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1.
不同生长期橡胶叶对六点始叶螨选择性及种群增长影响 总被引：1，自引：0，他引：1
为了探明不同生长期橡胶叶对六点始叶螨Eotetranychus sexmaculatus(Riley)选择性及种群增长的影响,在室内测定古铜期、淡绿期、稳定期、老化期的橡胶叶对六点始叶螨的产卵选择、取食选择、发育、存活及繁殖的影响。结果表明:六点始叶螨对不同生长期橡胶叶的取食选择和产卵选择由多到少依次为:古铜期、淡绿期、稳定期、老化期,说明该螨在转移为害过程中优先选择幼嫩叶片;世代发育历期以取食老化期的最长,为20.9 d,取食古铜期最短,为16.9 d。世代存活率、净生殖率(R0)、内禀增长率(rm)由大到小依次为:古铜期、淡绿期、稳定期、老化期。因此,古铜期的橡胶叶最适合六点始叶螨的发育、存活及种群增长,随着橡胶叶的老化越不利于该虫的生长发育及繁殖。 相似文献
2.
Vincent Boulanger Christophe Baltzinger Sonia Saïd Philippe Ballon Jean-Franois Picard Jean-Luc Dupouey 《Forest Ecology and Management》2009,258(7):1397-1406
As a result of diverse management policies, densities of red and roe deer have varied considerably for the last few decades in Europe. Their selective browsing on woody species can modify the interactions between competing species and thus change overall patterns of plant diversity in forests. However, no classification of woody species according to browsing by deer yet exists in Europe. The selectivity index, which measures the balance between availability and consumption of plant species by herbivores, could be used for such a classification. The aim of this study was, first, to rank woody species according to this selectivity index, then to test whether their rank changed when browsing pressure varied in space or time. We also explored morphological and ecological life traits (Ellenberg indicator values) that might explain differences in selectivity.In 2006, we re-sampled a network of 217 coupled floristic and browsing survey plots, which had been previously described twice (1976, 1981). The plots were located in the forest of Arc-en-Barrois (France), a large woodland area divided into a North and a South Forest which have had different histories of browsing pressure.For the three samples and the two forests, we calculated a selectivity index for 19 woody species. Dogwood (Cornus sp.) and field rose (Rosa arvensis) appeared to be the most selected species whereas beech (Fagus sylvatica), common mezereon (Daphne mezereum) and wild-service tree (Sorbus torminalis) were always avoided. The rank order of species according to their selectivity index remained stable over the three sample years and between the two forests (Spearman's rank correlations: ρ ≈ 0.8 spatially, and range from 0.3 to 0.8 temporally). This indicates that variations in browsing pressure did not strongly modify deer selectivity patterns. Selectivity was positively correlated with wood density and negatively correlated with maximum height of the species, but unrelated to other plant traits. Finally, selectivity can be seen as an intrinsic characteristic of those woody species, and could be used as an additional life trait when analyzing vegetation communities. 相似文献
3.
双斑萤叶甲成虫的取食选择性研究 总被引：2，自引：0，他引：2
为综合治理双斑萤叶甲的危害,拓展新的防治途径,对双斑萤叶甲成虫的取食选择性进行研究。试验中,采用四臂嗅觉仪测定和田间试验方法研究,结果表明,在6个玉米品种中,双斑萤叶甲成虫对垦粘1号的选择性强,对庆单4和四单19的选择性弱,在供试的2种植物中,对紫花苜蓿的选择性强。总体表现为双斑萤叶甲成虫对紫花苜蓿的选择性强,垦粘1号次之,庆单4和四单19弱。 相似文献
4.
[目的]明确不同番茄品种对美洲斑潜蝇的选择性差异。[方法]在温湿度恒定的小气候环境中,研究了美洲斑潜蝇对18个不同番茄品种及材料的选择性。通过零频率估计法测定了美洲斑潜蝇幼虫的种群密度,同时调查虫情指数。[结果]美洲斑潜蝇对不同番茄品种的选择性存在差异。野生番茄品种ZBNH11的虫情指数最低,其次是包头市农业科学研究所选育出的15个番茄品种及材料,而引进的钻红八号和普罗旺斯的虫情指数最高。[结论]研究结果为合理利用抗性品种减轻美洲斑潜蝇危害提供了理论依据。 相似文献
5.
本文用固定床反应器考察了Pd/C催化剂硫化前后 ,在环戊二烯加氢反应中的性能。结果表明环戊二烯的转化率从 86 4%上升到 98 2 % ,环戊烯的选择性从 86 9%上升到 98 8%。确定了最佳硫化条件。应用微型脉冲反应器研究了硫化过程和特性 相似文献
6.
