Idioscopus clypealis (mango leafhopper).

2021 ◽  
Author(s):  
R Ganeswaran
Keyword(s):  
Population Size ◽  
Indian Subcontinent ◽  
Uttar Pradesh ◽  
The Philippines ◽  
Yield Reduction ◽  
Bud Break ◽  
Flowering Stage ◽  
Flower Bud ◽  
Economic Injury ◽  
The Mean

Abstract Mango leafhoppers are major pests in the Indian subcontinent. The major damage caused is at the flowering stage and several studies have highlighted the reduction of yield which may be between 20 and 100% depending on population size. Verghese and Rao (1987) examined the critical infestation stages of I. clypealis in Uttar Pradesh, India. The mean density of cicadellids was 0.54-20.64 per panicle in 1983 and 0-6.03 per panicle in 1984. In both years, the peak population occurred when the fruit was pea sized. At the post-bloom stage a population of two adults per panicle was sufficient to cause yield reduction. It is suggested that the critical infestation stages are at post-bloom, when the fruit is marble sized, and 1 month before harvest, with corresponding critical population levels of two adults, 6-21 nymphs and 4-11 hoppers per panicle. In the Philippines, Corey et al. (1989) found that the economic injury levels for I. clypealis on two croppings of mangoes averaged 4.21, 4.30, 4.45 and 4.55 adults per panicle at 2, 10, 18 and 26 days, respectively, after flower bud break for the first cropping, and 4.79, 4.88, 5.06 and 5.18 adults per panicle for the second cropping.

Idioscopus nagpurensis (mango leafhopper).

2021 ◽  
Author(s):  
R. Ganeswaran
Keyword(s):  
Related Species ◽  
Indian Subcontinent ◽  
Uttar Pradesh ◽  
The Philippines ◽  
Yield Reduction ◽  
Bud Break ◽  
Flowering Stage ◽  
Flower Bud ◽  
Economic Injury ◽  
The Mean

Abstract Mango leafhoppers are major pests in the Indian subcontinent. The major damage is caused at the flowering stage and several studies have highlighted the reduction of yield which may be between 20 and 100% depending on population size. Verghese and Rao (1987) examined the critical infestation stages of the related species I. clypealis in Uttar Pradesh, India. The mean density of cicadellids was 0.54-20.64 per panicle in 1983 and 0-6.03 per panicle in 1984. In both years, the peak population occurred when the fruit was pea sized. At the post-bloom stage a population of two adults per panicle was sufficient to cause yield reduction. It is suggested that the critical infestation stages are at post-bloom, when the fruit is marble sized, and 1 month before harvest, with corresponding critical population levels of two adults, 6-21 nymphs and 4-11 hoppers per panicle. In the Philippines, Corey et al. (1989) found that the economic injury levels for I. clypealis on two croppings of mangoes averaged 4.21, 4.30, 4.45 and 4.55 adults per panicle at 2, 10, 18 and 26 days, respectively, after flower bud break for the first cropping, and 4.79, 4.88, 5.06 and 5.18 adults per panicle for the second cropping.

Idioscopus nitidulus (mango leafhopper).

2021 ◽  
Author(s):  
R Ganeswaran
Keyword(s):  
Indian Subcontinent ◽  
Uttar Pradesh ◽  
The Philippines ◽  
Economic Importance ◽  
Yield Reduction ◽  
Bud Break ◽  
Flowering Stage ◽  
Flower Bud ◽  
Economic Injury ◽  
The Mean

Abstract According to Viraktamath (1989), 14 idiocerine species in three genera (Amritodus, Busoniomimus and Idioscopus) breed on mango, and of these only six are of economic importance. Mango leafhoppers are major pests in the Indian subcontinent. The major damage caused is at the flowering stage and several studies have highlighted the reduction of yield which may be between 20 and 100% depending on population size. Verghese and Rao (1987) examined the critical infestation stages of the related species I. clypealis in Uttar Pradesh, India. The mean density of cicadellids was 0.54-20.64 per panicle in 1983 and 0-6.03 per panicle in 1984. In both years, the peak population occurred when the fruit was pea sized. At the post-bloom stage a population of two adults per panicle was sufficient to cause yield reduction. It is suggested that the critical infestation stages are at post-bloom, when the fruit is marble sized, and 1 month before harvest, with corresponding critical population levels of two adults, 6-21 nymphs and 4-11 hoppers per panicle. In the Philippines, Corey et al. (1989) found that the economic injury levels for I. clypealis on two croppings of mangoes averaged 4.21, 4.30, 4.45 and 4.55 adults per panicle at 2, 10, 18 and 26 days, respectively, after flower bud break for the first cropping, and 4.79, 4.88, 5.06 and 5.18 adults per panicle for the second cropping.

