Cases of Eastern equine encephalitis in humans associated with Aedes canadensis, Coquillettidia perturbans and Culiseta melanura mosquitoes with the virus in New York State from 1971 to 2012 by analysis of aggregated published data.

From 1971 to 2012, in New York State, years with human Eastern equine encephalitis (EEE) were more strongly associated with the presence of Aedes canadensis, Coquillettidia perturbans and Culiseta melanura mosquitoes infected with the EEE virus (Fisher's exact test, one-sided P = 0.005, 0.03, 0.03) than with Culiseta morsitans, Aedes vexans, Culex pipiens-restuans, Anopheles quadrimaculatus or Anopheles punctipennis (P = 0.05, 0.40, 0.33, 1.00, 1.00). The estimated relative risk of a case in a year in which the virus was detected vs. not detected was 14.67 for Ae. canadensis, 6.38 for Cq. perturbans and 5.50 for Cs. morsitans. In all 5 years with a case, Cs. melanura with the virus was detected. In no year was there a case in the absence of Cs. melanura with the virus. There were 18 years with no case in the presence of Cs. melanura with the virus. Such observations may identify the time of increased risk, and when the methods may be used to prevent or reduce exposure to vector mosquito species in this geographic region.

Identification of bloodmeals in Anopheles quadrimaculatus and Anopheles punctipennis from eastern equine encephalitis virus foci in northeastern U.S.A.

The host-feeding patterns of Anopheles quadrimaculatus Say and Anopheles punctipennis (Say) were examined in order to evaluate their potential contributions to the transmission of eastern equine encephalitis virus (EEEv) and other arboviruses in the northeastern U.S.A. Engorged mosquitoes of the two species were collected from EEEv foci in central New York (NY) and throughout New Jersey (NJ), and their bloodmeals were identified using a polymerase chain reaction (PCR)-based assay and sequencing portions of the mitochondrial cytochrome b gene. Analysis of 131 An. quadrimaculatus and 107 An. punctipennis from NY revealed that 97.7% and 97.2%, respectively, had acquired blood solely from mammalian hosts. Similarly, examination of 288 An. quadrimaculatus and 127 An. punctipennis from NJ showed 100% and 96.0%, respectively, contained mammalian-derived bloodmeals. Mosquitoes containing mixed bloodmeals from both avian and mammalian hosts were detected in 1.6% of An. quadrimaculatus from NY, and 2.8% and 4.0% of An. punctipennis from NY and NJ, respectively. White-tailed deer (Odocoileus virginianus) constituted the most common vertebrate host for these anopheline mosquitoes, accounting for 85.8-97.7% of all bloodmeals identified. The predominance of white-tailed deer as a source of bloodmeals supports enzootic amplification of deer-associated arboviruses in this region, including Jamestown Canyon, Cache Valley and Potosi viruses. One horse- and two human-derived bloodmeals were also detected in An. quadrimaculatus collected in NJ. Limited avian-derived bloodmeals were detected from mourning dove (Zenaida macroura), sharp-shinned hawk (Accipiter striatus) and house finch (Carpodacus mexicanus), mostly in mixed bloodmeals. Occasional feeding on avian hosts suggests that these mosquitoes may participate as epizootic-epidemic bridge vectors of EEEv from viraemic birds to mammalian hosts of concern, including horses and humans. An isolate of EEEv was recovered from the head and thorax of an An. punctipennis mosquito collected in NY.

The causes and processes of the mid-summer population crash of the potato aphids Macrosiphum euphorbiae and Myzus persicae (Hemiptera: Aphididae).

Populations of many phloem-feeding aphid species in temperate regions increase exponentially in early summer and then 'disappear', usually over a time-scale of a few days, in July. To understand these dynamics, empirical investigation of the causes and modelling of the processes underlying population change are required. Numbers of the aphids Myzus persicae(Sulzer) and Macrosiphum euphorbiae (Thomas), monitored over three years in commercial potato fields in the UK, increased to a maximum of 2-2.5 per leaflet on 16 July in 1999 and 2001, and then declined to < 0.25 per leaflet by 26 July. In 2000, aphid numbers remained very low (< 0.25 per leaflet) throughout the season. The onset of the crash in aphid numbers (16-19 July in 1999 and 2001) was consistently associated with changes in the phloem amino acid composition of potato leaflets. Natural enemies, including syrphids, parasitoids, coccinellids, chrysopids and entomopathogenic fungi, increased in abundance throughout the sampling period. The incidence of winged emigrant aphids prior to the crash was low (< 10%). Experimental manipulation during 2001 demonstrated that, during the crash period, the fecundity of aphids (caged on leaves to exclude natural enemies) was depressed by 25-45% relative to earlier in the season, and that presence of natural enemies reduced aphid numbers by up to 68%. Using these data, an excitable medium model was constructed, which provided a robust description of aphid population dynamics in terms of plant development-induced changes in aphid fecundity and temporal change in natural enemy pressure.

