Foci Of Infestation Research Articles

Counting nematodes made easy: leveraging AI-powered automation for enhanced efficiency and precision.

Counting nematodes is a labor-intensive and time-consuming task, yet it is a pivotal step in various quantitative nematological studies; preparation of initial population densities and final population densities in pot, micro-plot and field trials for different objectives related to management including sampling and location of nematode infestation foci. Nematologists have long battled with the complexities of nematode counting, leading to several research initiatives aimed at automating this process. However, these research endeavors have primarily focused on identifying single-class objects within individual images. To enhance the practicality of this technology, there's a pressing need for an algorithm that cannot only detect but also classify multiple classes of objects concurrently. This study endeavors to tackle this challenge by developing a user-friendly Graphical User Interface (GUI) that comprises multiple deep learning algorithms, allowing simultaneous recognition and categorization of nematode eggs and second stage juveniles of Meloidogyne spp. In total of 650 images for eggs and 1339 images for juveniles were generated using two distinct imaging systems, resulting in 8655 eggs and 4742 Meloidogyne juveniles annotated using bounding box and segmentation, respectively. The deep-learning models were developed by leveraging the Convolutional Neural Networks (CNNs) machine learning architecture known as YOLOv8x. Our results showed that the models correctly identified eggs as eggs and Meloidogyne juveniles as Meloidogyne juveniles in 94% and 93% of instances, respectively. The model demonstrated higher than 0.70 coefficient correlation between model predictions and observations on unseen images. Our study has showcased the potential utility of these models in practical applications for the future. The GUI is made freely available to the public through the author's GitHub repository (https://github.com/bresilla/nematode_counting). While this study currently focuses on one genus, there are plans to expand the GUI's capabilities to include other economically significant genera of plant parasitic nematodes. Achieving these objectives, including enhancing the models' accuracy on different imaging systems, may necessitate collaboration among multiple nematology teams and laboratories, rather than being the work of a single entity. With the increasing interest among nematologists in harnessing machine learning, the authors are confident in the potential development of a universal automated nematode counting system accessible to all. This paper aims to serve as a framework and catalyst for initiating global collaboration toward this important goal.

ANALYSIS OF THE SPATIAL ASSOCIATION OF FUMAGINA (Capnodium spp.) AND GREEN SCALE (Coccus viridis) IN COFFEE IN SULTEPEC, MEXICO

The coffee crop (Coffea arabica L.) presents phytosanitary problems that can be economically significant if not properly managed, such as green scale (Coccus viridis) and fumagina (Capnodium spp.). Geostatistics is a tool that allows the producer to make optimal, timely, and accurate decisions for the integrated management of these problems. The objective of the research was to analyze the distribution and spatial association of fumagina and green scale in the coffee crop in Sultepec, State of Mexico, Mexico. During the first semester of 2022, random coffee plots were marked and geo-referenced for sampling. Several methods were used to obtain the spatial distribution of fumagina and green scale. The results showed fits of Gaussian, exponential, and mostly spherical geostatistical models, which represent an aggregate distribution and an association of these problems with each other. The estimation of the infested and infected area for both problems was obtained using the ordinary kriging method, revealing the presence of foci of infection and infestation. In plot three, it was identified that these are maintained and increase as the sampling progresses, finding a high degree of dependence and spatial stability. It is concluded that the populations of green scale and fumagina have an r value of 0.70, indicating a high association and correlation between them, which leads to a spatial distribution and possible management of targeted control of these phytosanitary problems and, in turn, sustainable management of the crop.

Spatial patterns of the leaf crown borer Eupalamides cyparissias (Cramer, 1775) (Lepidoptera: Castiniidae) in coconut (Cocos nucifera L.) tropical region.

The leaf crown borer Eupalamides cyparissias (Cramer, 1775) is an important pest of coconut (Cocos nucifera L.) and other palms (Arecaceae) of economic importance, attacking the base of leaves, inflorescences, and infructescences, increasing fruit abortion. The objective of this study was to evaluate the spatial correlation of the infestation rate of E. cyparissias in coconut plantation blocks in the Brazilian Amazon, from January to December 2019, in the city of Santa Izabel, Pará, Brazil. The study area is a farm subdivided into 157 blocks of a commercial plantation of the green dwarf coconut. The Local Moran's Index was used to evaluate the existence of spatial autocorrelation of the E. cyparissias infestation rate in the 157 blocks with neighboring blocks. The infestation rate was calculated by the ratio between the number of plants attacked by the borer and the total number of plants in a block. There is a significant correlation of the symptomatology of the attack by E. cyparissias in the blocks of the experimental area, which indicates an aggregated pattern of distribution. There is no significant correlation between the attack by the borer and the age of the coconut tree; however there is a significant correlation between the attack by the borer and proximity to forest areas. These results indicate that forest regions are foci of infestation by the borer in coconut plantations.

