Evaluation of tea clones for resistance/tolerance to mites infestations and the influence of environmental factors on mites dynamics in Kenyan tea farms

2016 ◽  
Author(s):  
Jenipher A. Odak ◽  
P. Okinda Owuor ◽  
Lawrence O.A. Mang’uro ◽  
Evelyn Cheramgoi ◽  
Francis N. Wachira
Keyword(s):  
Relative Humidity ◽  
Environmental Factors ◽  
Abiotic Factors ◽  
Mitigation Strategies ◽  
Maximum Temperature ◽  
Ecological Zones ◽  
Average Rainfall ◽  
Highly Correlated ◽  
Mite Infestations ◽  
Tolerant Clones

Mites infestations reduce yields in tea production world wide. However, some tea cultivars are resistant/tolerant to mites attack. The resistance/susceptibility can also be influenced by abiotic factors. This study evaluated some new tea clones for mite resistance/susceptibility and influence of Environmental factors (weather parameters) on dynamics of mite infestations of Kenyan tea at different ecological zones, Kangaita, Kipkebe and Timbilil. Maximum population of mites was reported during March when maximum temperature, average rainfall and relative humidity ranges for the sites were 23.9-28.7°C, 27.7-50.1mm and 38.0-70.4% respectively. There was a sharp decline in mites population in April when average rainfall was high (398.4-514.4mm) which was accompanied by reduction in maximum temperature (18.8-27.5°C) and increase in relative humidity (44.0-82.2%). The minimum population density was found during August which was characterized by low maximum temperature (16.4-26.6°C), low average rainfall (4.8- 190.5mm) and high average relative humidity (46.0-80.9%). The mites infestation levels highly correlated with maximum temperatures in Kangaita (r<sup>2</sup> = 0.801), Kipkebe (r<sup>2</sup> = 0.693) and Timbilil (r<sup>2</sup> = 0.744). There were significant (p≤0.05) monthly variations in clonal mite infestations at all sites. Susceptible clones showed higher monthly mite infestations variations than the resistant/tolerant clones. Of the clones evaluated for the first time, eight new clones were identified as tolerant/resistant while two clones were susceptible to mites attack. Resistant/tolerant clones are recommended for commercial exploitation while mitigation strategies should be put in place in mites prone areas during hot seasons with high monthly temperatures and low humidity

scholarly journals Impact of abiotic factors on build-up of citrus psylla, Diaphorina citri Kuwayama population in Punjab, India

2014 ◽  
Vol 6 (2) ◽  
pp. 371-376 ◽  
Author(s):  
Hijam S. Devi ◽  
D. R. Sharma
Keyword(s):  
Relative Humidity ◽  
Disease Transmission ◽  
Minimum Temperature ◽  
Abiotic Factors ◽  
Winter Season ◽  
Seasonal Abundance ◽  
Maximum Temperature ◽  
Weak Links ◽  
Diaphorina Citri ◽  
Citrus Psylla

Seasonal abundance of citrus psylla (Diaphorina citri) Kuwayama was studied on Kinnow mandarin under Punjab conditions during 2012 and 2013. Population of D. citri was present throughout the year but only adults found surviving during December and February. There was no nymphal population when maximum temperature was > 39°C or < 7°C. Two population peaks of nymphs wer e observed, first in April-May and second in August- September. Thereafter, there was abrupt decline in nymphal population during June and July during both the years when the weather conditions i.e. maximum, minimum temperature (°C), relative humidity (%), rainfall (m m) and sunshine (hrs) ranged from 24.4-44, 22.4-31.8, 25.5-100, 0-108.0 and 0-13.5, respectively. Highest peaks of adult were found during May followed by June. With the decrease in temperature from the end of September, the population of D. citri started to decrease and reached its lowest during winter season. Correlation analysis for both the years indicated that maximum and minimum temperature, sunshine and rainfall were positively correlated with nymphal, adult and mixed population but the effect of rainfall on adult population was non-significant, while relative humidity was negatively correlated. The study is useful to find out the weak links of psyllid populations in relation to abiotic factors and that could be exploited to curb its infestation and disease transmission.

scholarly journals Phenological study of congeneric Myrcia species and Clethra scabra in wetland and drained habitats in a Montane Forest

2020 ◽  
Author(s):  
Vinícius Londe ◽  
Jaqueline Alves Pereira ◽  
Hildeberto Caldas de Sousa
Keyword(s):  
Relative Humidity ◽  
Abiotic Factors ◽  
Montane Forest ◽  
The Other ◽  
Maximum Temperature ◽  
Wetland Soil ◽  
Congeneric Species ◽  
Abiotic Conditions ◽  
Local Factors ◽  
The Tropics

