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High Dimension Multivariate Data Analysis for Small Group Samples of Chemical Volatile Profiles of African Nightshade Species

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Journal of Data Analysis and Information Processing 2024年第2期12卷 210-231页

作者： Lorna Chepkemoi Daisy Salifu Lucy Kananu Murungi Henri E. Z. Tonnang International Centre of Insect Physiology and Ecology (icipe) Nairobi Kenya Department of Horticulture and Food Security Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya

Quantitative headspace analysis of volatiles emitted by plants or any other living organisms in chemical ecology studies generates large multidimensional data that require extensive mining and refining to extract useful information. More often the number of variables and the quantified volatile compounds exceed the number of observations or samples and hence many traditional statistical analysis methods become inefficient. Here, we employed machine learning algorithm, random forest (RF) in combination with distance-based procedure, similarity percentage (SIMPER) as preprocessing steps to reduce the data dimensionality in the chemical profiles of volatiles from three African nightshade plant species before subjecting the data to non-metric multidimensional scaling (NMDS). In addition, non-parametric methods namely permutational multivariate analysis of variance (PERMANOVA) and analysis of similarities (ANOSIM) were applied to test hypothesis of differences among the African nightshade species based on the volatiles profiles and ascertain the patterns revealed by NMDS plots. Our results revealed that there were significant differences among the African nightshade species when the data’s dimension was reduced using RF variable importance and SIMPER, as also supported by NMDS plots that showed S. scabrum being separated from S. villosum and S. sarrachoides based on the reduced data variables. The novelty of our work is on the merits of using data reduction techniques to successfully reveal differences in groups which could have otherwise not been the case if the analysis were performed on the entire original data matrix characterized by small samples. The R code used in the analysis has been shared herein for interested researchers to customise it for their own data of similar nature.

关键词： Random Forest Similarity Percentage PERMANOVA ANOSIM Non-Metric Multi-Dimensional Scaling

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Mapping Air Quality Using Remote Sensing Technology: A Case Study of Nairobi County

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Open Journal of Air Pollution 2024年第1期13卷 1-22页

作者： Quinto Juma Meltus Faith Njoki Karanja Geospatial Engineering Department The University of Nairobi (UoN) Nairobi Kenya Data Management Modeling and Geoinformation Unit (DMMG) International Centre of Insect Physiology and Ecology (ICIPE) Nairobi Kenya

Nairobi County experiences rapid industrialization and urbanization that contributes to the deteriorating state of air quality, posing a potential health risk to its growing population. Currently, in Nairobi County, most air quality monitoring stations use low-cost, inaccurate monitors prone to defects. The study’s objective was to map Nairobi County’s air quality using freely available remotely sensed imagery. The Air Pollution Index (API) formula was used to characterize the air quality from cloud-free Landsat satellite images i.e., Landsat 5 TM, Landsat 7 ETM+, and Landsat 8 OLI from Google Earth Engine. The API values were computed based on vegetation indices namely NDVI, TVI, DVI, and the SWIR1 and NIR bands on the QGIS platform. Qualitative accuracy assessment was done using sample points drawn from residential, industrial, green spaces, and traffic hotspot categories, based on a passive-random sampling technique. In this study, Landsat 5 API imagery for 2010 provided a reliable representation of local conditions but indicated significant pollution in green spaces, with recorded values ranging from -143 to 334. The study found that Landsat 7 API imagery in 2002 showed expected results with the range of values being -55 to 287, while Landsat 8 indicated high pollution levels in Nairobi. The results emphasized the importance of air quality factors in API calibration and the unmatched spatial coverage of satellite observations over ground-based monitoring techniques. The study recommends the recalibration of the API formula for characteristic regions, exploring newer satellite sensors like those onboard Landsat 9 and Sentinel 2, and involving key stakeholders in a discourse to develop a suitable Kenyan air quality index.

