Spatially Explicit Changes in Potato Psyllid (Hemiptera: Triozidae) Populations in Three South Texas Potato Fields

2019 ◽  
Vol 113 (2) ◽  
pp. 988-1000 ◽  
Author(s):  
Don C Henne ◽  
Jenita Thinakaran
Keyword(s):  
Population Structure ◽  
Goodness Of Fit ◽  
Negative Binomial ◽  
Information Criterion ◽  
Potato Psyllid ◽  
Bactericera Cockerelli ◽  
Spatial And Temporal Patterns ◽  
Chi Square ◽  
Frequency Distributions ◽  
Potato Plants

Abstract Insect abundance is commonly recorded in the form of discrete counts taken from plants. Analyses of these counts provide information about spatial distributions and population structure. A study was conducted in the Lower Rio Grande Valley of Texas during April and May 2014 to determine how populations of potato psyllids [Bactericera cockerelli (Šulc)] within three potato fields change over time. It was found that potato psyllid populations in these potato fields frequently changed both spatially and temporally. Chi-square goodness of fit tests and Akaike’s Information Criterion indicated that the frequency distributions of potato psyllid counts conformed to a negative binomial distribution, implying an aggregated spatial pattern. Variance–mean ratios were always much larger than one, also implying spatially clumped populations. However, with a few exceptions, a Spatial Analysis by Distance IndicEs analysis showed that potato psyllid counts were mostly random in space, the clumping generally occurring on individual potato plants and rarely involving groups of potato plants in close proximity. Trends in proportions of plants infested by at least one potato psyllid and the clumping parameter k were similar for all three potato fields. Potato psyllid spatial population structure is a dynamic process that involves continuous adult movements leading to substantial redistribution of potato psyllids over limited time spans of 2 to 3 d. By capturing elements of their spatial and temporal patterns of redistribution, the study reported here is a step towards a better understanding of the population dynamics and movement of potato psyllids.

scholarly journals Mortality of Potato Psyllid (Hemiptera: Triozidae) on Host Clippings Inoculated With Ergot Alkaloids

2020 ◽  
Vol 113 (5) ◽  
pp. 2079-2085
Author(s):  
Navneet Kaur ◽  
W Rodney Cooper ◽  
Jennifer M Duringer ◽  
Arash Rashed ◽  
Ismael E Badillo-Vargas ◽  
...  
Keyword(s):  
Ergot Alkaloids ◽  
Morning Glory ◽  
Potato Psyllid ◽  
Bactericera Cockerelli ◽  
Artificial Diets ◽  
Synthetic Compounds ◽  
Potato Plants ◽  
Ipomoea Tricolor ◽  
Crude Extracts ◽  
Host Tissues

Abstract Our previous study provided correlative evidence that morning glory species harboring endophytic fungi (Periglandula) are resistant to potato psyllid [Bactericera cockerelli (Šulc)], whereas species free of fungi often allowed psyllid development. In this study, we manipulated levels of ergot alkaloids in host tissues by inoculating clippings from potato plants with extracts from morning glories that harbor Periglandula [Ipomoea leptophylla Torrey, Ipomoea imperati (Vahl) Grisebach, Ipomoea tricolor Cavanilles, Ipomoea pandurata (L.) G. F. Meyer, and Turbina corymbosa (L.)] and one species (Ipomoea alba L.) that does not harbor the endophyte. Ergot alkaloids (clavines, lysergic acid amides, and ergopeptines) were detected in potato clippings, thus confirming that leaves had taken up compounds from solutions of crude extracts. Psyllid mortality rates on inoculated clippings ranged between 53 and 93% in treatments producing biochemically detectable levels of alkaloids, when compared with 15% mortality in water controls or the alkaloid-free I. alba. We then tested synthetic analogs from each of the three alkaloid classes that had been detected in the crude extracts. Each compound was assayed by inoculating clippings of two host species (potato and tomato) at increasing concentrations (0, 1, 10, and 100 µg/ml in solution). Psyllids exhibited a large and significant increase in mortality rate beginning at the lowest two concentrations, indicating that even very small quantities of these chemicals led to mortality. Feeding by nymphs on artificial diets containing synthetic compounds resulted in 100% mortality within 48 h, irrespective of compound. Further testing of ergot alkaloids to characterize the mode of action that leads to psyllid mortality is warranted.

