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At least 19 recordsLinked to original sources
PubMed2004

Excito-repellency of deltamethrin on the malaria vectors, Anopheles minimus, Anopheles dirus, Anopheles swadiwongporni, and Anopheles maculatus, in Thailand.

This study compared the behavioral avoidance responses of 4 mosquito malaria vectors, Anopheles minimus, Anopheles dirus, Anopheles maculatus form B, and Anopheles swadiwongporni, to deltamethrin, the primary insecticide used for indoor residual spraying for malaria vector control in Thailand. Six test populations. representing 4 laboratory colonies and 2 wild-caught populations, were observed during and after exposure to deltamethrin at the operational dose (0.02 g active ingredient/m2) in excito-repellency escape chambers. The laboratory colonies included a deltamethrin-susceptible colony and a deltamethrin-resistant colony of An. minimus species A, 1 colony of An. dirus species B, and 1 colony of An. maculatus form B. The 2 wild-caught populations included An. swadiwongporni and members of the An. dirus complex. Times to escape by female mosquitoes during 30 min of exposure to deltamethrin-treated papers were observed in all populations and compared to nontreated paired controls in contact and noncontact test configurations. Strong behavioral avoidance was observed in the deltamethrin-resistant colony of An. minimus, followed by An. swadiwongporni and An. maculatus. The slowest escape response was observed in the colony of An. dirus species B. All 6 populations of Anopheles showed marked contact irritancy to deltamethrin compared to paired controls and noncontact repellency trials, in both controlled laboratory colonies and field-caught populations. The degree of repellency was less profound than irritancy but, in most cases, produced a significant escape response compared to paired controls. Avoidance behavior appears to be an innate behavior of mosquitoes, as indicated by the general avoidance response detected in all 4 species, regardless of deltamethrin susceptibility status, age, or nutritional and physiological status. Excito-repellency assays of the type described in this study should become an integral part of the overall assessment of an insecticide's ability to control disease transmission in any given area.

Animals↗
PubMed2000

Ontogenetic patterns and genetic variation in Anopheles (Anopheles) intermedius Chagas, 1908 and Anopheles (Anopheles) mattogrossensis Lutz & Neiva, 1911 (Diptera: Culicidae) in the Brazilian amazon.

Changes in the expression of genes were observed during development in populations of Anopheles (Anopheles) intermedius and Anopheles (Anopheles) mattogrossensis. Esterase showed seven zones of activity: EST1 was present in all developmental stages of both species; EST2 was observed only in larvae of A. intermedius and larvae and pupae of A. mattogrossensis, with greater activity in pupae; EST3 and EST5 were present in all developmental stages, with greater intensity in larvae; EST4 and EST6 showed weak activity in larvae of A. mattogrossensis and was not found in A. intermedius. Leucine aminopeptidase showed four zones of activity, of which LAP1 and LAP2 were found in all stages of A. intermedius, with highest activity in larvae, and in larvae only of A. mattogrossensis. LAP3 was detected in all stages of A. mattogrossensis and in larvae only of A. intermedius. LAP4 was detected only in larvae and pupae of A. mattogrossensis, with greater intensity in pupae. alpha-Glycerophosphate dehydrogenase showed a single zone of activity, detected in older fourth-instar larvae and becoming more intense from the pupal stage onwards.

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PubMed2003

[Egg morphology as an indirect method to identify Anopheles benarrochi, Anopheles oswaldoi and Anopheles rangeli (Diptera: Culicidae)].

In the Department of Putumayo in southern Colombia, malaria transmission has continued in the absence of the 4 traditional Latin American vector species--Anopheles darlingi, Anopheles nuneztovari, Anopheles albimanus or Anopheles trinkae. Human bait collections yielded Anopheles mosquitoes and a morphological variant of Anopheles benarrochi, the adult females of which can easily be misidentified as Anopheles oswaldoi. Species identification of females of Anopheles in the subgenus Nyssorhynchus is generally difficult due to overlapping morphological characters; therefore, progeny of field collected females were link-reared to assess species identity. Herein a robust method is presented to identify the species Anopheles benarrochi, Anopheles oswaldoi and Anopheles rangeli from southern Colombia, using the morphology of the eggs induced from wild-caught females. Eggs of A. rangeli and A. benarrochi were differentiated on the basis of the anterior crown. In A. rangeli, this feature is positioned apically with high walls. In A. benarrochi, anterior crown is positioned more ventrally with comparatively shorter walls. No crown is present in A. oswaldoi. These differences are clear with the aid of a dissecting microscope and make accurate species determination possible even in field conditions. Egg morphology is shown to be an accurate, albeit indirect, method for the taxonomic determination for the three southern Colombian species and may also be useful in other regions of Latin America where the morphological variant of A. benarrochi is sympatric with A. oswaldoi.