Dynamics of Panstrongylus megistus infestation, the primary vector of Trypanosoma cruzi in Minas Gerais, Brazil

Panstrongylus megistus is considered one of the primary species of epidemiological importance for the transmission of Chagas disease in Brazil due to its wide geographical distribution throughout the national territory, good ability to invade and colonize houses, and high rates of natural infection by the Trypanosoma cruzi. The importance of this species in Minas Gerais has been recognized since the 80s. It is responsible for the high prevalence rates of Chagas disease in the west of the state. Studies conducted in the municipality of Jaboticatubas show that P. megistus is still the most captured vector in the region, even after 40 years of uninterrupted actions of the Chagas Disease Control Program in the municipality. Despite the importance of the species, its population dynamics is little studied. Consequently, crucial genetic information such as genetic diversity and gene flow among environments have not been well characterized yet. In this context, this work presents a population genetic analysis at the microgeographic level using microsatellite markers in samples of P. megistus obtained from Jaboticatubas to better understand the infestation dynamics of the primary vector species of T. cruzi in the region. The observed and expected heterozygosity ranged from 0.26 to 0.47 and 0.47 to 0.65, respectively. Most loci presented Hardy-Weinberg disequilibrium due to the excess of homozygotes. The pairwise Fst ranged from 0.05 to 0.35, with the p value significant for all comparisons, indicating the absence of gene flow between them. The values of Fis found ranged from 0.25 to 0.52, all values of p ≤ 0.05, probably due to structured populations, inbreeding, or null alleles. The results suggest an extended stay of this species in the colonized environments, with rare dispersal to other locations. Such results differ from that observed for Triatoma brasiliensis and Triatoma dimidiata, species that present constant movement, even after colonization of the artificial environment, and are similar to the behavior of Triatoma infestans. Thus, the study reinforces the importance of continuous entomological surveillance in the areas of occurrence of P. megistus to avoid the installation and formation of new foci of household infestation in the region.

Incidence of alveolar echinococcosis in humans and animals in Kostanay region of the Republic of Kazakhstan

The research aims to study the spread of alveococcosis in humans and animals on the territory of the Kostanay region of the Republic of Kazakhstan. Studies on the diagnosis of alveococcosis in humans were conducted in the branch of the Ministry of Health of the Republic of Kazakhstan "Scientific-practical center of sanitary-epidemiological examination and monitoring", Kostanay, in 2010-2019. To determine the degree of invasion by alveococcosis, a pathoanatomic autopsy was performed on captured mouse-like rodents in the territory of the Kostanay region, where cases of human alveococcosis were registered. The incidence among the population of various age groups in the region was analyzed based on the results of blood samples by enzyme immunoassay (ELISA) and liver ultrasound. It is established that alveococcosis is a common disease among people living not only in the Kostanay region but also in the Republic of Kazakhstan in general. The main definitive hosts in the development cycle of the pathogen infestation on the territory of the Republic of Kazakhstan are foxes and dogs, intermediate hosts – 18 species of rodents, and for humans, alveococcosis is one of the most dangerous helminthic diseases, since in most cases it leads to death. Alveococcosis can be attributed to particularly dangerous infestations since the foci of infestation are formed not only in anthropogenic zones where the pathogen can devastate but also in natural biocenoses, where the main sources of the pathogen's spread in the external environment are foxes (Vulpes) and corsac foxes (Vulpes corsac). The maximum number of cases of alveococcosis in 2018-2020 was registered in intermediate hosts – mouse-like rodents, like common vole Microtus arvalis, the extent of A. multilocularis invasion was 3.1-3.5%. Based on the comparative analysis of the epizootic and epidemiological situation of alveococcosis in the territory of the Kostanay region, it should be noted that the risk of infection of the population with alveococcosis persists in all areas of the region.

