,由于其生物生态学特性而使其分布受到放牧干扰的显著影响。然而,放牧如何影响土壤动物多样性尚缺乏系统总结与梳理。通过文献计量分析发现,关于放牧对土壤动物的影响研究论文中,美国发文最多(18.36%),其次是中国(16.39%),新西兰以12.14%的占比位居第三;国内外相关发文量经历了三个阶段:1999-2006年为起步发展阶段,2007-2013年为稳步发展阶段,2014年至今为快速发展阶段,国内外发文量分别在2021、2020年达到最高(15篇、81篇);相关论文的引用率逐年升高,2021年以3813次的引用率达到最高,说明放牧对土壤动物的影响研究引起了越来越多国内外学者的关注和重视。总结发现,放牧对土壤动物分布的影响主要以地上栖居和地下栖居土壤动物为研究对象,既包括直接作用途径,亦包括间接作用途径,而且作用方向取决于放牧强度和放牧方式。综合分析表明,以往的研究多注重于放牧对土壤动物产生的影响,忽视了放牧对土壤动物产生影响的作用途径的深入研究。根据我国草地资源分布特征及放牧对土壤动物的影响研究现状,提出未来我国在此领域研究的重点,为未来草地土壤动物多样性研究提供新思路。  相似文献   

15.
Resistance of two strains of cotton aphid, Aphis gossypii Glover, to fenvalerate and imidacloprid were determined on cotton (Gossypium hirsutum L.) and cucumber (Cucumis sativa L.) after resistance selection of one strain to fenvalerate for 16 consecutive generations, and of a second strain to imidacloprid for 12 consecutive generations on cotton in greenhouses. Dose-response and activities of detoxication enzymes of the fenvalerate-resistant strain (R-fenvalerate), the imidacloprid-resistant strain (R-imidacloprid), and a susceptible strain (S) were determined. After 16 consecutive generations of selection, resistance of A. gossypii to fenvalerate increased >29,000-fold and to imidacloprid 8.1-fold. On cucumber. resistance of the R-fenvalerate strain to fenvalerate increased 700-fold and to imidacloprid 3.6-fold. However, the most significant finding in this study was that the R-imidacloprid strain exhibited cross-resistance to fenvalerate, with a resistance ratio of 108.9-fold on cotton and 3:3.5-fold on cucumber, whereas the R-fenvalerate strain did not show significant cross-resistance to imidacloprid on either plant species. Both resistant strains of A. gossypii were more resistant to fenvalerate on cotton than on cucumber, whereas their susceptibility to imidacloprid on otton and cucumber were not significantly different. The response of the S strain to fenvalerate and imidacloprid were similar on cotton and Cucumber. Activities of acetylcholinesterase (AChE) and alpha-naphthylacetate (alpha-NA) esterases of A. gossypii were significantly different among the three strains, with the R-fenvalerate strains having the highest, followed by the R-imidacloprid strain, and the S strain the lowest. The activities of the AChE and alpha-NA esterases for all three strains were also significantly higher on cotton than on cucumber. The resistance mechanism and resistance management strategies for the R-fenvalerate and R-imidacloprid strains of A. gossypii to fenvalerate and imidacloprid on cotton and cucumber are discussed.  相似文献   

16.
Adult female twospotted spider mites, Tetranychus urticae Koch, reared on lima bean plants were moved to cucumber, maize, or new lima bean plants (the latter being a control) and evaluated after 24 h or 7 d for changes in susceptibility to three pesticides and in levels of related detoxification enzymes. The largest and most consistent changes were observed in mites feeding on cucumber. Susceptibility of mites on cucumber to the synthetic pyrethroids bifenthrin and lambda-cyhalothrin was greater than that of mites reared on lima bean and maize after only 24 h on the plants, and remained higher after 7 d. Mites on cucumber also were more susceptible to the organophosphate dimethoate than were mites on lima bean, but only after 7 d on the host. Susceptibility was inversely related to activities of both general esterase and glutathione S-transferase (GST) in mites on cucumber; general esterase and GST activities were 60 and 25% lower, respectively, than activities of twospotted spider mite on lima bean after 7 d of feeding. Mites on maize were slightly but significantly more susceptible than those on lima bean to bifenthrin, but not to lambda-cyhalothrin, after 7 d and to dimethoate after 24 h but not after 7 d. General esterase and GST activities in twospotted spider mite fed on maize for 24 h were 20 and 16% higher, respectively, than activities in twospotted spider mite on lima bean, but general esterase activity was 30% lower than lima bean-fed mites and GST was not different after 7 d. Thus, plant-induced changes in general esterase activity, perhaps in combination with GST activity, in twospotted spider mite appear to be inversely related to, and possibly responsible for, changes in susceptibility of twospotted spider mite to several pesticides, particularly the synthetic pyrethroids. General esterases appear to play less of a role in the detoxification of the organophosphate insecticide dimethoate.  相似文献   

