Catalytic Asymmetric Cyclopropanations with Nonstabilized Carbenes.

Cyclopropanes are common building blocks in pharmaceuticals, agrochemicals, and organic materials. The most general methods for the synthesis of chiral cyclopropanes are catalytic additions of diazoalkanes to alkenes. However, a limitation of this approach is that diazoalkanes can only be safely handled on preparative scales if they possess stabilizing substituents. Here we show that gem-dichloroalkanes can serve as precursors to nonstabilized carbenes for asymmetric cyclopropanation reactions of alkenes. The process uses a cobalt catalyst and is proposed to involve the formation of a cationic carbenoid species bearing structural resemblance to the Simmons-Smith reagent. High levels of enantioselectivity are observed for monosubstituted, 1,1-disubstituted, and internal alkenes. The reaction is compatible with alkyl-substituted carbenes, which are susceptible to undergoing competing 1,2-hydride shifts.

Description of Brachymeria philornisae sp. n. (Hymenoptera: Chalcididae), a parasitoid of the bird parasite Philornis trinitensis (Diptera: Muscidae) in Tobago, with a review of the sibling species.

In this paper, we describe and illustrate a new species of parasitoid wasp as Brachymeria philornisae Delvare, sp. nov. The new species was reared from Philornis trinitensis Dodge & Aitken (Diptera: Muscidae) puparia that were found in the nests of the bird species Mimus gilvus (Vieillot) (Mimidae) and Tiaris bicolor (L.) (Thraupidae) in Tobago. The new species is of particular interest as it may be considered a potential biological control agent in locations where Philornis species are invasive, such as the Galapagos Islands. Closely related Brachymeria species had taxonomically ambiguous relationship in the past and are compared and reviewed. The species have been classified in the subgenus Pseudobrachymeria, but are here treated within the newly defined subconica species-group of Brachymeria as part of a sibling species complex designated as the subrugosa complex. Species assigned to the subconica species-group are listed and five, one unnamed, are assigned to the subrugosa complex and their females keyed. Species are separated by qualitative characters and morphometry using distance measurements. Trigonura annulipes Costa Lima is renamed as Brachymeria costalimai Delvare nom. nov. because of secondary homonymy.

Aedes aegypti (L.) mosquitoes in Trinidad, West Indies: longevity case studies.

Few laboratory and field studies have reported long survival periods for Ae. aegypti females and even fewer have designed experiments to characterize this important life history trait. This study was conducted under laboratory conditions to determine the number of blood meals taken by individual females, the number of eggs laid per individual female, the length of the gonotrophic cycle, and the duration of female survival. The results showed individual females oviposited between 670 and 1,500 eggs throughout their lifetimes, females undergoing large numbers of gonotrophic cycles and surviving up to 224 days. These results are discussed in the context of vector competence, unique alternating high and low oviposition patterns observed after week 14, and resource partitioning/allocation by older Ae. aegypti females after blood feeding.

Aedes aegypti (L.) in Latin American and Caribbean region: With growing evidence for vector adaptation to climate change?

Within Latin America and the Caribbean region the impact of climate change has been associated with the effects of rainfall and temperature on seasonal outbreaks of dengue but few studies have been conducted on the impacts of climate on the behaviour and ecology of Aedes aegypti mosquitoes.This study was conducted to examine the adaptive behaviours currently being employed by A. aegypti mosquitoes exposed to the force of climate change in LAC countries. The literature on the association between climate and dengue incidence is small and sometimes speculative. Few laboratory and field studies have identified research gaps. Laboratory and field experiments were designed and conducted to better understand the container preferences, climate-associated-adaptive behaviour, ecology and the effects of different temperatures and light regimens on the life history of A. aegypti mosquitoes. A. aegypti adaptive behaviours and changes in container preferences demonstrate how complex dengue transmission dynamics is, in different ecosystems. The use of underground drains and septic tanks represents a major behaviour change identified and compounds an already difficult task to control A. aegypti populations. A business as usual approach will exacerbate the problem and lead to more frequent outbreaks of dengue and chikungunya in LAC countries unless both area-wide and targeted vector control approaches are adopted. The current evidence and the results from proposed transdisciplinary research on dengue within different ecosystems will help guide the development of new vector control strategies and foster a better understanding of climate change impacts on vector-borne disease transmission.

Isolation and characterization of sylvatic mosquito-borne viruses in Trinidad: enzootic transmission and a new potential vector of Mucambo virus.

