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The brown planthopper, Nilaparvata lugens (Stal) (BPH) is one of the most important insect pests of rice in China and other east-southern Asian countries. 相似文献
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The brown planthopper, Nilaparvata lugens (Stal) (BPH) is one of the most important insect pests of rice in China and other east-southern Asian countries. 相似文献
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Paddy and Water Environment - This study examines management problems of WUA C1 of the Kpong Irrigation Scheme (KIS) in Ghana using the 13 evaluation indicators derived from theories of common-pool... 相似文献
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Kamaruzzaman BY Zahir MS John BA Waznah AS Jalal KC Shahbudin S Al-Barwani SM Goddard JS 《Pakistan journal of biological sciences: PJBS》2010,13(24):1208-1213
An effort to analyze selected heavy metal accumulation by the razor clam (Solen brevis) from Tanjung Lumpur was conducted on January to April 2010. A total of fifty individuals of Razor clam Solen brevis were sampled and metals such as Iron (Fe), Zinc (Zn), Copper (Cu), Manganese (Mn), Lead (Pb) and Cadmium (Cd) Concentrations were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Among the metals Fe occurred in elevated concentration in the soft tissue of razor clam followed by Zn. Cd was found to be in least concentration in the sample. Mean concentration of Fe, Zn, Mn, Cu, Cd and Pb in the soft tissue were 415.2 +/- 56.52, 87.74 +/- 11.85, 18.71 +/- 2.10, 8.64 +/- 1.75, 0.67 +/- 0.29 and 1.61 +/- 0.45 microg g(-1) dw, respectively indicating that the bioaccumulation of essential metals in the soft tissue was greater than the non essential heavy metals. Metal accumulation in the soft tissue of razor clam followed Fe > Zn > Mn > Cu > Pb > Cd order in present study. The observed concentration of acute toxicity of metals in Solen brevis (Family: Solenidae) from Tanjung Lumpur Coastal waters was lower than the permissible limit recommended by National and international standards proved that this species could be utilized for human consumption. 相似文献
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A population of the rice brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae), was abundant on a weed, Leersia hexandra, growing in irrigation canals near rice fields in the Philippines. When individuals of this population were placed on rice, Oryza sativa, feeding was low and they could not survive. Conversely, L. hexandra was not a host for the N. lugens population maintained on rice. Although the two N. lugens populations differed in feeding behaviour, under ‘no choice’ conditions in the greenhouse they interbred and produced progeny which could utilize both L. hexandra and O. sativa as a host. The Leersia population is important in the management of N. lugens on rice as it is attacked by the same predators, parasites and pathogens as the rice population. 相似文献
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Introduction of the System of Rice Intensification in Kenya: experiences from Mwea Irrigation Scheme
There are various avenues for intensifying agricultural production, the most common being increased use of fertilizers, supplemental
irrigation of crops, and adoption of high-yielding varieties. These options are rather widely known to farmers around the
world, but they have not been widely adopted by smallholders in sub-Saharan Africa. The low adoption rate is related to complex
technical and socio-economic issues, such as poor extension services, lack of capital, failure to mobilize the requisite water,
or simply, poverty. The System of Rice Intensification (SRI) is in a special category of innovation in that, farmers stand
to gain multiple benefits from its use, including the possibility of increasing rice yields substantially, saving water, and
getting better grain quality, using differently the assets that they already have. A major impediment for the adoption of
SRI in Africa has been lack of knowledge about this intervention, especially for farmers already practicing irrigated agriculture.