关键词： Air Quality Air Pollution Index (API) Satellite Imagery Vegetation Indices Nairobi County

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Comparison of Semi-Parametric Shared Frailty Models for Bees’Survival

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Journal of Data Analysis and Information Processing 2024年第2期12卷 267-288页

作者： Patience Isiaho Daisy Salifu Samuel Mwalili Henri E. Z. Tonnang Department of Statistics and Actuarial Sciences Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Data Management Modelling and Geo-Information Unit International Centre of Insect Physiology and Ecology (ICIPE) Nairobi Kenya

Survival analysis is a fundamental tool in medical science for time-to-event data. However, its application to colony organisms like bees poses challenges due to their social nature. Traditional survival models may not accurately capture the interdependence among individuals within a colony. Frailty models, accounting for shared risks within groups, offer a promising alternative. This study evaluates the performance of semi-parametric shared frailty models (gamma, inverse normal, and positive stable-in comparison to the traditional Cox model using bees’ survival data). We examined the effect of misspecification of the frailty distribution on regression and heterogeneity parameters using simulation and concluded that the heterogeneity parameter was more sensitive to misspecification of the frailty distribution and choice of initial parameters (cluster size and true heterogeneity parameter) compared to the regression parameter. From the data, parameter estimates for covariates were close for the four models but slightly higher for the Cox model. The shared gamma frailty model provided a better fit to the data in comparison with the other models. Therefore, when focusing on regression parameters, the gamma frailty model is recommended. This research underscores the importance of tailored survival methodologies for accurately analyzing time-to-event data in social organisms.

关键词： Correlated Failure Times Frailty Survival Analysis Unobserved Heterogeneity

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Modelling the Survival of Western Honey Bee Apis mellifera and the African Stingless Bee Meliponula ferruginea Using Semiparametric Marginal Proportional Hazards Mixture Cure Model

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Journal of Data Analysis and Information Processing 2024年第1期12卷 24-39页

Classical survival analysis assumes all subjects will experience the event of interest, but in some cases, a portion of the population may never encounter the event. These survival methods further assume independent survival times, which is not valid for honey bees, which live in nests. The study introduces a semi-parametric marginal proportional hazards mixture cure (PHMC) model with exchangeable correlation structure, using generalized estimating equations for survival data analysis. The model was tested on clustered right-censored bees survival data with a cured fraction, where two bee species were subjected to different entomopathogens to test the effect of the entomopathogens on the survival of the bee species. The Expectation-Solution algorithm is used to estimate the parameters. The study notes a weak positive association between cure statuses (ρ1=0.0007) and survival times for uncured bees (ρ2=0.0890), emphasizing their importance. The odds of being uncured for A. mellifera is higher than the odds for species M. ferruginea. The bee species, A. mellifera are more susceptible to entomopathogens icipe 7, icipe 20, and icipe 69. The Cox-Snell residuals show that the proposed semiparametric PH model generally fits the data well as compared to model that assume independent correlation structure. Thus, the semi parametric marginal proportional hazards mixture cure is parsimonious model for correlated bees survival data.

关键词： Mixture Cure Models Clustered Survival Data Correlation Structure Cox-Snell Residuals EM Algorithm Expectation-Solution Algorithm

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Efficacy of Metarhizium anisopliae in controlling the two-spotted spider mite Tetranychus urticae on common bean in screenhouse and field experiments

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Insect Science 2015年第1期22卷 121-128页

作者： David Mugisho Bugeme Markus Knapp Sunday Ekesi Adenirin Chabi-Olaye Hamadi Iddi Boga Nguya Kalemba Maniania International Centre of Insect Physiology and Ecology (icipe) Department of Botany Jomo Kenyatta University of Agriculture andTechnology (JKUA T) NairobL Kenya