Evaluating the presence of larvae of Lobesia botrana (Denis & Schiffermüller) developing on olive trees in some central-southern Italian regions

The present study was conducted in four central-southern Italian regions (Abruzzo, Campania, Molise, Puglia) in the years 2008 and 2016–2018, with the aim to verify in hilly areas characterized by the coexistence of vineyards and olive groves, the presence, frequency and density on olive trees of the larval instars of the European grapevine moth, Lobesia botrana on olive tree flowers, and to compare these parameters with those of other lepidopteran species as well. The sampling collection was conducted on the selected plots twice in each spring, during the phenological phase of flowering. The Lepidoptera larvae found in flower buds were identified through a chaetotaxy analysis. During samplings, 384 larvae belonging to three families (Geometridae, Tortricidae, and Praydidae) were found. The olive moth, Prays oleae, was by far the most abundant species (89.8% of the total collections) and was found in all samplings. L. botrana represented 8.2% of collected specimens and was found in all sampled fields, except in Molise during 2017. Prays oleae populations were significantly more abundant compared to L. botrana populations in all cases, except in Campania during 2017. The largest L. botrana populations were found in 2008 in Abruzzo olive groves, with 0.3 larvae per inflorescence, whereas in the other years and experimental fields the densities ranged between 0 and 0.14 larvae per inflorescence, from 3 to 24 times lower compared to P. oleae. At similar levels of infestation, L. botrana did not represent a harmful pest for olive trees; however, its presence cannot be considered occasional, as it has been found constantly, year after year, even on different olive cultivars. Kruscal-Wallis results showed significant differences among the olive orchards differently related with vineyards and suggests a direct link of L.botrana populations in olive groves and neighbouring vineyards. Olive trees located near vineyards can thus represent an important infestation focus and an insect reservoir, from which the first annual generation of L. botrana adult moths easily move and colonise the surrounding areas, including the neighbouring vineyards. Our results should be considered in IPM programmes for the control of L. botrana in those territories where vineyards and olive trees are closely cultivated.

<p class="Body"><strong>Host preference, population dynamics, distribution, and injuries of <em>Oligonychus punicae</em> (Acari: Tetranychidae) in an eucalyptus clonal minigarden</strong></p>

Oligonychus punicae has potential for development in several species of eucalyptus. In this study was evaluated the preference for permanence and oviposition of O. punicae in different eucalyptus species. Additionally, we evaluated its dynamics and population distribution, as well as injuries in strains of Eucalyptus urophylla in a clonal minigarden. The preference for permanence and oviposition of O. punicae was evaluated using a test with and without choice in six species of Eucalyptus. We also analyzed the dynamics, population distribution and injury levels by O. punicae on E. urophylla in a clonal minigarden. We collected samples for 24 months and counted the number of eggs, immature and adult individuals. We calculated the Morisita dispersion index. We estimated injuries on leaves of E. urophylla using visual notes. In the test with choice, Eucalyptus urophylla was the preferred host of O. punicae for permanence and oviposition. In the test without choice, the oviposition of O. punicae in eucalyptus species did not differ statistically until 24 hours of evaluation. However, there was a significant difference after 48 hours, with greater oviposition on Eucalyptus brassiana, Eucalyptus tereticornis and Eucalyptus grandis. In the population survey, we collected 3,293 mites. The population peak of O. punicae occurred in March and April 2018 and April 2019. Oligonychus punicae presented an aggregate distribution and caused injuries of 20% on average in leaves. These results are important to guide management strategies in specific infestation foci and optimizing the use of phytosanitary products.

<p class="Body"><strong>Host preference, population dynamics, distribution, and injuries of <em>Oligonychus punicae</em> (Acari: Tetranychidae) in an eucalyptus clonal minigarden</strong></p>