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PubMed1998

Ultrastructure of eggs of Anopheles rondoni, Anopheles lutzii, and Anopheles parvus, three species of the subgenus Nyssorhynchus.

The ultrastructures of the eggs of Anopheles (Nyssorhynchus) rondoni (Neiva & Pinto), Anopheles (Nyssorhynchus) lutzii Cruz, and Anopheles (Nyssorhynchus) parvus (Chagas) are described and illustrated with scanning electron micrographs. The egg of Anopheles rondoni is similar in several respects to those of other species of the Argyritarsis Section. The egg of An. lutzii is similar to that of Anopheles antunesi Galvão and Amaral in having floats widely joined anteriorly on the ventral side, and the anterior end barely visible beyond the floats. The egg of An. parvus is remarkable in possessing an anterior fingerlike structure that bears several lobed tubercles at the apex. The fingerlike structure and the micropyle are within the prominent anterior crown formed by the frill. The egg of An. parvus has floats with the anterior pole uppermost, which is an unusual position for Anopheles.

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PubMed2006

Identification, sequence analysis, and comparative study on GSTe2 insecticide resistance gene in three main world malaria vectors: Anopheles stephensi, Anopheles culicifacies, and Anopheles fluviatilis.

Glutathione S-transferases (GSTs) are soluble dimeric proteins that are involved in the metabolism, detoxification, and excretion of a large number of endogenous and exogenous compounds such as insecticides from the cell. In the current study, field specimens of Anopheles stephensi Liston, Anopheles fluviatilis James, and Anopheles culicifacies Giles collected from Sistan and Baluchistan province in Iran and subjected to World Health Organization susceptibility test. Only An. stephensi was resistant to 4% DDT. DNA extraction and rDNA-ITS2-polymerase chain reaction (PCR) for correct species identification, followed by amplification of GSTe2 gene, including exon I and II and full sequence of intron I, identified a 500-bp fragment in these three species. These fragments were purified and sequenced from both ends. The comparison of coding sequence of GSTe2 gene between these species and with Anopheles gambiae Giles showed 82 to 86% similarity at nucleic acid levels and identified nucleotide polymorphisms within An. culicifacies and An. stephensi populations. Species-specific differences have been detected in intron I of GSTe2 gene. This is in concordance with the previous studies and confirmed the conserved nature of intron sequence in GSTe2 gene of each species, probably useful as a molecular marker for species-specific identification. Phylogenetic analysis based on rDNA-ITS2, and coding (exon I and II) and noncoding sequences of GSTe2, showed the systematic relatedness between Iranian malaria vectors and the possibility of using these sequences in both differentiation of Anopheles species and defining their evolutionary relationship with the only available GSTe2 sequence of An. gambiae. These data may be useful for implementation and evaluation of malaria control programs in aspects of population genetics and molecular resistance.

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PubMed1996

Some observations on the biting behavior of Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus and their implications for malaria control.

Studies were carried out in three villages in western Kenya on the biting behavior of Anopheles gambiae s.s., Anopheles arabiensis, and Anopheles funestus. Blood feeding behavior and departure from houses were studied under the impact of permethrin-impregnated eaves-sisal curtains. Only 2-13% of the female vector population was collected biting before 2200 hr. Over 90% of the villagers went to bed by 2100 hr. An. funestus was 6.6-8.2 times more likely to bite people indoors than outdoors, while An. gambiae s.l. females were only 2 times as likely. Under the influence of permethrin-impregnated sisal curtains placed under the eaves of village houses, there was a marked egress of blood-fed An. funestus and An. gambiae s.s. Permethrin seems to have induced exophily of half-gravid female An. gambiae s.s. While An. gambiae s.s. remained highly anthropophagic under the impact of permethrin, An. funestus shifted to feeding more on cattle. An arabiensis were largely zoophilic. Our results underline the difficulties of controlling An. gambiae s.s., the principal African malaria vector. New strategies must be found to control this vector.

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PubMedDate not supplied

Larvicidal activity of Bacillus sphaericus 2362 against Anopheles nuneztovari, Anopheles darlingi and Anopheles braziliensis (Diptera, Culicidae).

In this present study, preliminary data was obtained regarding the mortality rate of the Amazonian anophelines, Anopheles nuneztovari, Anopheles darlingi and Anopheles braziliensis when subjected to treatment with Bacillus sphaericus strain 2362, the WHO standard strain. Initially, experiments were conducted to test the mortality rate of the three species of anopheline larvae. The third larval instar of An. nuneztovari and the second and third larval instars of An. darlingi proved to be the least susceptible. In other experiments, the same three mosquito species were tested with the standard strain 2362, An. nuneztovari was the least susceptible to this insect pathogen, while An. braziliensis was the most susceptible. This latter species showed a difference in the level of LC50 concentration, when compared to the former, of 2.4, 2.5 and 1.8 in readings taken 24, 48 and 72 hours after exposure to the bacillus.

