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Gregory M. Williams

Bio: Gregory M. Williams is an academic researcher from Rutgers University. The author has contributed to research in topics: Aedes albopictus & Population. The author has an hindex of 13, co-authored 28 publications receiving 631 citations. Previous affiliations of Gregory M. Williams include North Carolina State University & University of Delaware.

Papers
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Journal ArticleDOI
TL;DR: The BG-Sentinel trap with and without lures provides effective chemical and visual cues for host-seeking Ae.
Abstract: Standard surveillance traps in North America for adult Aedes albopictus (Skuse) (Diptera: Culicidae), an invasive mosquito with public health implications, are currently ineffective. We compared the efficacy of the BG-Sentinel trap (BGS) with and without lures (BG-lure, octenol, and CO2), the Centers for Disease Control and Prevention light trap (CDC) with and without lures, and the gravid trap (GT) for Ae. albopictus collection in two urban sites in New Jersey. The BGS with or without lures collected more Ae. albopictus compared with other trap configurations and was more specific for Ae. albopictus. In Camden County, the BGS with lures collected three times more Ae. albopictus than the CDC (with CO2 only) and five times more than the GT. In Mercer County, BGS with lures collected the most mosquitoes, with 3 times more Ae. albopictus than the CDC with all lures and 50 times more than the GT. The BGS collected more male Ae. albopictus than other traps in both counties, providing further population monitoring. The GT and BGS provided a relative measure of the enzootic activity of West Nile virus in Culex spp. and the potential epidemic activity of WNV in Ae. albopictus. The BGS provides effective chemical and visual cues for host-seeking Ae. albopictus and should be used as a part of existing surveillance programs and new initiatives targeting this mosquito.

175 citations

Journal ArticleDOI
TL;DR: Paucity of data on host-feeding patterns and behavior of 43 mosquito species that are reported as suspected West Nile virus (WN) vectors has limited full evaluation of their vectorial capacity, and Culex salinarius appear to be the most likely bridge vectors.
Abstract: Paucity of data on host-feeding patterns and behavior of 43 mosquito species that are reported as suspected West Nile virus (WN) vectors has limited full evaluation of their vectorial capacity. Recent studies addressing this issue need additional confirmation and should also be expanded to include collections of species or subpopulations attracted to humans. We used 4 types of collection methods to collect mosquitoes, including omnidirectional Fay–Prince traps, Centers for Disease Control–type light traps, gravid traps, and human-landing collections. Mosquitoes were collected during 2 full WN transmission seasons in 2001 and 2002, at 9 different sites across Delaware. We collected from various habitats, including salt marshes, brackish water areas, woodlands, a tire dump, a racetrack, and a mushroom farm. Blood-meal analyses were performed on parous mosquitoes by using a sandwich-type enzyme-linked immunosorbent assay. We tested primarily for 5 common host species, including rabbits, dogs, deer, ...

65 citations

Journal ArticleDOI
TL;DR: The results demonstrate the advantage of using gravid traps for West Nile virus surveillance over light traps or resting boxes, which is nearly 33 times greater than the infection rate from light traps.
Abstract: West Nile virus surveillance was conducted at five sites in New Castle County, DE, and one site in Salem County, NJ, from June through September, 2004, using dry ice-baited Centers for Disease Control miniature light traps, infusion-baited gravid traps, and resting boxes. All trap types were simultaneously placed at each site every two weeks and run overnight. Collected mosquitoes were identified to species, pooled, and analyzed for virus using a real-time reverse transcriptase polymerase chain reaction test. In total, 47,972 mosquitoes in 29 species or species groups were analyzed. Light traps collected 60,201 mosquitoes in 28 species or species groups. Gravid traps collected 3,195 mosquitoes in 19 species or species groups. Resting boxes collected 99 mosquitoes in nine species or species groups. In total, 1,500 mosquito pools were tested for WNV resulting in ten positive pools. All positive pools consisted of Culex pipiens, Culex restuans, or Culex salinarius. Seven positive pools were from gravid traps and three were from light traps despite testing almost 14 times as many pools from light traps. The overall infection rate from gravid traps was nearly 33 times greater than the infection rate from light traps, 2.29 and 0.07 infected mosquitoes per 1,000, respectively. The results demonstrate the advantage of using gravid traps for West Nile virus surveillance over light traps or resting boxes.