Farmers generally have good business sense and will adopt technologies or practices once the benefits are proven and the risks
are seen as minor. SRI should be attractive for these reasons, but there are various issues to be resolved before large numbers
of farmers can adopt the method. This article reports on the steps taken and the technical and socio-economic issues addressed
in efforts to introduce SRI and promote it in Kenya, specifically in the Mwea Irrigation Scheme. A diverse set of individuals
and institutions in Kenya together embarked on the evaluation and dissemination of SRI methods in this East African country
beginning in July 2009. If the new methods can perform in Kenya as in other countries, this will bring much benefit to rice
farmers and rice consumers in the region. SRI is coming to Kenya relatively late, as it was the thirty-ninth country from
which favorable SRI results have been reported. This means that Kenyans can learn from others’ experience and evaluations,
and there is also now more of a supportive institutional framework. The initial results from on-farm SRI trials have been
positive, although not conclusive. They have given impetus to Kenyan farmers and institutions to collaborate within a multi-sectoral,
multi-level coalition that has provided an informal, multi-faceted platform for the evaluation, adaptation and dissemination
of SRI practices. The initiative in Kenya is now gaining more formal status and more resources. This experience is presented
to show the kinds of things that have been and can be done to utilize the SRI opportunity for raising land, labor, and water
productivity in the rice sector. 相似文献
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The brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is a long-distance migratory insect pest in temperate eastern Asia and a typical recurrent pest induced by pesticides. We investigated the effect of sublethal concentrations of insecticides on the flight capacity on this species. An automated flight-mill system was used to assess the flight capacity of adults reared on untreated and insecticide-treated plants. In most instances, the flight duration of adult females exposed to high concentrations of imidacloprid, triazophos or deltamethrin was significantly greater than that of untreated controls. Compared to the controls, the flight duration of females increased by 140% (from 103 to 245.9 min), 119% (from 103 to 226 min) and 78% (from 103 to 183.3 min) with 10 ppm imidacloprid, 40 ppm triazophos and 3 ppm deltamethrin, respectively, yet no significant difference in the flight duration of males was found between the insecticide treatments and the controls. The high concentrations of the three insecticides significantly enhanced the flight speed and the flight distance of both males and females, with the exception of the flight speed of adult males treated with deltamethrin. For example, the flight speed of adult females and males treated with 10 ppm imidacloprid, 40 ppm triazophos and 6 ppm deltamethrin increased by 75% (from 0.39 to 0.68 km/h), 154% (from 0.39 to 0.98 km/h) and 124% (from 0.39 to 0.87 km/h) for females and by 141% (from 0.32 to 0.77 km/h), 73% (from 0.32 to 0.55 km/h) and 48% (from 0.32 to 0.47 km/h) for males, respectively, compared to the controls. In addition, the percentages of individuals treated with imidacloprid and triazophos flying for over 60 min doubled compared to the control. These findings are relevant for understanding the migration and outbreak patterns of N. lugens. 相似文献
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The Mae Lao Irrigation Scheme is one of the largest irrigation projects in Northern Thailand. According to the field reconnaissance,
water shortage usually occurs during the dry season. And it is very difficult to equally distribute available water to the
paddy fields from the upstream to the downstream parts of the system. To understand and identify the causes of the problems,
the measurement of water level and flow rate along all canals may be effective. However, it is not easy to achieve this in
such a large-scale irrigation system. Thus, the numerical simulation becomes the second option. The objective of this study
is to identify and quantify the real water shortage causes by developing an Unsteady Irrigation Water Distribution and Consumption
model which can simulate the water movement and consumption in the whole irrigation system. The beneficial area of the right
main canal is modeled based on the physical aspect of the system. The components of the model consist of canal networks, control
structures, and paddy fields. A canal is divided into several portions called reach. The Saint-Venant equations are applied
to describe the unsteady water movement in each reach. Flow movement at the control structure is expressed by the boundary
condition. The paddy fields are modeled to make paddy block and connected to each reach. The water consumption in each paddy
block is estimated by Paddy Tank model. The numerical model is successfully developed showing the ability to simulate the
water movement and consumption properties in this irrigation system. 相似文献
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Nine brown planthopper(BPH) resistance genes have been registered so far, but of them only Bph1, bph2, Bph3, bph4, Bph9,and other three unregistered genes Bph10(t), Bph(t), bph(t) were located on chromosome 3, 4, 10, and 12, respectively, by using traditional and molecular mapping methods. To use the genes for BPH resistance in rice breeding and production, interspecific hybrids between cultivated rice and accessions of O. eichingeri (2n=24, CC), a wild rice species from Africa, with strong resistance to BPH and whitebacked planthopper were produced. 相似文献
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Satoshi Kono Tassanee Ounvichit Atsushi Ishii Masayoshi Satoh 《Paddy and Water Environment》2012,10(1):75-81
In principle, participatory irrigation management (PIM) means the involvement of irrigation users in all aspects at all levels
of irrigation management. In practice, all over the world efforts are being made to realize the principles. However, in the