Evaluation of Leaf Consumption and Determination of Economic Injury Level Caused by Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Brassica oleracea var. acephala (Brassicales: Brassicaceae)

2019 ◽  
Vol 112 (4) ◽  
pp. 1805-1811
Author(s):  
Angélica Massarolli ◽  
Bruna Camila Gualda Bersani ◽  
Fernando Henrique Dalla Roza ◽  
Alessandra Regina Butnariu ◽  
Mônica Josene Barbosa Pereira ◽  
...  
Keyword(s):  
Pest Control ◽  
Plutella Xylostella ◽  
Yield Reduction ◽  
Economic Injury Level ◽  
Control Cost ◽  
Collard Greens ◽  
Market Values ◽  
Leaf Consumption ◽  
Economic Injury ◽  
The Mean

Abstract Plutella xylostella (L.) is a microlepidopteran found in all brassica-producing regions of the world. However, no economic injury level (EIL) has been established for this pest in collard greens. Therefore, studies evaluating the EIL of P. xylostella in this crop based on the number of caterpillars per plant can assist pest monitoring and the most effective time for pest control, ensuring profits and the use of pesticides only when required. The present study assessed leaf consumption of caterpillars at different levels of infestation and determinined the EIL for P. xylostella in collard greens. Based on the yield reduction index of collard greens for P. xylostella, EIL was estimated for different scenarios of pest control costs, setting the market value of the bunch of collard greens, and, alternatively, with prices varying and the control cost fixed. In simulated scenarios for 7 d after infestation, the number of caterpillars per plant was always below 1.38, whereas for 10 d, the maximum number was 1.25 caterpillars per plant. When simulating scenarios with different market values for the bunch of collard greens the lower the price of the collard greens bunch, the higher the mean number of caterpillars per plant to compensate the application cost. The mean number of caterpillars per plant ranged from 4.59 to 0.38 in the evaluation for 7 d, and from 4.17 to 0.35 caterpillars per plant for 10 d according to the price of the bunch of collard greens.

scholarly journals Study of Bunchy Top of Banana Virus (BBTV) and its Control by Integrated Disease Management (IDM)

2021 ◽  
Vol 10 (11) ◽  
pp. 416-429
Author(s):  
S. S. Waghmare S. R. Adat ◽  
V. K. Mohite A. A. Waghule ◽  
S. S. Patale
Keyword(s):  
Tamil Nadu ◽  
Andhra Pradesh ◽  
Uttar Pradesh ◽  
The Philippines ◽  
International Exchange ◽  
Economic Losses ◽  
Yield Reduction ◽  
Banana Bunchy Top Virus ◽  
Banana Production ◽  
The Tropics

India is the top country by Banana production in the world as of 2019, bananas production in India was 30.5 million tonnes that accounts for 26.02% of the world's bananas production. The top 5 countries (others are China, Indonesia, Brazil, and Ecuador) account for 53.94% of it. The world's total bananas production was estimated at 117 million tonnes in 2019.In India, states like Andhra Pradesh, Gujarat, Tamil Nadu, Maharashtra, Kerala, Uttar Pradesh, Bihar and Madhya Pradesh contribute more than 70 per cent of the country's banana production. Banana and plantain (Musa spp.), produced in 10.3 million ha in the tropics, are among the world's top 10 food crops. They are vegetative propagated using suckers or tissue culture plants and grown almost as perennial plantations. They are vulnerable to pests and pathogens, especially viruses which causes reduction in yield and are also hinders to the international exchange of germplasm. The most economically important viruses of banana and plantain are Banana bunchy top virus (BBTV), a complex of banana streak viruses (BSVs) and Banana bract mosaic virus (BBrMV). BBTV is known to cause the most serious economic losses contributing to yield reduction of up to 100% and responsible for a dramatic reduction in cropping area. The BSVs exist as episomal and endogenous forms are known to be worldwide in distribution. In India and the Philippines, BBrMV is known to be economically important.

scholarly journals Country-level determinants of the severity of the first global wave of the COVID-19 pandemic: an ecological study

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e042034
Author(s):  
Tiberiu A Pana ◽  
Sohinee Bhattacharya ◽  
David T Gamble ◽  
Zahra Pasdar ◽  
Weronika A Szlachetka ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Vaccination Coverage ◽  
Urban Areas ◽  
Ecological Study ◽  
Environmental Parameters ◽  
The Philippines ◽  
International Travel ◽  
Bcg Vaccination ◽  
Country Level ◽  
The Mean