Patterns of macroparasite aggregation in wildlife host populations

Parasitology ◽  
1998 ◽  
Vol 117 (6) ◽  
pp. 597-610 ◽  
Author(s):  
D. J. SHAW ◽  
B. T. GRENFELL ◽  
A. P. DOBSON
Keyword(s):  
Poisson Distribution ◽  
Negative Binomial Distribution ◽  
Binomial Distribution ◽  
Goodness Of Fit ◽  
Negative Binomial ◽  
Data Sets ◽  
Frequency Distributions ◽  
System A ◽  
Host Sex ◽  
Host Parasite

Frequency distributions from 49 published wildlife host–macroparasite systems were analysed by maximum likelihood for goodness of fit to the negative binomial distribution. In 45 of the 49 (90%) data-sets, the negative binomial distribution provided a statistically satisfactory fit. In the other 4 data-sets the negative binomial distribution still provided a better fit than the Poisson distribution, and only 1 of the data-sets fitted the Poisson distribution. The degree of aggregation was large, with 43 of the 49 data-sets having an estimated k of less than 1. From these 49 data-sets, 22 subsets of host data were available (i.e. host data could be divided by either host sex, age, where or when hosts were sampled). In 11 of these 22 subsets there was significant variation in the degree of aggregation between host subsets of the same host–parasite system. A common k estimate was always larger than that obtained with all the host data considered together. These results indicate that lumping host data can hide important variations in aggregation between hosts and can exaggerate the true degree of aggregation. Wherever possible common k estimates should be used to estimate the degree of aggregation. In addition, significant differences in the degree of aggregation between subgroups of host data, were generally associated with significant differences in both mean parasite burdens and the prevalence of infection.

scholarly journals Relative Abundance of Potato Psyllid Haplotypes in Southern Idaho Potato Fields During 2012 to 2015, and Incidence of ‘Candidatus Liberibacter solanacearum’ Causing Zebra Chip Disease

Plant Disease ◽  
2017 ◽  
Vol 101 (5) ◽  
pp. 822-829 ◽  
Author(s):  
Jennifer Dahan ◽  
Erik J. Wenninger ◽  
Brandon Thompson ◽  
Sahar Eid ◽  
Nora Olsen ◽  
...  
Keyword(s):  
Potato Industry ◽  
Potato Psyllid ◽  
Bactericera Cockerelli ◽  
Zebra Chip ◽  
Spatial And Temporal Patterns ◽  
Candidatus Liberibacter Solanacearum ◽  
South Central ◽  
Zebra Chip Disease ◽  
Four Seasons ◽  
Candidatus Liberibacter

Zebra chip (ZC) disease, a serious threat to the potato industry, is caused by the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso). Five haplotypes (hapA to hapE) of this pathogen have been described so far in different crops, with only hapA and hapB being associated with ZC in potato. Both haplotypes are vectored and transmitted to a variety of solanaceaeous plants by the tomato/potato psyllid, Bactericera cockerelli (Šulc). Psyllids are native to North America, and four haplotypes have been identified and named based on their predominant geographic association: Northwestern, Central, Western, and Southwestern. Although all psyllid haplotypes have been found in southern Idaho potato fields, data on relative haplotype abundances and dynamic changes in the fields over time have not previously been reported. Here, psyllid samples collected in Idaho potato fields from 2012 to 2015 were used to clarify spatial and temporal patterns in distribution and abundance of psyllid and Lso haplotypes. A shift from hapA toward hapB population of Lso was revealed during these four seasons, indicating possible evolution of Lso in Idaho fields. Although we confirmed that Western psyllids were the most abundant by far during the four seasons of observation, we also observed changes in abundance of other haplotypes, including increased diversity of psyllid haplotypes during 2015. Seasonal changes observed for the Northwestern and Central haplotypes could potentially be linked to psyllid migration and/or habitat changes. South-central Idaho exhibited more diversity in psyllid haplotypes than southwestern Idaho.

scholarly journals Translation, Cross-Cultural Adaptation, and Psychometric Properties of the Malay-Translated Kihon Checklist Among Elderly Patients In The Emergency Department

