Detection of Babesia microti and Borrelia burgdorferi in host-seeking Ixodes scapularis (Acari: Ixodidae) in Monmouth County, New Jersey.

The etiological agents that cause human babesiosis (Babesia microti) and Lyme disease (Borrelia burgdorferi) share a common tick vector (Ixodes scapularis Say) and rodent reservoir (Peromyscus leucopus), but because the geographical distribution of babesiosis is more restricted than Lyme disease, it was not considered a nationally notifiable disease until 2011. Although recent studies have shown dramatic increases in the number of cases of babesiosis and expansion of its range, little is known about infection and coinfection prevalence of these pathogens in the primary tick vector. Of the 478 I. scapularis nymphs collected within six Monmouth County, NJ, municipalities between 2004 and 2006, 4.0 and 10.0% were infected with B. microti and B. burgdorferi, respectively, while 2.9% were coinfected. Analysis of the 610 I. scapularis adults collected during the same period yielded an infection prevalence of 8.2% for B. microti and 45.2% for B. burgdorferi, while 6.2% were coinfected. The potential public health importance of these findings is discussed.

Isolations of Cache Valley virus from Aedes albopictus (Diptera: Culicidae) in New Jersey and evaluation of its role as a regional arbovirus vector.

The Asian tiger mosquito, Aedes albopictus (Skuse), is an invasive species and a major pest problem in urban and suburban locales in New Jersey. To assess its potential role as an arbovirus vector, we sampled Ae. albopictus from two New Jersey counties over a 3-yr period and estimated the prevalence of virus infection by Vero cell culture and reverse transcription-polymerase chain reaction assays. Three virus isolates were obtained from 34,567 field-collected Ae. albopictus, and all were identified as Cache Valley virus by molecular methods. Ae. albopictus (N = 3,138), collected in Mercer County from late July through early September 2011, also were retested for West Nile virus (WNV) by reverse transcription-polymerase chain reaction, and all were negative. These results corroborate previous findings showing that Ae. albopictus may occasionally acquire Cache Valley virus, a deer-associated arbovirus, in nature. In contrast, we did not detect WNV infection in Ae. albopictus despite concurrent WNV amplification in this region.

Experiences with the large-scale operation of the Biogents Sentinel trap.

We obtained 160 Biogents Sentinel traps (BGS-traps) to monitor adult mosquito populations for the Area-wide Pest Management Program for the Asian tiger mosquito (Aedes albopictus) in New Jersey. We deployed between 90 and 110 BGS-traps weekly from May through October of 2008, 2009, 2010. and 2011. Here we detail our experience: challenges with acquisition, defects in construction, as well as actions taken to correct problems we found and preempt them in the future. Further, we describe the impact of these problems on our research and provide a cost analysis of repairs.

Efficacy of Duet dual-action adulticide against caged Aedes albopictus with the use of an ultra-low volume cold aerosol sprayer.

Duet was field evaluated against caged Aedes albopictus, with the use of a truck-mounted ultra-low volume (ULV) cold aerosol sprayer at the rate of 90.6 ml/ha. Cages were placed in 3 rows stationed 30.5, 61.0, and 91.5 m downwind of the spray vehicle. Initial knockdown was >99% with mortality ranging between 95.8% and 98.0% across the distances. Volume median diameter (VMD) and droplet density were slightly reduced (16.4% and 18.6%, respectively) by distance. Reduction in VMD and droplet density, however, did not reduce mortality. The ULV application of Duet is an effective adulticide against Ae. albopictus and may be a useful tool for use in mosquito abatement programs.

A model to predict evaporation rates in habitats used by container-dwelling mosquitoes.

Container-dwelling mosquitoes use a wide variety of container habitats. The bottle cap is often cited as the smallest container habitat used by container species. When containers are small, the habitat conditions can greatly affect evaporation rates that in turn can affect the species dynamics within the container. An evaporation rate model was adapted to predict evaporation rates in mosquito container habitats. In both the laboratory and field, our model was able to predict actual evaporation rates. Examples of how the model may be applied are provided by examining the likelihood of Aedes albopictus (Skuse), Aedes aegypti (L.), and Culex pipiens pipiens (L.) completing their development within small-volume containers under typical environmental conditions and a range of temperatures. Our model suggests that under minimal direct sunlight exposure, both Ae. aegypti and Ae. albopictus could develop within a bottle cap before complete evaporation. Our model shows that under the environmental conditions when a plastic field container was sampled, neither Ae. albopictus or Cx. p. pipiens could complete development in that particular container before the water evaporated. Although rainfall could replenish the habitat, the effects of evaporation would increase larval density, which could in turn further decrease developmental rates.