Prevalence of legionella waterline contamination and Legionella pneumophila antibodies in general dental practitioners in London and rural Northern Ireland.

OBJECTIVES: To determine the prevalence of legionellae in dental unit waterlines (DUWL) in general dental practices in London and rural Northern Ireland and whether the organism occurs at a high enough frequency and magnitude in DUWL to represent a threat to dentists' health. MATERIALS AND METHOD: Two hundred and sixty six (166 London, 100 Northern Ireland) randomly selected dental surgeries were recruited. Standardised 250 ml water samples were taken from the DUWL and 1 litre samples from the surgery cold water tap to measure the prevalence of legionellae. The dentists provided a blood sample for legionella serology. RESULTS: The prevalence of legionellae was very low (0.37%). Legionellae were not isolated from DUWL or surgery basin taps in Northern Ireland. Legionella spp were isolated from the DUWL and surgery basin of one practice in London and from the cold water supply of a further three practices. The prevalence of Legionella pneumophila antibodies was less than that seen in a comparable group of London blood donors. CONCLUSION: The risk to dentists' health from potential exposure to legionellae in this cohort of dentists was very low and this was confirmed by the very low seroprevalence and antibody titres to legionella detected in the dentists.

Mosquito surveillance and polymerase chain reaction detection of West Nile virus, New York State.

West Nile (WN) virus was detected in the metropolitan New York City (NYC) area during the summer and fall of 1999. Sixty-two human cases, 7 fatal, were documented. The New York State Department of Health initiated a departmental effort to implement a statewide mosquito and virus surveillance system. During the 2000 arbovirus surveillance season, we collected 317,676 mosquitoes, submitted 9,952 pools for virus testing, and detected 363 WN virus-positive pools by polymerase chain reaction (PCR). Eight species of mosquitoes were found infected. Our mosquito surveillance system complemented other surveillance systems in the state to identify relative risk for human exposure to WN virus. PCR WN virus-positive mosquitoes were detected in NYC and six counties in the lower Hudson River Valley and metropolitan NYC area. Collective surveillance activities suggest that WN virus can disperse throughout the state and may impact local health jurisdictions in the state in future years.

In vitro insecticidal effects of fipronil and beta-cyfluthrin on larvae of the blowfly Lucilia sericata.

The insecticidal effects of the phenylpyrazole, fipronil, and a pyrethroid, beta-cyfluthrin, on larvae of the blowfly Lucilia sericata were determined in laboratory assays. When first stage larvae of L. sericata were reared on homogenized pig liver which had been treated with known amounts of test compounds, both fipronil and beta-cyfluthrin induced significant levels of mortality compared to acetone and water controls. However, fipronil was approximately 10 times more toxic than beta-cyfluthrin to L. sericata larvae following ingestion. Beta-cyfluthrin had little effect on mortality until concentrations of approximately 0.5 ppm were reached. In contrast, fipronil effected L. sericata mortality at a concentration of 0.05 ppm and 100% mortality was reached by 0.5 ppm. The lethal concentration (LC50) value for beta-cyfluthrin was 1.56 ppm as compared to 0.14 ppm for fipronil. Following contact of first and third stage larvae with cloth impregnated with known amounts of test compound, the mortality profiles of fipronil and beta-cyfluthrin were similar. At short contact times, the LC50 values for fipronil were lower than those for beta-cyfluthrin. However, at the highest contact time evaluated for the first stage larvae, 300 s, there was a reversal in this trend. The results suggest that the phenylpyrazole fipronil may represent a new potential insecticide for development against blowfly strike of sheep.

Quantitative estimates of porous media wettability from proton NMR measurements.

Nuclear magnetic resonance (NMR) relaxation time distributions provide information on the abundance and distribution of two immiscible fluids in the pores of fine-grain chalk samples. A model based on relative shifts of the water-relaxation component as a function of saturation results in a wettability index that is strongly correlated with independent dynamic measurements of wettability. Scales of wetting-phase film thickness for NMR and dynamic measurements explain differences in results between the two methods.

Occurrence of Ixodes scapularis (Acari: Ixodidae) on a selected segment of the Appalachian Trail.

A 918-km section of the Appalachian National Scenic Trail from the West Virginia-Maryland border to the Massachusetts-Vermont border was surveyed for the presence of Ixodes scapularis Say. The trail and its edges were drag-sampled during 4 hikes between May and October 1991. Trips were designed to survey areas of the Appalachian Trail when I. scapularis might be questing and to revisit states endemic for Lyme disease during differing times. After sampling for ticks, meteorological and ecological characteristics were measured at each site. In total, 1,776 km of the Appalachian Trail were hiked during 88 d and resulted in sampling 489 sites. All life stages of Ixodes scapularis (n = 46) were collected from 21 sites within a 331-km range of the Appalachian Trail between Salisbury, CT, to Delaware Water Gap, PA. This segment of Appalachian Trial is easily accessible to a large urban population and should be posted with tick warning signs to alert the public to the presence of I. scapularis.

