Morphometric and molecular analyses of the sand fly species Lutzomyia shannoni (Diptera: Psychodidae: Phlebotominae) collected from seven different geographical areas in the southeastern United States

A morphometric and molecular study of adult male and female Lutzomyia shannoni (Dyar 1929) collected at seven different locations within the southeastern United States was conducted to assess the degree of divergence between the grouped specimens from each location. The collection locations were as follows: Fort Bragg, NC; Fort Campbell, KY; Fort Rucker, AL; Ossabaw Island, GA; Patuxent National Wildlife Research Refuge, MD; Suwannee National Wildlife Refuge, FL; and Baton Rouge, LA. Forty males and forty females from each location were analyzed morphometrically from 54 and 49 character measurements, respectively. In addition, the molecular markers consisting of the partial cytochrome c oxidase subunit I (from 105 sand flies: 15 specimens/collection site) and the partial internal transcribed spacer 2 (from 42 sand flies: six specimens/collection site) were compared. Multivariate analyses indicate that the low degree of variation between the grouped specimens from each collection site prevents the separation of any collection site into an entity that could be interpreted as a distinct population. The molecular analyses were in concordance with the morphometric study as no collection location grouped into a separate population based on the two partial markers. The grouped specimens from each collection site appear to be within the normal variance of the species, indicating a single population in the southeast United States. It is recommended that additional character analyses of L. shannoni based on more molecular markers, behavioral, ecological, and physiological characteristics, be conducted before ruling out the possibility of populations or a cryptic species complex within the southeastern United States.     

Titers of vesicular stomatitis virus, New Jersey serotype, in naturally infected male and female Lutzomyia shannoni (Diptera: Psychodidae) in Georgia.

Seven isolates of the New Jersey serotype of vesicular stomatitis (VSNJ) virus were obtained from pooled specimens of phlebotomine sand flies, Lutzomyia shannoni Dyar, collected on Ossabaw Island, Chatham County, Ga., in 1989 and 1990. Three isolates, including two from males, were obtained from light-trapped sand flies in 1989. Four isolates were obtained from pools of sand flies collected from hollow trees in 1990. Three of the latter pools contained from 4.0 to 4.7 log10 of plaque-forming units of virus per ml, suggesting that the positive flies in these pools had supported VSNJ virus replication. One of these high-titered isolates was obtained from a pool of male sand flies. These data provide further support for the hypotheses that L. shannoni is a biological vector of VSNJ virus at this enzootic focus and that transovarial transmission of the virus occurs in nature.     

Rapid identification of mitochondrial cytochrome B haplotypes by single strand conformation polymorphism in Lutzomyia longipalpis (Diptera: Psychodidae) populations

Newly designed primers amplified a 365-bp fragment including the 3' end of mitochondrial cytochromeb (cyt b). Field collected specimens of the sand fly, Lutzomyia longipalpis (Lutz and Neiva), from two Brazil locations provided test DNA. The primers, based on consensus sequences from a taxonomic spectrum of arthropods, have also amplified DNA successfully from Lutzomyia shannoni Dyar, Lutzomyia cruzi (Mangabeira), and the mosquito Aedes albopictus (Skuse). Single strand conformation polymorphism (SSCP) was used to recognize the presence of L. longipalpis haplotypes; these were verified subsequently by sequencing the polymerase chain reaction products. The sensitivity of SSCP was demonstrated by (1) the detection of single nucleotide differences in SSCP variants and (2) no sequence variation in specimens with the same SSCP mobility. The application of new primers and the SSCP technique provided a valuable addition to available population genetic tools: they increased the efficiency of detection of variability in the cyt b gene and decreased the time required for screening large numbers of specimens to detect nucleotide variation.     

Seasonal abundance of Lutzomyia shannoni (Diptera: Psychodidae) on Ossabaw Island, Georgia.