ObjectiveWe aimed to identify the country-level determinants of the severity of the first wave of the COVID-19 pandemic.DesignEcological study of publicly available data. Countries reporting >25 COVID-19 related deaths until 8 June 2020 were included. The outcome was log mean mortality rate from COVID-19, an estimate of the country-level daily increase in reported deaths during the ascending phase of the epidemic curve. Potential determinants assessed were most recently published demographic parameters (population and population density, percentage population living in urban areas, population >65 years, average body mass index and smoking prevalence); economic parameters (gross domestic product per capita); environmental parameters (pollution levels and mean temperature (January–May); comorbidities (prevalence of diabetes, hypertension and cancer); health system parameters (WHO Health Index and hospital beds per 10 000 population); international arrivals; the stringency index, as a measure of country-level response to COVID-19; BCG vaccination coverage; UV radiation exposure; and testing capacity. Multivariable linear regression was used to analyse the data.Primary outcomeCountry-level mean mortality rate: the mean slope of the COVID-19 mortality curve during its ascending phase.ParticipantsThirty-seven countries were included: Algeria, Argentina, Austria, Belgium, Brazil, Canada, Chile, Colombia, the Dominican Republic, Ecuador, Egypt, Finland, France, Germany, Hungary, India, Indonesia, Ireland, Italy, Japan, Mexico, the Netherlands, Peru, the Philippines, Poland, Portugal, Romania, the Russian Federation, Saudi Arabia, South Africa, Spain, Sweden, Switzerland, Turkey, Ukraine, the UK and the USA.ResultsOf all country-level determinants included in the multivariable model, total number of international arrivals (beta 0.033 (95% CI 0.012 to 0.054)) and BCG vaccination coverage (−0.018 (95% CI −0.034 to –0.002)), were significantly associated with the natural logarithm of the mean death rate.ConclusionsInternational travel was directly associated with the mortality slope and thus potentially the spread of COVID-19. Very early restrictions on international travel should be considered to control COVID-19 outbreaks and prevent related deaths.

scholarly journals Characterization of Maize Genotypes (Zea mays L.) for Resistance to Striga asiatica and S. hermonthica and Compatibility with Fusarium oxysporum f. sp. strigae (FOS) in Tanzania

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1004
Author(s):  
John Lobulu ◽  
Hussein Shimelis ◽  
Mark D. Laing ◽  
Arnold Angelo Mushongi ◽  
Admire Isaac Tichafa Shayanowako
Keyword(s):  
Grain Yield ◽  
Fusarium Oxysporum ◽  
Biocontrol Agent ◽  
Zea Mays L ◽  
Control Treatment ◽  
Yield Reduction ◽  
Maize Genotypes ◽  
Significant Yield ◽  
The Mean

Striga species cause significant yield loss in maize varying from 20 to 100%. The aim of the present study was to screen and identify maize genotypes with partial resistance to S. hermonthica (Sh) and S. asiatica (Sa) and compatible with Fusarium oxysporum f. sp. strigae (FOS), a biocontrol agent. Fifty-six maize genotypes were evaluated for resistance to Sh and Sa, and FOS compatibility. Results showed that FOS treatment significantly (p < 0.001) enhanced Striga management compared to the untreated control under both Sh and Sa infestations. The mean grain yield was reduced by 19.13% in FOS-untreated genotypes compared with a loss of 13.94% in the same genotypes treated with FOS under Sh infestation. Likewise, under Sa infestation, FOS-treated genotypes had a mean grain yield reduction of 18% while untreated genotypes had a mean loss of 21.4% compared to the control treatment. Overall, based on Striga emergence count, Striga host damage rating, grain yield and FOS compatibility, under Sh and Sa infestations, 23 maize genotypes carrying farmer preferred traits were identified. The genotypes are useful genetic materials in the development of Striga-resistant cultivars in Tanzania and related agro-ecologies.

scholarly journals The Ancestry of a Sample of Sequences Subject to Recombination

Genetics ◽  
1999 ◽  
Vol 151 (3) ◽  
pp. 1217-1228 ◽  
Author(s):  
Carsten Wiuf ◽  
Jotun Hein
Keyword(s):  
Genetic Distance ◽  
Population Size ◽  
Upper Bound ◽  
Recombination Rate ◽  
Common Ancestor ◽  
Recent Common Ancestor ◽  
Sequence Length ◽  
Most Recent Common Ancestor ◽  
The Mean ◽  
Mean Time

