CDC Gravid Trap Research Articles

NOVEL TRAP CONFIGURATION FOR LIVE CAPTURE OF MOSQUITOES

Diverse mosquito traps are available for mosquito and arbovirus surveillance. The delicate nature of the mosquito body makes them vulnerable to damage as they pass through the trap's fan, which can lead to rapid desiccation or mortality within the capture chamber. This can negatively affect surveillance accuracy, impacting both the precise identification of mosquitoes and the reliable execution of molecular assays for arbovirus detection. In this study, we report a novel modification to three widely used mosquito traps: CDC light trap, BG-Sentinel trap, and CDC gravid trap, incorporating a mesh funnel and updraft design to address these issues. We compared updraft and downdraft configurations of light traps under field conditions and compared the effectiveness of the modified BG and gravid trap to unaltered counterparts in semi-field environments. Subsequently, we conducted field validation of modified mosquito traps to assess their trapping effectiveness in terms of mosquito abundance and species composition in coastal forest and suburban areas. Our findings revealed that there was no significant difference in trapping effectiveness between different fan configurations. The adaptation made to the BG trap exhibited higher recapture rates of Culex quinquefasciatus and Aedes albopictus in comparison to the unmodified BG-Sentinel trap. The modification of the gravid trap was equivalent to unaltered CDC gravid trap. During our field trial, the modified light traps had a higher collection rate of mosquitoes with a wider spectrum of species diversity than modified BG or gravid traps, regardless of site. The modified BG traps captured more arbovirus vector species (Culex and Aedes species), with an increase in Ae. albopictus (11 times) and Ae. aegypti (1.75 times) when compared to the light traps. The modified gravid traps mostly collected Culex spp., accounting for over 47% of the collected mosquitoes. The results indicate that the novel trap configuration preserves trap functionality and improves specimen quality by avoiding the death and dismemberment of collected mosquitoes.

Environmental and geographical factors influence the occurrence and abundance of the southern house mosquito, Culex quinquefasciatus, in Hawai‘i

Hawaiian honeycreepers, a group of endemic Hawaiian forest birds, are being threatened by avian malaria, a non-native disease that is driving honeycreepers populations to extinction. Avian malaria is caused by the parasite Plasmodium relictum, which is transmitted by the invasive mosquito Culex quinquefasciatus. Environmental and geographical factors play an important role in shaping mosquito-borne disease transmission dynamics through their influence on the distribution and abundance of mosquitoes. We assessed the effects of environmental (temperature, precipitation), geographic (site, elevation, distance to anthropogenic features), and trap type (CDC light trap, CDC gravid trap) factors on mosquito occurrence and abundance. Occurrence was analyzed using classification and regression tree models (CART) and generalized linear models (GLM); abundance (count data) was analyzed using generalized linear mixed models (GLMMs). Models predicted highest mosquito occurrence at mid-elevation sites and between July and November. Occurrence increased with temperature and precipitation up to 580 mm. For abundance, the best model was a zero-inflated negative-binomial model that indicated higher abundance of mosquitoes at mid-elevation sites and peak abundance between August and October. Estimation of occurrence and abundance as well as understanding the factors that influence them are key for mosquito control, which may reduce the risk of forest bird extinction.

A Comparison of Hay and Fish Emulsion-Infused Water as Oviposition Attractants for the CDC Gravid Trap.

Multiple oviposition attractants are used for Culex (Diptera: Culicidae) mosquito surveillance in the CDC Gravid Trap, including hay and fish emulsion-infused water. Despite the use of both in the United States, no research has compared their attractiveness. We conducted trapping throughout Louisiana to assess the attractiveness of hay and fish emulsion-infused water in various habitat types and climates. Our results indicate that fish emulsion-infused water attracts more mosquitoes overall, more Culex quinquefasciatus (Say, 1823), and a wider diversity of mosquitoes than hay-infused water. This trend was maintained, regardless of habitat type or climate.

An Efficient Alternative to the CDC Gravid Trap for Southern House Mosquito (Diptera: Culicidae) Surveillance.