2021 ◽  
Author(s):  
Suhaila Naema Laili Suhairi ◽  
Hashim Embong ◽  
Shamsuriani Md Ja ◽  
Afliza Abu Bakar
Keyword(s):  
Emergency Department ◽  
Elderly Patients ◽  
Psychometric Properties ◽  
Goodness Of Fit ◽  
Factor Model ◽  
Information Criterion ◽  
Internal Consistency Reliability ◽  
Assessment Tools ◽  
Elderly Subjects ◽  
Chi Square

Abstract BackgroundThe insufficiency of gold standard assessment tools is the current challenge of frailty detection in an emergency department (ED). This study aimed to translate and evaluate the psychometric properties of the Malay-translated Kihon Checklist (KCL) for frailty assessment among Malaysian elderly patients presenting to the ED.MethodThe 25-item English version of the KCL was translated to Malay language through a forward and backward translation procedure. Three expert panels considered the items and pilot-tested on 15 elderly subjects. The final version was administered to 250 elderly patients who presented in the ED. Using confirmatory factor analysis (CFA), we compared the prior factorial models of the KCL. Model fits were determined using the Chi-square test/degree of freedom (df), comparative fit index (CFI), Tucker–Lewis index (TLI), root mean square error of approximation (RMSEA), Akaike information criterion (AIC), Bayesian information criterion (BIC), and expected cross-validation index (ECVI).ResultsAnalysis revealed that none of the prior models (seven-, two-, and one-factorial model) fit the data. After modification, one-factor model with 10 items had a superior fit (Chi-square/df, 54.434/35; CFI, 0.962; TLI, 0.951; RMSEA, 0.047 (95% confidence interval (CI), 0.019–0.071); AIC, 94.434; BIC, 164.863; ECVI, 0.379). The internal consistency reliability for the pooled 10 items was acceptable, i.e., 0.786.ConclusionThe CFA revealed that a one-factor model with 10 items had superior goodness-of-fit than other hypothesized factorial models. The scale demonstrated adequate construct validity and acceptable reliability with caution interpretation of some items.

scholarly journals Australian state influenza notifications and school closures in 2019

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1899
Author(s):  
Anna Mae Scott ◽  
Mina Bakhit ◽  
Justin Clark ◽  
Melanie Vermeulen ◽  
Mark Jones ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Negative Binomial ◽  
School Closure ◽  
School Closures ◽  
Chi Square ◽  
Exact Test ◽  
Australian State ◽  
Chi Square Test ◽  
The Impact ◽  
Vacation Period

Background: The impact of school holidays on influenza rates has been sparsely documented in Australia. In 2019, the early winter influenza season coincided with mid-year school breaks, enabling us the unusual opportunity to examine how influenza incidence changed during school closure dates. Methods: The weekly influenza data from five Australian state and one territory health departments for the period of week 19 (mid-May) to week 35 (early September) 2019 were compared to each state’s public school closure dates. We used segmented regression to model the weekly counts and a negative binomial distribution to account for overdispersion due to autocorrelation. The models’ goodness-of-fit was assessed by plots of observed versus expected counts, plots of residuals versus predicted values, and Pearson’s Chi-square test. The main exposure was the July two-week school vacation period, using a lag of one week. The effect is estimated as a percent change in incidence level, and in slope. We also dichotomized the change in weekly counts into decreases versus increases (or no change). The proportion of decreases were then compared for each of three periods (pre-vacation, vacation, post-vacation) using Fishers exact test. Results: School holidays were associated with significant declines in influenza incidence. The models showed acceptable goodness-of-fit. The numbers and percentages of decreases in weekly influenza counts from the previous week for all states combined were: 19 (33%) pre-vacation; 11 (92%) decreases during the vacation; and 19 (59%) decreases post-vacation (P=0.0002). The first decline during school holidays is seen in the school aged (5-19 years) population, with the declines in the adult and infant populations being smaller and following a week later. Conclusions: Given the significant and rapid reductions in incidence, these results have important public health implications. Closure or extension of holiday periods could be an emergency option for state governments.