Mosquito surveillance was carried out in three forested regions of Trinidad during July 2007-March 2009. A total of 185,397 mosquitoes representing at least 46 species was collected, divided into pools of 1-50 mosquitoes according to species and sex, and screened for arboviruses using cytopathic effect assays on Vero cell monolayers. Eighty-five viruses were isolated, including members of the genera Alphavirus (Mucambo virus; MUCV) and Orthobunyavirus (Caraparu, Oriboca, Bimiti, and Wyeomyia viruses). Species of the Culex subgenus Melanoconion accounted for 56% of the total number of mosquitoes collected and 97% of the viruses isolated; Cx. (Mel.) portesi accounted for 92% of virus isolations. Our results also implicate for the first time Aedes (Ochlerotatus) hortator as a potential vector of MUCV. Phylogenetic analyses of 43 MUCV strains suggest population subdivision within Trinidad, consistent with the hypothesis of enzootic maintenance in localized rodent populations.

Initial reliability and validity of the lift-and-raise hamstring test.

The Lift-and-Raise hamstring flexibility test was developed as a field-based assessment to eliminate the effects of individual and developmental differences in arm, leg, and trunk lengths found with the commonly used Sit-and-Reach tests. This study assessed the initial reliability of the prototype instrument and its validity by comparing obtained values from a Cybex Testing and Rehabilitation System. Flexibility of the left leg was assessed on 53 college-aged participants (women, n = 28; men, n = 25) using the Lift-and-Raise test by 2 independent testers to determine initial reliability measures. The Cybex Testing and Rehabilitation System was compared with the Lift-and-Raise test when assessing the left hamstring of 39 college-aged students (women, n = 23; men, n = 16) to establish initial validity. A high intraclass correlation coefficient emerged between the 2 testers (r = 0.944) on the Lift-and-Raise instrument and between the Lift-and-Raise test and the Cybex testing protocol (r = 0.891). Based on initial results, the Lift-and-Raise test seems to be a reliable and valid test to measure hamstring flexibility.

Isolation and phylogenetic analysis of Mucambo virus (Venezuelan equine encephalitis complex subtype IIIA) in Trinidad.

In the 1950s and 1960s, alphaviruses in the Venezuelan equine encephalitis (VEE) antigenic complex were the most frequently isolated arboviruses in Trinidad. Since then, there has been very little research performed with these viruses. Herein, we report on the isolation, sequencing, and phylogenetic analyses of Mucambo virus (MUCV; VEE complex subtype IIIA), including 6 recently isolated from Culex (Melanoconion) portesi mosquitoes and 11 previously isolated in Trinidad and Brazil. Results show that nucleotide and amino acid identities across the complete structural polyprotein for the MUCV isolates were 96.6-100% and 98.7-100%, respectively, and the phylogenetic tree inferred for MUCV was highly geographically- and temporally-structured. Bayesian analyses suggest that the sampled MUCV lineages have a recent common ancestry of approximately 198 years (with a 95% highest posterior density (HPD) interval of 63-448 years) prior to 2007, and an overall rate of evolution of 1.28 x 10(-4) substitutions/site/yr.

A comparison of surveillance systems for the dengue vector Aedes aegypti in Port of Spain, Trinidad

When the currently used larval surveillance system (visual inspection) for the dengue vector Aedes aegypti was compared with the surveillance for the presence of eggs by ovitrapping in Port of Spain, Trinidad, it was found that the latter (39.1 percent) was significantly more sensitive than the visual inspection system (10.1 percent). At the same time, the presence of the nuisance mosquito Culex quinquefasciatus was detected in 38.4 percent of the households. Both Ae. aegypti and Cx. quinquefasciatus showed preference for ovipositional attractants in ovitraps: hay infusion > yeast suspension > plain tap water. Although all the socioeconomic and geographic areas produced both mosquito species in 1996, upper middle class (UMC) areas (8.6-43.4 percent), produced more Ae. aegypti than did lower middle class (LMC) area 7.8-38.8 percent), which produced more than working class (WC) areas (3.9-29.9 percent). For Cx. quinquefasciatus, the order of production was reversed with WC areas (50.1 percent) > LMC areas (30.0 percent) > UMC areas (26.0 percent). Change in vector surveillance strategies incorporating some ovitrapping and stratified sampling are recommended for Caribbean countries(AU)

Evaluation of Caribbean strain of macrocyclops and mesocyclops (cyclopoida: cycopoidae) as a biological tool for the dengue vector, aedes aegypti