West Nile virus (WNV) is the most prevalent arbovirus found throughout the United States. Surveillance of surface breeding Culex vectors involved in WNV transmission is primarily conducted using CDC Gravid traps. However, anecdotal claims from mosquito abatement districts in Louisiana assert that other trap types may be more suited to WNV surveillance. To test the validity of these assertions, we conducted a series of trapping trials and WNV surveillance over 3 yr to compare the efficacy of multiple trap types. First, we compared the CDC Gravid trap, CO2-baited New Standard Miniature Blacklight traps, and CO2-baited CDC light traps with either an incandescent light, a red light, or no light. We found that the CDC Gravid trap and CO2-baited no-light CDC Light trap collected the most mosquitoes. Second, we conducted additional, long-term trapping and WNV surveillance to compare these two trap types. We found that CO2-baited no-light CDC traps collected more of the local WNV vector, Culex quinquefasciatus (Say, Diptera, Culicidae), and detected WNV with greater sensitivity. Finally, we conducted trapping to compare the physiological states of Cx. quinquefasciatus and diversity of collected mosquitoes. CO2-baited no-light CDC light traps collected more unfed Cx. quinquefasciatus while Gravid traps collected more blooded Cx. quinquefasciatus; both traps collected the same number of gravid Cx. quinquefasciatus. Additionally, we found that CO2-baited no-light CDC light traps collected a larger diversity of mosquito species than Gravid traps.

The invasive Asian tiger mosquito Aedes albopictus in Romania: towards a country-wide colonization?

Currently, five invasive Aedes mosquito species are of concern in Europe according to the European Centre for Disease Prevention and Control: Aedes aegypti, Ae. albopictus, Ae. atropalpus, Ae. japonicus, and Ae. koreicus. Among these, only Ae. albopictus was reported to occur in Romania, in Bucharest. The aim of this study was to update the knowledge on the distribution of this invasive mosquito species in Romania, by investigating new potential locations. Monitoring of Ae. albopictus was carried out between May 2017 and October 2018. Three types of traps (CDC-Gravid Traps, CDC miniature Light Traps, ovitraps) were placed in 53 localities in 13 counties at sites suitable for container-breeding mosquitoes. Collected adult mosquitoes were counted and identified according to morphological criteria. Larvae were found present in domestic containers and rain catch basins. Aedes albopictus adults and eggs were collected in 10 localities in eight counties across Romania. Our study confirms nine new localities and seven counties where Ae. albopictus became established in Romania, highlighting the need for surveillance to further assess the species' distribution and abundance, as well as the pathogen transmission risk related to that vector species.

Timely Public Health Intervention and Vectorborne Response Planning

Timely Public Health Intervention and Vectorborne Response Planning

La Crosse Virus Vectors Are Host-Seeking and Ovipositing After 1700 H in Eastern Tennessee.

La Crosse virus (LACV) is transmitted via the bites of infected Aedes mosquitoes (Ae. triseriatus, Ae. albopictus, and Ae. japonicus) and causes La Crosse encephalitis, which is the most commonly diagnosed arbovirus in eastern Tennessee children. This study identified host-seeking and oviposition activity of LACV vectors over a diel period, as it relates to traditional working hours. Nineteen sites in Knox County, TN, were monitored with host-seeking (Centers for Disease Control and Prevention [CDC] miniature light traps) and oviposition traps (CDC gravid traps) during 2 diel periods (0900-1700 h and 1700-900 h). We collected 2,444 adult mosquitoes, comprising 19 different species of which 1,337 (54.7%) were LACV vectors: Ae. albopictus (1,207 specimens), Ae. triseriatus (85 specimens), and Ae. japonicus (45 specimens). These species were active throughout the sampling period, but significantly more were collected from 1700-0900 h. The CDC gravid trap was the most effective method for monitoring Ae. japonicus; there were no trap effects or trap × time interactive effects for Ae. albopictus or Ae. triseriatus. Overall, significantly more LACV vectors were collected from 1700-0900 h compared to 0900-1700 h. Information gathered in this study improves vector surveillance, helps communities control mosquito populations, and minimizes nontarget effects.

Evaluation of collection methods for Culex quinquefasciatus, Aedes aegypti, and Aedes simpsoni in northeastern Tanzania.

In East Africa, significant morbidity and mortality are caused by infections spread by Culex quinquefasciatus and Aedes aegypti. Sticky traps have been shown to be effective tools for sampling populations of Aedes mosquitoes and have been found to catch Cx. quinquefasciatus. Thus, they could potentially be used to sample populations of this species. This study compared Sticky ovitraps (SO) and MosquiTraps (MQT) with the CDC Gravid trap (CDC-GT) for collection of Culex and Aedes mosquito populations in Tanzania. A follow-up experiment was carried out using traps set for a 24-h period to accommodate the oviposition habits of Aedes aegypti and Ae. simpsoni s.l. mosquitoes. The results showed that the CDC-GT caught significantly more Cx. quinquefasciatus and Ae. aegypti than the SO or MQT, but there was no significant difference in the number of mosquitoes caught between the two sticky traps or of Ae. simpsoni s.l. caught among the three trap types. The results suggest that CDC-GTs are the most appropriate in sampling of Cx. quinquefasciatus. Although CDC-GTs collected more Ae. aegypti than the sticky traps, the simplicity and cost benefit of sticky traps facilitates large scale studies. All three trap types should be considered for monitoring Aedes mosquitoes.

