Evaluation of onion (Allium cepa) germplasm entries for resistance to onion thrips, Thrips tabaci (Lindeman) in Tanzania

2017 ◽  
Vol 37 (02) ◽  
pp. 98-113 ◽  
Author(s):  
Gabriel Michael Njau ◽  
Agnes M. S. Nyomora ◽  
Fekadu Fufa Dinssa ◽  
Jian-Cheng Chang ◽  
P. Malini ◽  
...  
Keyword(s):  
Negative Relationship ◽  
Thrips Tabaci ◽  
Sub Saharan Africa ◽  
Leaf Damage ◽  
Leaf Angle ◽  
Total Phenol Content ◽  
Onion Thrips ◽  
Leaf Toughness ◽  
Biochemical Basis ◽  
Significant Negative Relationship

AbstractOnion thrips,Thrips tabaci(Lindeman), is a prominent species infesting onion and tomato in the northern highlands of Tanzania. It causes considerable leaf damage by direct feeding and also transmits theIris yellow spot virus(IYSV). Hence, one of the objectives of this study was to identify the most resistant onion entries againstT. tabaci.One highly resistant (VI038552) and two resistant onion entries (VI038512 and AVON 1067) were identified againstT. tabaci. Besides thrips resistance, the bulb size of VI038512 was also equivalent to one of the commercial varieties, Texas. The highly resistant VI038552 recorded the highest yield, followed by the resistant entry, VI038512. However, the yield of AVON 1067 was significantly lower. Elucidation of the biophysical bases of resistance revealed that there was a significant negative correlation between leaf angle as well as leaf toughness and thrips damage. The total epicuticular wax content in the leaves had a weak and non-significant negative relationship with thrips damage. The scanning electron microscopic study confirmed that the wax crystals occurred as filaments, rods, platelets, tubes and complex dendritic structures, and that they were densely arranged in resistant or moderately resistant entries. Studies on the biochemical basis of resistance confirmed that there was a significant negative relationship between total phenol content and thrips damage. Similarly, the relationship between total foliar amino acids or total sugars and thrips damage was inversely correlated and non-significant. Hence, entries VI038552 and VI038512 could be promising candidates for breeding programmes aimed at developing onion varieties that are resistant to thrips and that are high yielding, which will help to enhance the productivity of onions in sub-Saharan Africa.

scholarly journals Spatial and seasonal distribution of Bulinus globosus and Biomphalaria pfeifferi in Ingwavuma, uMkhanyakude district, KwaZulu-Natal, South Africa: Implications for schistosomiasis transmission at micro-geographical scale

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Tawanda Manyangadze ◽  
Moses John Chimbari ◽  
Owen Rubaba ◽  
White Soko ◽  
Samson Mukaratirwa
Keyword(s):  
South Africa ◽  
Dissolved Oxygen ◽  
Intermediate Host ◽  
Negative Relationship ◽  
Sub Saharan Africa ◽  
Significant Negative Relationship ◽  
Generalised Linear Mixed Model ◽  
Kwazulu Natal ◽  
Geographical Scale ◽  
Bulinus Globosus