Population dynamics of Lutzomyia shannoni were monitored from April 1986 through December 1987 on Ossabaw Island, Ga. Most (99%) of the 19,788 adult sand flies were collected in light traps supplemented with dry ice; less than or equal to 1% were aspirated from diurnal resting sites. Adult sand flies first appeared in April and were followed by peaks of abundance during May 1986, and May and July 1987. Numbers of adults captured fell rapidly in October and November 1986 and in September and October 1987. No specimens were collected in December 1986 or in March, November, and December 1987. Light trap catch was affected positively by mean nightly air temperature and negatively by rainfall 14 d before collection, but not by wind speed or moon phase. Vesicular stomatitis viral activity, as measured by antibodies in feral and domestic swine, roughly corresponded to the seasonal appearance of adult L. shannoni during 1986 and 1987. Significantly more adults (72%) were collected in light traps at ground level (0.5m) than at heights of 4 and 8m. Most resting adults were collected from dark, moist tree holes and cavities of various hardwoods.     

First collection records of phlebotomine sand flies (Diptera: Psychodidae) from New Jersey

The phlebotomine sand flies Lutzomyia (Psathyromyia) shannoni (Dyar) and Lutzomyia (Helcocyrtomyia) vexator (Coquillett) are reported for the first time from New Jersey. Both species were collected from ultraviolet CO2-baited Centers for Disease Control light traps during a state-wide phlebotomine survey conducted in 2007 and 2008. L. shannoni has previously been reported from New Jersey; however, this observation was made in error. These collections do not represent a northern range expansion for either species.     

Distribution of phlebotomine sand fly genotypes (Lutzomyia shannoni, Diptera: Psychodidae) across a highly heterogeneous landscape

Genetic variability of eight Colombian field populations and two laboratory colonies of a tropical forest sand fly, Lutzomyia shannoni Dyar, was assessed by comparing allozyme frequencies at 20 enzyme loci. Substantial genetic variability was noted in all strains, with mean heterozygosities of 13-21% and alleles per locus of 2.0-2.8. Four loci were monomorphic. Six populations in north and central Colombia showed close genetic similarity (Nei's distances, 0.01-0.09), despite mountainous environment, discontinuous forest habitat, and elevation differences from 125 to 1,220 m. Two samples representing the Orinoco (near Villavicencio) and Amazon (near Leticia) river basins were similar (Nei's distance, 0.08) but diverged substantially from the central six samples (Nei's distances, 0.26-0.40). Although the range of L. shannoni extends from the southeastern United States to northern Argentina, three genetically distinct, geographically discrete, groups were discerned by the current analysis: Orinoco-Amazon river basins, north-central Colombia, and eastern United States.     

Funnel trap for the capture of phlebotomine sand flies (Diptera: Psychodidae) from tree holes

A funnel trap that fitted over holes leading into hollow trees was used to capture adult phlebotomine sand flies, Lutzomyia shannoni Dyar, on Ossabaw Island, Chatham County, Ga. These insects rested in hollow trees during the day and were collected by funnel traps as they egressed from the tree holes at night. The trap is lightweight, durable, inexpensive, waterproof, and selective. Using this trap, greater than 100 healthy L. shannoni ++were captured per night by a single investigator during July and August 1988 when adult flies were abundant on the island.     

Trans-beta-farnesene as a feeding stimulant for the sand fly Lutzomyia longipalpis (Diptera: Psychodidae).

The aphid alarm pheromone, trans-beta-farnesene (TBF), was found to stimulate feeding in both male and female Lutzomyia longipalpis Lutz & Neiva. Four other structurally related compounds (farnesol; 808 farnesene; trans, trans-farnesyl acetate; farnesyl methyl ether) were slightly less stimulating to these insects. The effect of TBF varied with sand fly age and the concentration of the chemical used. In contrast, TBF did not stimulate feeding in either sex of four other sand fly species (L. shannoni Dyar, Phlebotomus papatasi (Scopoli), P. argentipes Annandale & Brunetti, P. perniciosus Newstead). TBF might be useful in enhancing L. longipalpis field collections or in developing a poison bait for the control of this species.     

