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921.
922.
Yêyinou Laura Loko Paterne Agre Azize Orobiyi Innocent Dossou-Aminon Yves Roisin Manuele Tamo 《国际虫害防治杂志》2016,62(1):75-84
Destruction of yam (Dioscorea spp.) tubers by termites is a major constraint to yam production in Central Benin. To obtain the basic information for the development of appropriate strategies of termites management in yam, a structured questionnaire was used to interview 142 farmers about their knowledge of termite species of yam, susceptibility of yam landraces, and management practices in 14 villages through the study area. A total of 45 vernaculars names of termites were recorded corresponding to 10 species. All the names given to termite species had a signification, mainly related to morphological aspects, type of damage, and termite caste. Eleven features were used by farmers to identify yam termites. The infestation of yam fields mostly occurred from October to April with Amitermes evuncifer and Trinevitermes oeconomus being the most damaging termite species. Overall, eight factors were identified by farmers as favouring the proliferation of termites in yam fields with drought being the most frequently reported factor. Farmers identified 11 yam landraces that were highly susceptible to termites attack, while 12 yam landraces were listed as resistant. Application of chemicals was the most commonly reported control method, followed by destruction of termite nest, and application of botanical extracts. According to farmers, the high multiplication rate of termites is the most important constraint in managing the issue of termites in yam. 相似文献
923.
Conflicts between wildlife and agriculture have increased as cultivation has expanded into previously unexploited areas. As frequent consumers of such crops, parrots (Psittaciformes) are often persecuted, despite the lack of measured economic impacts they may cause. This situation has compromised attempts to manage potential damage and endangered parrot populations. Here, we evaluate and measure actual crop damage and characterize the foraging areas used by the burrowing parrot (Cyanoliseus patagonus) in northeastern Patagonia, Argentina. We found that damage to field crops was economically insignificant, affecting 0.1%–0.4% of the sunflower harvest, with no damage detected in other more important crops in the region. The parrots mainly consumed grain left or spilled after harvesting, and unharvested grain from cultivated pastures and road margins. This grain represents a loss attributable to harvest machines, being independent from the presence of parrots. Given the negligible damage measured here, we conclude that there is no need for management of parrots as crop pests in northeastern Patagonia. Our study provides further support to the view that parrot damage has been often exaggerated and overstated. 相似文献
924.
三板拼接式小型U形混凝土衬砌渠道冻胀破坏力学模型 总被引:5,自引:5,他引:0
研究土体冻胀对渠道混凝土衬砌结构的影响,对于保障季节性冻土地区渠道输水效率具有重要意义。以三板拼接式小型U形渠道混凝土衬砌结构为对象,研究其在冻胀作用下的受力状态。依据叠加原理将冻胀视为重力、切向冻结力、法向冻结力及法向冻胀力的共同作用,利用结构整体及局部的平衡关系,根据渠道的结构型式、破坏特征及原型观测结果,建立了衬砌结构的冻胀破坏力学模型,给出了便于设计应用的计算公式。对野外观测中的某渠道各部位内力计算结果表明,三板拼接式小型U形渠道混凝土衬砌结构以压弯为主,与实际破坏特征相吻合。刚性接缝处承受较大的轴力和剪力,是结构受力的薄弱位置。为减轻冻胀破坏程度,进一步建议衬砌板直线段倾角α在[22,26]度间取值,坡板弧段圆心角θ略大于U形渠底圆心半角,法向冻结力的合力作用点为从渠顶沿直线段向下2/3处。研究结果可以为季冻区三拼式小型U形混凝土衬砌渠道的设计提供参考依据。 相似文献
925.
926.