采用田间罩笼和盆栽试验的方法研究了葱蝇成虫对4种寄主植物的产卵选择,采用室内培养的方法研究了幼虫对寄主植物的取食选择。结果表明：在4种寄主植物中,田间罩笼试验以洋葱上葱蝇的发生数量最多,其次为大蒜和大葱,韭菜上数量最少|盆栽试验中,葱蝇成虫对4种寄主植物的产卵选择与田间罩笼试验结果一致,均以在洋葱上落卵量最多,韭菜上落卵量最少|葱蝇1龄和3龄幼虫对寄主植物的取食选择,均以选择洋葱的幼虫最多,大葱的次之,韭菜和大蒜上的较少。表明葱蝇成虫的产卵选择是决定葱蝇幼虫在不同寄主植物上发生程度差异的重要因素,诱杀成虫是葱蝇防治的重要措施之一。 相似文献
7.
不同土壤对钾的选择吸附特性 总被引：3，自引：0，他引：3
用K Ca交换平衡法对砖红壤、红壤、土、黑土和水稻土K的选择吸附特性研究结果表明 :KG 和KV 系数随着K Ca平衡体系中吸附相中钾与钙比率的变化而改变 ,其曲线特征说明土壤胶体存在着对K亲和力不同的吸附点位。在低钾饱和度时 ,土壤对K的高选择吸附主要归于粘粒矿物楔形区域电荷点位吸附 ,五种土壤楔形区域相对吸附点位顺序为 :黑土 >土 >水稻土 >红壤 >砖红壤 ,该相对吸附点位顺序与土壤含有风化云母和蛭石有关。在高钾饱和度时 ,五种土壤对K的吸附主要发生于粘粒矿物的晶层表面电荷点位 ,粘粒矿物的晶层表面电荷起源也许起决定作用 ,此时KG 选择系数的大小顺序为 :砖红壤 >红壤 >黑土 >土 >水稻土 相似文献
8.
以雷尼镍作催化剂对混合脂肪酸进行选择性加氢正交试验和单因素水平试验,对所得产品进行凝固点测定和韦氏法碘值测定后得出最佳反应条件:原料1在温度200℃,压力0.6 MPa,时间60 min,催化剂ω(A)=0.6%,搅拌速度250~300 r/min条件下所得产品碘值从120.84降到100以下而凝固点控制在10℃以内;原料2在温度200℃,压力0.4 MPa,时间45 min,催化剂用量ω(A)=0.3%,搅拌速度为250 r/min的条件下碘值从97降到85而凝固点控制在15℃左右,验证了混合脂肪酸选择性加氢的可行性。 相似文献
9.
完达山林区马鹿的冬季食性 总被引：5，自引：1，他引：4
2003～2004年在黑龙江省完达山林区,根据野外啃食痕迹调查,对马鹿冬季食性进行了研究。结果表明,榆、紫椴、榛、暴马丁香、杨、黄檗是马鹿主要的冬季食物(44．31％、10．07％、7．60％、7．17％、6．56％、6．38％),组成马鹿冬季大宗食物。马鹿对榆、核桃楸、龙牙楤木、紫椴、毛接骨木、黄檗、水曲柳、狗枣猕猴桃、柳、托盘、疣枝卫矛表现出正选择。杨、榛和暴马丁香虽然是马鹿的主要食物,但相对于它们较高的可获得性而言,马鹿对它们表现出负选择。 相似文献
10.
Improvement of intra-row mechanical weed control is important to reduce the reliance on herbicides in arable crops and vegetables. Covering weeds by soil is an important weed control mechanism of weed harrows. A shallow post-emergence harrow cultivation controls weeds but also damages the crop to some extent. This paper explores how plants get covered by soil and how a plant’s resistance against being covered is related to its height, flexibility and shape of leaves. Seedlings of two contrasting species were sown in bins filled with a sandy soil and harrowed by a small model harrow in the laboratory. Covering selectivity (percentage covered ryegrass/percentage covered garden cress) could be influenced by soil moisture content, working depth and working speed. Differences in covering were related to spatial patterns of plant downward bending and soil surface level upheaval. These patterns are associated with soil failure patterns near tines and soil flow patterns, connected with different effects of plant height and plant flexibility. This study indicates that relationships between weed control and crop covering may not only depend on weed and crop characteristics but also on soil conditions and implement settings. As less than 10% of the covered plants were buried deeper than 15 mm, covering would mainly cause growth reduction and little killing. Limited burial depth may be an important cause for limited weed control effectiveness of harrowing. 相似文献