63 citations

Journal ArticleDOI
TL;DR: This paper reports on the remote characterization of flying mosquitoes using a continuous-wave infrared optical remote sensing system and discusses the limitations of using wing beat frequency alone to identify insect species.
Abstract: Mosquito-borne diseases are a major challenge for Human health as they affect nearly 700 million people every year and result in over 1 million deaths. Reliable information on the evolution of population and spatial distribution of key insects species is of major importance in the development of eco-epidemiologic models. This paper reports on the remote characterization of flying mosquitoes using a continuous-wave infrared optical remote sensing system. The system is setup in a controlled environment to mimic long-range lidars, mosquitoes are free flying at a distance of ~ 4 m from the collecting optics. The wing beat frequency is retrieved from the backscattered light from mosquitoes transiting through the laser beam. A total of 427 transit signals have been recorded from three mosquito species, males and females. Since the mosquito species and gender are known a priori, we investigate the use of wing beat frequency as the sole predictor variable for two Bayesian classifications: gender alone (two classes) and species/gender (six classes). The gender of each mosquito is retrieved with a 96.5% accuracy while the species/gender of mosquitoes is retrieved with a 62.3% accuracy. Known to be an efficient mean to identify insect family, we discuss the limitations of using wing beat frequency alone to identify insect species.

51 citations

Journal ArticleDOI
TL;DR: Overall, seasonal distribution of vectors was bimodal, with peaks occurring during early and late summer, and ponds with shallow sides and heavy shade generally produced an abundance of mosquitoes, unless insect predators were abundant.
Abstract: We performed longitudinal surveys of mosquito larval abundance (mean mosquito larvae per dip) in 87 stormwater ponds and constructed wetlands in Delaware from June to September 2004. We analyzed selected water quality factors, water depth, types of vegetation, degree of shade, and level of insect predation in relation to mosquito abundance. The 2004 season was atypical, with most ponds remaining wet for the entire summer. In terms of West Nile virus (WNV) vectors, wetlands predominantly produced Aedes vexans, Culex pipiens pipiens, and Culex restuans. Retention ponds generally produced the same species as wetlands, except that Cx. p. pipiens was more abundant than Cx. restuans in retention ponds. Aedes vexans and Culex salinarius were the most abundant species in Conservation Restoration Enhancement Program ponds. Sand filters uniquely produced high numbers of Cx. restuans, Cx. p. pipiens, and Aedes japonicus japonicus, a newly invasive vector species. Sites that alternately dried and flooded, mostly detention ponds, forebays of retention ponds, and some wetlands often produced Ae. vexans, an occasional WNV bridge vector species. Overall, seasonal distribution of vectors was bimodal, with peaks occurring during early and late summer. Ponds with shallow sides and heavy shade generally produced an abundance of mosquitoes, unless insect predators were abundant. Bright, sunny ponds with steep sides and little vegetation generally produced the fewest mosquitoes. The associations among mosquito species and selected vegetation types are discussed.

50 citations


Cited by
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Journal ArticleDOI
TL;DR: Culex salinarius is a bridge vector to humans, while CX.
Abstract: To evaluate the role of Culex mosquitoes as enzootic and epidemic vectors for WNV, we identified the source of vertebrate blood by polymerase chain reaction amplification and sequencing portions of the cytochrome b gene of mitochondrial DNA. All Cx. restuans and 93% of Cx. pipiens acquired blood from avian hosts; Cx. salinarius fed frequently on both mammals (53%) and birds (36%). Mixed-blood meals were detected in 11% and 4% of Cx. salinarius and Cx. pipiens, respectively. American robin was the most common source of vertebrate blood for Cx. pipiens (38%) and Cx. restuans (37%). American crow represented <1% of the blood meals in Cx. pipiens and none in Cx. restuans. Human-derived blood meals were identified from 2 Cx. salinarius and 1 Cx. pipiens. Results suggest that Cx. salinarius is an important bridge vector to humans, while Cx. pipiens and Cx. restuans are more efficient enzootic vectors in the northeastern United States.

337 citations

Journal ArticleDOI
TL;DR: Urbanization substantially increased the density, larval development rate, and adult survival time of Ae.
Abstract: Introduction Aedes albopictus is a very invasive and aggressive insect vector that causes outbreaks of dengue fever, chikungunya disease, and yellow fever in many countries. Vector ecology and disease epidemiology are strongly affected by environmental changes. Urbanization is a worldwide trend and is one of the most ecologically modifying phenomena. The purpose of this study is to determine how environmental changes due to urbanization affect the ecology of Aedes albopictus.

