Displaying publications 1 - 20 of 251 in total

Abstract:
Sort:
  1. Fulltext The toxicity of angiotensin converting enzyme inhibitors to larvae of the disease vectors Aedes aegypti and Anopheles gambiae
    Abu Hasan Z', Williams H, Ismail NM, Othman H, Cozier GE, Acharya KR, et al.
    Sci Rep, 2017 03 27;7:45409.
    PMID: 28345667 DOI: 10.1038/srep45409
    The control of mosquitoes is threatened by the appearance of insecticide resistance and therefore new control chemicals are urgently required. Here we show that inhibitors of mosquito peptidyl dipeptidase, a peptidase related to mammalian angiotensin-converting enzyme (ACE), are insecticidal to larvae of the mosquitoes, Aedes aegypti and Anopheles gambiae. ACE inhibitors (captopril, fosinopril and fosinoprilat) and two peptides (trypsin-modulating oostatic factor/TMOF and a bradykinin-potentiating peptide, BPP-12b) were all inhibitors of the larval ACE activity of both mosquitoes. Two inhibitors, captopril and fosinopril (a pro-drug ester of fosinoprilat), were tested for larvicidal activity. Within 24 h captopril had killed >90% of the early instars of both species with 3rd instars showing greater resistance. Mortality was also high within 24 h of exposure of 1st, 2nd and 3rd instars of An. gambiae to fosinopril. Fosinopril was also toxic to Ae. aegypti larvae, although the 1st instars appeared to be less susceptible to this pro-drug even after 72 h exposure. Homology models of the larval An. gambiae ACE proteins (AnoACE2 and AnoACE3) reveal structural differences compared to human ACE, suggesting that structure-based drug design offers a fruitful approach to the development of selective inhibitors of mosquito ACE enzymes as novel larvicides.
    Matched MeSH terms: Anopheles/drug effects*
  2. The distribution of common Anopheles mosquitoes in northwestern Peninsular Malaysia
    Abu Hassan A, Rahman WA, Salmah MR, Rashid MZ, Jaal Z, Adanan CR, et al.
    J Vector Ecol, 1997 Dec;22(2):109-14.
    PMID: 9491360
    Using cow-baited net traps in the coastal and hilly areas of northern peninsular Malaysia, 21 species of Anopheles mosquitoes were found. The distribution of common Anopheles is presented. The composition of the anopheline mosquito fauna was more diversified in the coastal areas than in the hilly areas. The displacement of Anopheles sundaicus by Anopheles subpictus and the disappearance of Anopheles hackeri in the coastal area were noted.
    Matched MeSH terms: Anopheles*
  3. Test for association between dieldrin resistance and 2La inversion polymorphism in Anopheles coluzzii from Lagos, Nigeria
    Adeogun AO, Brooke BD, Olayanju DR, Adegbehingbe K, Oyeniyi TA, Olakiigbe AK, et al.
    Trop Biomed, 2019 Sep 01;36(3):587-593.
    PMID: 33597480
    The assortment of paracentric chromosomal inversion 2La is associated with the maintenance of dieldrin resistance in laboratory colonies of the malaria vector Anopheles gambiae. This association has not been tested in field populations. The aim of this study was to test the association between inversion 2La and dieldrin resistance in a field population of An. coluzzii in Nigeria. Field collected immature stages of Anopheles were raised to adults and exposed to 4% dieldrin according to WHO criteria. Knockdown was recorded at 10 min intervals for 1 hour and final mortality was recorded 24 hours post exposure. Species and inversion 2La diagnostic PCR assays were conducted on the resistant and susceptible mosquitoes. The mosquitoes were highly resistant to 4% dieldrin (17.1% knock down and 25.7% final mortality; KDT50 and KDT95 calculated as 170 and 1, 514 minutes respectively). Frequencies of 2La in both the resistant and susceptible cohorts assorted within HardyWeinberg estimates (χ2=1.32, p=0.8 for dead/susceptible mosquitoes and χ2=2.54, p=0.5 for survivors or resistant mosquitoes). However, a higher number of heterozygous mosquitoes were observed in the resistant cohort compared to the susceptible, with significant variation in karyotype frequencies (χ2=11.08, DF=2, p<0.05) and a significantly higher frequency of the 2La inversion arrangement in the resistant cohort (Pearson's χ2 = 4.58, p = 0.03.). These data are the first to associate paracentric chromosome inversion 2La and dieldrin resistance in field population of An. coluzzii. Dieldrin resistance shows a weak but significant association with 2La whose assortment is affected by positive heterosis. Variation in the assortment of 2La inversion arrangements between resistant and susceptible cohorts of this An. coluzzii population suggests that dieldrin resistance is at least partially linked to inversion 2La which may explain the persistence of dieldrin resistance in this population despite a significant absence of selection for resistance to this insecticide.