Oligonychus punicae has potential for development in several species of eucalyptus. In this study was evaluated the preference for permanence and oviposition of O. punicae in different eucalyptus species. Additionally, we evaluated its dynamics and population distribution, as well as injuries in strains of Eucalyptus urophylla in a clonal minigarden. The preference for permanence and oviposition of O. punicae was evaluated using a test with and without choice in six species of Eucalyptus. We also analyzed the dynamics, population distribution and injury levels by O. punicae on E. urophylla in a clonal minigarden. We collected samples for 24 months and counted the number of eggs, immature and adult individuals. We calculated the Morisita dispersion index. We estimated injuries on leaves of E. urophylla using visual notes. In the test with choice, Eucalyptus urophylla was the preferred host of O. punicae for permanence and oviposition. In the test without choice, the oviposition of O. punicae in eucalyptus species did not differ statistically until 24 hours of evaluation. However, there was a significant difference after 48 hours, with greater oviposition on Eucalyptus brassiana, Eucalyptus tereticornis and Eucalyptus grandis. In the population survey, we collected 3,293 mites. The population peak of O. punicae occurred in March and April 2018 and April 2019. Oligonychus punicae presented an aggregate distribution and caused injuries of 20% on average in leaves. These results are important to guide management strategies in specific infestation foci and optimizing the use of phytosanitary products.

A Spatiotemporal Analysis and Dispersal Patterns of the Potato Cyst NematodeGlobodera pallidain Idaho

The potato cyst nematode Globodera pallida is a globally regulated potato pest. It was detected for the first time in the United States in the state of Idaho in 2006, and as of February 2019, the infestation is limited to 1,326 hectares. G. pallida is a specialized obligate sedentary endoparasite that can survive in the soil for up to 30 years in the absence of its potato host. In highly infested fields, the nematode can reduce tuber yields up to 80% and is spread mainly through the movement of soil, tubers, or farm equipment. The objectives of this study were to describe the spatiotemporal pattern of G. pallida in infested fields and model its dispersal patterns in southeastern Idaho. We used geostatistical tools and simulation models for precise mapping and to describe the relationships between G. pallida incidence and the spatial configurations. We found that the nematode is spatially clustered and prevalent around edges of fields, and its dispersal pattern followed the direction of cultivation. We found that the absence of potato in an infested field significantly reduced the number of cysts sampled each year subsequent to the initial delimitation sampling in 2007. Phytosanitary measures prohibiting the growth of potato contributed to stopping nematode reproduction, and the use of chemical fumigants and biofumigant cover crops contributed to a significant reduction in egg viability. We observed a process of a nonlinear decline in the prevalence of cysts as the distance separation from the primary infestation focus increased. A power law model was used to fit G. pallida dispersal capabilities. This study contributed to describing G. pallida infestation for Idaho. The goal of this study is to provide information on the spatial pattern and landscape ecology of G. pallida in Idaho for policy makers, industry, and researchers as well as facilitate common understandings on the challenges and opportunities for controlling this pest in Idaho.

ГЕЛЬМИНТОЦЕНОЗЫ И ПРОТОЗООЦЕНОЗЫ ДИКИХ ЖИВОТНЫХ (СЕМ. ОЛЕНЬИ) В ПОДЗОНЕ ГРАБОВО-ДУБОВО-ТЕМНОХВОЙНЫХ ЛЕСОВ БЕЛАРУСИ

Losses, associated with the massive spread of parasitic diseases, influence greatly the possible progressive growth in the num-ber of hunting species of wild an-imals. The article provides an assessment of the epizo-otic situation of parasitoses of wild cloven-hoofed animals ( species Deers ) of the horn-beam-oak-dark forests sub-zone of Belarus. The comparative efficacy of anthelmintics of a wide spectrum of ac-tion, possessing im-munomodulatory activity, is given. Ecological and parasitological studies of wild cloven-hoofed animals were car-ried out (2015-2018) in hunting farms of 9 terri-torial districts of the central forest-growing subzone, where the highest density of ani-mals was recorded by the route method, as well as at stations - GLHU "Berezinsky for-estry", GLHU "Ivatsevichy forestry ", Roga-chevskaya, Uzdenskaya and Minskaya ROS RGOO" BOOR " In total, samples of organs and tissues from 55 shot animals were studied, us-ing methods of excrement samples, generally accepted in parasitology. During the statisti-cal processing of the collected material in order to assess the infestation of an-imals by parasites, the following indicators were used: the extent of invasion (EI) and the intensity of invasion (II). Experiments have shown that the class of nematodes is the most species-rich in the helminthoses of wild artiodactyl animals. Widespread helminthiases in elk and red deer are - mecystocirrhosis and strongyloi-dosis, and in European roe deer - tri-chostrongyloidosis. The focus of helminthic infestation in elk should be considered pine young stands, complex spruce forests, renewable felling, for red deer - a complex pine for-est, a com-plex spruce forest, and for European roe - broad-leaved plantations, black alder forests and agricultural fields. For deworming of wild animals high antiparasitic efficiency was shown by new complex remedies - "Polyparatsid" and "Tetrahelminthicide", which have an im-munostimulating effect.