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PubMed2006

Distribution of Anopheles albimanus, Anopheles vestitipennis, and Anopheles crucians associated with land use in northern Belize.

Anthropogenic land use changes often alter natural patterns of disease transmission. The goal of this study was to determine whether phosphorus input from sugarcane, Saccharum officinarum L., cultivation in northern Belize could pose a significant environmental impact on malaria transmission by changing vegetation structure and composition of wetlands and associated larval habitats. Our primary focus was on the increased dominance of cattail, Typha domingensis Pers., a favored habitat for Anopheles vestitipennis Dyar & Knab. A land cover classification based on satellite imagery was used to select 20 marshes impacted by agricultural runoff and 20 marshes surrounded by forest (nonimpacted). A 100-m transect was established into each of the 40 marshes. Water, vegetation, and larval sampling were conducted at the 0-, 10-, 25-, 50-, and 100-m locations along the transect. Analyses of larval density data indicated that Anopheles albimanus Wiedemann was negatively correlated with percentage of cover of Typha (R2 = 0.39, P < 0.001) but positively correlated with sparse Eleocharis cellulosa Torr. (rush) cover (R2 = 0.19, P < 0.05) and presence of cyanobacterial mats (CBM) (R2 = 0.33, P < 0.0001). An. vestitipennis was found to be positively correlated with percentage of cover of Typha (R2 = 0.19, P < 0.001). Canonical correspondence analysis identified CBM and light as the variables associated with the presence of An. albimanuts larvae, Typha cover with An. vestitipennis larvae, and Eleocharis and absence of light with Anopheles crucians (Wiedemann). A positive correlation also existed between marshes adjacent to agricultural activities and presence of An. vestitipennis (R2 = 0.37, P < 0.05). These results indicate that marshes in proximity to agricultural fields are conducive for Typha growth, thereby providing habitat for the more efficient malaria vector

Agriculture↗
PubMed2001

[Molecular identification of sibling Anopheles species: example of the Anopheles minimus and Anopheles dirus complexes, major malarial vectors in Southeast Asia].

Effective control of malaria vectors requires precise identification of species. This is especially important within complexes of species that cannot be distinguished based on morphological features. Two methods based on polymerase chain reaction (PCR) analysis have been developed to identify 2 species in the Anopheles minimus complex and 5 species of the Minimums group as well as 4 species of the Anopheles dirus complex. Association of oligonucleotide couples in the form of multiplex PCR has allowed development of two simple, reliable PCR techniques adapted to each one of these species complexes that comprise the major vectors of malaria in Southeast Asia. Specifically designed to meet the needs of entomologist working in the field for reliable, cost-effective tests, these techniques will facilitate assessment of the geographical distribution of each vector. These data will help to better target vector control measures.

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PubMed1983

Value of cuticular and internal hydrocarbons for the identification of larvae of Anopheles gambiae Giles, Anopheles arabiensis Patton and Anopheles melas Theobald.

Gas chromatographic profiles of the cuticular and internal lipids extracted from 4th-instar larvae of the Anopheles gambiae complex have shown quantitative differences in their chain length distributions. For example, hydrocarbons extracted with 95% ethanol showed relative differences in peak heights eluting at Kovat indices (KI's) 2840 (An. gambiae 1.21, An. arabiensis 1.39 and An. melas 1.14) and 3150 (An. gambiae 6.73, An. arabiensis 13.40 and An. melas 13.50). However, while using the non-hydrocarbon fractions, differences were obtained at a KI of 2160 (An. gambiae 0.45, An. arabiensis 0.45 and An. melas 1.16) and at a KI of 2430 (An. gambiae 2.90, An. arabiensis 1.81 and An. melas 3.50). Utilizing the total ethanol extract and omitting the TLC (thin layer chromatography) step, thus saving four hours of analysis time, good separation was achieved at a KI of 2060 (An. gambiae 0.60, An. arabiensis and An. melas 0.0) and at a KI of 2430 (An. gambiae 1.13, An. arabiensis 0.69 and An. melas 1.59). Other differences were also noted in the profiles which could identify one or more of the three species. Good separation could be made on single larvae as well as on small batches of specimens. It was concluded that analysis of cuticular and internal lipids provides a useful biochemical method of distinguishing larvae of these species, but further studies are needed on these and other species of the An. gambiae complex collected from many localities in Africa.

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PubMed2005

Comparative susceptibility of three important malaria vectors Anopheles stephensi, Anopheles fluviatilis, and Anopheles sundaicus to Plasmodium vivax.