Abstract Background Schsistosomiasis is endemic in sub-Saharan Africa. It is transmitted by intermediate host snails such as Bulinus and Biomphalaria. An understanding of the abundance and distribution of snail vectors is important in designing control strategies. This study describes the spatial and seasonal variation of B. globosus and Bio. pfeifferi and their schistosome infection rates between May 2014 and May 2015 in Ingwavuma, uMkhanyakude district, KwaZulu-Natal province, South Africa. Methods Snail sampling was done on 16 sites once every month by two people for 30 min at each site using the scooping and handpicking methods. Snails collected from each site were screened for schistosome mammalian cercariae by the shedding method. The negative binomial generalised linear mixed model (glmm) was used to determine the relationship between abundances of the intermediate host snails and climatic factors [rainfall, land surface temperatures (LST), seasons, habitats, sampling sites and water physico-chemical parameters including pH and dissolved oxygen (DO)]. Results In total, 1846 schistosomiasis intermediate host snails were collected during the study period. Biompharia pfeifferi was more abundant (53.36%, n = 985) compared to B. globosus (46.64%, n = 861). Bulinus globosus was recorded at 12 sites (75%) and Bio. pfeifferi was present at 7 sites (43.8%). Biompharia pfeifferi cohabited with B. globosus at all the sites it was present. High numbers of Bio. pfeifferi (n = 872, 88.5%) and B. globosus (n = 705, 81.9%) were found between winter and mid-spring. Monthly rainfall showed a statistically significant negative relationship with the abundance of B. globosus (p < 0.05). Dissolved oxygen (DO) had a statistically significant positive relationship with the abundance of Bio. pfeifferi (p < 0.05) while (LST) had a statistically significant negative relationship (p < 0.05). More B. globosus (8.9%, n = 861) were shedding schistosome mammalian cercariae compared to Bio. pfeifferi (0.1%, n = 985) confirming the already documented high prevalence of S. haematobium in Ingwavuma compared to S. mansoni. Conclusion Results of this study provide updated information on the distribution of schistosomiasis intermediate host snails in the study area and contributes towards the understanding of the transmission dynamics of schistosomiasis at the micro-geographical scale in this area. Graphic Abstract

Globalization, Poverty, Environmental Degradation and Economic Growth Nexus: Empirical Analysis of SAARC Regions

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Adiqa Kiani ◽  
Ejaz Ullah ◽  
Khair Muhammad
Keyword(s):  
Economic Growth ◽  
Sri Lanka ◽  
Empirical Analysis ◽  
Environmental Degradation ◽  
Negative Relationship ◽  
Policy Makers ◽  
Significant Negative Relationship ◽  
The Impact

The main objective of this study is to investigate the impact of poverty, globalization, and environmental degradation on economic growth in the selected SAARC countries. This study is employed panel Autoregressive Distributive Lag (ARDL) technique for empirical analysis using selected SAARC regions including India, Pakistan, Bangladesh, Nepal and Sri Lanka over the period of 1980 to 2018. Globalization impacts economic growth positively and significantly.  In addition to this the significant negative relationship is found between population and economic growth. The results show that poverty is positively related with environmental degradation. Furthermore, the results indicate that globalization is positively and significantly associated with environmental degradation in the SAARC region. Finally, the results show that urbanization is positive and significantly associated with environmental degradation, which could be the serious concerns for the policy makers to control.

Eliminating Thrips in Microshoot Cultures

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 506d-506
Author(s):  
Robert R. Tripepi ◽  
Holly J. Schwager ◽  
Mary W. George ◽  
Joseph P. McCaffrey
Keyword(s):  
Betula Pendula ◽  
Culture Media ◽  
Dry Weight ◽  
Thrips Tabaci ◽  
Shoot Cultures ◽  
Onion Thrips ◽  
Ulmus Americana ◽  
Shoot Height ◽  
Tissue Culture Media ◽  
Plant Tissue Cultures

