545 research outputs found
Dispersion pattern and sampling plan for Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae) in a citrus orchard
The ecology of the psyllid and its spatial distribution as the basis for the development of a reliable sampling plan are very important. The abundance and spatial distribution of Diaphorina citri (Hemiptera: Psyllidae) were studied in a commercial citrus orchard in southwestern Sarawak, Malaysia from April 2013 to December 2014. The spatial distribution of D. citri eggs, nymphs and adults were analysed using Taylor’s power law and Iwao’s patchiness regression. Taylor’s power law fitted the data better and produced higher values of R2 than Iwao’s regression model but did not work well with the egg populations. Based on both regression models, the field dispersion patterns of D. citri eggs, nymphs and adults were aggregated among flush shoots in individual trees as indicated by the regression slopes that were significantly >1. By homogeneity tests on both regression methods, the slopes of Taylor’s power law and Iwao’s regression model did not differ significantly for the D. citri population on honey tangerine for both years. The minimum number of flush shoots per tree required for estimates of D. citri densities varied from 2, 4 and 6 flush shoots for adults, nymphs and eggs, respectively, for the average density of each developmental stage obtained during our studies. Prediction suggested that a sampling plan consisting of 10 trees with the optimum number of six flush shoots per tree was required for a reasonably accurate density estimation of the three life stages of D. citri acceptable enough for population studies and pest management program in citrus orchards
Foraminiferal evidence for the intensification of the east Australia current during the LGM
Abstrac
An Economic and Statistical Analysis of Selected Structural Characteristics of Louisiana Agricultural Sector and Its Impact on Resource Situations.
This study focuses on the importance of structural change in the farm sector and its interactive relationship with the nonfarm sector. This relationship was exemplified through an overview and trend analysis of the structural change and resource adjustments that have occurred in the farming areas in Louisiana between 1959 and 1982. Extrapolative forecasting techniques, such as trend extrapolation, Markov Process, negative exponential and age cohort analysis, were used to project changes in farm numbers to the year 2000. The results show declining farm numbers and the continuation of present trends. Large and medium size farms will increase while small and hobby farms will decrease in number. Evaluation results show that trend extrapolation and Markov Process provide better projections than the other two techniques when judged on the basis of mean squared error and mean absolute error. The impacts of selected structural determinants on farm numbers and resource adjustments were estimated by econometric models. Sector interdependency through intersector flow of goods and services formed the conceptual framework of the models. The determinants have a significant impact on structural transformation and resource adjustments in the farm and nonfarm sectors. However, the impacts on different size categories were varied due to differences in the natural resource base, enterprise mix, geographic characteristics, and demographic distribution of the area. Impact multipliers show positive relationships between farm numbers, farm employment and farm earnings. However, negative relationships were estimated for nonfarm employment, nonfarm earnings and total earnings in selected farming areas. The model assumed no area interaction and internalized all resource adjustments which brought about the trade-off effect. Average profit per farm appears to be most promising in promoting economic growth since it has a positive impact on employment, earnings and personal income in all farming areas. Farm earnings were found to have a positive impact on consumption expenditures, nonfarm earnings, total employment, area population and indirectly affects the number of nonbasic business establishments
Knowledge Management and IT Project Success: A Meta-analytic Review
There are fragmented and contradictory findings in relation to the factors influencing IT project success. The aim of this study is to examine the antecedents of IT project success. A meta-analytic review was undertaken using the Comprehensive Meta-Analysis Software. A systematic review of the literature identified 612 articles on IT project success. Of these, 46 articles used a range of constructs in studying IT project success. The meta-analytic review resulted in 24 antecedents of IT project success. The result could be explained by adopting a knowledge management perspective as the antecedents (such as team environment, team process, team integration and social factors) were necessary for the creation, storage and transfer of knowledge in leading to IT project success. Theoretical and practical implications are discussed in relation to understanding the contributions of knowledge management to IT project success
Seasonal Abundance and Suppression of Fruit-Piercing Moth Eudocima phalonia (L.) in a Citrus Orchard in Sarawak