Stochastic model of contractions at a point in the duodenum

1975 ◽  
Vol 229 (3) ◽  
pp. 613-617 ◽  
Author(s):  
RB Singerman ◽  
EO Macagno ◽  
Glover ◽  
J Christensen
Keyword(s):  
Slow Wave ◽  
Goodness Of Fit ◽  
Human Subjects ◽  
Real Data ◽  
Type Model ◽  
Chi Square ◽  
Frequency Distributions ◽  
The Real ◽  
Goodness Of Fit Tests ◽  
Wave Cycle

Contractions at one point in the human duodenum were studied as a time series. Manometric records were made over long time periods from the duodenum in fed human subjects. A 5-s grid was superimposed on the time axis of the records. Each 5-s interval was treated as a slow-wave cycle within which either a contraction or a no-contraction could occur. The resulting series of alternating runs of contractions and no-contractions was tested for the existence of trends. Trends were found indicating possible temporal dependence. A Markov-type model was used to try to generate data similar to the real data. Success was achieved by a model that assumed a probability of contraction dependent on the three previous slow-wave cycles. The frequency distributions obtained from the real and generated data were compared using Chi-square goodness-of-fit tests and found to be statistically similar. The correlations in time found for the contractions might be due to a time dependency in the controls for contraction over four successive slow-wave periods, 20 s in humans.

Measuring Investment Importance Perception in Equity Shares: A Scale for Individual Investors

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
M. Rakesh Krishnan ◽  
C. Ganesh
Keyword(s):  
Factor Analysis ◽  
Root Mean Square ◽  
Goodness Of Fit ◽  
Information Criterion ◽  
Individual Investors ◽  
Mean Square ◽  
Goodness Of Fit Test ◽  
Chi Square ◽  
Root Mean Square Residual ◽  
Fit Index

This study focused on developing a scale for measuring Investment Importance Perception in Equity shares (IIPe) of individual investors. Item generation (from equity share investors) and content validity was performed (with expert panel) to gather the initial pool of items for the scale. Exploratory Factor Analysis (EFA) was used for item reduction and for establishing the dimensions of IIPe. Further, Confirmatory Factor Analysis (CFA) was used test the measurement validity. Parameters were estimated with maximum likelihood (ML) through the use of AMOS (version 16). The assumptions for multivariate normality were checked by looking into the skewness and kurtosis value of the individual items of the scale. The chi-square goodness-of-fit test guided evaluation of model fit along with established fit indices such as goodness of fit index (GFI), comparative fit index (CFI), incremental fit index (IFI), standardized root mean square residual (SRMR), root-mean-square error of approximation (RMSEA) and Akaike Information Criterion (AIC).

scholarly journals Australian state influenza notifications and school holiday closures in 2019

F1000Research ◽  
2021 ◽  
Vol 8 ◽  
pp. 1899
Author(s):  
Anna Mae Scott ◽  
Mina Bakhit ◽  
Justin Clark ◽  
Melanie Vermeulen ◽  
Mark Jones ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Negative Binomial ◽  
State Governments ◽  
Health Departments ◽  
Chi Square ◽  
Australian State ◽  
Show Evidence ◽  
Chi Square Test ◽  
Predicted Values ◽  
The Impact

Background: The impact of school holidays on influenza rates has been sparsely documented in Australia. In 2019, the early winter influenza season coincided with mid-year school breaks, enabling us the unusual opportunity to examine how influenza incidence changed during school holiday closure dates. Methods: The weekly influenza data from five Australian state and one territory health departments for the period of week 19 (mid-May) to week 39 (early October) 2019 were compared to each state’s public-school holiday closure dates. We used segmented regression to model the weekly counts and a negative binomial distribution to account for overdispersion due to autocorrelation. The models’ goodness-of-fit was assessed by plots of observed versus expected counts, plots of residuals versus predicted values, and Pearson’s Chi-square test. The main exposure was the July two-week school holiday period, using a lag of one week. The effect is estimated as a percent change in incidence level, and in slope. Results: School holidays were associated with significant declines in influenza incidence in three states and one territory by between 41% and 65%. Two states did not show evidence of declines although one of those states had already passed its peak by the time of the school holidays. The models showed acceptable goodness-of-fit. The first decline during school holidays is seen in the school aged (5-19 years) population, with the declines in the adult and infant populations being smaller and following a week later. Conclusions: Given the significant and rapid reductions in incidence, these results have important public health implications. Closure or extension of holiday periods could be an emergency option for state governments.