Distribution of phlebotomine sand flies (Diptera: Psychodidae) in a primary forest-crop interface, Salta, Argentina

Disordered urbanization and deforestation are the main activities proposed as causal factors of re-emergence of American cutaneous leishmaniasis caused by Leishmania braziliensis. The purpose of this work was to investigate, in the hyperendemic area of Argentina, the distribution of Phlebotomine sand flies at the modified primary vegetation-crop interface, as one of the potential sites where the effects of changing landscape on sand fly populations may be manifested. Twenty samplings were made between June 2004 and August 2005. The traps to catch sand flies were set on two consecutive nights every month (except in 5 mo, where it became every 15 d). The relationship between sand fly abundance and meteorological and landscape variables was analyzed using non-metric multidimensional scaling and Kendall's correlation coefficients. Lutzomyia neivai (Pinto) was the most abundant species, followed by Lutzomyia migonei (Fran?a), Lutzomyia cortelezzii (Brèthes), Lutzomyia shannoni (Dyar), and Lutzomyia punctigeniculata (Floch and Abonnenc). Traps located close to modified areas collected the greatest numbers of sand flies, whereas traps located in the least modified area (adjacent to the primary vegetation) collected the fewest. There was a strong negative correlation between the abundance of sand flies and precipitation. This study shows that even small modifications in the landscape led to an increase in sand fly abundance, mainly Lu. neivai, a Leishmania braziliensis vector. This underscores the need for recommendations about the risk of American cutaneous leishmaniasis before any environmental intervention is done in an endemic area, as well as for the monitoring of sand fly population dynamics at the site of intervention, before, during, and after the process.     

椎体成形治疗胸腰段压缩骨折的力学研究

目的探讨体位复位结合椎体成形治疗创伤性压缩骨折的生物力学及形态学变化。方法6具新鲜小牛T12-L3的L1制作创伤性压缩骨折模型后,采用体位复位结合椎体成形强化。于完整、损伤、成形即刻、3000次疲劳后测试并观察标本的生物力学及形态学变化,数据行统计学处理。结果体位复位结合椎体成形即刻L1椎前高度、应变与完整状态无显著差异(P>0.05),脊柱标本稳定性恢复至完整状态(P>0.05)。3000次疲劳后L1椎前高度及应变无明显变化(P>0.05)。生理载荷作用下垂直压缩、后伸时标本刚度值与完整状态无统计学差异(P>0.05),前屈、左/右弯屈时标本刚度值达不到完整状态(P<0.05),左/右旋转时部分维持标本的稳定性。疲劳后在4N穖的纯力偶矩的作用下,T12-T13、L2-L3各向运动范围和完整状态一致(P>0.05)。T13-L1后伸、左/右旋转与完整状态相比无差异(P>0.05),前屈时达不到完整水平,但与损伤状态有显著性差异(P<0.05),左/右弯曲与损伤状态相比无差异(P>0.05);L1-L2后伸、左/右旋转与完整状态相比无差异(P>0.05),前屈与损伤状态相比无差异(P>0.05),左/右弯曲疲劳后运动范围增加,但和损伤状态有显著性差异(P<0.05)。强化和完整椎体抗极限压缩强度无差异(P>0.05)。形态学示疲劳后伤椎仍呈解剖复位,未见骨水泥断裂现象发生。结论体位复位结合椎体成形术后即刻可以有效稳定创伤性压缩骨折,3000次疲劳载荷循环后脊柱标本的生物力学性能出现不同程度的下降。     

Temporal and spatial variation of phlebotomine (Diptera: Psychodidae) community diversity in a cutaneous leishmaniasis endemic area of Costa Rica

Phlebotomine sand fly species composition and diversity were studied in Acosta, an area of Costa Rica endemic for cutaneous leishmaniasis. Two CDC miniature light traps per house were set overnight in 72 houses distributed in 6 localities, once a month, during the rainy seasons of 1994 and 1995. Of the 22 species collected, the most common were Lutzomyia serrana (Damasceno & Arouck), L. youngi Feliciangelli & Murillo, L. ylephiletor (Fairchild & Hertig), L. shannoni (Dyar), L. cruciata (Coquillett), L. gomezi (Nitzulescu), L. sanguinaria (Fairchild & Hertig), and Warileya rotundipennis (Fairchild & Hertig). The Czekanowsky index and the Sorensen index as modified by Bray and Curtis to consider abundance were used to compare species composition and beta-diversity. Comparisons were made among localities within years, between years, and localities each year. The data strongly indicated that phlebotomine species composition is more stable than diversity or abundance.     