Two insecticides, acephate or azadirachtin, were added to tissue culture media to determine their effectiveness in controlling onion thrips (Thrips tabaci Lindeman.) and to determine if these insecticides could damage the plant shoot cultures. To test for insecticide phytotoxicity, microshoots from European birch (Betula pendula), American elm (Ulmus americana), `Pink Arola' chrysanthemum (Dendranthema grandiflora), `America' rhododendron (Rhododendron catawbiense), `Golden Emblem' rose (Rosa hybrida), and `Gala' apple (Malus domestica) were placed in 130-ml baby food jars containing 25 ml of medium supplemented with 6.5, 13, or 26 mg/l Orthene® (contained acephate) or 0.55, 1.1, or 2.2 ml/l Azatin® (contained azadirachtin). Control jars lacked insecticide. To test for thrips control, 13 mg/l Orthene® or 0.55 ml/l Azatin® was added to Murashige and Skoog medium, and 10 thrips were placed on `Gala' apple microshoots in each jar. Jars were sealed with plastic wrap. In both studies, microshoot dry weight and heights were determined. In the second study, the total number of thrips per jar was also determined 3 weeks after inoculation. Microshoots on Orthene®-treated media lacked phytotoxicity symptoms, regardless of the concentration used. In contrast, Azatin® hindered plant growth, decreasing shoot height or dry weight by up to 85% depending on the species. Both insecticides prevented thrips populations from increasing, since less than 10 thrips were found in jars with insecticide-treated medium. Control jars, however, contained an average of almost 70 thrips per jar. This study demonstrated that both Orthene® and Azatin® were effective for eradicating thrips from plant tissue cultures, but Orthene® should probably be used because Azatin® was phytotoxic to all species tested.

Organization-Based Self-Esteem Affects Employees' Exchange Relationship Perceptions and Extrarole Behavior

2016 ◽  
Vol 44 (3) ◽  
pp. 509-517 ◽  
Author(s):  
Yanhan Zhu
Keyword(s):  
Social Exchange ◽  
Positive Relationship ◽  
Mainland China ◽  
Negative Relationship ◽  
Self Esteem ◽  
Moderating Effect ◽  
Exchange Relationship ◽  
Significant Positive Relationship ◽  
Significant Negative Relationship ◽  
Practical Implications

The 2 types of exchange relationship perceptions—social exchange relationship perceptions (SERPs) and economic exchange relationship perceptions (EERPs)—constitute the primary concept for understanding individual behavior in the workplace. Using a sample of 581 employees from Mainland China, I explored the effects of SERPs and EERPs on employee extrarole behavior (ERB), as well as the moderating effect of organization-based self-esteem (OBSE) on the relationships between SERPs and ERB, and between EERPs and ERB. The results revealed a significant positive relationship between SERPs and ERB, a significant negative relationship between EERPs and ERB, and a significant moderating effect for OBSE. Theoretical and practical implications of these findings are discussed.

scholarly journals Financial Performance of Iranian Banks from 2013 to 2019: A Panel Data Approach

2021 ◽  
Vol 14 (6) ◽  
pp. 257
Author(s):  
Pejman Ebrahimi ◽  
Maria Fekete-Farkas ◽  
Parisa Bouzari ◽  
Róbert Magda
Keyword(s):  
Financial Performance ◽  
Inflation Rate ◽  
Banking Sector ◽  
Stock Exchange ◽  
Screening Method ◽  
Negative Relationship ◽  
Statistical Population ◽  
Explanatory Variables ◽  
Significant Negative Relationship ◽  
Research Population

It is widely believed that the financial system is dependent on the banking industry, and its strength and development are vital for economic prosperity. This paper tried to show the financial performance of Iranian banks listed on the Tehran Stock Exchange (TSE) during 2013–2019, as the research population. The statistical population included 18 banks listed on the TSE from 2013 to 2019, which were sampled using a screening method. The results indicated a significant relationship between explanatory variables of capital ratio and the financial performance of banks in all models. However, a significant negative relationship was found between the inflation rate and the financial performance of banks in all models. Furthermore, it seems that banks with high asset strength are more profitable than the others. Regulators should guarantee that banks remain highly capitalized for a viable banking sector in Iran.

scholarly journals Within-Season Changes in Land-Use Impact Pest Abundance in Smallholder African Cassava Production Systems

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 269 ◽  
Author(s):  
Andrew Kalyebi ◽  
Sarina Macfadyen ◽  
Andrew Hulthen ◽  
Patrick Ocitti ◽  
Frances Jacomb ◽  
...  
Keyword(s):  
Land Use ◽  
Bemisia Tabaci ◽  
Large Scale ◽  
Production Systems ◽  
Smallholder Farmers ◽  
Negative Relationship ◽  
Central Africa ◽  
Sub Saharan Africa ◽  
Smallholder Farming ◽  
Manihot Esculenta Crantz