scholarly journals First Report of “Candidatus Liberibacter psyllaurous” or “Ca. Liberibacter solanacearum” Associated with Severe Foliar Chlorosis, Curling, and Necrosis and Tuber Discoloration of Potato Plants in Honduras

Plant Disease ◽  
2010 ◽  
Vol 94 (3) ◽  
pp. 376-376 ◽  
Author(s):  
M. Rehman ◽  
J. C. Melgar ◽  
J. M. Rivera C. ◽  
A. M. Idris ◽  
J. K. Brown
Keyword(s):  
16S Rdna ◽  
Disease Incidence ◽  
Pcr Amplification ◽  
Potato Production ◽  
The United States ◽  
Potato Psyllid ◽  
Bactericera Cockerelli ◽  
Water Control ◽  
Potato Plants ◽  
Candidatus Liberibacter

From 2006 to 2009, all commercial potato fields in Azacualpa F.M. Honduras were heavily infested with the potato psyllid Bactericera cockerelli (Sulc.). Plants exhibited interveinal chlorosis, vein-greening, downward curling, stunting, above ground tuber formation, and brownish flecks in some tubers. Disease incidence ranged from 50 to 95%. Leaf samples and psyllids were collected from seven fields in two potato-growing regions of Honduras. Total DNA was purified from the leaves of 30 symptomatic and three asymptomatic plants. DNA was extracted from 20 adult and 10 immature (4th to 5th instar) psyllids according to Frohlich et al (1). PCR primers, PSY680F 5′-GTTCGGAATAACTGGGCGTA-3′ and PSY1R 5′-CCCATAAGGGCCATGAGGACT-3′, were used to amplify a 680-bp fragment of the 16S rDNA for the recently described “Candidatus Liberibacter physallaurous” (2) and “Ca. L. solanacearum” (3). PSY1R/PSY680F primer design was based on the association of a previously undescribed liberibacter with vein-greening symptoms in greenhouse tomato plants in Arizona from 2006 to 2007 (GenBank Accession No. GQ926918) that lead to the hypothesis that a similar bacterium could be associated with symptomatic potato plants in Honduras. PCR amplification, cloning, and sequencing of the resultant 16S rDNA amplicons indicated that 17 of 30 potato plants, 8 of 20 adult and 7 of 10 third to fourth instar psyllids, respectively, were positive for liberibacter based on 99 to 100% shared nucleotide sequence (nt) identity with the analogous sequence from liberibacter (EU812558 [2]). To substantiate these results, a second molecular marker was targeted using the 1611F and 480R primers (~980 bp) that amplify the 16S-23S-ITSrDNA of liberibacter (2) for selected liberibacter-positive samples (above). Amplicons of the expected size were obtained from 12 of 17 potato and 7 of 10 immature psyllids. No PCR product of the expected size was obtained from asymptomatic potato samples or the PCR negative (water) control. The resultant PCR amplicons were cloned and 12 to 15 clones per amplicon were sequenced. The sequences were aligned and the percentage pair wise nt identity was calculated by Clustal W revealing that the 16S rDNA and 16S-23S-ITS sequences, respectively, shared 99 to 100% nt identity with each other. BLAST analysis against the NCBI database indicated that the 16S rRNA sequences from potato plants (GQ926922) and immature psyllids (GQ926923), and the 16S-ITS-23S sequence from potato plants (GQ926924) and immature psyllids (GQ926925), shared 98.5 to 100% nt identity with ‘Ca. Liberibacter’ reported from potato (EU812556; [2,4]) and tomato (EU812558, EU812559, EU935005; [2,3]). Evidence for the widespread presence of liberibacter and the potato psyllid in potato fields in Honduras, together with foliar and tuber symptoms that are reminiscent of those recently described in potato plants in the United States affected with ‘zebra chip’ disease (4), suggest that a similar or identical disease of the potato also occurs in Honduras. This emergent disease poses a serious threat to potato production in Honduras and elsewhere in Central America. References: (1) D. R. Frohlich et al., Mol. Ecol. 8:1683, 1999. (2) A. K. Hansen et al. Appl. Environ. Microbiol. 78:5862, 2008. (3) L. W. Liefting et al. Plant Dis. 93:208, 2009. (4) J. E. Munyaneza et al. J. Econ. Entomol. 100:656, 2007.

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