When 15 Caribbean strains of copepods (Cyclopoida: Cyclopidae) were assessed for their predation ability against mosquito larvae, Macrocyclops albidus from Nariva, Mesocyclops aspericornis from Oropouche and Me.longisetus from El Socorro, Trinidad, were most effective against Aedes aegypti but not against the nuisance mosquito, Culex quinquefasciatus. Me.longisetus and Me.aspericornis prevented any mosquito survival over 25 weeks of observation despite weekly challenges with Aedes aegypti. The copepods were tolerant to dosages of the insecticide temephos which are usually toxic to mosquito larvae. This indicated their ability to be incorporated into an integrated control system of biological and chemical components. Microbial studies done on the copepods showed the presence of only Aeromonas sobria, Pseudomonas sp., Alcaligenes and gram-positive bacilli. The application of these copepods has not yet been recommended for use in drinking water (AU)

The effect of the cibarial armature on blood meal haemolysis of four anopheline mosquitoes

The cibarial armatures of Anopheles albitarsis Lynch Arribalzaga, A. aquasalis Curry, A. bellator Dyar & Knab and A. homunculus Komp are described for the first time. Ten to 15 minutes after blood feeding, higher levels of blood haemolysis were observed among A. bellator (14.9 percent) and A. homunculus (14 percent) mosquitoes which possessed type C cibarial armatures than among A. albitarsis (3.3 percent) and A. aquasalis (3.2 percent) which possessed type B cibarial armatures. In contrast, there were no significant differences among the four species in levels of extra-erythrocytic haemolysis when measured immediately after one hour. The blood processing physiology observed for the four anopheline species is discussed at the enzymatic, mechanical and taxonomic levels as it relates to innate vector competence (AU)

Water storage and dengue in Trinidad and Tobago: community perception and reality - abstract

A knowledge, attitude and practices (KAP) survey of 591 householders and inspection of 753 households for production of the dengue vector Aedes aegypti revealed that as many as 78 percent of households in Trinidad and Tobago stored water. Tanks (63 percent), drums/barrels (29 percent) and buckets (26 percent) were the commonest potential vector production sites, while drums >cans>buckets>tyres, proved to be the major actual producers of Ae aegypti. However, most of these were perceived as "useful by 100 percent of the population; 60 percent thought that old tyres were "useful" and only containers such as coconut shells and small bottles were perceived by 40 percent of the population as "garbage". Special messages of mosquito source reduction will need to be designed. Dengue was recognized as a "serious" illness but only 54 percent were aware of its manifestations. The urban population of Woodbrook where the experience of dengue (16.3 percent) was highest could better tell of the symptoms of dengue (56.8 percent). Conversely, in Tobago with no history of the disease, only 18.3 percent knew of any symptom of the illness. The community that had experienced the highest dengue prevalence as a whole showed least mosquito production - based on the house, container and Breteau indices for the whole country. The authors conclude that health education messages which emphasize the symptoms of Dengue and especially Dengue Haemorrhagic Fever (DHF) and link the transmission of these diseases to the nuisance mosquito, Ae, aegypti, may be one of the most important tools encouraging behaviour modification. This could lead to reduced mosquito production and a mitigation of dengue transmission (AU)

Laboratory colonization and maintenance of Toxorhynchites moctezuma

A colony of Toxorhynchites moctezuma was established at the Caribbean Epidemiology Centre in Trinidad in 1984. Toxorhynchites moctezuma was maintained in cages with high humidities. Eggs were deposited most frequently in a cut bicycle tire containing water. A minimum of 42 h was required for hatching, but 94 percent hatched between 43 and 51 h. Aedes aegypti larvae were supplied as prey. Larval development times varied with the quantity of prey offered, but when fed ad lib, peak developmental time was 18 days. Mean pupal developmental time was 5.5 days. Although only 12 percent of larvae survived to pupation in 3 years of production, our experience indicates this species would be a likely candidate for mass production and release.(AU)

Yellow fever studies in Trinidad, 1988-1989: attempts to demonstrate Transovarial Transmission of yellow fever virus in Haemagogus mosquitoes collected in nature

Subsequent to an epizootic of yellow fever (YF) in monkeys and the isolation of yellow fever (YF) virus from sylvatic mosquitoes in December, 1988 and January, 1989 in south-east Trinidad, ovitrapping for mosquito eggs was started in January, 1989, in an attempt to demonstrate transovarial transmission of the virus. Multi-paddle ovitraps were used. From a total of 52,632 eggs collected in various parts of the country, the following species of mosquitoes were reared: Haemagogus janthinomys (54 percent), Hg. leucocelaenus (32 percent), Aedes insolitus (12 percent), Hg. equinus (1 percent). When mosquito eggs were removed from the hard board paddles then vacuum-treated for hatching, the process proved very economical in storage space. Most eggs were obtained at the start of the wet season, four to five months after the isolation yellow fever virus from wild caught adult mosquitoes and monkey carcasses. When adult mosquitoes reared from eggs were processed for yellow fever virus, no virus was detected from any of the mosquito pools to indicate that transovarial transmission had occurred (AU)