302 citations

Journal ArticleDOI
TL;DR: In this paper, the authors identify a range of research needs: (1) the roles of design and location of urban ponds in influencing biodiversity, (2) the function of urban wetlands for stormwater and pollution management, and (3) public perceptions of urban ecosystems and how those perceptions are influenced by interactions with natural systems.
Abstract: Recent research has demonstrated that ponds contribute a great deal to biodiversity at a regional level as networks of habitat patches that also act as ‘stepping stones’ to facilitate the movement of species through the landscape. Similarly, a great deal of biodiversity persists in urban environments where synanthropic communities are supplemented by species that thrive in disturbed environments. Aquatic urban biodiversity appears to persist despite anthropogenic stressors: an array of anthropogenic pollutants (road salt and heavy metals), invasive species, and active mismanagement—particularly the removal of riparian vegetation. Optimizing urban ponds for different ecosystem services results in conflicting priorities over hydrological, geochemical, ecological, aesthetic, and cultural functions. The socio-ecosystem approach to environmental management opens a path to greater incorporation of biodiversity into town planning and sustainability, while accounting for cultural attitudes to urban ecosystems. I identify a range of research needs: (1) the roles of design and location of urban ponds in influencing biodiversity, (2) the function of urban wetlands for stormwater and pollution management, and (3) public perceptions of urban ecosystems and how those perceptions are influenced by interactions with natural systems. Urban wetlands offer an important opportunity to educate the general public on natural systems and science in general using a resource that is located on their doorstep. In the face of increasing pressures on natural systems and increasing extent and intensity of urbanization, a more comprehensive appreciation of the challenges and opportunities provided by urban ponds could play a substantial role in driving sustainable urban development.

208 citations

Journal ArticleDOI
01 Feb 2021
TL;DR: Supervised machine learning models for COVID-19 infection were developed in this work with learning algorithms which include logistic regression, decision tree, support vector machine, naive Bayes, and artificial neutral network using epidemiology labeled dataset for positive and negative CO VID-19 cases of Mexico.
Abstract: COVID-19 or 2019-nCoV is no longer pandemic but rather endemic, with more than 651,247 people around world having lost their lives after contracting the disease. Currently, there is no specific treatment or cure for COVID-19, and thus living with the disease and its symptoms is inevitable. This reality has placed a massive burden on limited healthcare systems worldwide especially in the developing nations. Although neither an effective, clinically proven antiviral agents' strategy nor an approved vaccine exist to eradicate the COVID-19 pandemic, there are alternatives that may reduce the huge burden on not only limited healthcare systems but also the economic sector; the most promising include harnessing non-clinical techniques such as machine learning, data mining, deep learning and other artificial intelligence. These alternatives would facilitate diagnosis and prognosis for 2019-nCoV pandemic patients. Supervised machine learning models for COVID-19 infection were developed in this work with learning algorithms which include logistic regression, decision tree, support vector machine, naive Bayes, and artificial neutral network using epidemiology labeled dataset for positive and negative COVID-19 cases of Mexico. The correlation coefficient analysis between various dependent and independent features was carried out to determine a strength relationship between each dependent feature and independent feature of the dataset prior to developing the models. The 80% of the training dataset were used for training the models while the remaining 20% were used for testing the models. The result of the performance evaluation of the models showed that decision tree model has the highest accuracy of 94.99% while the Support Vector Machine Model has the highest sensitivity of 93.34% and Naive Bayes Model has the highest specificity of 94.30%.

185 citations

Journal ArticleDOI
TL;DR: Its successful invasion likely does not involve superior direct competitive abilities, but it is associated with the use of diverse larval habitats and a cold tolerance that allows an expanded seasonal activity range in temperate climates.
Abstract: Aedes japonicus japonicus (Theobald) (Diptera: Culicidae) has recently ex- panded beyond its native range of Japan and Korea into large parts of North America and Central Europe. Population genetic studies begun immediately after the species was detected in North America revealed genetically distinct introductions that subsequently merged, likely contributing to the success- ful expansion. Interactions, particularly in the larval stage, with other known disease vectors give this invasive subspecies the potential to influence local disease dynamics. Its successful invasion likely does not involve superior di- rect competitive abilities, but it is associated with the use of diverse larval habitats and a cold tolerance that allows an expanded seasonal activity range in temperate climates. We predict a continued but slower expansion of Ae. j. japonicus in North America and a continued rapid expansion into other areas as this mosquito will eventually be considered a permanent resident of much of North America, Europe, Asia, and parts of Hawaii.

176 citations