Accurate identification of mosquitoes is crucial for the management and control of vector species. Although Singapore is a tropical country with high mosquito diversity, there are no identification keys specific to its mosquito fauna. An illustrated identification key to the genera of the adult female mosquitoes of Singapore is presented. Twenty genera are characterized and two genera found in Malaysia, Culiseta and Topomyia, are also included. The key will aid non-taxonomically trained operational officers in adult mosquito identification. The key to the genera provides the first crucial step in the process to species identification.
A second case of a gordian worm (hairworm) "parasitic" in man is recorded from Malaya. A previous literature is critically discussed especially in regard to the mode of human infection. It is suggested that water-borne larvae reach the gut, invade the tissues and are finally voided with the faeces or passed with urine. Other modes of infection are considered less likely by the authors.
Prior to 1965, Singapore was part of the Malaya (now Malaysia) and was usually not mentioned when mosquito records were reported for Malaya. Consequently, many species that occurred in Singapore were not listed in the world mosquito catalog, and the available checklist for Singapore since 1986 is incomplete, with some imprecise species information. In updating this checklist, we examined and verified mosquito specimens collected from Singapore in various depositories, including a thorough review of past taxonomic literature. Here, we report a checklist of 182 mosquito species, 33 new distribution records, and a consolidated status list of vectors for Singapore. As Singapore is a travel hub and hosts one of the busiest container ports in the world, there is a risk of introducing mosquito species and their associated pathogens of human disease to the country. Hence, the distribution records are important to increase our knowledge on mosquito ecology as well as to understand the risk of newly introduced vectors and their associated pathogens.
The expansion of mosquito-borne diseases such as dengue, yellow fever, and chikungunya in the past 15 years has ignited the need for active surveillance of common and neglected mosquito-borne infectious diseases. The surveillance should be designed to detect diseases and to provide relevant field-based data for developing and implementing effective control measures to prevent outbreaks before significant public health consequences can occur. Mosquitoes are important vectors of human and animal pathogens, and knowledge on their biodiversity and distribution in the Afrotropical region is needed for the development of evidence-based vector control strategies. Following a comprehensive literature search, an inventory of the diversity and distribution of mosquitoes as well as the different mosquito-borne diseases found in Cameroon was made. A total of 290 publications/reports and the mosquito catalogue website were consulted for the review. To date, about 307 species, four subspecies and one putative new species of Culicidae, comprising 60 species and one putative new species of Anopheles, 67 species and two subspecies of Culex, 77 species and one subspecies of Aedes, 31 species and one subspecies of Eretmapodites, two Mansonia, eight Coquillettidia, and 62 species with unknown medical and veterinary importance (Toxorhynchites, Uranotaenia, Mimomyia, Malaya, Hodgesia, Ficalbia, Orthopodomyia, Aedeomyia, and Culiseta and Lutzia) have been collected in Cameroon. Multiple mosquito species implicated in the transmission of pathogens within Anopheles, Culex, Aedes, Eretmapodites, Mansonia, and Coquillettidia have been reported in Cameroon. Furthermore, the presence of 26 human and zoonotic arboviral diseases, one helminthic disease, and two protozoal diseases has been reported. Information on the bionomics, taxonomy, and distribution of mosquito species will be useful for the development of integrated vector management programmes for the surveillance and elimination of mosquito-borne diseases in Cameroon.