Spatial Analysis and Population Dynamics of Haplaxius crudus (Hemiptera: Cixiidae) in Coconut Amazon

Haplaxius crudus is the primary vector of the phytoplasma that causes the Lethal Yellowing of Coconut, a disease that has become a barrier to the establishment of large coconut plantations in the world. The objective of this study was to determine the spatial distribution pattern and population dynamics of H. crudus adults by correlating them with the abiotic factors, such as temperature and rainfall in commercial dwarf coconut palm plantations. Collection of American palm cixiid was carried out using yellow sticky traps fixed to the abaxial part of the coconut leaves. The sampled plants were georeferenced to obtain the geographic coordinates and geostatistical analysis, besides the planialtimetric survey of the experimental plot for the preparation of the map that shows the topographic conformation of the terrain. Insects were found at the study site throughout the year, showing greater abundance in months when the average monthly temperatures and rainfall were not significant. The climatic factors showed a correlation with the total of insects, positive for the temperature, with 0.733 and negative for the precipitation with -0.606. The spatial distribution of H. crudus displayed an aggregate pattern, explained by the spherical model. The infestation focus occurred in the periphery of the plot, near a Brachiaria humidicola pasture. It was concluded that the infestation of the H. crudus showed a behavior directly related to the local climatic conditions and the aggregate spatial distribution explained by the spherical model, therefore, forming shrubs with a radius of 154 to 190 m, with areas of influence between 7.45 and 17.80 ha, which coincide with the lower part of the terrain.

Humid-thermal index for a new management approach of Ommatissus lybicus.

The Dubas bug, Ommatissus lybicus, is a serious insect pest for the date palm Phoenix dactylifera in Oman and other date palm growing countries throughout the Middle East and North Africa. Climate is a key factor affecting the insect population dynamics, including O. lybicus. There are limited studies of O. lybicus relating to microclimate. The aim of this study was to investigate the efficiency of the various humid thermal indices (HTIs) and daily accumulation of temperature and humidity to model the relationship with O. lybicus. The highly infested locations showed a strong relationship with cumulative daily mean relative humidity (RhCm ), followed by daily minimum temperature (Tmin ) for pooled data over two seasons. The next best regression models for the relationship between the infestation and climate was with the absolute factors, daily maximum humidity (Rhmx ) and daily minimum humidity (Rhmin ), compared with HTIm/m (ratio of mean humidity to mean temperature) for the autumn season. The best regression model for the spring season was daily mean humidity (Rhm ) and daily maximum temperature (Tmax ). Daily cumulative temperature was the best predictive model for O. lybicus infestation on date palms, considering the microclimate data at each location separately. The predication model points to the areas that are prone to infestation and need focus for monitoring and allocation of management resources. © 2019 Society of Chemical Industry.

Primary Pulmonary Hydatid Disease

Echinococcosis is a parasitic disease endemic in many parts of the world. Liver is the most common affected organ followed by lungs. However, the infestation of the latter is usually secondary to another infected organ system. Symptoms are not specific and can be produced by the mass effect or cyst complications. In the article we are reporting a case of pulmonary echinococcosis in a middle aged male, where the patient presented with symptoms of fever, cough with expectoration, weight loss and dysponea. An extensive work-up showed no other foci of infestation, hence final diagnosis was done based on chest radiography and tomography scan findings and was successfully treated with Albendazole.Bangladesh Crit Care J September 2018; 6(2): 105-107

Polyandry, genetic diversity and fecundity of emigrating beetles: understanding new foci of infestation and selection