Impact of naled (Dibrom 14) on the mosquito vectors of eastern equine encephalitis virus.

In central New York, aerial mosquito adulticide applications have been used in response to eastern equine encephalitis (EEE) outbreaks and have targeted the swamp habitats of the primary enzootic vector of EEE virus, Culiseta melanura (Coquillett). The organophosphate insecticide naled (1, 2, dibromo-2, 2-dichloroethyl dimethyl phosphate) has been the insecticide of choice in this region. This study reports on analyses of 11 years (1984-94) of mosquito collection data from Cicero and Toad Harbor swamps in relation to applications of naled. Naled applications were successful in achieving short-term reductions in mosquito abundance. However, despite repetitive applications, populations of the primary vector of EEE virus, Cs. melanura, have increased 15-fold at Cicero Swamp. Preventive applications had no noticeable impact on the enzootic amplification of EEE virus, and isolations of virus following preventive applications have resulted in additional spraying. The possibility that applications of naled contributed to increased populations of Cs. melanura discredits the rationale that preventive applications of naled reduce the risk of EEE.

Fecundity of naturally bloodfed Culiseta melanura.

Naturally bloodfed Culiseta melanura were collected annually from resting boxes in and around a swamp in Oswego County, NY from 1982 to 1989. Females were held individually in a laboratory until they oviposited. Except in 1982, every other female was provided a 10% dextrose solution. Females were classed as alive or dead following oviposition and female size was based on abdomen length, measured after oviposition. Egg rafts from each female were held individually and the numbers of larvae and unhatched eggs were counted. Fecundity (number of eggs laid per female) was based on number of larvae plus unhatched eggs. Rafts from 2,120 females averaged 129 eggs and 106 larvae per raft. Rafts from females that were alive following oviposition were significantly larger and produced more larvae than those of females that died following oviposition. Availability of sugar influenced female survival but not egg raft production. Size and fecundity of females decreased from May through September. These differences were attributed to the temperature and larval density of breeding crypts. Seasonal changes in size may influence the vector efficiency of Cs. melanura.

Evidence for multiple foci of eastern equine encephalitis virus (Togaviridae:Alphavirus) in central New York State.

A regional surveillance system for eastern equine encephalitis (EEE) virus was established in central New York in 1984 after the 2nd human EEE fatality occurred in 1983. Extensive mosquito surveillance activities were coordinated with the rapid laboratory processing of mosquito specimens for EEE virus. Active surveillance for EEE infections in humans and equines also was initiated. Results of long-term surveillance detected the presence of multiple Culiseta breeding swamps. A 6-yr interepizootic period (1984-1989) was followed by 2 yr of equine EEE. In 1990, there were 7 equine cases and a record number of EEE virus isolations from mosquitoes (n = 86), wild birds (n = 27), and sentinel pheasants (n = 7). In 1991, 7 equine cases also occurred, although there were fewer isolations from mosquitoes (n = 40). The sequence to the appearance of EEE virus at swamps and upland sites and at individual swam complexes, and the spatial and temporal distribution of equine cases provide evidence for multiple foci of EEE virus in central New York. The role of infected Culiseta melanura (Coquillett) in the transfer of EEE virus between swamp and upland areas and among swamp complexes is advanced.

Field trials with methoprene, temephos, and Bacillus thuringiensis serovar israelensis for the control of larval Culiseta melanura.

In 1992, Altosid (methoprene) pellets, Abate (temephos) 5 CG, and Bactimos (Bacillus thuringiensis serovar israelensis) granules were applied aerially to small field plots within a Culiseta breeding swamp. Aspects measured included the deposition and diffusion of larvicides into larval crypts and effects on larval Culiseta melanura and nontarget aquatic organisms. Formulations were deposited at approximately 50% of application rates. The presence of methoprene in 8 crypt water samples indicated that this larvicide was able to diffuse into Cs. melanura larval crypts. Methoprene was selected for evaluation in a large-scale field trial. In the spring of 1993, methoprene pellets applied to 25% of the study area were an effective larvicide against Cs. melanura. The inhibitory effect on pupae exceeded 81% over a 5-wk posttreatment period.

Use of a modified chemical transfer pump for sampling Culiseta melanura larvae.

The cryptic nature of Culiseta melanura larval habitats has limited the use of the conventional one-pint dipper for enumerating the larval density of this species. A modified chemical transfer pump was used in a survey of a known breeding swamp. Field trials assessed the practicality and potential biases towards instars in open vs. closed crypts. From 148 samples taken at 37 sites, 631 Cs. melanura larvae were collected. Closed crypts accounted for 21% of the positive samples. The pump had utility in the field but a relative scarcity of 4th-instar larvae in the samples may indicate a source of bias toward younger instars.