execution of PIM, role sharing between farmers and government is a serious problem, and thus a clear method and ideas are
needed to improve PIM. In particular, a broad discussion of role sharing is demanded. This article illustrates how the Japanese
way of role sharing in PIM is realized based on the case of the Toyogawa Irrigation Project. Organizationally, the project
is jointly managed by five entities, including both the public sector and the farmers’ organizations. These entities have
clearly divided their functional roles, with the ultimate decision power in all aspects of irrigation management given to
organized farmers. The power is realized either directly or through the land improvement districts’ representative system
depending on the levels of the irrigation system. The public entity provides coordination support to create a transparent
forum of discussion together with scientific information for farmers’ understanding and decision making. The participatory
institutional line-up of this project enables the upland areas that suffered periodically from water deficits. 相似文献
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Crop yield and populations of brown planthopper Nilaparvata lugens (Stål), whitebacked planthopper Sogatella furcifera (Horvath) (Homoptera: Delphacidae), green leafhopper Nephotettix spp. (Homoptera: Cicadellidae), and hemipteran and spider predators were monitored on rice varieties susceptible, moderately resistant, and highly resistant to N. lugens, under insecticide-treated and insecticide-free conditions. Nilaparvata lugens outbreaks and hopperburned plants were observed only in plots of the insecticide-treated susceptible varieties. In insecticide-free plots, the yield of the susceptible variety was lower than those of resistant varieties in only one of four seasons. In plots of a moderately resistant and a highly resistant variety, populations of N. lugens, S. furcifera, Nephotettix spp., and predators were generally similar, and yields did not differ, under both insecticide-treated and insecticide-free conditions. In insecticide-free plots, predator-N. lugens ratios were generally higher on resistant varieties than susceptible varieties. Two conclusions can'be drawn from our results relevant to the question of what levels of N. lugens host plant resistance are appropriate for farmers who do not overuse insecticides. First, susceptible varieties will not necessarily be damaged by N. lugens, even when N. lugens outbreaks occur in adjacent plots. Second, moderate and high levels of N. lugens resistance do not appear to be incompatible with biological control of N. lugens or other homopteran pests. 相似文献
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The brown planthopper Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is a classical resurgent rice pest induced by insecticides. The past focus on resurgence mechanisms has been on the stimulation of the reproduction of adult females induced by insecticides. To date, the role that males play as a resurgence of N. lugens has not been investigated. The present study examined changes in protein levels in both male accessory glands and female ovaries induced by the insecticides triazophos and deltamethrin as well as the stimulating effect of treated males on the fecundity of adult females via mating following foliar sprays of the insecticides. For adults that had been exposed as nymphs to treated rice plants, the protein content in both the male accessory glands and in the female ovaries of N. lugens were significantly affected by male mating status, insecticide and insecticide concentration. There was a higher protein content in male accessory glands when males were exposed to triazophos as third instars compared to fifth instars, and there was a higher protein content before mating compared to after mating. In addition, the protein levels in male accessory glands after mating for individuals exposed to high doses of the two insecticides as 3rd and 5th instars were significantly lower than untreated control except for exposed to triazophos as 3rd instar, indicating that treated males transferred more male accessory gland protein to adult females via mating. The protein content was also affected by different combinations of treated mating pairs. Adult males (♂t) developed from third instar nymphs treated with triazophos stimulated the fecundity of the female significantly via mating (♂t × ♀ck) with untreated females (♀ck) (control females), increasing the reproductive rate by 43.5% as compared to the mating (♂ck × ♀ck) of untreated males and females. Also, the fecundity of the females after the mating (♂t × ♀t) of treated males and females was significantly higher than that after the mating (♂ck × ♀t) of untreated males with treated females. These findings indicated that the reproductive effects of insecticide on males can be transferred to females via mating. The present findings provide valuable information for understanding the potential role that males play in the pesticide-induced resurgence of N. lugens. 相似文献
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Quang Huy Hoang Naritaka Kubo Ngan Giang Hoang Hajime Tanji 《Paddy and Water Environment》2009,7(2):123-133
Ba Lai Irrigation Project is located at coastal area in the Mekong Delta. In dry season when the flow rate decreases and the
strong east wind blows into the delta, the salinity intrusion increases and seriously affects agricultural and domestic water
use. Intakes of Ba Lai system have to be closed for 1–3 months depending on their locations, and no water supply during this
period often causes water pollution in the project area. In order to solve such problems, this study aims to seek gate operation
procedures for salinity control and water environment improvement. A numerical model is developed to simulate water movement,
salinity concentration and duration of remaining water (water age) within the system under three scenarios: (1) without control
structures, (2) with available control structures, (3) with the full control structures. Through the numerical simulations,
control structures are confirmed to be an effective measure for the salinity control and suitable gate operation schedules
are proposed to improve the water environment in the project. 相似文献