Field Surveillance Methods for West Nile Virus.

Surveillance of West Nile virus (WNV) in populations of mosquitoes or sentinel animals is of primary importance when assessing the risks to human health posed by naturally circulating WNV. In this chapter we focus on methods for detection of both WNV and its enzootic transmission. Methods for virus detection include CDC mini light trap, CDC gravid trap, and dead bird surveillance. Methods for transmission detection include passive box traps, chicken-baited traps, and sentinel chickens.

Comparative study on the effectiveness of different mosquito traps in arbovirus surveillance with a focus on WNV detection

The selection of the ideal trap for arbovirus surveillance is an issue of primary importance to increase the sensitivity of virus detection and the cost-effectiveness of the entomological surveillance. During the summer 2011, the effectiveness of five types of mosquito traps (CDC gravid trap, CO2-baited trap, BG-Sentinel™ and two experimental prototypes) to attract females potentially infected with West Nile virus were assessed. The study was carried out in three natural wetland sites located in the Emilia-Romagna Region (Northern Italy), using a Latin square scheme. Single night collections of adult females were performed and determination of species and physiological state (gravid, nulliparous or parous) was made upon return to the laboratory. The species most frequently collected in the gravid trap was Culex pipiens sl. L., being gravid females the large majority of the individuals. Species diversity was much higher in CO2-baited traps, which may therefore enable a more comprehensive description of the vector species composition and their role in arboviruses circulation. Our findings indicate that gravid traps can be a valid tool and should be integrated in the West Nile virus surveillance system in the Emilia-Romagna region, mainly based on collections made with CO2-baited traps.

Detection of Japanese encephalitis virus genotype V in Culex orientalis and Culex pipiens (Diptera: Culicidae) in Korea.

Japanese encephalitis virus (JEV) causes significant viral encephalitis and is distributed throughout the Asian countries. The virus is known to be transmitted by Culex tritaeniorhynchus, which mainly breeds in rice paddies in Korea. In this study, we investigated the presence of other mosquito species that can transmit JEV as a second or regional vector. We selected five cities where patients have experienced JE in the last 5 years as mosquito-collecting locations and subdivided them into four collection sites according to the mosquito habitats (cowshed, downtown area, forest, and swamp). Mosquitoes were caught using the BG-Sentinel trap, CDC black-light trap, Fay-Prince trap, and Gravid trap. A total of 993 pools from 22,774 mosquitoes were prepared according to their species, collection date, and site. We performed a SYBR Green 1-based real-time RT-PCR assay to detect JEV from the mosquito pools. A total of six JEV-positive pools were detected from Culex orientalis and Culex pipiens caught in the Gangwon-do and Gyeonngi-do provinces. All the detected JEVs were revealed as genotype V by phylogenetic analysis of the envelope gene. Our findings confirm that a new genotype of JEV was introduced in Korea and suggest that two mosquito species may play a role in JEV transmission.

Mosquitoes of Western Yunnan Province, China: seasonal abundance, diversity, and arbovirus associations.

ObjectiveThe western borderland between Yunnan Province, China, and Myanmar is characterized by a climate that facilitates year-round production of mosquitoes. Numerous mosquito-transmitted viruses, including Japanese encephalitis virus circulate in this area. This project was to describe seasonal patterns in mosquito species abundance and arbovirus activity in the mosquito populations.MethodsMosquitoes were collected in Mangshi and Ruili cities of Dehong Prefecture near the border of China and Burma in Yunnan Province, the Peoples Republic of China in 2010. We monitored mosquito species abundance for a 12-month period using ultraviolet light, carbon dioxide baited CDC light and gravid traps; and tested the captured mosquitoes for the presence of virus to evaluate mosquito-virus associations in rural/agricultural settings in the area.ResultsA total of 43 species of mosquitoes from seven genera were collected, including 15 Culex species, 15 Anopheles spp., four Aedes spp., three Armigeres spp., one Mimomyia spp., two Uranotaenia spp. and three Mansonia spp.. Species richness and diversity varied between Mangshi and Ruili. Culex tritaeniorhynchus, Culex quinquefasciatus, Anopheles sinensis and Anopheles peditaeniatus were the most abundant species in both sampling sites. Ultraviolet light traps collected more specimens than CDC light traps baited with dry ice, though both collected the same variety of mosquito species. The CDC gravid trap was the most effective trap for capture of Culex quinquefasciatus, a species underrepresented in light trap collections. A total of 26 virus strains were isolated, which included 13 strains of Japanese encephalitis virus, four strains of Getah virus, one strain of Oya virus, one strain from the orbivirus genus, and seven strains of Culex pipien pallens densovirus.ConclusionsThe present study illustrates the value of monitoring mosquito populations and mosquito-transmitted viruses year-round in areas where the climate supports year-round adult mosquito activity.

