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1.
Fourteen commercial leek fields with first and second generation Leek moth, Acrolepiopsis assectella Z., (LM) injury were sampled during 1986 in The Netherlands. For both generations, plant injury was more prevalent in the perimeter of the field than in interior portions. A sequential sampling program for use in making treatment decisions for LM was developed. An economic analysis of the value of sampling information derived from the sequential sampling program was performed. The parameters used for the analysis were crop yield and value, expected level of LM infestation, potential loss of value due to LM infestation, effectiveness of insecticide application, and cost of sampling. Due mainly to the high value of the crop and low cost of treatment, analysis indicates that there is little difference between a sampling-based management plan and prophylactic application of insecticides in terms of pest control costs. Additionally, such a sampling-based management plan is relatively insensitive to changes in the parameters used in the model. Thus, development of a threshold linked to a sampling procedure will not reduce pest control costs. Use of the sampling-based management plan will also not significantly increase pest control costs and will likely result in reduced insecticide use compared with a prophylactic treatment program.
Zusammenfassung In den Niederlanden wurde 1986 der durch den Befall der ersten und zweiten Generation der Lauchmotte (Acrolepiosis assectella Z.) verursachte Schaden auf 14 kommerziell genutzten Porreefeldern ermittelt. Für beide Generationen wurde an den Feldrändern ein deutlich höherer Befall als in dem inneren Bereich eines Feldes festgestellt. Zur Bekämpfung der Lauchmotte wurde als Entscheidungsmodell ein sequentielles Probenahmeverfahren entwickelt. Der Informationsgehalt der sequentiellen Befallserhebung wurde einer ökonomischen Bewertung unterzogen. Hierbei wurden folgende Parameter zugrunde gelegt: Erntemenge und Ertrag, erwarteter Befallsgrad sowie hierdurch verursachter möglicher Ertragsverlust, Wirkungsgrad einer Insektizidbehandlung und Kosten der Stichprobennahme. Die Analyse der einzelnen Parameter ergab nur eine geringe Kostendifferenz zwischen einer gezielten Bekämpfung nach sequentieller Probenahme und prophylaktischen Insektizidspritzungen, bedingt durch den hohen Wert der Kultur und die niedrigen Kosten einer Bekämpfung. Darüber hinaus its das Verfahren einer gezielten Lauchmottenbekämpfung gegeüber Veränderungen der obengenannten Parameter relativ unempfindlich. Deshalb wird die Entwicklung eines Schwellenwertes der mit Probenahmeverfahren verbunden ist die Bekämpfungskosten nicht reduzieren. Die anwendung der Probenahmeplans würde Bekämpfungskosten auch nicht erhöhen und würde wahrscheinlich Insecktizidverbrauch reduzieren im Vergleich zu einen prophylaktischen Behandlungsprogramm.相似文献
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A total of 24 commercial fields of cabbages and Brussels sprouts were sampled in a grid fashion with 20–25 equally spaced
cells with four plants per cell. Using this data base of 80–100 plants, we conducted computer stimulations to compare the
treatment decisions that would be made for the major insect pests using published sequential sampling programs and a newly
developed variable-intensity sampling program. Additionally, we compared the number of samples required to make the decision.
At low thresholds (10–20%) for both Lepidoptera and cabbage aphids, variable intensity-sampling required a smaller sample
size and provided more reliable decisions, while at high thresholds (40–50%) sequential sampling provided more reliable decisions.
In both procedures, the occurrence of incorrect decisions was minimal. The number of cases in which a decision would not be
reached after a 40-plant sample was lower for variable-intensity sampling. Considering the number of samples required to make
a correct decision and the greater need for reliable decisions at lower thresholds, variable-intensity sampling was superior
to sequential sampling. Additionally, variable-intensity sampling has the advantage of requiring samples to be taken in a
greater area of the field and thus increases the probability of detecting localized infestations. Although variable-intensity
sampling was not designed to classify pest populations for treatment decisions but rather to achieve sampling precision around
the population mean, our present studies indicate that it can also be an effective method to aid in treatment decisions. 相似文献
5.
Intercropping as a method to reduce crop losses is an old technique, especially in the tropics. During 1977 and 1978 intercropping experiments of Brussels sprouts with Spergula arvensis showed a significant pest reducing effect. Mamestra brassicae and Evergestis forficalis populations showed a strong reduction, whereas Pieris rapae did not seem to respond to intercropping. Late cabbage root fly infestation of the sprout buttons was reduced drastically. Brevicoryne brassicae incidence was decreased in dense intercropping plots only. Injury due to caterpillar feeding showed a grading response to intercropping density, as did the total caterpillar populations. Log dose-effect regression lines allow a comparison of various intercropping densities with other control methods on insect pest population reducing potential.