Cassava (Manihot esculenta Crantz), an important commercial and food security crop in East and Central Africa, continues to be adversely affected by the whitefly Bemisia tabaci. In Uganda, changes in smallholder farming landscapes due to crop rotations can impact pest populations but how these changes affect pest outbreak risk is unknown. We investigated how seasonal changes in land-use have affected B. tabaci population dynamics and its parasitoids. We used a large-scale field experiment to standardize the focal field in terms of cassava age and cultivar, then measured how Bemisia populations responded to surrounding land-use change. Bemisia tabaci Sub-Saharan Africa 1 (SSA1) was identified using molecular diagnostics as the most prevalent species and the same species was also found on surrounding soybean, groundnut, and sesame crops. We found that an increase in the area of cassava in the 3–7-month age range in the landscape resulted in an increase in the abundance of the B. tabaci SSA1 on cassava. There was a negative relationship between the extent of non-crop vegetation in the landscape and parasitism of nymphs suggesting that these parasitoids do not rely on resources in the non-crop patches. The highest abundance of B. tabaci SSA1 nymphs in cassava fields occurred at times when landscapes had large areas of weeds, low to moderate areas of maize, and low areas of banana. Our results can guide the development of land-use strategies that smallholder farmers can employ to manage these pests.

scholarly journals Young L2 learners’ online processing of information in a graded reader during reading-only and reading-while-listening conditions: A study of eye-movements

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Raquel Serrano ◽  
Ana Pellicer-Sánchez
Keyword(s):  
Reading Comprehension ◽  
Reading Fluency ◽  
Negative Relationship ◽  
Auditory Input ◽  
Reading Tests ◽  
Textual Information ◽  
Multimodal Texts ◽  
Time Processing ◽  
Online Processing ◽  
Significant Negative Relationship

AbstractCombining reading with auditory input has been shown to be an effective way of supporting reading fluency and reading comprehension in a second language. Previous research has also shown that reading comprehension can be further supported by pictorial information. However, the studies conducted so far have mainly included adults or adolescents and have been based on post-reading tests that, although informative, do not contribute to our understanding of how learners’ processing of the several sources of input in multimodal texts changes with the presence of auditory input and the effect that potential differences could have on comprehension. The present study used eye-tracking to examine how young learners process the pictorial and textual information in a graded reader under reading only and reading-while-listening conditions. Results showed that readers spent more time processing the text in the reading only condition, while more time was spent processing the images in the reading-while-listening mode. Nevertheless, comprehension scores were similar for the readers in the two conditions. Additionally, our results suggested a significant (negative) relationship between the amount of time learners spent processing the text and comprehension scores in both modes.

Workplace disability and job satisfaction in Britain: A co-worker test?

2021 ◽  
pp. 0143831X2110142
Author(s):  
Getinet Astatike Haile
Keyword(s):  
Job Satisfaction ◽  
Negative Relationship ◽  
Organisational Culture ◽  
Seemingly Unrelated Regression ◽  
Unrelated Regression ◽  
Significant Negative Relationship ◽  
Using Data

The article examines the link between workplace disability (WD) and workplace job satisfaction (JS) using data from WERS2011. Controlling for a rich set of workplace characteristics including organisational culture, the study finds a significant negative relationship between JS and the share of disabled respondents within workplaces. Notably, Seemingly Unrelated Regression (SUR)-based analysis distinguishing between disabled and non-disabled respondents reveals that the negative relationship found is specific to non-disabled respondents. Moreover, disability equality policies are found to be significantly positively related with disabled respondents’ JS while they are negatively related with the JS of their non-disabled counterparts. The article ponders if there is a co-worker aspect to the WD–JS link and whether HR policies may need to take heed of co-worker dynamics in this respect.

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