Keys to the Anopheline mosquitoes (Diptera: Culicidae) of Pakistan

This article provides taxonomic keys for the identification of the fourth-instar larvae and females of 24 species of anopheline mosquitoes (seven species in subgenus Anopheles and 17 species in subgenus Cellia) recorded from Pakistan. The keys are based on literature sources as well as the examination of field and museum collections.     

"Industrious, submissive, and free of diseases": 156 years of physicians in Liidlii Kue/Fort Simpson, Northwest Territories

INTRODUCTION: Physician recruitment to rural and remote communities poses a major challenge to health care delivery in Canada. Rather than focusing solely on the politics and policies that contribute to the shortage of family physicians in Canada's North, we argue that more attention should be paid to the reasons that lead, and have led, family physicians to the North, and also to the factors that contribute to physician retention. METHODS: We used archival research and semi- and unstructured interviews to provide a history of medicine in Liidlii Kue/Fort Simpson, NWT, and to describe the features of physicians who have served and continue to serve this Northern community. RESULTS: Results show that medicine in Liidlii Kue/Fort Simpson can be divided into 4 distinct eras: the prehospital era (1848-1916), the early hospital era (1917-1925), the middle era (1926-1972) and the government era (1973-present). Thirty-eight physicians were identified as having worked in Liidlii Kue/Fort Simpson. Of those, 19 were contacted. Nine physicians and the offspring of 1 deceased physician were interviewed. We found physicians fell into 1 of 4 categories: new graduates, those seeking midcareer (or midlife) change, those about to retire and international medical graduates. CONCLUSION: By examining Liidlii Kue/Fort Simpson as a case study, this research fills the dearth of knowledge in the factors that contribute to physician recruitment and retention in Canada's North.     

Spatial and temporal patterns of phlebotomine sand flies (Diptera: Psychodidae) in a cutaneous leishmaniasis focus in northern Argentina

Phlebotomine sand flies (Diptera: Psychodidae) were captured in an area of Argentina endemic for American cutaneous leishmaniasis (ACL). A total of 44,944 flies were collected during a 130-wk interepidemic period from 1990 through 1993. These sand flies included Lutzomyia neivai (Pinto) (97.8%), Lutzomyia migonei (Franca) (1.2%), Lutzomyia cortelezzii (Brèthes) (0.8%), Lutzomyia shannoni (Dyar) (0.1%), and Lutzomyia punctigeniculata (Floch and Abonnenc) (0.1%). Lutzomyia neivai was more abundant in secondary forests and peridomestic environments associated with human cases than in primary forest or xeric thorn scrub areas. Time series analyses of species densities suggested a bimodal or trimodal annual pattern related to rainfall peaks, a 5-wk reproductive cycle, and peridomestic local populations that were located adjacent to secondary forests. In general, sand fly abundance was correlated with the rainfall of the previous year. Lutzomyia neivai spatial distributions were consistent with ACL incidence patterns during the study and in the recent outbreaks in Argentina. However, Lu. migonei also may be involved in peridomestic transmission. Our results suggest that there is a need for improved, long-term surveillance of sand flies and ACL cases, as well as development of effective intervention strategies.     

Parasitic arthropods of sympatric meadow voles and white-footed mice at Fort Detrick, Maryland.