17.
卷蛾分索赤眼蜂雌蜂的颜色偏好性   总被引:1,自引:0,他引:1  
为了确定卷蛾分索赤眼蜂Trichogrammatoidea bactrae Nagaraja 雌蜂的颜色偏好性, 在室内通过在培养皿底部黏贴彩纸的方法测定卷蛾分索赤眼蜂雌蜂对红、 黄、 黑、 紫、 绿、 白、 蓝7种颜色的行为趋性反应。结果表明, 卷蛾分索赤眼蜂雌蜂在红、 黄、 紫、 绿和蓝5种颜色上的滞留时间都极显著地高于对照(P<0.01), 在黑和白2种颜色上的滞留时间与对照没有显著差异(P>0.05); 对黄色的首次选择率极显著高于对照(P< 0.01), 对红、 紫、 绿和蓝色的首次选择率均显著高于对照(P<0.05), 对黑色和白色的首次选择率与对照没有显著差异。当雌蜂分别在黄与红、 紫、 绿和蓝两两颜色之间选择时, 雌蜂在黄色彩纸上的滞留时间显著长于其他4种颜色。当雌蜂对红、 紫、 绿、 蓝和黄色5种颜色一起选择时, 在首次选择率、 滞留次数上5种颜色间都没有明显差异(P>0.05); 但在红色和蓝色上的滞留时间显著长于紫色(P<0.05), 在这3种颜色上的滞留时间与在黄色和绿色上的滞留时间均无显著差异(P>0.05)。卷蛾分索赤眼蜂雌蜂在7种颜色卵卡上分别与透明纸(对照)上的米蛾卵的选择寄生时, 在黄色卵卡上的寄生卵量极显著多于对照(P<0.01), 黑色卵卡上的寄生卵量极显著少于对照(P<0.01), 其他5种颜色的卵卡上的寄生卵量与对照没有显著差异(P>0.05)。结果说明, 卷蛾分索赤眼蜂雌蜂对黄色最为偏好, 其次偏好红、 紫、 绿和蓝色, 较不喜好白色和黑色。  相似文献   

18.
The toxic effect of killed and live Shigella sonnei cultures on normal mice and on mice, tolerant to Shigella O-antigen and to human erythrocytes of different blood groups (in the ABO system) was under study. The toxicity of shigellae, introduced intraperitoneally, has been found to depend on their viability, on their capacity for penetration into the blood, and on the split character of immunological tolerance to Shigella antigens.  相似文献   

19.
This study examined the effects of feeding interval, access to host plants (thus, a source of sap), and plant defenses on the predatory insect, Podisus maculiventris Say (Hemiptera: Pentatomidae). The experiment consisted of a 2 × 2 design with two feeding intervals (1 day or 5 days) and predators living on either tomato plants or plastic plants. Females fed every day had greater body weights and egg hatch rates than females fed every five days. Females on tomato plants lived longer than females on plastic plants. However, access to plants did not alleviate the effects of low prey level on predator weight or reproductive output. In a second experiment, third instar nymphs were placed on either tomato plants or plastic plants for four days to examine the effects of tomato trichome defenses on these predators. Nymphs on tomato plants experienced 50% mortality compared to 15% mortality for nymphs on plastic plants. Some nymphs living on tomato plants were trapped by the hairy trichomes of the plant; others had gummed up legs from the exudates of the plants’ glandular trichomes, which inhibited their movement and ability to feed on prey. Although predators appeared to benefit from feeding on tomato plants, their ability to live on the plants was negatively affected by the defensive features of the plants. The potential effects of trichome defenses on predator survival and population dynamics must be considered when evaluating the benefits of plants on insect predator life histories and efficacy as biological control agents.  相似文献   

20.
【目的】明确草地贪夜蛾Spodoptera frugiperda对寄主植物水稻和玉米的取食和产卵选择性与适合度,进而分析草地贪夜蛾对水稻的为害风险。【方法】采用自由选择法,测定草地贪夜蛾对水稻和玉米的取食、产卵选择性。调查取食水稻和玉米苗的草地贪夜蛾的生长发育、存活率、繁殖力的差异,用种群增长趋势指数(I)评价水稻对草地贪夜蛾的适合度。【结果】草地贪夜蛾对水稻和玉米的取食和产卵选择性存在显著差异。接虫后2-48 h,幼虫对玉米的取食选择率随时间延长而逐渐增加,而幼虫对水稻的取食选择率随时间延长而逐渐降低;接虫后48 h,2龄幼虫和4龄幼虫对玉米的取食选择率分别为93.06%和59.72%,分别是对水稻的取食选择率的66.95倍和21.48倍。自由产卵6 d,在玉米上的产卵量是在水稻上的8.64倍。与取食玉米苗的相比,取食水稻苗的草地贪夜蛾幼虫发育历期延长,卵孵化率、幼虫存活率、化蛹率和成虫羽化率均显著降低,雌性比率下降,雌成虫寿命显著缩短,单雌产卵量显著减少。取食玉米苗的草地贪夜蛾的种群增长趋势指数(I)为165.93,其在水稻上的相对适合度为0.21。【结论】相较于水稻,草地贪夜蛾在...  相似文献   

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