    Matched MeSH terms: Anopheles/genetics*
  4. Fulltext Mapping of mosquito breeding sites in malaria endemic areas in Pos Lenjang, Kuala Lipis, Pahang, Malaysia
    Ahmad R, Ali WN, Nor ZM, Ismail Z, Hadi AA, Ibrahim MN, et al.
    Malar J, 2011;10:361.
    PMID: 22166101 DOI: 10.1186/1475-2875-10-361
    The application of the Geographic Information Systems (GIS) to the study of vector transmitted diseases considerably improves the management of the information obtained from the field survey and facilitates the study of the distribution patterns of the vector species.
    Matched MeSH terms: Anopheles/growth & development*
  5. Fulltext Recent advances on the use of biochemical extracts as filaricidal agents
    Al-Abd NM, Nor ZM, Al-Adhroey AH, Suhaimi A, Sivanandam S
    Evid Based Complement Alternat Med, 2013;2013:986573.
    PMID: 24298292 DOI: 10.1155/2013/986573
    Lymphatic filariasis is a parasitic infection that causes a devastating public health and socioeconomic burden with an estimated infection of over 120 million individuals worldwide. The infection is caused by three closely related nematode parasites, namely, Wuchereria bancrofti, Brugia malayi, and B. timori, which are transmitted to human through mosquitoes of Anopheles, Culex, and Aedes genera. The species have many ecological variants and are diversified in terms of their genetic fingerprint. The rapid spread of the disease and the genetic diversification cause the lymphatic filarial parasites to respond differently to diagnostic and therapeutic interventions. This in turn prompts the current challenge encountered in its management. Furthermore, most of the chemical medications used are characterized by adverse side effects. These complications urgently warrant intense prospecting on bio-chemicals that have potent efficacy against either the filarial worms or thier vector. In lieu of this, we presented a review on recent literature that reported the efficacy of filaricidal biochemicals and those employed as vector control agents. In addition, methods used for biochemical extraction, screening procedures, and structure of the bioactive compounds were also presented.
    Matched MeSH terms: Anopheles
  6. Fulltext The suitability of P. falciparum merozoite surface proteins 1 and 2 as genetic markers for in vivo drug trials in Yemen
    Al-abd NM, Mahdy MA, Al-Mekhlafi AM, Snounou G, Abdul-Majid NB, Al-Mekhlafi HM, et al.
    PLoS One, 2013;8(7):e67853.
    PMID: 23861823 DOI: 10.1371/journal.pone.0067853
    The accuracy of the conclusions from in vivo efficacy anti-malarial drug trials depends on distinguishing between recrudescences and re-infections which is accomplished by genotyping genes coding P. falciparum merozoite surface 1 (MSP1) and MSP2. However, the reliability of the PCR analysis depends on the genetic markers' allelic diversity and variant frequency. In this study the genetic diversity of the genes coding for MSP1 and MSP2 was obtained for P. falciparum parasites circulating in Yemen.
    Matched MeSH terms: Anopheles/parasitology
  7. Molecular identification of Anopheles (Cellia) sundaicus from the Andaman and Nicobar islands of India
    Alam MT, Das MK, Ansari MA, Sharma YD
    Acta Trop, 2006 Jan;97(1):10-8.