试验旨在研究中草药复合微生态制剂(CHCP)对急性肝脏损伤蛋鸡肝脏的保护作用。试验分两部分:①用四氯化碳豆油(SCCl4)建立蛋鸡急性肝脏损伤模型。选取1 d健康蛋雏鸡108只随机分为4组,模型Ⅰ~Ⅲ组分别按1、2、4 mL/kg体重灌胃10%(V/V)SCCl4,对照组按2 mL/kg体重灌胃豆油,分别在14、28及35 d时各灌胃一次;②CHCP对蛋鸡急性肝脏损伤的影响。选择1 d 健康蛋雏鸡60只随机分为5组:对照组(豆油)、模型对照组(SCCl4)及低、中、高剂量CHCP组(SCCl4+1‰ CHCP、SCCl4+2‰ CHCP、SCCl4+4‰ CHCP),7 d起饮水使用CHCP,14、28 d按2 mL/kg体重剂量给鸡灌胃10% SCCl4。结果表明,按2 mL/kg体重剂量在14、28 d分别灌胃10% SCCl4即可造成蛋鸡肝脏损伤,引起肝细胞脂肪变性,空泡样变严重,核固缩,坏死;与模型对照组相比,低、中、高剂量CHCP组蛋鸡血清谷草转氨酶(AST)含量分别降低4.35%(P > 0.05)、7.57%(P > 0.05)及9.79%(P < 0.05),中、高剂量CHCP组血清谷丙转氨酶(ALT)含量分别降低34.92%(P < 0.01)、36.51%(P < 0.01),血清总胆红素(TB)含量分别降低25.49%(P < 0.01)、27.45%(P < 0.01);蛋鸡肝细胞切片显示CHCP不同剂量组肝细胞充血减轻,未见脂滴空泡,排列整齐,细胞质丰富而均匀。结果表明,本试验所用的CHCP按2‰、4‰饮水使用均能减少肉鸡肝细胞坏死,降低血清转氨酶活性及TB水平,对SCCl4诱导的肝脏损伤有保护作用。 相似文献
927.
Abstract In a study of the effects of inter‐cropping and mixed‐cropping of cowpea and sorghum during the kharif, 1982 and 1983, the incidence of leafhoppers and the damage caused by defoliators were most reduced in a row inter‐crop, less in mixed, within row, farming and least in a pure crop of cowpea. Greater green fodder and dry‐matter yields of cowpea were obtained in inter‐crop between rows and in mixed‐crop, within row farming. 相似文献
928.
R. T. Gahukar 《国际虫害防治杂志》2013,59(4):415-420
Abstract During recent years, blister beetles have gained importance in species diversity and as pests of food crops in West Africa. Among the 97 species reported, Psalydolytta fusca Oliv, and P. vestita Duf. are economically important beetle species. Beetle abundance is generally associated with the flowering of crops in a region. Regular intensive weeding and early crop establishment are recommended for pest management in food crops. Global pest control strategies are discussed in the context of subsistence agriculture. 相似文献
929.
Biology, damage pattern, incidence levels and status of the leaf miner Aphanisticus aeneus Kerremans (Coleoptera: Buprestidae) were studied in accessions of Saccharum spp. Egg, grub and pupal periods of the miner lasted 6.0 ± 0.8, 18.5 ± 1.9 and 7.0 ± 1.3 days, respectively; adults lived for 8–10 days. The grub tunneled the leaf on the lower surface just above the epidermis forming a linear channel; infested tissues showed brownish discoloration. The extent of leaf miner attack among the 331 accessions of Saccharum spp. ranged 4.00%–76.47% on cane basis and 7.14%–100.00% on leaf basis; the mined leaf area ranged 3.22–11.00 cm2. When the accessions were grouped on the basis of an infestation index developed with the above three parameters, 267 occupied very low category, 51 were in low category, 11 were in moderate category and 2 were placed in high incidence category. All accessions showed miner attack in at least one study year. Within each of the four Saccharum spp., accessions differed significantly among the three study years for all infestation parameters. Among the four species, while S. robustum accessions recorded significantly highest infestation index, the other three species remained on par. 相似文献
930.
The dimpling bug, Campylomma austrina Malipatil, has been recognised since 2002 as a serious mango pest in the Northern Territory, Australia. To fully understand the damage the bug causes and its relationship with ants, field experiments were conducted in five mango orchards in the Darwin area from 2001 to 2003 along with laboratory rearing trials. The latter revealed that the dimpling bug sucked sap mainly from the ovary of the flowers. As the ovary ripened, each puncture resulted in a black pimple on the skin of the marble-sized fruit (<5 mm in diameter). All of the most heavily damaged marble-sized fruits (>10 pimples/fruitlet) dropped from the trees. A field survey and field experiments showed that marble-sized fruit damage levels on trees bearing abundant weaver ants, Oecophylla smaragdina Fabricius, were similar to those protected by chemical insecticides, however both suffered less damage than trees bearing fewer or no weaver ants or black ants, Iridomyrmex sp. We propose that the weaver ant is an efficient bio-control agent of the dimpling bug, and to limit the bug damage, high levels of weaver ant populations are required in mango orchards. 相似文献