| 417 matches found in 278 documents. Search time: 0.021 seconds. |
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Score: 12.00 |
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| | Journal: Pest Manag . Sci . Citation: V : 62 ( 11 ) P : 1109-15 Year: 2006 | | Literature: oryza Field: abstract Doc ID: pub16964592 Accession (PMID): 16964592 | | Abstract: From paddy field observations in 2002 and 2004 , fenoxaprop-P-ethyl resistance in Chinese sprangletop ( Leptochloa chinensis ( L ) Nees ) has been studied using information collected from 11 sites in the Saphan-Sung district of Bangkok , Thailand .
The resistant Chinese sprangletop was found in nine rice fields , whereas the susceptible Chinese sprangletop was found in only two rice fields .
In greenhouse experiments , both fenoxaprop-P-ethyl-resistant and susceptible Chinese sprangletop from the same location were investigated for 50% growth reduction based on phytotoxicity , plant height and fresh and dry weight .
The resistant Chinese sprangletop showed apparent resistance at 14-21 days after herbicide application at a rate of 21 . 1-337 . 6 g AI ha ( -1 ) .
The resistance index of resistant Chinese sprangletop was 10-25 times higher than that of the susceptible Chinese sprangletop .
In addition , Chinese sprangletop did not exhibit multiple resistance to oxadiazon , propanil and quinclorac .
According to acetyl-CoA carboxylase ( ACCase ) assays , the level of ACCase specific activity in the resistant Chinese sprangletop was significantly higher than that in the susceptible Chinese sprangletop .
Similarly , the ACCase activity of the resistant Chinese sprangletop was 10 times less sensitive to fenoxaprop-P-ethyl than that of the susceptible Chinese sprangletop , based on the I50 values .
The present study of the mechanism responsible for resistance in the biotypes investigated indicated that there was a close association between the concentration-response at the whole-plant level and ACCase sensitivity to fenoxaprop-P-ethyl , and resistance to fenoxaprop-P-ethyl was conferred by a modified ACCase at the target site , as suggested by higher specific activity and less sensitivity to the herbicide .
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Score: 9.00 |
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| | Journal: Citation: V : 81 ( 6 ) P : 463-73 Year: | | Literature: oryza Field: abstract Doc ID: pub2100760 Accession (PMID): 2100760 | | Abstract: To support the continued use and the registration of monocrotophos , a field study was conducted at Calauan , Laguna , The Philippines , to assess exposure and the resulting health risk to 21 spraymen applying monocrotophos to rice crop by knapsack spraying during 3 consecutive days .
The findings of the study were as follows : exposure of uncovered hands and of the skin of the back to the concentrate was visually observed during the filling , and respectively loading operations ; During spraying exposure from airborne diluted formulation occurred ; in addition contamination of the lower parts of the body took place because of direct contact with the sprayed crop ; Determination of the amount of the urinary metabolite dimethylphosphate excreted in 24 hours urine samples demonstrated absorption of monocrotophos into the body of the spraymen .
The half-life of elimination of the urinary metabolite from the body was on average 18 hours ; No clinically significant inhibitions of whole blood or red blood cell cholinesterase activities were found , ie , 30% below baseline values .
However , 8 of 21 spraymen had plasma cholinesterase levels below 50% of baseline values ; --No acute adverse health effects associated with the application of monocrotophos were observed , which was in accordance with the absence of clinically significant cholinesterase depressions .
The conclusion of the study was that the use of monocrotophos under prevailing typical conditions in the Philippines , which varies from a frequency of one application per season to a maximum of 3 applications each on 3 consecutive days per week , and where label safety instructions are not necessarily observed , is not expected to pose an acute health risk under the prevailing conditions and practices , which includes filling , spraying and cleaning activities .
From the experience in this study it is clear that proper spraying technique and adequate use of personal protection will significantly reduce exposure .
As such a reduction is highly recommendable , advice on proper spray procedures and adequate personal protection has been reinforced . | |
Score: 7.00 |
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| | Journal: Trop . Med . Int . Health Citation: V : 5 ( 7 ) P : 472-81 Year: 2000 | | Literature: oryza Field: abstract Doc ID: pub10964269 Accession (PMID): 10964269 | | Abstract: We conducted a community-randomized controlled trial in Pakistan to determine the efficacy of indoor residual spraying with alphacypermethrin ( Fendona , Cyanamid , NJ , USA ) , applied at 25 mg/m2 , to prevent falciparum and vivax malaria .
Wettable powder ( WP ) and suspension concentrate ( SC ) formulations were tested against an unsprayed control in an irrigated rice-growing area of Sheikhupura district , Punjab province .
The study area of 180 km2 was divided into nine sectors , which were assigned at random to control , WP , or SC treatments in replicates of 3 .
Sentinel villages were selected from each sector for entomological and disease monitoring .
Malaria was monitored by fortnightly active case detection ( ACD ) and by cross sectional parasite surveys on schoolchildren .