Sylvatic yellow fever activity in Trinidad 1988-1989

Of a total of 18,068 mosquitoes (361 pools) collected in south-eastern Trinidad forests from December, 1988 to May, 1989, 47 species belonging to 14 genera were identified. Five yellow fever virus isolates were made from Haemagogus janthinomys and one from Sabethes chloropterus. All the other pools of mosquitoes examined were negative for the virus. The mosquito isolates were made in December and January. In addition, in late February and early March, two infected howler monkeys (Alouatta sp.) were detected. Since March, despite continued surveillance, no yellow fever virus has been detected in mosquitoes or monkeys. There has been no reported human infection (AU)

Studies on yellow fever in inter-epizootic period in Trinidad

Following an outbreak of yellow fever in Trinidad in 1978-1979, a study was undertaken to investigate the jungle reservoirs and vectors of yellow fever virus in the inter-epizootic period, to seek evidence of natural transovarial transmission of yellow fever virus in Haemagogus collected. These were made four months after the last detection of virus in that area of the island and could not positively be attributed to transovarial transmission. None of the 42,815 progeny of wild mosquitoes yielded virus. No yellow fever virus was isolated from 34,300 mosquitoes other than Haemagogus nor from 15 vertebrates collected in areas of former virus activity. Good progress was made in optimizing the use of the AP-61 cell line resulting in rapid isolation and identification of dengue and yellow fever viruses from Caribbean countries (AU)

Studies on yellow fever in inter-epizootic period in Trinidad

Following an outbreak of yellow fever in Trinidad in 1978-1979, a study was undertaken to investigate the jungle reservoirs and vectors of yellow fever virus in the inter-epizootic period, to seek evidence of natural transovarial transmission of yellow fever virus in Haemagogus collected. These were made four months after the last detection of virus in that area of the island and could not positively be attributed to transovarial transmission. None of the 42,815 progeny of wild mosquitoes yielded virus. No yellow fever virus was isolated from 34,300 mosquitoes other than Haemagogus nor from 15 vertebrates collected in areas of former virus activity. Good progress was made in optimizing the use of the AP-61 cell line resulting in rapid isolation and identification of dengue and yellow fever viruses from Caribbean countries.

Sylvatic yellow fever activity in Trinidad 1988-1989

Of a total of 18,068 mosquitoes (361 pools) collected in south-eastern Trinidad forests from December, 1988 to May, 1989, 47 species belonging to 14 genera were identified. Five yellow fever virus isolates were made from Haemagogus janthinomys and one from Sabethes chloropterus. All the other pools of mosquitoes examined were negative for the virus. The mosquito isolates were made in December and January. In addition, in late February and early March, two infected howler monkeys (Alouatta sp.) were detected. Since March, despite continued surveillance, no yellow fever virus has been detected in mosquitoes or monkeys. There has been no reported human infection.

Yellow fever studies in Trinidad, 1988-1989: attempts to demonstrate Transovarial Transmission of yellow fever virus in Haemagogus mosquitoes collected in nature

Subsequent to an epizootic of yellow fever (YF) in monkeys and the isolation of yellow fever (YF) virus from sylvatic mosquitoes in December, 1988 and January, 1989 in south-east Trinidad, ovitrapping for mosquito eggs was started in January, 1989, in an attempt to demonstrate transovarial transmission of the virus. Multi-paddle ovitraps were used. From a total of 52,632 eggs collected in various parts of the country, the following species of mosquitoes were reared: Haemagogus janthinomys (54 per cent ), Hg. leucocelaenus (32 per cent ), Aedes insolitus (12 per cent ), Hg. equinus (1 per cent ). When mosquito eggs were removed from the hard board paddles then vacuum-treated for hatching, the process proved very economical in storage space. Most eggs were obtained at the start of the wet season, four to five months after the isolation yellow fever virus from wild caught adult mosquitoes and monkey carcasses. When adult mosquitoes reared from eggs were processed for yellow fever virus, no virus was detected from any of the mosquito pools to indicate that transovarial transmission had occurred.