Abstract Although important, phenological studies comparing congeneric species or the same species growing in different habitats are still scarce for the tropics. Herein, we integrate phylogeny, ecology and biometeorology to verify whether the phenophases of congeneric species Myrcia laruotteana and Myrcia amazonica or Clethra scabra differ when their populations inhabit wetland and drained habitats and to determine what abiotic factors affect the vegetative and reproductive phenophases of these species in distinct habitat patches. We collected data on phenological events of 80 trees for 1 year in Itacolomi State Park, Brazil, and related them to abiotic local factors. Contrary to our expectation, the phenophases of the congeneric species did not differ between habitats, but the reproductive phenophases of C. scabra did and was greater in drained soil. Phenophases of C. scabra were affected by the depth of the water table and maximum temperature in the wetland soil. Insolation, precipitation, maximum temperature and relative humidity influenced Myrcia and Clethra in the drained soil. The differences between C. scabra populations suggest that this species is phenotypically plastic and can present distinct phenophases depending on the habitat it inhabits. On the other hand, the congeneric Myrcia species may have similar phenophases in distinct habitats because of their shared similarities during their evolution. This study provides a better understanding of the ecology of these species and their adaptations to different abiotic conditions. Data of this nature are important in a changing world and can inform strategies for adaptive management.

scholarly journals Seasonal abundance and effect of abiotic factors on mango leaf hopper Amritodus atkinsoni (Leth.) population on wild and different cultivators of mango in Jammu region

2013 ◽  
Vol 14 (3) ◽  
pp. 161-168
Author(s):  
Shakha Sharma ◽  
J.S Tara
Keyword(s):  
Relative Humidity ◽  
Minimum Temperature ◽  
Significant Positive Correlation ◽  
Abiotic Factors ◽  
Agricultural Science ◽  
Seasonal Abundance ◽  
Maximum Temperature ◽  
Leaf Hopper ◽  
Series Of Experiments ◽  
Agricultural Science And Technology

The mango leaf hopper Amritodus atkinsoni (Leth.) is a very serious pest of mango in J&K region. A series of experiments were conducted on seasonal abundance and the influence of abiotic factors on the incidence of A. atkinsoni on wild and different cultivars of mango viz Dashehari, Langra, Malda and Amarpalli  at Sher-e-Kashmir University of Agricultural Science and Technology Jammu, and, at a mango orchard at Nagbani. The mango hoppers (adults) started appearing with the panicle emergence during the months of February-March and reached its peak ranging from 9.6 to 14.2 in wild and all cultivars under study during May-June. After this the hopper population started declining, but showed another peak (6.6 to 9.8) during August-September which is comparatively lower than the previous one. This clearly indicates that the species breeds twice a year thus a bivoltine species. From September onwards, the hoppers went on declining and vanished by the end of December as they migrate to cracks and crevices of tree trunk and overwinter as adults. Abiotic factors such as maximum temperature (X1), minimum temperature (X2), morning relative humidity (X3), evening relative humidity (X4) and rainfall (X5) had much impact on the growth of hopper population. The hopper population correlated negatively and significantly with morning relative humidity (r = -0.635 to - 0.816) and evening relative humidity (r = - 0.289 to - 0.556) and showed a significant positive correlation with mean maximum temperature (r = 0.692 to 0.915) and minimum temperature (r = 0.590 to 0.881) in wild and all four cultivars, whereas rainfall remained fluctuating throughout the study period thus didn’t show any significant impact.

scholarly journals Influence of Abiotic Factors on Population of Aphid Complex and Its Coexisting Natural Enemies in Mustard Agroecosystem

2021 ◽  
pp. 150-154
Author(s):  
Somala Karthik ◽  
U. Mukherjee
Keyword(s):  
Relative Humidity ◽  
Negative Correlation ◽  
Natural Enemies ◽  
Abiotic Factors ◽  
Maximum Temperature ◽  
Peak Activity ◽  
Rabi Season ◽  
Mustard Aphid ◽  
Positive Correlation ◽  
Syrphid Larvae

A field experiment was conducted to determine the population build-up of mustard aphid and their natural enemies in relation to abiotic factors at TCA, Dholi during the Rabi season of 2018-19 and 2019-20 respectively. The incidence of mustard aphid started in the 2nd and 3rd SMW of 2019 and 2020 respectively and reached maximum in 8th SMW in both the years. However, the predatory activity of coccinellids, syrphid larvae and spiders were started from 3rd SW with their peak activity at 3rd and 4th week of February in both the years. Mustard aphid population exhibited positive correlation with maximum temperature (0.347 & 0.543), minimum temperature (0.317 & 0.152) and negative correlation with relative humidity (-0.083 & -0.479) during 2019 & 2020 respectively and rainfall (-0.35) during 2020. However, natural enemies viz., coccinellids, syrphid larvae and spiders exhibited positive correlation with Tmax, Tmin, rainfall and negative correlation with RH in both the years.