Mosquito populations were monitored by space spraying of rooms and by cattle-landing catches .
The spray campaign took place in June 1997 and covered 96% of compounds .
During the 7 months after spraying , the incidence of falciparum malaria was 95% lower and that of vivax malaria 80% lower in WP-sprayed than unsprayed sectors .
Similar results were obtained for sectors sprayed with the SC formulation .
Cross-sectional surveys gave estimates of efficacy comparable to those obtained by ACD .
Anopheles culicifacies was 80% less abundant and Astephensi , the predominant anopheline , was up to 68% less abundant in sprayed areas over the 7-month period .
Reductions in anopheline parous rates indicated that the single-spray treatment was effective for the entire transmission season .
Sprayed surfaces lacked odour , which contributed to the popularity of the campaign .
Alphacypermethrin is a promising insecticide for the control of malaria in Pakistan and South Asia generally .
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Score: 7.00 |
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| | Journal: Citation: V : 2 ( 3 ) P : 181-206 Year: | | Literature: oryza Field: abstract Doc ID: pub15612416 Accession (PMID): 15612416 | | Abstract: Endotoxins from Bacillus thuringiensis ( Bt ) produced in transgenic pest-resistant Bt crops are generally not toxic to predatory and parasitic arthropods .
However , elimination of Bt-susceptible prey and hosts in Bt crops could reduce predator and parasitoid abundance and thereby disrupt biological control of other herbivorous pests .
Here we report results of a field study evaluating the effects of Bt sprays on non-target terrestrial herbivore and natural enemy assemblages from three rice ( Oryza sativa L ) fields on Luzon Island , Philippines .
Because of restrictions on field-testing of transgenic rice , Bt sprays were used to remove foliage-feeding lepidopteran larvae that would be targeted by Bt rice .
Data from a 546-taxa Philippines-wide food web , matched abundance plots , species accumulation curves , time-series analysis , and ecostatistical tests for species richness and ranked abundance were used to compare different subsets of non-target herbivores , predators , and parasitoids in Bt sprayed and water-sprayed ( control ) plots .
For whole communities of terrestrial predators and parasitoids , Bt sprays altered parasitoid richness in 3 of 3 sites and predator richness in 1 of 3 sites , as measured by rarefaction ( in half of these cases , richness was greater in Bt plots ) , while Spearman tests on ranked abundances showed that correlations , although significantly positive between all treatment pairs , were stronger for predators than for parasitoids , suggesting that parasitoid complexes may have been more sensitive than predators to the effects of Bt sprays .
Species accumulation curves and time-series analyses of population trends revealed no evidence that Bt sprays altered the overall buildup of predator or parasitoid communities or population trajectories of non-target herbivores ( planthoppers and leafhoppers ) nor was evidence found for bottom-up effects in total abundances of non-target species identified in the food web from the addition of spores in the Bt spray formulation .
When the same methods were applied to natural enemies ( predators and parasitoids ) of foliage-feeding lepidopteran and non-lepidopteran ( homopteran , hemipteran and dipteran ) herbivores , significant differences between treatments were detected in 7 of 12 cases .
However , no treatment differences were found in mean abundances of these natural enemies , either in time-series plots or in total ( seasonal ) abundance .
Analysis of guild-level trajectories revealed population behavior and treatment differences that could not be predicted in whole-community studies of predators and parasitoids .
A more conclusive test of the impact of Bt rice will require field experiments with transgenic plants , conducted in a range of Asian environments , and over multiple cropping seasons . | |
Score: 7.00 |
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| | Journal: Citation: V : 16 ( 8 ) P : 1493-6 Year: 2005 | | Literature: oryza Field: abstract Doc ID: pub16262065 Accession (PMID): 16262065 | | Abstract: This paper studied the variation of the temporal and spatial niches of rice sheath blight-causing Rhizoctonia solani under spraying fungicide .
The results showed that between fungicide treatments and control , the spatial niche breadth of Rhizoctonia solani was different , while its temporal niche breadth was similar .
The spatial niche breadth of Rhizoctonia solani was 0 . 5240 when spraying fungicide at booting and full heading stages , 0 . 5742 at booting and milkfilling stages , and 0 . 8577 at tillering stage , while the control was 0 . 8563 .
Spraying fungicide had little effect on temporal niche breath .
The spatial niche breath , percentage of diseased leaves and sheathes , index of disease , and control effect all suggested that spraying fungicide two times in rice growth period was better than spraying it one time .
Spraying fungicide at booting and full heading stages and at booting stage and milkfilling stages had the best effects .
Fungicide could not only narrow the spatial niche breadth , limit the spread of Rhizoctonia solani on top leaves which were important for the yield , but also narrow the temporal niche breadth , limit the spread of Rhizoctonia solani during the yield formation period of rice .
But , spraying fungicide only changed the distribution of the fungus niches and narrowed the niches during rice yield formation period , with no changes in the whole niches of Rhizoctonia solani . | |