    PMID: 16125659
    Anopheles (Cellia) sundaicus (Rodenwaldt) is an important malaria vector in the Andaman and Nicobar islands of India where it breeds in freshwater as well as in brackish water. To establish the molecular identity of An. sundaicus on these islands we analyzed samples from four geographically isolated areas-Teressa, Nancowry, Car Nicobar and Katchal islands. PCR-amplification and nucleotide sequence analysis were performed for internal transcribed spacer 2 (ITS2) and domain-3 (D3) of 28S rRNA. The ITS2 region of An. sundaicus from all four islands was identical but different from An. sundaicus A of Vietnam and An. sundaicus s.s of Malaysia. Furthermore, freshwater and brackish water forms of An. sundaicus did not reveal any sequence variation. Similarly, the D3 sequences were identical among all An. sundaicus samples from the four islands. D3 sequences for a species of the Sundaicus Complex are reported here for the first time and thus could not be compared with other regional isolates of this species. In conclusion, probably only one member of the Sundaicus Complex exists on the Andaman and Nicobar islands, which breeds in freshwater as well as in brackish water and is different from the An. sundaicus A and Malaysian An. sundaicus s.s. The identification of a new sibling species of the Sundaicus Complex in these islands is significant from the viewpoint of vector control strategies.
    Matched MeSH terms: Anopheles/classification*; Anopheles/genetics
  8. Population dynamics of adult mosquitoes (Diptera: Culicidae) in malaria endemic villages of Kuala Lipis, Pahang, Malaysia
    Ali WN, Ahmad R, Nor ZM, Ismail Z, Lim LH
    Southeast Asian J. Trop. Med. Public Health, 2011 Mar;42(2):259-67.
    PMID: 21710845
    Mosquitoes in malaria endemic areas needs to be monitored constantly in order to detect demographic changes that could affect control measures. A 12-month mosquito population survey was conducted in several malaria endemic areas in Pos Lenjang, Kuala Lipis, Pahang, Malaysia. Collection of mosquitoes using a human landing catch technique was carried out indoors and outdoors for 12 hours from 7:00 PM to 7:00 AM for 42 nights. Anopheles maculatus Theobald (31.0%), Armigeres flavus Leicester (11.3%), Armigeres annulitarsis Leicester (11.0%), Culex vishnui Theobald (9.6%) and Aedes albopictus Skuse (7.0%) were the predominant species caught in the study area. The salivary gland and midgut of all anopheline mosquitoes were dissected to determine the presence of malaria parasites but none were positive. A high rate of human biting by An. maculatus was detected during December, but the rate was lower in January. Mosquito larvae were carried by the rapid current of the river downstream causing a decrease in the larvae population. Of the five predominant species, only Ar. annulitarsis exhibited a significant positive correlation in numbers with monthly rainfall (p < 0.05). An. maculatus biting activity peaked during 10:00 PM to 11:00 PM. Ae. albopictus, Ar. annulitarsis, and Ar. flavus exhibited similar activities which peaked during 7:00 PM to 8.00 PM.
    Matched MeSH terms: Anopheles*
  9. Fulltext Charaterization of mosquito larval habitats in Qatar
    Alkhayat FA, Ahmad AH, Rahim J, Dieng H, Ismail BA, Imran M, et al.
    Saudi J Biol Sci, 2020 Sep;27(9):2358-2365.
    PMID: 32884417 DOI: 10.1016/j.sjbs.2020.07.006
    Mosquito borne diseases have remained a grave threat to human health and are posing a significant burden on health authorities around the globe. The understanding and insight of mosquito breeding habitats features is crucial for their effective management. Comprehensive larval surveys were carried out at 14 sites in Qatar. A total of 443 aquatic habitats were examined, among these 130 were found positive with Culex pipiens, Cx. quinquefasciatus, Cx. mattinglyi, Ochlerotatus dorsalis, Oc. caspius and Anopheles stephensi. The majority of positive breeding habitats were recorded in urban areas (67.6%), followed by livestock (13.8%), and least were in agriculture (10.7%). An. stephensi larvae were positively correlated with Cx. pipien, Cx. quinquefasciatus, and negatively with water salinity. Large and shaded habitats were the most preferred by An. stephensi. In addition, Cx. pipiens was positively associated with the turbidity and pH, and was negatively associated with vegetation and habitat size. A negative association of Cx. quinquefasciatus with dissolved oxygen, water temperature, and salinity, while positive with habitat surface area was observed. Oc. dorsalis was negatively correlated with pH, water temperature, depth, and habitat surface area, whereas salinity water was more preferable site for females to lay their eggs. These results demonstrate that environmental factors play a significant role in preference of both anopheline and culicine for oviposition, while their effective management must be developed as the most viable tool to minimize mosquito borne diseases.