The 3 laboratory-colonized malaria vectors, i.e., Anopheles stephensi, An. sundaicus, and An. fluviatilis, were studied for their comparative susceptibility to Plasmodium vivax sporogony. There was no significant difference in oocyst and sporozoite recruitment by these 3 species, whereas the geometric mean (GM) of the oocyst number per midgut was significantly lower in An. fluviatilis as compared with that in the other 2 species. There was no difference in the GM of oocyst between An. stephensi and An. sundaicus. Adaptability to laboratory conditions and susceptibility to plasmodial infection suggest that An. fluviatilis and An. sundaicus can also be used as a vector model for vector-parasite interaction studies.

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PubMed1993

Experimental infection of Anopheles gambiae s.s., Anopheles freeborni and Anopheles stephensi with Plasmodium malariae and Plasmodium brasilianum.

Susceptibility to infection of 2 strains of Anopheles gambiae s.s., An. freeborni and An. stephensi, was determined for 2 closely related malaria parasites, Plasmodium malariae and P. brasilianum. Neither strain of An. gambiae supported development of oocyst densities as great as the other 2 anopheline mosquitoes. The ZAN strain of An. gambiae s.s. from Zanzibar was more susceptible to infection with the strain of P. malariae from Uganda than the G-3 strain of An. gambiae s.s. from The Gambia. All species and strains of mosquitoes supported complete development to the presence of sporozoites in the salivary glands.

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PubMed1998

[Comparison of the morphology of wing spot between Anopheles minimus and Anopheles fluviatilis].

AIM: To compare the morphology of wing spot between Anophelesminimus Theobald, 1901 and Anopheles fluviatilis James, 1902 and find out the reliable diagnostic characteristics. METHODS: Anopheles minimus were collected from Jinuo Village, Jinghong County, Yunnan Province. Anopheles fluviatilis were collected from Lingyun County, Guangxi Zhuang Autonomous Region. Measurements of the wing-length and the length of pale and dark spots on the costa and V1 were made with a microscope fitted with an ocular micrometer. RESULTS: A total of 52 females and 60 males of Anopheles minimus and 40 females and 60 males of Anopheles fluviatilis were examined. It was found that the presence of presecutor pale spot and the ratio of sector pale spot to sector dark spot were the important diagnostic morphological characteristics between the above mentioned two species. CONCLUSION: Obvious differentiations exist in the morphology of wing spots between Anopheles minimus and Anopheles fluviatilis.

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PubMed2005

Variability and genetic differentiation among Anopheles (Ano.) intermedius Chagas, 1908 and Anopheles (Ano.) mattogrossensis Lutz & Neiva, 1911 (Diptera: Culicidae) from the Brazilian Amazon.

Anopheles (Anopheles) intermedius and Anopheles (Ano.) mattogrossensis are Brazilian anopheline species belonging to the scarcely studied Anopheles subgenus. Few studies have been done on the genetic differentiation of these species. Both species have been found infected by Plasmodium and are sympatric with other anopheline species from the Nyssorhynchus subgenus. Eighteen enzymatic loci were analyzed in larval specimens of An. intermedius and An. mattogrossensis aiming to estimate the variability and genetic differentiation between these species. An. mattogrossensis population showed higher genetic variability (P = 44.4 and Ho = 0.081 +/- 0.031) than that of An. intermedius (P = 33.3 and Ho = 0.048 +/- 0.021). Most analyzed loci showed genotypic frequencies according to Hardy-Weinberg equilibrium, except for LAP1 and LAP2 in An. intermedius, and EST1 and PGM loci in An. mattogrossensis. The genetic distance between these species (D = 0.683) was consistent with the inter-specific values reported for Anopheles subgenus. We verified that the polymorphism and heterozygosity percentile values found in both species and compared to those in the literature, showed no relation between the level of isozyme variability and geographical distribution. The low variability found in these two species is probably more related to the niche they occupy than to their geographic distribution.

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PubMed2004

Description and bionomics of Anopheles (Cellia) ovengensis (Diptera: Culicidae), a new malaria vector species of the Anopheles nili group from south Cameroon.

Mosquito species of the Anopheles nili group (Diptera: Culicidae) transmit malaria to humans along rivers in Africa. To date, the An. nili group includes the species Anopheles nili s.s. and its pale-winged variant known as the "Congo form," Anopheles somalicus and Anopheles carnevalei. Larval and adult mosquito collections in the forest region of Campo, in southern Cameroon, uncovered an additional morphological variant provisionally called "Oveng form" that was subsequently found to be genetically distinct from the other members of the An. nili group. In this study, we provide further biological data that characterizes this new taxon and justifies elevation to specific rank. We propose calling this new species Anopheles ovengensis, after its geographical origin. We present a morphological description of the adult female and fourth instars and original data on the biology, ecology, and role as a human malaria vector of this new species in its type location. We provide dichotomous keys for identification of adult females and fourth instars that can be used at least in tropical areas of west and central Africa.

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