Surveillance methods for Coquillettidia crassipes were studied in an open housing estate near Kuala Lumpur using three types of traps Trinidad 10 trap, modified Lard can trap and IMR trap, each baited with chicken or pigeon. All traps attracted Cq. crassipes. There was no significant difference in the catches in the three traps. There was also no significant difference between chicken and pigeon as bait. Catches at heights of 1.5, 3, 4.5 and 6 m did not show any significant difference in density. Cq. crassipes was active at night with an early peak during the first hour of the night and a minor peak between 0100 and 0200 hours. The activity of the parous and nulliparous sections of the population was similar, except that a higher proportion of the parous females was active during the second peak compared with the nulliparous females. The parous rate was 22.3%, and the probability of survival through one day for two gonotrophic cycles was 0.711 and 0.650. The infection rate for Cardiofilaria was 29 out of 1052 (2.76%) and the infective rate (L3 larvae) was 13 out of 1052 (1.24%). 48.3% of the infected Cq. crassipes had a worm burden of more than ten larvae. One of the chickens in the traps was positive for microfilariae of Cardiofilaria four weeks after exposure as bait. Laboratory bred Cq. crassipes fed on this chicken produced infective larvae in ten days, and these were inoculated into clean chickens and pigeons. Microfilariae appeared in the chickens but not in pigeons. The adult worms recovered await identification.
Field observations were made on Coquillettidia crassipes during a study of Mansonia in a swamp forest ecotype in Tanjong Karang. There was an increase in abundance in July consistent with the increase in abundance of Mansonia and an increase in rainfall. The biting cycle showed a dramatic early peak during the period 1900-2000 hours. The probability of daily survival through one day for the first three gonotrophic cycles was 0.770, 0.722 and 0.759. Two of the 54 Cq. crassipes dissected were infective, with two and 25 L3 larvae of Brugia. Both subperiodic B. malayi and B. pahangi developed into L3 larvae in laboratory bred Cq. crassipes. The index of experimental infection was higher for B. pahangi. Mansonia bonneae and Ma. uniformis showed higher indices of experimental infection than Cq. crassipes for subperiodic B. malayi. It is concluded that in an endemic area with a high density of Cq. crassipes it could act as a secondary vector of Brugian filariasis.
Mosquitoes are principal vectors of major vector-borne diseases. They are widely found throughout urban and rural areas in Malaysia. They are responsible for various vector-borne diseases such as dengue, malaria, filariasis and encephalitis. A total of 158 mosquito larvae specimens were collected from the National Zoo, Malaysia, from 11 types of breeding habitats during the study period from end of May 2007 to July 2007. Aedes albopictus was the predominant species (35.4%), followed by Tripteroides aranoides (26.6%), Lutzia halifaxii (11.4%), Aedes alboscutellatus (10.1%), Aedes caecus (8.9%), Armigeres spp. (4.4%), Malaya genurostris (2.5%) and Culex vishnui (0.6%). It is important to have a mosquito free environment in a public place like the zoo. Routine larval surveillance should be implemented for an effective mosquito control program in order to reduce mosquito population.
Seaweeds are one of the most widely studied natural resources for their biological activities. Novel seaweed compounds with unique chemical structures have been reported for their pharmacological properties. The urge to search for novel insecticidal compound with a new mode of action for development of botanical insecticides supports the relevant scientific research on discovering the bioactive compounds in seaweeds. The mosquitocidal potential of seaweed extracts and their isolated compounds are documented in this review paper, along with the discussion on bioactivities of the major components of seaweeds such as polysaccharides, phenolics, proteins, terpenes, lipids, and halogenated compounds. The effects of seaweed extracts and compounds toward different life stages of mosquito (egg, larva, pupa, and adult), its growth, development, and reproduction are elaborated. The structure-activity relationships of mosquitocidal compounds are discussed to extrapolate the possible chemical characteristics of seaweed compounds responsible for insecticidal properties. Furthermore, the possible target sites and mode of actions of the mosquitocidal seaweed compounds are included in this paper. The potential synergistic effects between seaweeds and commercial insecticides as well as the toxic effects of seaweed extracts and compounds toward other insects and non-target organisms in the same habitat are also described. On top of that, various factors that influence the mosquitocidal potential of seaweeds, such as abiotic and biotic variables, sample preparation, test procedures, and considerations for a precise experimental design are discussed. The potential of active seaweed extracts and compounds in the development of effective bioinsecticide are also discussed.