The frequency of polyandry and its ecological (and therefore selective) advantages remain unclear, especially in the field, where such tests are seldom conducted. We quantified the fecundity and level of polyandry in field populations of two stored grain beetles, Tribolium castaneum (Herbst) and Rhyzopertha dominica (F.), by comparing resident with dispersing individuals at common sites. Almost all females caught in flight had mated, with paternity analysis from 110 parent–offspring arrays revealing that most females had mated with more than one male (T. castaneum: 90.6, R. dominica: 70.2%). No difference in the extent of polyandry between beetles collected from grain in storage and beetles caught in flight was detected for either species, and the degree of polyandry did not impact overall fecundity. Levels of polyandry were similar to those in recently established (first generation) laboratory cultures of both species. Our results provide the first direct evidence of polyandry in wild populations of T. castaneum and R. dominica, and that females that have mated several times have the potential to produce offspring of multiple genotypes in the field. Females thus invade resource patches (whether previously colonised or not) with considerable genetic diversity to distribute across their offspring, an advantage in a newly colonised site because it increases the chances of her offspring establishing there. This advantageous consequence of polyandry to dispersing individuals, and the fact that most of the individual beetles sampled in the field had mated multiple times, provides justification as to why polyandry should not be viewed as an evolutionary paradox.

Risk of infestation of population by opisthorchiasis causative agent in the middle and lower current of the Iset river. influence of loimopotential of the focus of infestation on the risk values

The risk of infestation of the population by the opisthorchiasis causative agent in the middle and lower reaches of the Iset River was estimated. Areas with the highest risk of peoples infection by Opisthorchis felineus’ metacercaria are identified. These territories are confined to the zones of removal of the opisthorchiasis causative agent, which are river beds and large water bodies that constantly connect with rivers. Steady risk of infection of the population is determined by the loimopotential of the opisthorchiasis natural focus. The general infestation of juveniles fishes in the middle and lower current of the Iset River made 9,9 %, annuals – 21,5 %, two-year-olds – 19,5 %.

A simple, biologically sound, and potentially useful working classification of Chagas disease vectors.

Current working classifications of Chagas disease vectors rely on a loose mix-up of biological and operational matters. They are therefore confusing and ineffective. I propose a very simple classification that makes biological sense and can be operationally useful. It considers a four-level hierarchy of species (which can be native or non-native); populations (either wild or non-wild); infestation foci (natural, domestic or peridomestic); and individual bugs (which can be solitary house-invaders or part of a hidden infestation focus). This classification translates into a clear, algorithmic scheme for triatomine control-surveillance that may be useful at every operationally relevant scale, from multi-country initiatives to on-site control-surveillance action.

BIOLOGICAL CONTROL OF CITRUS WOOLLY WHITE FLY ALEUROTHRIXUS FLOCCOSUS MASK (HOMOPTERA: ALEYRODIDAE) BY CALES NOACKI HOW (HYMENOPTERA: APHELINIDAE) IN SOME TANZANIAN SMALL-SCALE CITRUS ORCHARDS

Calesnoacki How (Hymenoptera: Aphelinidae) wwas released in citrus groves in Muheza (05°10' 0S, 38°46' 0E) and Morogoro (06° 49' 0" S, 37° 40' 0 E) Townships to control Aleurothrixusfloccosus Mask (Homoptera: Alleyrodidae). Sleeve cage and “free release” methods were used to introduce the parasitoid onto selected citrus trees. C. noacki adults and mummies were released at selected sites between 08:00 and 09:30 am on 14th September 1999.
 Adults were first observed 90 days after introduction. They were also recovered from 2nd and 3rd CWWF instars. At Morogoro, CWWF infestations by adults, eggs and nymphs were reduced by between 6 and 12 fold 90 days after release and between 30 and 300 fold 60 months after. At Muheza decreases were between 140 and 700 and 12 and 17 fold, respectively compared. Parasitoid recovery indicated its establishment. Recoveries were also on trees up to two kilometres away from release sites. Parasitoid release was also accompanied by vigour improvement of previously heavily infested citrus trees. This is the first report of successful use of C. noacki for control of A. floccosus in Tanzania, which was prevented from spreading from the original small infestation foci.

Mating disruption of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) in a storage facility: Spatio-temporal distribution changed after long-term application

In the present study, we evaluated the application of mating disruption (MD) for stored-product Pyralidae in a large storage facility of amylaceous products in central Greece. Dispensers were placed in late 2010 until fall 2015, and the stored-product Pyralidae populations were monitored by using pheromone-baited sticky traps and Petri dishes containing semolina were used as oviposition traps. The infesting species that was found was the Mediterranean flour moth, E. kuehniella (Zeller). After the application of MD, the numbers of adult males found on the pheromone-baited traps were reduced in the MD-treated facility, as compared with the untreated (UTC), no MD, facility. Similarly, the numbers of larvae in the oviposition traps were also reduced, as compared with the UTC facility. During the successive years of MD deployment, there was a noticeable decrease in the number of Ephestia kuehniella male adults in the MD-treated facility, but the high density areas, and the infestation foci, were different among years. Hence, in 2014, the majority of the male adults were found at the areas where some years earlier, during the beginning of MD, there were no individuals, or their numbers were low. This suggests that, despite the effectiveness of the method, may be a spatial displacement to other areas. This fact could eventually alter the monitoring protocol, as new infestation foci may occur.