    Matched MeSH terms: Anopheles
  10. Fulltext Microsatellite and mitochondrial markers reveal strong gene flow barriers for Anopheles farauti in the Solomon Archipelago: implications for malaria vector control
    Ambrose L, Cooper RD, Russell TL, Burkot TR, Lobo NF, Collins FH, et al.
    Int J Parasitol, 2014 Mar;44(3-4):225-33.
    PMID: 24440418 DOI: 10.1016/j.ijpara.2013.12.001
    Anopheles farauti is the primary malaria vector throughout the coastal regions of the Southwest Pacific. A shift in peak biting time from late to early in the night occurred following widespread indoor residue spraying of dichlorodiphenyltrichloro-ethane (DDT) and has persisted in some island populations despite the intervention ending decades ago. We used mitochondrial cytochrome oxidase I (COI) sequence data and 12 newly developed microsatellite markers to assess the population genetic structure of this malaria vector in the Solomon Archipelago. With geographically distinct differences in peak A. farauti night biting time observed in the Solomon Archipelago, we tested the hypothesis that strong barriers to gene flow exist in this region. Significant and often large fixation index (FST) values were found between different island populations for the mitochondrial and nuclear markers, suggesting highly restricted gene flow between islands. Some discordance in the location and strength of genetic breaks was observed between the mitochondrial and microsatellite markers. Since early night biting A. farauti individuals occur naturally in all populations, the strong gene flow barriers that we have identified in the Solomon Archipelago lend weight to the hypothesis that the shifts in peak biting time from late to early night have appeared independently in these disconnected island populations. For this reason, we suggest that insecticide impregnated bed nets and indoor residue spraying are unlikely to be effective as control tools against A. farauti occurring elsewhere, and if used, will probably result in peak biting time behavioural shifts similar to that observed in the Solomon Islands.
    Matched MeSH terms: Anopheles/genetics*; Anopheles/parasitology*
  11. Fulltext Colonization of Anopheles cracens: a malaria vector of emerging importance
    Amir A, Sum JS, Lau YL, Vythilingam I, Fong MY
    Parasit Vectors, 2013;6:81.
    PMID: 23537404 DOI: 10.1186/1756-3305-6-81
    Anopheles cracens has been incriminated as a vector for the simian malaria parasite, Plasmodium knowlesi, that is the fifth Plasmodium species infecting humans. Little experimental data exists on this mosquito species due to the lack of its availability in laboratories.
    Matched MeSH terms: Anopheles/growth & development*
  12. Green-synthesised nanoparticles from Melia azedarach seeds and the cyclopoid crustacean Cyclops vernalis: an eco-friendly route to control the malaria vector Anopheles stephensi?
    Anbu P, Murugan K, Madhiyazhagan P, Dinesh D, Subramaniam J, Panneerselvam C, et al.
    Nat Prod Res, 2016 Sep;30(18):2077-84.
    PMID: 26679526 DOI: 10.1080/14786419.2015.1114935
    The impact of green-synthesised mosquitocidal nanoparticles on non-target aquatic predators is poorly studied. In this research, we proposed a single-step method to synthesise silver nanoparticles (Ag NP) using the seed extract of Melia azedarach. Ag NP were characterised using a variety of biophysical methods, including UV-vis spectrophotometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. In laboratory assays on Anopheles stephensi, Ag NP showed LC50 ranging from 2.897 (I instar larvae) to 14.548 ppm (pupae). In the field, the application of Ag NP (10 × LC50) lead to complete elimination of larval populations after 72 h. The application of Ag NP in the aquatic environment did not show negative adverse effects on predatory efficiency of the mosquito natural enemy Cyclops vernalis. Overall, this study highlights the concrete possibility to employ M. azedarach-synthesised Ag NP on young instars of malaria vectors.
    Matched MeSH terms: Anopheles*
  13. Fulltext New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi
    Ang JXD, Kadir KA, Mohamad DSA, Matusop A, Divis PCS, Yaman K, et al.
    Parasit Vectors, 2020 Sep 15;13(1):472.