To advance our limited knowledge of global mosquito biogeography, we analyzed country occurrence records from the Systematic Catalog of the Culicidae (http://www.mosquitocatalog. org/main.asp), and we present world maps of species richness and endemism. A latitudinal biodiversity gradient was observed, with species richness increasing toward the equator. A linear log-log species (y)-area (x) relationship (SAR) was found that we used to compare observed and expected species densities for each country. Brazil, Indonesia, Malaysia, and Thailand had the highest numbers of species, and Brazil also had the highest taxonomic output and number of type locations. Brazil, Australia, the Philippines, and Indonesia had the highest numbers of endemic species, but excluding small island countries, Panama, French Guiana, Malaysia, and Costa Rica had the highest densities of total species and endemic species. Globally, 50% of mosquito species are endemic. Island countries had higher total number of species and higher number of endemic species than mainland countries of similar size, but the slope of the SAR was similar for island and mainland countries. Islands also had higher numbers of publications and type locations, possibly due to greater sampling effort and/or species endemism on islands. The taxonomic output was lowest for some countries in Africa and the Middle East. A consideration of country estimates of past sampling effort and species richness and endemism is proposed to guide mosquito biodiversity surveys. For species groups, we show that the number of species of Anopheles subgenus Anopheles varies with those of subgenus Cellia in a consistent manner between countries depending on the region. This pattern is discussed in relation to hypotheses about the historical biogeography and ecology of this medically important genus. Spatial analysis of country species records offers new insight into global patterns of mosquito biodiversity and survey history.
CDC Light traps were used to study the attractant effect of CO2 and 1-octen-3-ol on trap catches of mosquito populations at three different locations in Malaysia. There was a significant increase in the number of mosquitos caught in traps baited with CO2 and CO2 with 1-octen-3-ol. The number of mosquitos caught in the CDC light trap and in the CDC light trap baited with 1-octen-3-ol alone were very few. 1-octen-3-ol and CO2 acted synergistically in attracting significantly greater numbers of Culex tritaeniorhynchus. However Anopheles sp. were not very attracted to light traps even with attractants added to them.
Five mark-release-recapture experiments with wild caught Ma. uniformis were conducted in an open swamp area at Batang Berjuntai in Selangor, 40 km from Kuala Lumpur, Malaysia, between May 1983 and January 1985. A total of 64 (0.14%) from the 45,950 females released were recaptured feeding on humans and cattle and resting in cattle-sheds. Substantially fewer (0.03% to 0.09%) females were recaptured from releases of blood-fed females than from releases of unfed females (0.20% to 0.23%). More than 70% of all recaptures were taken within a radius of 1.5 km around the point of release and the longest detected flight was 3.5 km. The mean dispersal distance for blood-fed and unfed females was 1.445 +/- 1.06 and 1.706 +/- 1.03 km, respectively. However, there was no significant difference in the overall mean dispersal of the two groups of females (p greater than 0.05). The duration of the gonotrophic cycle in the field was between 3 to 4 days. Daily survivorship estimates (0.783-0.867) based on the recapture rates of date specific marked females was comparable to that estimated vertically from the dissection of unmarked females (0.751-0.795). These experiments revealed the remarkable flying ability of Ma. uniformis and the importance of reinvasion must be recognized when control operations are restricted to small areas.
Five strains of Ma. uniformis from Malaysia were tested for their susceptibility to infection with subperiodic B. malayi. All were found to be susceptible with infection rates ranging from 62% to 100%. The susceptibility rates were directly related to the microfilarial densities of the cat at the time of feeding. Statistical analysis showed no significant difference (p greater than 0.05) among the means of the indices of experimental infection as well as the percentage of infective mosquitoes of the five strains and an old laboratory colony. They were all equally susceptible to subperiodic B. malayi.
Descriptions of the eggs of Mansonia uniformis, Ma. indiana and Ma. annulifera are provided with the aid of scanning electron micrographs. Eggs of these three species, although similar in shape and colour, are covered by outer chorionic reticulum and tubercles which provide reliable morphological character for their identification. Size, distribution and number of lobes on the large tubercles present in the region between the anterior tube and posterior region, are important distinguishing features. Measurements of egg sizes and other chorionic differences are also discussed.