scholarly journals Influência dos Fatores Ambientais e da Quantidade de Néctar na Atividade de Forrageio de Abelhas em Flores de Adenocalymma bracteatum (Cham.) DC. (Bignoniaceae)

2013 ◽  
Vol 6 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Keila Nogueira da Silva ◽  
João Cloves Stanzani Dutra ◽  
Mateus Nucci ◽  
Leandro Pereira Polatto
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Environmental Factors ◽  
Plant Species ◽  
Abiotic Factors ◽  
Pearson Correlation ◽  
Foraging Activity ◽  
Nectar Production ◽  
Focal Area ◽  
Effective Pollinators

Resumo. Este trabalho teve como objetivo avaliar a influência diária dos fatores ambientais e da quantidade de néctar na frequência de forrageio de abelhas em flores de Adenocalymma bracteatum (Cham.) DC. Para isso, foi demarcada uma área focal e registrada a atividade de forrageio das abelhas em um intervalo de 30 minutos para cada hora, das 6:00 às 17:30 h, nas flores da referida espécie vegetal durante quatro dias não consecutivos. Também foi avaliada a produção acumulativa de néctar e o seu consumo pelos visitantes no decorrer do dia. Dados referentes à temperatura, umidade relativa do ar, luminosidade e velocidade do vento foram anotados no início de cada hora. Para verificar se as frequências de forrageios das espécies de abelhas estavam correlacionadas com os fatores abióticos, foram realizados testes de correlação de Pearson. Dentre as espécies registradas, Oxaea flavescens Klug apresentou o maior número de forrageios. O número de forrageio no decorrer do dia não se manteve uniforme, o que faz acreditar que a atividade de forrageio das abelhas sofreu interferência dos fatores ambientais e da quantidade de néctar presente nas flores de A. bracteatum. Os polinizadores efetivos foram responsáveis por 51,6% do total de visitas por flor em A. bracteatum, enquanto os pilhadores de recursos perfizeram 33,1% e os furtadores de recursos realizaram somente 15,3% do total de visitas por flor. Houve ainda, forrageios de formigas e moscas. As formigas sugavam néctar extrafloral, possivelmente conferindo proteção contra pilhagem de néctar. Já as moscas pousavam na corola, mas não extraíram néctar nem pólen. Influence in the Environmental Factors and the Amount of Nectar in the Foraging Activity of Bees on Flowers Adenocalymma bracteatum (Cham.) DC. (Bignoniaceae) Abstract. This study aimed to evaluate the daily influence of environmental factors and the amount of nectar in the foraging frequency of bees on flowers Adenocalymma bracteatum (Cham.) DC. For this, a focal area was demarcated and registered foraging activity of bees in a 30-minute break for every hour from 6:00 a.m. to 5:30 p.m., in the flowers of this plant species during four non-consecutive days. Also was analyzed the nectar production and its consumption by visitors throughout the day. Data relating to temperature, relative humidity, luminosity, and wind speed were recorded at the beginning of each hour. To check if the frequencies of foraging the bee species were correlated with abiotic factors, tests of Pearson correlation were performed. Among the species recorded, Oxaea flavescens Klug had the highest number of foraging. The number of foraging during the day did not remain uniform, which makes to believe that foraging activity of bees suffered interference from environmental factors and the amount of nectar present in flowers of A. bracteatum. The effective pollinators were responsible for 51.6% of total visits per flower in A. bracteatum, while the robber’s resources totaled 33.1%, and only 15.3% of all visits were made by thieves’ resource. There was also foraging of ants and flies. Nectar present around the flower was sucked by ants, possibly conferring protection against robbery nectar. There were flies landing on the corolla of the flowers, but nectar and pollen were not collected.

scholarly journals Associations of Acute Exposure to Airborne Pollutants with COVID-19 Infection: Evidence from China

2021 ◽  
Author(s):  
Bingqing Lu ◽  
Na Wu ◽  
Jiakui Jiang ◽  
Xiang Li
Keyword(s):  
Relative Humidity ◽  
Environmental Factors ◽  
Generalized Additive Model ◽  
Additive Model ◽  
Mitigation Strategies ◽  
Atmospheric Pollutants ◽  
Acute Exposure ◽  
Airborne Pollutants ◽  
Relative Risks ◽  
Pollutant Concentrations