    PMID: 32933567 DOI: 10.1186/s13071-020-04345-2
    BACKGROUND: Plasmodium knowlesi is a significant cause of human malaria in Sarawak, Malaysian Borneo. Only one study has been previously undertaken in Sarawak to identify vectors of P. knowlesi, where Anopheles latens was incriminated as the vector in Kapit, central Sarawak. A study was therefore undertaken to identify malaria vectors in a different location in Sarawak.

    METHODS: Mosquitoes found landing on humans and resting on leaves over a 5-day period at two sites in the Lawas District of northern Sarawak were collected and identified. DNA samples extracted from salivary glands of Anopheles mosquitoes were subjected to nested PCR malaria-detection assays. The small subunit ribosomal RNA (SSU rRNA) gene of Plasmodium was sequenced, and the internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the mosquitoes were sequenced from the Plasmodium-positive samples for phylogenetic analysis.

    RESULTS: Totals of 65 anophelines and 127 culicines were collected. By PCR, 6 An. balabacensis and 5 An. donaldi were found to have single P. knowlesi infections while 3 other An. balabacensis had either single, double or triple infections with P. inui, P. fieldi, P. cynomolgi and P. knowlesi. Phylogenetic analysis of the Plasmodium SSU rRNA gene confirmed 3 An. donaldi and 3 An. balabacensis with single P. knowlesi infections, while 3 other An. balabacensis had two or more Plasmodium species of P. inui, P. knowlesi, P. cynomolgi and some species of Plasmodium that could not be conclusively identified. Phylogenies inferred from the ITS2 and/or cox1 sequences of An. balabacensis and An. donaldi indicate that they are genetically indistinguishable from An. balabacensis and An. donaldi, respectively, found in Sabah, Malaysian Borneo.

    CONCLUSIONS: Previously An. latens was identified as the vector for P. knowlesi in Kapit, central Sarawak, Malaysian Borneo, and now An. balabacensis and An. donaldi have been incriminated as vectors for zoonotic malaria in Lawas, northern Sarawak.

    Matched MeSH terms: Anopheles/classification*; Anopheles/genetics; Anopheles/parasitology
  14. Plasmodium knowlesi: the emerging zoonotic malaria parasite
    Antinori S, Galimberti L, Milazzo L, Corbellino M
    Acta Trop, 2013 Feb;125(2):191-201.
    PMID: 23088834 DOI: 10.1016/j.actatropica.2012.10.008
    Plasmodium knowlesi was initially identified in the 30s as a natural Plasmodium of Macaca fascicularis monkey also capable of experimentally infecting humans. It gained a relative notoriety in the mid-30s as an alternative to Plasmodium vivax in the treatment of the general paralysis of the insane (neurosyphilis). In 1965 the first natural human infection was described in a US military surveyor coming back from the Pahang jungle of the Malaysian peninsula. P. knowlesi was again brought to the attention of the medical community when in 2004, Balbir Singh and his co-workers reported that about 58% of malaria cases observed in the Kapit district of the Malaysian Borneo were actually caused by P. knowlesi. In the following years several reports showed that P. knowlesi is much more widespread than initially thought with cases reported across Southeast Asia. This infection should also be considered in the differential diagnosis of any febrile travellers coming back from a recent travel to forested areas of Southeast Asia. P. knowlesi can cause severe malaria with a rate of 6-9% and with a case fatality rate of 3%. Respiratory distress, acute renal failure, shock and hyperbilirubinemia are the most frequently observed complications of severe P. knowlesi malaria. Chloroquine is considered the treatment of choice of uncomplicated malaria caused by P. knowlesi.
    Matched MeSH terms: Anopheles/parasitology
  15. Fulltext Laboratory evaluation of three commercial coil products for protection efficacy against Anopheles gambiae from southern Ghana: a preliminary study
    Avicor SW, Wajidi M FF, Jaal Z
    Trop Biomed, 2015 Jun;32(2):386-9.