Twelve species of parasitic arthropods (one sucking louse, two fleas, one tick, and eight mites) were recovered from 51 meadow voles, Microtus pennsylvanicus (Ord); whereas nine species (one sucking louse, one bot, three fleas, one tick, and three mites) were collected from 48 white-footed mice, Peromyscus leucopus (Rafinesque), live-trapped on the grounds of Fort Detrick, Frederick County, MD., during 1990 and 1991. The most commonly collected arthropods from M. pennsylvanicus were the fur mite, Listrophorus mexicanus Fain (approximately 2,720 specimens); the tropical rat mite, Ornithonyssus bacoti (Hirst) (987); the laelapid mites, Laelaps kochi Oudemans (733) and Androlaelaps fahrenholzi (Berlese (322); the sucking louse, Hoplopleura acanthopus (Burmeister) (121); the tick, Dermacentor variabilis (Say) (47); and the chigger mite, Neotrombicula whartoni (Ewing) (45). Arthropod densities were lower on P. leucopus, from which the most frequently recorded species were the sucking louse, Hoplopleura hesperomydis (Osborn) (98 specimens); the fleas, Epitedia wenmanni (Rothschild) (85) and Orchopeas leucopus (Baker) (61); and the mite, A. fahrenholzi (83). Although six species of arthropods parasitized both species of rodents, only two of these, A. fahrenholzi and D. variabilis, were relatively common on both hosts. Therefore, although the habitats of both host species partially overlap, their associated parasitic arthropods remain principally host specific. The potential significance of these findings with respect to vector-borne disease transmission is discussed.     

Evaluation of effectiveness of a facet wiring technique: Anin vitro biomechanical investigation

The effects of facet wiring procedure commonly used for stabilizing cervical spines after laminectomy or bilateral facet dislocation on the motion behavior of whole cervical spines are investigated using a Selspot II^® system. A fresh human ligamentous intact specimen was potted at T1/T2 vertebra and clinically relevant loads applied to the topmost vertebra (C2) of the specimen. The resulting three rotational components of each of the five vertebral bodies (C3-C7) were recorded. Specimen was injured to mimic total laminectomies at C5 and C6 vertebral levels and tested again. The injured specimen was stabilized, using a facet wiring construct, across C4-C7 segment before testing for the final time. The injured specimens, compared to the intact specimens, demonstrated an increase in flexion-extension of about 10%. Facet wiring imparted stability to the cervical spine by stiffening segments up to roughly four times intact values.     

Sensilla on the terminalia of Lutzomyia spp. (Diptera: Psychodidae) sand flies

Sensilla on the male terminalia of four different species of sand flies (Diptera: Psychodidae) are described. Two species belonged to the same species complex: Lutzomyia longipalpis (Lutz & Neiva) and L. cruzi (Mangabeira). Other Brazilian species complex was represented by L. lenti (Mangabeira) and L. carmelinoi (Ryan, Fraiha, Lainson & Shaw). Approximately 5-15 sensilla were found on the initial part of the styles of all species. Structurally, the sensory organs were similar to small coeloconica sensilla. Their number varied both individually and interspecifically. These sensilla may play an important role in the copulation behavior of these species of sand flies.     

The taxonomic status of genetically divergent populations of Lutzomyia longipalpis (Diptera: Psychodidae) based on the distribution of mitochondrial and isozyme variation

The sand fly, Lutzomyia longipalpis (Lutz & Neiva) reputedly is a complex of cryptic species; however, there is currently no consensus as to the number of species in the complex or their geographic distributions. We conducted phylogenetic analyses of 31 populations from throughout the species range, using seven isozyme loci and genes in the mitochondrial genome. Analyses of these two independent sets of markers were largely concordant and revealed four distinct clades that support the existence of four species. The four clades have distinct geographic ranges: (1) Brazil (Species A = Lu. longipalpis sensu stricto), (2) Laran (Species B = Lu. pseudolongipalpis), (3) cis-Andean (Species C), and (4) trans-Andean (Species D). The cis-Andean clade may be subdivided further into two groups, one in Colombia and one in northwestern Venezuela, but their taxonomic status remains unresolved. Knowledge that Lu. longipalpis is a complex of species may ultimately shed light on anomalies in the epidemiology of visceral leishmaniasis in the New World.