Zusammenfassung Durch Untersaaten können Ertragsverluste an Kulturpflanzen reduziert werden. Das ist ein altes, bewährtes Verfahren, besonders in den Tropen. Die Einsaat von Spergula arvensis in Rosenkohlbeständen führte in 2-jährigen Untersuchungen zur signifikanten Verringerung des Schädlingsbefalls. Während die Populationen von Mamestra brassicae und Evergestis forficalis stark zurückgingen, blieb die von Pieris rapae unbeeinflusst. Eine Abnahme von Brevicoryne brassicae konnte nur in Parzellen mit hohen Spergula-Dichten festgestellt werden. Die Abundanz der Raupen sowie die Beschädigungsintensität durch diese, zeigten eine Abhängigkeit von der Untersaatdichte. Die Regressionsgerade Untersaatdichte zur Effektivität erlaubt einen Vergleich verschiedener Spergula-Dichten mit anderen Methoden, die das Schädlingspotential reduzieren.相似文献
6.
RNA and DNA binding zinc fingers in Xenopus TFIIIA. 总被引:4,自引:0,他引:4
7.
Pustjens T. F. S. Streukens B. Vainer J. Gho B. Ruiters A. W. Stein M. Ilhan M. Veenstra L. Theunissen R. Bekkers S. C. A. M. van’t Hof A. W. J. Rasoul S. 《Netherlands heart journal》2020,28(2):75-80
Netherlands Heart Journal - To compare ischaemia-driven complete coronary revascularisation by percutaneous coronary intervention (PCI) with usual care in patients with non-ST-elevation myocardial... 相似文献
8.
Leonardus W. J. E. Beurskens Lieske H. Schrijver Dick Tibboel Mark F. Wildhagen Maarten F. C. M. Knapen Jan Lindemans Jeanne de Vries Régine P. M. Steegers‐Theunissen 《Birth defects research. Part A, Clinical and molecular teratology》2013,97(1):60-66
BACKGROUND
Vitamin A has been related to the etiology of congenital diaphragmatic hernia (CDH). We performed a case‐control study to investigate whether maternal dietary vitamin A intake is related to CDH in the offspring.METHODS
Thirty‐one pregnancies diagnosed with CDH and 46 control pregnancies were included during the study. After CDH diagnosis and inclusion of controls by risk set sampling, maternal vitamin A intake was investigated with a food frequency questionnaire. Serum retinol and retinol‐binding protein were determined. Univariable and multivariable logistic regression models were used to calculate risk estimates with adjustment for potential confounders.RESULTS
We found no significant differences in the overall nutrient and vitamin A intake between case and control mothers. After stratification in body mass index (BMI) categories, case mothers with normal weight showed a lower energy adjusted vitamin A intake (685 vs. 843 μg retinol activity equivalents [RAEs] / day; p = 0.04) and a slightly lower serum retinol (1.58 vs. 1.67 μmol/L; p = 0.08) than control mothers. Vitamin A intake <800 μg retinol activity equivalents (recommended daily intake) in normal weight mothers was associated with a significantly increased CDH risk (odds ratio [OR], 7.2; 95% confidence interval [CI], 1.5–34.4; p = 0.01). Associations were not significantly different in underweight and overweight mothers.CONCLUSIONS
In normal‐weight mothers, dietary vitamin A intake during pregnancy below the recommended daily intake is significantly associated with an increased risk of a child with CDH. This finding supports the retinoid hypothesis in human CDH, but warrants further investigation in larger study populations. Birth Defects Research (Part A), 2013. © 2013 Wiley Periodicals, Inc. 相似文献9.
Background
Adaptive, context-dependent control of locomotion requires modulation of centrally generated rhythmic motor patterns through peripheral control loops and postural reflexes. Thus assuming that the modulation of rhythmic motor patterns accounts for much of the behavioural variability observed in legged locomotion, investigating behavioural variability is a key to the understanding of context-dependent control mechanisms in locomotion. To date, the variability of unrestrained locomotion is poorly understood, and virtually nothing is known about the features that characterise the natural statistics of legged locomotion. In this study, we quantify the natural variability of hexapedal walking and climbing in insects, drawing from a database of several thousand steps recorded over two hours of walking time.Results
We show that the range of step length used by unrestrained climbing stick insects is large, showing that step length can be changed substantially for adaptive locomotion. Step length distributions were always bimodal, irrespective of leg type and walking condition, suggesting the presence of two distinct classes of steps: short and long steps. Probability density of step length was well-described by a gamma distribution for short steps, and a logistic distribution for long steps. Major coefficients of these distributions remained largely unaffected by walking conditions. Short and long steps differed concerning their spatial occurrence on the walking substrate, their timing within the step sequence, and their prevalent swing direction. Finally, ablation of structures that serve to improve foothold increased the ratio of short to long steps, indicating a corrective function of short steps.Conclusions
Statistical and functional differences suggest that short and long steps are physiologically distinct classes of leg movements that likely reflect distinct control mechanisms at work. 相似文献10.
Kim P. C. Kuypers Eef L. Theunissen Janelle H. P. van Wel Elizabeth B. de Sousa Fernandes Perna Anke Linssen Anke Sambeth Benjamin G. Schultz Johannes G. Ramaekers 《PloS one》2016,11(2)