    PMID: 26691267 MyJurnal
    Residents in irrigated urban agricultural sites face numerous mosquito problems such as increased mosquito populations and reduced insecticides susceptibility due to the creation of mosquito breeding sites and agricultural use of insecticides and hence require effective protective products against them. In this study, the protection effectiveness of three pyrethroid formulated mosquito coils of Malaysian origin against Anopheles gambiae sensu lato from an irrigated urban agricultural site in Ghana were evaluated for their potential use. Sucrose fed An. gambiae s.l. were exposed to insecticide-containing coils in a 70 cm x 70 cm x 70 cm glass chamber to assess the insecticidal effect of the coils. The 0.005% metofluthrin coil caused the most rapid knockdown of 50% of the test mosquitoes. The mean lethal effect of the coils on An. gambiae s.l. were as follows; 0.005% metofluthrin (86%), 0.3% d-allethrin (74.33%), 0.15% d-trans allethrin (72%) and the 0.25% d-allethrin reference coil (69%). The 0.005% metofluthrin coil achieved the highest insecticidal effect on An. gambiae s.l. compared to the other coils and hence performed better than the others as an anti-mosquito product. All the three test coils were effective against An. gambaie s.l. from the irrigated agricultural site compared to the reference coil.
    Matched MeSH terms: Anopheles/physiology*
  16. To coil or not to coil: application practices, perception and efficacy of mosquito coils in a malaria-endemic community in Ghana
    Avicor SW, Wajidi MFF, Owusu EO
    Environ Sci Pollut Res Int, 2017 Sep;24(26):21138-21145.
    PMID: 28730366 DOI: 10.1007/s11356-017-9737-3
    Although evidence of mosquito coils' impact on disease epidemiology is limited, they are popularized as mosquito-borne disease prevention devices. Their usage affects the environment, human and mosquito health. This study investigated the perception, usage pattern and efficacy of coils in a predominantly poor malaria-endemic Ghanaian peri-urban area. Information on protection methods, perception and usage pattern was garnered using questionnaires. The efficacy of commonly used coils in the area was then assessed on the malaria vector, Anopheles gambiae, in a glass chamber. Sole or co-application of mosquito control methods and risky usage practices were reported. Coils were deemed harmful to humans and mosquitoes, and their perceived effectiveness varied, with several factors influencing their purchase. High d-allethrin concentration coils induced quicker mosquito knockdown; however, mortality was less than 85%. The coil usage pattern compromises users' health and can enhance mosquito tolerance to d-allethrin. The coils were ineffective against the vector, outlining a dichotomy between the users' perception of efficacy and the observed efficacy. Hence, the usage of other safer and more effective vector control methods should be encouraged to protect households.
    Matched MeSH terms: Anopheles
  17. Twelve months records of mosquito-breeding in Telok Anson with special reference to hydrogen-ion concentration
    Badenoch AG
    Malayan Medical Journal, 1932;7:82-7, 90.
    Matched MeSH terms: Anopheles
  18. Cytogenetic studies of some species complexes of Anopheles in Thailand and Southeast Asia
    Baimai V, Green CA, Andre RG, Harrison BA, Peyton EL
    Southeast Asian J. Trop. Med. Public Health, 1984 Dec;15(4):536-46.
    PMID: 6543543
    Recent studies on cytogenetics, behavioral, geographical and distinct morphological characters on adult, pupal and larval stages have revealed that "balabacensis" is a species complex. Anopheles dirus the mainland species, is distributed widely in Thailand and is renowned for its role as primary vector of human malarial parasites. Further, evidence from cytogenetic and taxonomic studies suggests that "An. dirus" is a species complex comprising at least four distinct species provisionally designated: dirus A, B, C and D. These cryptic species are distinguishable only partially morphologically, but can be separated on the basis of metaphase chromosomes using the Giemsa and Hoechst 33258 staining techniques. Apparently, these siblings show distinct patterns of geographic distribution in Thailand and Peninsular Malaysia. The recognition of dirus as a complex of species in Thailand and Peninsular Malaysia requires a re-evaluation of the role that the individual members of this complex have in the transmission of malaria parasites in this region. Cytological analysis of gene rearrangements in ovarian polytene chromosomes has shown that An. maculatus is a sibling-species complex consisting of at least four species in Thailand provisionally designated: maculatus A, B, C and G. These siblings are sympatric in some populations. Furthermore, species B is so highly polymorphic for chromosome rearrangements that four geographic forms can be recognized. It is not known whether these four forms are subspecies or yet further species within the species B complex. These sibling-species must be differentiated in order to understand any differential capabilities in their transmission of human malaria parasites. Anopheles nivipes was elevated from synonymy under An. philippinensis to full species status by Reid, a decision recently confirmed by cross mating experiments. The Thailand Malaria Division does not differentiate these two species and only identifies An. philippinensis, yet, An. nivipes is by far the most common of the two species in Thailand. Furthermore, preliminary surveys of the ovarian polytene chromosomes of several widely separated populations of An. nivipes in Thailand have revealed at least two distinct chromosomal types of nivipes based on fixed inversions on the X chromosomes.