Geographical distribution and prevalence of selected Borrelia, Ehrlichia, and Rickettsia infections in Amblyomma americanum (Acari: Ixodidae) in New Jersey.

We used published accounts to describe the known statewide distribution of the lone star tick, Amblyomma americanum, in New Jersey and field surveys to characterize the geographical range of A. americanum and selected A. americanum-transmitted pathogens in Monmouth County, the hypothesized northern limit of the species distribution. Ticks were collected using standardized methods from 50 widely dispersed public access areas within 18 municipalities to produce estimates of relative abundance among sites. Collected A. americanum adults were stored at -80 degrees C until processed for DNA extraction. Individual ticks were subjected to polymerase chain reaction analyses to detect the presence of Ehrlichia chaffeensis, E. ewingii, Rickettsia amblyommii, and Borrelia lonestari. The range of A. americanum was generally limited to the southern half of New Jersey. Within Monmouth County, we collected A. americanum from 9 of 18 municipalities (50%) and 24 (48%) of the surveyed properties. We found at least 1 pathogen at 17 (70.8%) sites located within 6 of 9 municipalities, while all 4 target pathogens were detected in 5 of those 6 (83.3%) municipalities. The geographical distribution of A. americanum and its associated pathogens appeared to be restricted to the southern portion of the county. Possible factors governing the distribution are discussed.

A droplet collection device and support system for ultra-low-volume adulticide trials.

A supporting stand to suspend rotating impactors and mosquito cages is a requirement for field tests during pesticide efficacy trials. We present schematics for a collection device and associated support system for sampling droplets of ultra-low-volume (ULV) sprays during mosquito adulticide applications. This system offers the advantages of cost efficiency, increased ease of deployment, off-season storage, visibility, stability, and ULV collection efficacy. Use of this system ensures that droplet collection and meteorological equipment is at appropriate and consistent heights between trials. The 2 arms of the support allow for placement of multiple cages, light-emitting or reflecting devices, and wind-indicating ribbons to be attached to the station. The support described makes possible deployment of stations over a wider variety of terrains, increasing the extent of field trials. Presentation of the simple design and fabrication of the rotating collection device (impactor), T-station, and its support is provided.

Field efficacy of BG-Sentinel and industry-standard traps for Aedes albopictus (Diptera: Culicidae) and West Nile virus surveillance.

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.

Sentinel chicken coop modification for canopy-level arbovirus disease surveillance.

A pulley-block system for elevating sentinel chicken coops was designed to conduct mosquito-borne virus surveillance in the forest canopy. This modified design allows traditional captive sentinel bird cages to be hoisted easily to the desired height and lowered at regular intervals for routine maintenance and sampling of the flocks. The design specifications of this canopy system are modifications that can easily be incorporated to existing rabbit hutches used in ground-level captive sentinel systems.

Ability of 4-poster passive topical treatment devices for deer to sustain low population levels of Ixodes scapularis (Acari: Ixodidae) after integrated tick management in a residential landscape.

In a recent study, the combined use of 4-Posters and Maxforce TMS bait boxes along with a barrier application of deltamethrin resulted in accelerated control of Ixodes scapularis Say by sequentially attacking each postembryonic life stage. We report the results of a follow-up study to test the ability of 4-Posters used alone to sustain the high levels of control achieved through the integrated tick management (ITM) approach after withdrawal of the bait boxes. In the first year after withdrawal, we observed declines in the level of control of larvae on small mammals, as well as of numbers of host-seeking larvae in the treatment area. There was no difference in the level of control of host-seeking adults in the treatment area after 2 yr. Within 2 yr, we observed a decline in control of subadult ticks infesting small mammals, but continued to see significant control of both host-seeking nymphs (85.9%) and larvae (89.0%) in the treatment area. The inconsistency that we observed between the apparent ability of 4-Posters to sustain high levels of control of host-seeking ticks, although having less effect on tick burdens on small mammal hosts, may be explained by the host-seeking ecology of immature I. scapularis.