Seasonal population of the fruit-piercing moths Eudocima spp. was monitored throughout the citrus growing seasons in a citrus orchard and in site adjacent to secondary forest from July 2007 to June 2009. The moth was detected practically throughout the year with activity lowest during the wet months (September-February) when fruits are still available and while highest during the dry months (May-June) which also coincided with the main fruiting season. The effects of an nC24 horticultural mineral oil (HMO) on the citrus fruit damage caused by fruit-piecing moths was also determined. The percent fruit damage was significantly lowest (P≤0.05) in HMO-treated plots (8.4), followed by Dimethoate-treated plots (11.6) and untreated plots (22.5). However, there was no significant difference between HMO and Dimethoate treated plots indicating HMO is effective in reducing percent fruit damage
Distribution patterns of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) eggs, nymphs and adults in a Malaysian citrus orchard
Spatial distribution of eggs, nymphs and adults of Diaphorina citri (Hemiptera: Psyllidae) was studied in a commercial orchard in SW Sarawak, Malaysia, using mean–variance test, the index of dispersion, and the negative binomial distribution. To further ascertain and confirm the distribution pattern in the population of the psyllid, dispersion indices (index of mean crowding, Lloyd’s index of patchiness, Taylor’s power law and Iwao’s patchiness regression) were calculated. Measurable tests showed that distribution of eggs and nymphs in naturally occurring psyllid populations was highly aggregated, resulting from initially aggregated migration of adults and a contagious dispersion of them on flushes as the population density increased of metals in the present study can be used as suitable reference for future studies
Local oestrogen therapy modulates extracellular matrix and immune response in the vaginal tissue of post-menopausal women with severe pelvic organ prolapse
This study investigates the effect of local oestrogen therapy (LET) on the expression of proteins participating in collagen/elastin biogenesis and immune markers in vaginal tissues of post-menopausal women with severe pelvic organ prolapse (POP). Vaginal biopsies were collected from the anterior vaginal wall of informed and consented 52 post-menopausal women with severe POP undergoing total hysterectomy. Twenty-nine of the 52 women were treated with LET (in the form of vaginal oestrogen cream or tablet), while the remaining 23 untreated patients served as the controls. This study was approved by Sinai Health System REB. Vaginal tissue specimens were analysed for gene and protein expression using real-time RT-PCR and Luminex assays, protein localization and immune cell infiltration were assessed by immunohistochemistry. Forty-four cytokines were detected. We found that LET application: (a) significantly increased (P \u3c 0.05) gene and protein expression levels of extracellular matrix (ECM) structural proteins, collagen and elastin, as well as the expression of ECM maturation enzyme BMP1; (b) decreased protein expression level of ECM degradation enzymes MMP1, MMP2 and MMP3 accompanied by an increase in their tissue inhibitors, TIMP1 and TIMP4; (c) significantly increased (P \u3c 0.05) the gene and protein expression levels of 14 vaginal cytokines involved in leucocyte infiltration, which was confirmed by immunohistochemistry. Our results indicate that LET plays an important role in the activation of immune system within the local vaginal environment, limiting the undesirable ECM degradation, which supports the strengthening of vaginal ECM in post-menopausal women, therefore resisting menopause/age-related changes and inducing urogenital tract tissue regeneration
Effect of horticultural mineral oil on Huanglongbing transmission by Diaphorina citri Kuwayama (Hemiptera: Psyllidae) population in a commercial citrus orchard in Sarawak, Malaysia, Northern Borneo
Diaphorina citri Kuwayama transmits a destructive citrus disease caused by a fastidious bacterium ‘Candidatus Liberibacter asiaticus’ (CLas) designated as Huanglongbing (HLB) which posed a risk of detrimental threat to the Malaysian citrus industry. All D. citri life stages show a lumped habit on young flushes and its population fluctuations was closely related to accessibility of young flushes. The study aimed to investigate if the appearance of young flush shoots on citrus influences ACP population fluctuation and if horticultural mineral oil (HMO) could reduce spread of HLB transmission by ACP in a commercial healthy orchard. Field research was carried out from 1 April 2011 to 1 December 2014 in a 2-year-old 1 ha citrus farm that consisted of 200 PCR-certified disease-free grafted non-bearing honey tangerine (Citrus reticulata L.) in southwestern Sarawak, Malaysia. The experiment had two treatments namely control (unsprayed) and nC24 HMO with four replications arranged in a simple randomized block design. ACP eggs, nymphs, and adults per flush shoot was assessed and HLB incidence was monitored for visual inspection of the citrus trees for the current existence of usual signs of characteristic symptoms of HLB such as yellowing shoots, leaf mottling, and corky or enlarged veins on leaves. HLB-specific primer was employed in 16S rDNA polymerase chain reaction to detect the CLas gene in diseased trees. Increase in abundance of D. citri is mainly affected by the citrus flushing cycles and their life stages are completed on these flush shoots. Relative degree of aggregation index for D. citri adults increased during periods of cyclic production of new flush. HMO-treated plots produced a significantly lower percentage up to 11.43% of diseased trees against 42.20% in untreated control plots. HMO is effective against D. citri and recommended to be incorporated in the IPM program to prevent infection and reduce the spread of HLB
- …