Comparison of different trapping methods for surveillance of mosquito vectors of West Nile virus in Rhône Delta, France

Five trapping methods were compared for monitoring potential vectors of the West Nile virus in four areas in the Camargue Plain of France: carbon dioxide traps, bird-baited traps, gravid traps, resting boxes, and human landing catches. A total of 73,721 specimens, representing 14 species, was trapped in 2006. Results showed significant differences in species and abundance between the type of traps. Many more specimens were collected using CO(2) traps than any other method, with an average of 212 specimens per night per trap (p<0.05). Culex pipiens was the most abundant species collected (36.8% of total with CO(2) traps), followed by Aedes caspius (22.7%), Anopheles hyrcanus (18.3%), Culex modestus (18.3%), and Aedes detritus (3.2%). Bird-baited traps captured only eight specimens per night per trap on average, mainly Cx. pipiens (89.9%). The species collected and their abundance are influenced by the trap location, at ground or canopy level. Culex pipiens was twice as abundant in the canopy as on the ground, whereas it was the opposite for Ae. caspius, An. hyrcanus, and Ae. detritus. Culex modestus was equally abundant at both levels. Resting boxes and gravid traps were much less efficient, capturing around 0.3 specimens per night per trap. Results are discussed in relation to West Nile virus surveillance.

Evaluation of gravid traps for the collection of Culex quinquefasciatus, a vector of lymphatic filariasis in Tanzania

Although several studies have suggested that gravid traps might be useful for collection of mosquitoes, particularly Culex quinquefasciatus, to monitor transmission of the nematode Wuchereria bancrofti (xenomonitoring), there has not been a study to see which of the currently available gravid traps is most effective in endemic areas. The present study evaluated the comparative efficacy for collection of Cx quinquefasciatus of four commercially available gravid traps: the CDC, Frommer Updraft, Reiter-Cummings and Harris County traps. Trap evaluations were conducted in two locations in Tanzania, Ifakara and Tanga. Mosquitoes collected were identified to species, sex, and gonotrophic status. In both locations, the CDC gravid trap collected the highest number of mosquitoes, the highest number of Cx quinquefasciatus, and the highest proportion of gravid mosquitoes. Although it damaged the highest proportion of mosquitoes as they passed through the trap fan, the CDC gravid trap also contained the highest number of living mosquitoes, when the traps were collected in the morning. The CDC gravid traps collected significantly more phlebotomine sandflies than the other traps and in Tanga, where they were more frequent, the highest number of biting midges. The effectiveness of all four gravid traps should encourage the sampling of Cx quinquefasciatus where it is an important disease vector or nuisance mosquito. The unexpected collection of phlebotomine sandflies and biting midges indicates that gravid traps might usefully collect other insects, including those of medical importance.

OCHLEROTATUS JAPONICUS JAPONICUS IN THE STATE OF KENTUCKY

Ochlerotatus j. japonicus (Theobald) was first collected and identified in 2003 from CDC gravid trap collections in Boone, Campbell, and Wolfe counties, Kentucky. Subsequent collections during 2004 and 2005 indicate that the species has become established in Boone, Campbell, Fayette, Fleming, Grant, Jefferson, and Kenton counties.