The efficacy of aqueous and emulsifiable formulations of the fungus Metarhizium anisopliae isolate icipe78 was evaluated on the population density of Tetranychus urticae infesting common bean plants under screenhouse and field conditions. Synthetic acaricide abamectin was included as a check. Bean plants were artificially infested with T. urticae and allowed to multiply. Three treatments were applied in the screenhouse and 1 treatment in field trials. Mite density was recorded 2 d before spraying and weekly postspraying. The number of pods per plant, number of seeds per pod, and the dry weight of seeds per plant were recorded only in the screenhouse trials. In both screenhouse and field trials, fungal formulations applied at the concentration of 108 conidia/mL and the aearicide reduced the population density of mites as compared to the controls. There were signif- icant differences in T. urticae population densities between the treatments at the various post-spraying sampling dates. In the screenhouse, the mite densities were near zero from 3-week postspraying in the treated leaves. At 4-week postspraying, there were no more leaves in the untreated control （T1） and in the control water ＋ Silwet-L77 （T2）. Fungal formulations were as effective as abamectin in reducing mite densities in both screenhouse and field experiments. There were significant differences in the production parameters during the 2 screenhouse trials, with fungal and abamectin treatments generally having the highest yield. Results of this study underline the potential of the M. anisopliae isolate icipe78 as an alternative to acaricides for T. urticae management.

关键词： acaricide common beans entomopathogenic fungus formulations microbial control two-spotted mite

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Update of the ex-ante impact assessment of the biological control of Plutella xylostella(Diamondback moth) in Kenya

Update of the ex-ante impact assessment of the biological co...

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5th International Workshop on Management of the Diamondback Moth and Other Crucifer Insect Pests

作者： Ibrahim Macharia Dagmar Mithfer Bernard Lhr International Centre of Insect Physiology and Ecology(icipe)

The ex-ante impact assessment of the biological control of the diamondback moth (DBM) in Kenya predicted a benefit-cost ratio of 24:*** result is based on yield losses due to DBM of 31%,which were measured in farmer f... 详细信息

关键词： Diamondback moth Update of the ex-ante impact assessment of the biological control of Plutella xylostella in Kenya

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Generalized Estimating Equations for Repeated Measures Logistic Regression in Mosquito Dose-Response

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Open Journal of Statistics 2013年第5期3卷 293-298页

作者： Gabriel Otieno Gichihu A. Waititu Daisy Salifu African Insect Science for Food and Health (icipe) Nairobi Kenya Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

Dose-response studies in arthropod research usually involve observing and collecting successive information at different times on the same group of insects exposed to different concentrations of stimulus. When the same measure is collected repeatedly over time, the data become correlated and Probit Analysis technique which is the standard method in analyzing bioassay experiments data cannot be used. Lethal time is estimated when the speed of kill is of interest since mortality varies over time. We evaluate a complementary approach, repeated measures logistic regression using Generalized Estimating Equations (GEE), for lethal time determination in mosquito dose response. Mortality data from anopheles larva exposed to 3 botanical extracts (B,C,E) at 4 concentration levels: 500 mg/ml, 250 mg/ml, 50 mg/ml and 12.5 mg/ml were used. The result shows the estimated LT50 values with concentration 500 mg/ml being the most virulent chemical for extract B (LT50 = 10.3 hrs), C (LT50 = 7.2 hrs) and E (LT50 = 10.3 hrs). The least virulent chemical was concentration 12.5 mg/ml for extract B (LT50 = 52.1 hrs), C (LT50 = 70.7 hrs) and E (LT50 = 55.0 hrs). We conclude that repeated measures of logistic regression via GEE can be used as a tool to estimate LT50 more effectively in repeated measures of arthropod data.

关键词： Dose-Response GEE Lethal Time Probit Analysis Repeated Measures

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Role of conspecifics and personal experience on behavioral avoidance of contaminated flowers by bumblebees

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Current Zoology 2019年第4期65卷 447-455页

作者： Bertrand Fouks Emily G. Robb H. Michael G. Lattorff lnstitut fur Biologie Molekulare Okologie Martin-Luther-Universitat Halle-Wittenberg Hoher Weg Halle (Saale) Germany Centre for Ecological and Evolutionary Synthesis (CEES) Department of Biosciences University of Oslo Oslo Norway Microbes and Pathogens Biology The Institute for Global Food Security School of Biological Sciences Queen's University Belfast United Kingdom lnternational Centre of Insect Physiology and Ecology (icipe) Nairobi Kenya German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Deutscher Platz Leipzig Germany