Abstract In this article we discuss the ancestry of sequences sampled from the coalescent with recombination with constant population size 2N. We have studied a number of variables based on simulations of sample histories, and some analytical results are derived. Consider the leftmost nucleotide in the sequences. We show that the number of nucleotides sharing a most recent common ancestor (MRCA) with the leftmost nucleotide is ≈log(1 + 4N Lr)/4Nr when two sequences are compared, where L denotes sequence length in nucleotides, and r the recombination rate between any two neighboring nucleotides per generation. For larger samples, the number of nucleotides sharing MRCA with the leftmost nucleotide decreases and becomes almost independent of 4N Lr. Further, we show that a segment of the sequences sharing a MRCA consists in mean of 3/8Nr nucleotides, when two sequences are compared, and that this decreases toward 1/4Nr nucleotides when the whole population is sampled. A measure of the correlation between the genealogies of two nucleotides on two sequences is introduced. We show analytically that even when the nucleotides are separated by a large genetic distance, but share MRCA, the genealogies will show only little correlation. This is surprising, because the time until the two nucleotides shared MRCA is reciprocal to the genetic distance. Using simulations, the mean time until all positions in the sample have found a MRCA increases logarithmically with increasing sequence length and is considerably lower than a theoretically predicted upper bound. On the basis of simulations, it turns out that important properties of the coalescent with recombinations of the whole population are reflected in the properties of a sample of low size.

ECONOMIC INJURY LEVELS OF THE TARNISHED PLANT BUG, LYGUS LINEOLARIS (HEMIPTERA (HETEROPTERA): MIRIDAE), ON GREEN BEANS IN QUEBEC

1980 ◽  
Vol 112 (3) ◽  
pp. 306-310 ◽  
Author(s):  
R. K. Stewart ◽  
A. R. Khattat
Keyword(s):  
Chemical Control ◽  
Crude Protein ◽  
Lygus Lineolaris ◽  
Green Beans ◽  
Flower Bud ◽  
Tarnished Plant Bug ◽  
Yield And Quality ◽  
Economic Injury ◽  
Plant Stage ◽  
Effect Of Feeding

AbstractCaged microplots of “Contender” green beans, Phaseolus vulgaris L., were artificially infested with various densities of Lygus lineolaris (Palisot de Beauvois) to determine the effect of feeding on yield and quality, and to establish economic injury levels. Plants infested at bloom or pod set stage were more severely injured than those infested at the flower bud stage. Higher infestation levels reduced crop yield, but the percentage of crude protein in bean seeds was not affected. Based on 1975 crop values and chemical control costs, economic injury levels ranged between 0.3 and 4.4 insects/10 plants depending on crop use, chemical control, and plant stage infested.

POSTPARTUM AMENORRHOEA IN RURAL EASTERN UTTAR PRADESH, INDIA

1998 ◽  
Vol 30 (2) ◽  
pp. 227-243
Author(s):  
K. N. S. YADAVA ◽  
S. K. JAIN
Keyword(s):  
Higher Education ◽  
Uttar Pradesh ◽  
Current Status Data ◽  
North India ◽  
Current Status ◽  
Data Sets ◽  
Survival Status ◽  
The Mean ◽  
The Difference ◽  
Using Data

This paper calculates the mean duration of the postpartum amenorrhoea (PPA) and examines its demographic, and socioeconomic correlates in rural north India, using data collected through 'retrospective' (last but one child) as well as 'current status' (last child) reporting of the duration of PPA.The mean duration of PPA was higher in the current status than in the retrospective data;n the difference being statistically significant. However, for the same mothers who gave PPA information in both the data sets, the difference in mean duration of PPA was not statistically significant. The correlates were identical in both the data sets. The current status data were more complete in terms of the coverage, and perhaps less distorted by reporting errors caused by recall lapse.A positive relationship of the mean duration of PPA was found with longer breast-feeding, higher parity and age of mother at the birth of the child, and the survival status of the child. An inverse relationship was found with higher education of a woman, higher education of her husband and higher socioeconomic status of her household, these variables possibly acting as proxies for women's better nutritional status.

scholarly journals Effective population size: the effects of sex, genotype, and density on the mean and variance of offspring numbers in the flour beetle, Tribolium castaneum

1980 ◽  
Vol 36 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Michael J. Wade
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Tribolium Castaneum ◽  
Black Body ◽  
Body Colour ◽  
Effective Population ◽  
Flour Beetle ◽  
Colour Mutant ◽  
Mean And Variance ◽  
The Mean

SUMMARYIn this paper I present the results of an experimental study of the effects of genotype and density on the mean and variance of offspring numbers in both sexes of the flour beetle, Tribolium castaneum. From the observed variance in offspring numbers the effective population size at several different densities is estimated using the methods of Crow & Morton (1955).I found that both the mean and variance of offspring numbers varied with genotype and density. In general, males were more variable in offspring numbers than females and this variability increased with density. Individuals homozygous for the black body colour mutant, b/b, were less variable in offspring numbers than + / + individuals, but the latter produced more offspring at most densities. As density increased, + / + individuals became more variable in offspring numbers whereas b/b individuals were less sensitive in this regard. These findings are discussed in relation to the ecology of selection at the black and closely linked loci.

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