All that glisters is not gold: sampling-process uncertainty in disease-vector surveys with false-negative and false-positive detections.

BackgroundVector-borne diseases are major public health concerns worldwide. For many of them, vector control is still key to primary prevention, with control actions planned and evaluated using vector occurrence records. Yet vectors can be difficult to detect, and vector occurrence indices will be biased whenever spurious detection/non-detection records arise during surveys. Here, we investigate the process of Chagas disease vector detection, assessing the performance of the surveillance method used in most control programs – active triatomine-bug searches by trained health agents.Methodology/Principal FindingsControl agents conducted triplicate vector searches in 414 man-made ecotopes of two rural localities. Ecotope-specific ‘detection histories’ (vectors or their traces detected or not in each individual search) were analyzed using ordinary methods that disregard detection failures and multiple detection-state site-occupancy models that accommodate false-negative and false-positive detections. Mean (±SE) vector-search sensitivity was ∼0.283±0.057. Vector-detection odds increased as bug colonies grew denser, and were lower in houses than in most peridomestic structures, particularly woodpiles. False-positive detections (non-vector fecal streaks misidentified as signs of vector presence) occurred with probability ∼0.011±0.008. The model-averaged estimate of infestation (44.5±6.4%) was ∼2.4–3.9 times higher than naïve indices computed assuming perfect detection after single vector searches (11.4–18.8%); about 106–137 infestation foci went undetected during such standard searches.Conclusions/SignificanceWe illustrate a relatively straightforward approach to addressing vector detection uncertainty under realistic field survey conditions. Standard vector searches had low sensitivity except in certain singular circumstances. Our findings suggest that many infestation foci may go undetected during routine surveys, especially when vector density is low. Undetected foci can cause control failures and induce bias in entomological indices; this may confound disease risk assessment and mislead program managers into flawed decision making. By helping correct bias in naïve indices, the approach we illustrate has potential to critically strengthen vector-borne disease control-surveillance systems.

Modeling disease vector occurrence when detection is imperfect II: Drivers of site-occupancy by synanthropic Triatoma brasiliensis in the Brazilian northeast.

BackgroundUnderstanding the drivers of habitat selection by insect disease vectors is instrumental to the design and operation of rational control-surveillance systems. One pervasive yet often overlooked drawback of vector studies is that detection failures result in some sites being misclassified as uninfested; naïve infestation indices are therefore biased, and this can confound our view of vector habitat preferences. Here, we present an initial attempt at applying methods that explicitly account for imperfect detection to investigate the ecology of Chagas disease vectors in man-made environments.MethodologyWe combined triplicate-sampling of individual ecotopes (n = 203) and site-occupancy models (SOMs) to test a suite of pre-specified hypotheses about habitat selection by Triatoma brasiliensis. SOM results were compared with those of standard generalized linear models (GLMs) that assume perfect detection even with single bug-searches.Principal Findings Triatoma brasiliensis was strongly associated with key hosts (native rodents, goats/sheep and, to a lesser extent, fowl) in peridomestic environments; ecotope structure had, in comparison, small to negligible effects, although wooden ecotopes were slightly preferred. We found evidence of dwelling-level aggregation of infestation foci; when there was one such focus, same-dwelling ecotopes, whether houses or peridomestic structures, were more likely to become infested too. GLMs yielded negatively-biased covariate effect estimates and standard errors; both were, on average, about four times smaller than those derived from SOMs.Conclusions/SignificanceOur results confirm substantial population-level ecological heterogeneity in T. brasiliensis. They also suggest that, at least in some sites, control of this species may benefit from peridomestic rodent control and changes in goat/sheep husbandry practices. Finally, our comparative analyses highlight the importance of accounting for the various sources of uncertainty inherent to vector studies, including imperfect detection. We anticipate that future research on infectious disease ecology will increasingly rely on approaches akin to those described here.