Pollinators use multiple cues whilst foraging in eluding direct cues from flowers and in direct cues from other pollinators. The use of indirect social cues is common in social in sects, such as honeybees and bumblebees, where a social environment facilitates the ability to use such cues. Bumblebees use cues to forage on flowers according to previous foraging experiences. Flowers are an essential food source for pollinators but also pose a high risk of parasite infection through the shared use of flowers leading to parasite spillover. Nevertheless, bumblebees have evolved behavioral defense mechanisms to limit parasite infection by avoiding contaminated flowers. Mechanisms underlying the avoidance of contaminated flowers by bumblebees are poorly understood. Bumblebees were recorded having the choice to forage on non-contaminated flowers and flowers contaminated by a trypan osome gut parasite, Crithidia bombi. The use of different treatments with presence or absence of con specifics on both con taminated and non-contami nated flowers allowed to investigate the role of social visual cues on their pathogen avoidance behavior. Bumblebees are expected to use social visual cues to avoid contaminated flowers. Our study reveals that the presence of a con specific on flowers either con taminated or not does not help bumblebee foragers avoiding contaminated flowers. Nevertheless, bumblebees whereas gaining experie nee tend to avoid their con specific when placed on contami nated flower and copy it whe n on the non-contami nated flower. Our experime nt suggests a detrime ntal impact of floral see nt on disease avoidanee behavior.

关键词： Host-parasite in teractions social learning pollinators inadvertent social information behavioral immunity copying behavior

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RELATIVE ABUNDANCE OF EGGS LAID BY HELICOVERPA ARMIGERA ON THREE VEGETABLE CROPS AND THREE OTHER TARGET CROPS IN KENYA

RELATIVE ABUNDANCE OF EGGS LAID BY HELICOVERPA ARMIGERA ON T...

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The ⅩⅤth International Plant Protection Congress

作者： S.SITHANANTHAM C.M.MATOKA J.BAYA S.NJIHIA C.KARIUKI C.P.W.ZEBITZ J.C.MONJE S.HASSAN International Center of Insect of Physiology and Ecology ICIPE P.O.Box 30772 Nairobi Kenya International Center of Insect of Physiology and Ecology ICIPE P.O.Box 30772 Nairobi Kenya International Center of Insect of Physiology and Ecology ICIPE P.O.Box 30772 Nairobi Kenya Institute of Phytomedicine University of Hohenheim 70593 Stuttgart Germany Institute of Phytomedicine University of Hohenheim 70593 Stuttgart Germany Institute for Biological Control BBA D-64287 Darmstadt Germany Institute for Biological Control BBA D-64287 Darmstadt Germany Kenya Agricultural Research Institute KARI P.O.Box 30148 Nairobi Kenya

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Traditional uses of wild grasses amongst three Kenyan farming communities

Traditional uses of wild grasses amongst three Kenyan farmin...

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ⅩⅪ International Grassland Congress and the Ⅷ International Rangeland Congress

作者： N.M.Ng'ang'a F.N.Muyekho Z.R.Khan R.S.Copeland Kenya Agricultural Research Institute(KARI) P.O.Box 450 KitaleKenya International Centre of Insect Physiology and Ecology(icipe) P.O.Box 30772 NairobiKenya

＜正＞Introduction In Kenya,587 grass species and 142 genera have been documented（Ibrahim ＆ Kabuye,1988）,and the distribution and uses of some of these grasses have been described（Muyekho,Barrion ＆ Khan,2004;Skerman ＆ Riveros, 1990;Ibrahim ＆ Kabuye,1988）.However,except for studies on forage yields and their nutritive value for livestock *** information available lacks quantification on the importance to which different communities attach to different traditional uses for different wild grass species in Kenya.

关键词： on-farm conservation resource poor farmers

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