Abstract The outbreak of COVID-19, caused by SARS-CoV-2 has spread across many countries globally. Greatly limited study concerned the effect of airborne pollutants on COVID-19 infection, while exposure to airborne pollutants may harm human health. This paper aimed to examine the associations of acute exposure to ambient atmospheric pollutants to daily newly COVID-19 confirmed cases in 41 Chinese cities. Using a generalized additive model with Poisson distribution controlling for temperature and relative humidity, we evaluated the association between pollutant concentrations and daily COVID-19 confirmation at single-city level and multi-city level. We observed a 10 μg/m3 rise in levels of PM2.5 (lag 0−14), O3 (lag 0−1), SO2 (lag 0) and NO2 (lag 0−14) were positively associated with relative risks of 1.050 (95% CI: 1.028, 1.073), 1.011 (1.007, 1.015), 1.052 (1.022, 1.083) and 1.094 (1.028, 1.164) of daily newly confirmed cases, respectively. Further adjustment for other pollutants did not change the associations materially (excepting in the model for SO2). Our results indicated that COVID-19 incidence may be susceptible to airborne pollutants such as PM2.5, O3, SO2 and NO2, and mitigation strategies of environmental factors are required to prevent spreading.

scholarly journals OPTIMIZATION OF ENVIRONMENTAL FACTORS CONDUCIVE FOR STRIPE RUST OF WHEAT

2017 ◽  
Vol 29 (2) ◽  
pp. 239
Author(s):  
Yasir Ali ◽  
Muhammad A. Khan ◽  
Muhammad Atiq ◽  
Waseem Sabir ◽  
Arslan Hafeez ◽  
...  
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Environmental Factors ◽  
Disease Severity ◽  
Puccinia Striiformis ◽  
Yellow Rust ◽  
Maximum Temperature ◽  
Wheat Crop ◽  
Severe Condition ◽  
Wheat Diseases

Wheat rusts are the significant diseases of wheat crop and potential threats worldwide. Among all major wheat diseases occurring in all wheat growing areas of the world, yellow rust caused by Puccinia striiformis f. sp. tritici is a big hazard when it occurs in severe condition. The susceptible germplasm and conducive environmental conditions contribute towards wide outbreak of rust diseases. In the present study, eight wheat lines were screened out and correlated with epidemiological factors (temperature, relative humidity, rainfall and wind speed). Results showed that maximum disease severity was observed at minimum and maximum temperature ranging from 13.7-16.7 and 23.5-27.65 0C respectively. Their disease severity was increased with increase in relative humidity ranging from 52-64 %. Similarly, rain fall ranging from 5.7-21.99 mm and wind speed 6.88-11.73 km/h respectively proved conducive for yellow rust development in Sargodha. A positive correlation was observed between disease severity and all environmental factors.

Surveillance of pea leaf miner (P. horticola) infesting pea (Pisum sativum) in relation with abiotic factors

2019 ◽  
Vol 25 (2) ◽  
Author(s):  
Ram Keval ◽  
H.S. Vanajakshi ◽  
Sunil Verma ◽  
Babli Bagri
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Minimum Temperature ◽  
Abiotic Factors ◽  
Negative Relationship ◽  
Positive Association ◽  
Leaf Miner ◽  
Maximum Temperature ◽  
Seasonal Incidence ◽  
Sunshine Hours

To study the seasonal incidence of insect pests of pea (P. sativum) the investigation was carried out during Rabi session of 2016-17 and 2017-18, at Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi. The incidence of pests infesting pea was recorded from 50th SMW to 11th SMW. During the observation it was found that P. horticola showed its appearance in the field from 1st to 11th SMW with peak population (71% leaf infestation) in 7th SMW. When population was correlated with abiotic factors it was found that there was positive association with maximum temperature (r = 0.759**), minimum temperature (r = 0.672**), wind speed (r = 0.449).and sunshine hours (r =0.583*) whereas a negative relationship was maintained with morning relative humidity (r =-0.496) and evening relative humidity (r=-0.515), during 2016- 17. Similarly, during 2017-18 there was a positive association with maximum temperature (r = 0.360), minimum temperature (r =0.431), wind speed (r = 0.544*) and sunshine hours(r=0.493) whereas a negative relationship was maintained with morning relative humidity (r =-0.277) and evening relative humidity (r=-0.365).

scholarly journals Population dynamics of early shoot borer, Chilo infuscatellus Snellen on sugarcane as influenced by weather conditions