Wettability and fluid saturations determined from NMR T1 distributions.

The abundance and distribution of brine and decane are determined from T1 distributions at different stages of a water-flood test in water-wet and oil-wet chalks. The T1 distributions generated from multi-exponential decomposition of inversion-recovery data provide more information than obtained from stretched and bi-exponential fits. Chalk samples because of their uniform pore size and ideal sedimentary rocks for NMR investigations of wettability since water and decane interactions with pore walls of differing wettability are easily distinguished.

Detection of Listeria species and Listeria monocytogenes using polymerase chain reaction.

Five oligonucleotide sequences are described that were used as primers in the polymerase chain reaction (PCR) to amplify specific sequences from Listeria DNA. When all five primers were used in combination, three PCR products were possible; a Listeria specific product that occurs with DNA from any Listeria sp., a Listeria monocytogenes specific product that occurs only in the presence of DNA from this organism and a universal product that is found using DNA from any bacterial source. The occurrence of these PCR products was used as a diagnostic test on bacteria isolated from various food samples to detect Listeria sp. and L. monocytogenes.

Isolation, growth characteristics, and long-term storage of fungi cultivated by attine ants.

Seven pure-culture strains of fungi cultivated by attine ants (ant-garden fungi) were isolated from locally maintained leaf-cutting ant colonies. An ant-garden fungus strain obtained from an Atta cephalotes colony, when offered to ants of the colony from which the fungus was isolated, was accepted as their own. Young fungus cultures were harvested and incorporated into the fungus garden, and cultures of intermediate age were used to begin a new fungus garden; old cultures were simply harvested. To facilitate further research on this fungus, growth characteristics of the different isolates were studied under a variety of conditions. They grew better at 24 degrees C than at 30 degrees C, and growth did not occur at an incubation temperature of 37 degrees C. In a broth culture medium, growth was enhanced by aeration of the culture and by addition of yeast extract, olive oil, sesame oil, peanut oil, soybean oil, corn oil, sunflower oil, cottonseed oil, walnut oil, safflower oil, or mineral oil. Glycerol did not noticeably affect growth, but Tween 80 inhibited growth. These fungi were extremely sensitive to cycloheximide, growth being totally inhibited at cycloheximide concentrations ranging from 0.4 to 4.0 mug/ml. To date, the ant-garden fungus isolates have remained viable in long-term mineral oil-overlay storage cultures for up to 4 years.

Mark-recapture studies on the Culiseta (Diptera: Culicidae) vectors of eastern equine encephalitis virus.

Natural populations of Culiseta melanura (Coquillett) and Cs. morsitans (Theobald) were marked and released at three sites associated with the Toad Harbor-Big Bay Swamp eastern equine encephalitis (EEE) virus focus in central New York. Collections of Culiseta from surveillance sites within 12.8 km of the release sites were screened for marked specimens. A total of 172 marked specimens were recaptured. The majority of recaptured mosquitoes were collected at sites associated with the swamp complex, but some were collected at seven of the eight recapture sites, up to 9.8 km from a release site. The distances traveled by 103 recaptured individuals were used to calculate the mean distance traveled and flight ranges for sexes and cohorts of both species. The mean distance traveled for females that were marked and released from resting shelters was 4 km for Cs. melanura and 5 km for Cs. morsitans. The mean distance traveled for females marked and released from a CDC + CO2 light trap was 9 km and 8 km for Cs. melanura and Cs. morsitans, respectively. The flight ranges of these species overlap the EEE epizoötic zone, and the results of these studies support the hypothesis that these species are involved in the transfer of EEE virus from swamp to upland habitats.

Comparative deterrency of two terpenoids to two genera of attine ants.

Caryophyllene and caryophyllene epoxide are two terpenoids found in neotropical plants and known to be deterrent to leafcutter ants. To estimate the variation in deterrent activity of these compounds toward the generaAtta andAcromyrmex, behavioral bioassays were conducted over a range of concentrations. The responses of four captive colonies ofAtta cephalotes and two captive colonies ofAcromyrmex octospinosus, all from a single locality in Costa Rica, were studied. Although specific patterns of deterrency differed in the two genera, in both cases caryophyllene epoxide concentrations of 0.70 mg/g or greater, and caryophyllene concentrations of 7.0 mg/g or greater, significantly deterred the harvest of potential substrates. Individual colonies within each genus did not differ significantly in their responses to caryophyllene epoxide. The mean response of the two genera to caryophyllene epoxide differed significantly, but responses to caryophyllene did not.Acromyrmex octospinosus was more sensitive to low concentrations and less sensitive to high concentrations of caryophyllene epoxide than wasAtta cephalotes.