Efficacy of Four Trap Types for Detecting and MonitoringCulexspp. in North Central Florida

The effectiveness of four types of mosquito traps at sampling Culex mosquitoes was compared at two north central Florida study sites (a commercial dairy and a swine research unit) with highly eutrophic lagoons that have a history of producing large populations of Culex mosquitoes. Traps evaluated included a John Hock (JH) model 1012 CDC style light trap, JH model 1712 CDC Gravid Trap (GT), and American Biophysics Corporation's Mosquito Magnet-Experimental (MM-X) and commercial model MM-Professional (MM-Pro) traps. The MM-X and MM-Pro traps are based on new counterflow technology. Culex nigripalpus Theobald and Culex quinquefasciatus Say were the two most abundant species collected, and they were the dominant species at the dairy site and swine research unit, respectively. Culex erraticus Dyar & Knabb and Culex salinarius Coquillett also were caught but in much lower numbers than the two dominant species at the swine unit, and rarely at the dairy site. At the dairy site the MM-Pro collection of total female Cx. quinquefasciatus was significantly greater than all other trap types (MM-Pro > GT > MM-X = CDC), and the MM-Pro also caught the most Cx. nigripalpus, but not significantly more than the CDC or MM-X (MM-Pro = CDC = MM-X > GT). At the swine research unit the largest number of female Cx. quinquefasciatus were caught in the MM-X trap, but the only significant difference was with the CDC trap (MM-X = MM-Pro = GT > CDC). For Cx. nigripalpus the CDC trap caught the most females, but these collections were only significantly different from the MM-Pro and GT (CDC = MM-X > MM-Pro > GT). The GT caught significantly more gravid female Cx. quinquefasciatus than all the other trap types at both sites, but collected very few gravid Cx. nigripalpus at either site.

Efficacy of Four Trap Types for Detecting and Monitoring &lt;I&gt;Culex&lt;/I&gt; spp. in North Central Florida

The effectiveness of four types of mosquito traps at sampling Culex mosquitoes was compared at two north central Florida study sites (a commercial dairy and a swine research unit) with highly eutrophic lagoons that have a history of producing large populations of Culex mosquitoes. Traps evaluated included a John Hock (JH) model 1012 CDC style light trap, JH model 1712 CDC Gravid Trap (GT), and American Biophysics Corporation's Mosquito Magnet-Experimental (MM-X) and commercial model MM-Professional (MM-Pro) traps. The MM-X and MM-Pro traps are based on new counterflow technology. Culex nigripalpus Theobald and Culex quinquefasciatus Say were the two most abundant species collected, and they were the dominant species at the dairy site and swine research unit, respectively. Culex erraticus Dyar & Knabb and Culex salinarius Coquillett also were caught but in much lower numbers than the two dominant species at the swine unit, and rarely at the dairy site. At the dairy site the MM-Pro collection of total female Cx. quinquefasciatus was significantly greater than all other trap types (MM-Pro > GT > MM-X = CDC), and the MM-Pro also caught the most Cx. nigripalpus, but not significantly more than the CDC or MM-X (MM-Pro = CDC = MM-X > GT). At the swine research unit the largest number of female Cx. quinquefasciatus were caught in the MM-X trap, but the only significant difference was with the CDC trap (MM-X = MM-Pro = CT > CDC). For Cx. nigripalpus the CDC trap caught the most females, but these collections were only significantly different from the MM-Pro and GT (CDC = MM-X > MM-Pro > GT). The GT caught significantly more gravid female Cx. quinquefasciatus than all the other trap types at both sites, but collected very few gravid Cx. nigripalpus at either site.

Mosquito Hosts of Arboviruses from Indian River County, Florida, during 1998

Adult mosquitoes were collected for virus isolation from two sites in Indian River County, FL, from May 5 through August 13, 1998 using dry ice-baited CDC light traps (81 trap-nights) and CDC gravid traps (254 trap-nights). A total of 46,150 female mosquitoes (923 mosquito-pools, 50 females/pool) were processed for virus isolation. These females represented 18 species of mosquitoes, with Culex nigripalpus comprising 77.4% of all mosquitoes collected, followed by Aedes infirmatus (4.9%), Ae. vexans (4.0%) and Cx. erraticus (2.4%). No St. Louis encephalitis (SLE) and eastern equine encephalitis (EEE) virus isolates were obtained. Keystone (KEY) and Tensaw (TEN) viruses were isolated from Ae. albopictus (one isolate of KEY); Anopheles crucians (two isolates of TEN); Cx. nigripalpus (one isolate of TEN and 2 isolates of KEY); Coquilletidia perturbans (two isolates of TEN); and Wyeomyia vanduzeei (one isolate of TEN). All isolates were obtained from mosquitoes collected in CDC light traps, except for the KEY virus isolate from Ae. albopictus, which was collected in a CDC gravid trap. The isolation of TEN virus from Wy. vanduzeei is a first record for Florida.