2018 ◽  
Vol 10 (4) ◽  
pp. 1297-1302
Author(s):  
Kanwar Kumar ◽  
Maha Singh Jaglan ◽  
Tarun Verma
Keyword(s):  
Population Dynamics ◽  
Relative Humidity ◽  
Environmental Factors ◽  
Weather Conditions ◽  
Control Measures ◽  
Maximum Temperature ◽  
Research Station ◽  
Chilo Infuscatellus ◽  
Positive Correlation ◽  
Shoot Borer

A field experiment on population dynamics of early shoot borer, Chilo infuscatellus Snellen on sugarcane was carried out during 2016-17 crop season at the research farm of CCS Haryana Agricultural University, Regional Research Station, Karnal. Studies on population dynamics revealed thathighest incidence (3.81 per cent in CoH 160, 4.60 per cent in CoH 119 and 3.12 per cent in CoS 767) of C. infuscatellus was recorded during 24th SMW. Correlation of C. infuscatellus population with various environmental factors revealed that there was a significant positive correlation with maximum temperature (Tmax.) and had a non-significant and positive correlation with minimum temperature (Tmin.) and sun shine hours (SSH) (r= 0.513, 0.287 and 0.452) on CoH 160, (r= 0.504, 0.321 and 0.431) on CoH 119 and(r= 0.537, 0.276 and 0.445) on CoS 767, respectively whereas it has non-significant and negative correlation with relative humidity (morning), relative humidity (evening) andrainfall (r= -0.172, -0.206 and -0.147) on CoH 160, (r= -0.147, -0.172 and -0.130) on CoH 119 and(r= -0.187, -0.223 and -0.160) on CoS 767. Multiple regression analysis of C. infuscatellus population with weather parameters showed that there was 77 per cent (CoH 160), 75 per cent (CoH 119) and 76 per cent (CoS767) variability in dead heart formation due to various environmental factors. The population dynamics revealed by this study have far reaching significance in pest management strategy as integrated control measures may be focused only during the period wherein population exceeds economic threshold level (ETL).

scholarly journals Temporal Variability, Trends of Climatic Variables and Drought Analysis of Rajshahi and Sylhet District, Bangladesh

2021 ◽  
Vol 46 (2) ◽  
pp. 133-141
Author(s):  
Fatamatuj Sunny ◽  
Md Selim Miah ◽  
Md Younus Mia ◽  
Ruksana Haque Rimi
Keyword(s):  
Relative Humidity ◽  
Minimum Temperature ◽  
Climatic Variables ◽  
Maximum Temperature ◽  
Climate Index ◽  
Climatic Data ◽  
Climatic Indices ◽  
Sen’S Slope ◽  
Average Maximum ◽  
Average Rainfall

The study was conducted to quantify the change of selected climatic variables (rainfall, relative humidity, maximum and minimum temperature) over 50 years at Rajshahi and Sylhet districts in Bangladesh. Annual, seasonal, and monthly climatic data comparisons have been executed between 1968-1992 and 1993-2017 through trend analysis. The Mann-Kendall statistic and Sen's Slope model were used to reveal the trends and estimate the magnitude of change respectively. Prediction of the climatic variable of 10 years (2018-2027) was made based on the ARAR algorithm using MaxStat Pro software. Rainfall data were used to analyze drought by using climatic indices (De Mortone Aridity Index, IdM; Seleaninov Hydrothermic Index, IhS; Donciu Climate Index, IcD). Average rainfall was decreasing dramatically in monsoon season at Rajshahi and in both premonsoon and monsoon seasons at Sylhet. The negative change of average rainfall in the monsoon at Rajshahi from 1968-1992 to 1993-2017 was found 29.17 mm. The maximum temperature was increasing in all seasons in both Rajshahi and Sylhet. Annual Mannkendall trend test and Sen’s slope revealed that relative humidity was decreasing and maximum temperature was increasing significantly at Sylhet for the period 1993-2017. At Rajshahi, during 1968-1992, relative humidity was increasing by 0.247 % per year, and minimum temperature was decreasing 0.049℃ per year. Rainfall was decreasing insignificantly in both time scales. ARAR algorithm predicted that average maximum temperature might become comparatively higher than the previous 50 years. 1992 and 2010 were identified as drought years from all climatic indices, and 1969, 1981, and 1997 as excessive wet years at Rajshahi. No drought events were identified during 1968-2017 at Sylhet and the year 2017 to be an excessively wet year. IhS predicted 2020, 2025, and 2027 as drought years and 2024 as an excessive wet year at Sylhet. Asiat. Soc. Bangladesh, Sci. 46(2): 133-141, December 2020

Sign in / Sign up

Export Citation Format

Share Document