    Matched MeSH terms: Anopheles/classification; Anopheles/genetics*
  19. Population cytogenetics of the malaria vector Anopheles leucosphyrus group
    Baimai V
    Southeast Asian J. Trop. Med. Public Health, 1988 Dec;19(4):667-80.
    PMID: 3238480
    Until recently, very little was known of Anopheles species complexes and their relationships to epidemiology and malaria transmission in Southeast Asia. During the past eight years, extensive studies on the genetics of natural populations of anopheline mosquitoes in this region, involving the interdisciplinary efforts of taxonomists, operational entomologists and biologists, have revealed groups of cryptic species of Anopheles vectors, particularly the An. leucos phyrus group. This species group comprise seventeen species and two subspecies widely distributed in the forested areas of Southeast Asia. Among these species. An. dirus Peyton and Harrison, has been shown by cytogenetic and morphological studies to be a complex of at least seven isomorphic species, provisionally designated species A, B, C, D, E, F and takasagoensis, on the Southeast Asian mainland. Cytological identification of these species is based on distinct banding patterns of salivary gland polytene chromosomes as well as heterochromatin differences in mitotic karyotypes. The five species found in Thailand (A-D, F) exhibit distinct geographic distributions. Species A is widespread throughout Thailand except in the south. Species B had been found in sympatry with species C in southern Thailand and both seem to show north-south clinal geographic variation. Species D is common on the west side of southern Thailand and along the Thai-Burmese border in sympatry with species A. Species F, An. nemophilous Peyton and Ramalingam, has been found in a population at the Thai-Malaysian border in this study although it was known to be common in southern and western Thailand and Peninsular Malaysia. Species E is known only from western India. The five species found in Thailand also exhibit seasonal variation in relative abundance and different nocturnal biting cycles. Chromosomal polymorphisms have been observed in mitotic and polytene chromosomes of An. dirus A and D. Species B and C also show heterochromatin variation in the sex chromosomes, but are monomorphic for the standard sequence in polytene chromosomes. These biological characteristics of the An. dirus complex may have implications for understanding the epidemiology of malaria in Southeast Asia. Recent cytogenetic studies of wild-caught samples of An. leucosphyrus from Sumatra, Kalimantan and southern Thailand have revealed the presence of two distinct species within this taxon. Species A is widely distributed in southern Thailand, East Malaysia and Kalimantan, while species B is confined to Sumatra. The two isomorphic species are vectors of human malaria within their range of distribution.(ABSTRACT TRUNCATED AT 400 WORDS)
    Matched MeSH terms: Anopheles/classification; Anopheles/genetics*
  20. Cytogenetic evidence for two species within the current concept of the malaria vector Anopheles leucosphyrus in Southeast Asia
    Baimai V, Harbach RE, Sukowati S
    J Am Mosq Control Assoc, 1988 Mar;4(1):44-50.
    PMID: 3193098
    Karyotypes and crossing relationships were investigated for three allopatric populations of Anopheles leucosphyrus in Southeast Asia: South Kalimantan, Sumatra and Thailand. The mitotic karyotypes of these populations were similar to those previously observed in other species of the An. leucosphyrus group. Populations from Thailand and South Kalimantan exhibited telocentric and subtelocentric sex chromosomes, respectively, with a distinctive band of intercalary heterochromatin in the X chromosome. Strikingly different submetacentric X and Y chromosomes were observed in the population from Sumatra, and it seems likely that the evolution of these chromosomes occurred through the acquisition of constitutive heterochromatin. Sterile F1 males were observed in crosses between the Sumatra population and the populations from South Kalimantan and Thailand. No genetic incompatibility was observed in crosses between the latter two populations. We believe that the present concept of An. leucosphyrus includes two allopatric species, one inhabiting Borneo, West Malaysia and southern Thailand and one confined to Sumatra.
    Matched MeSH terms: Anopheles/genetics*; Anopheles/microbiology
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links