Anopheles Mosquito Larvae Research Articles

Resistance Level of Mosquito Species (Diptera: Culicidae) from Shandong Province, China.

This study describes the aquatic habitats, species composition, and the insecticide resistance level of the mosquito Culex pipiens pallens in Shandong Province, China. A cross-sectional survey of mosquito larval habitats was conducted from May to November 2014 to determine the species composition and larval abundance. Larvae were collected using the standard dipping technique, and a total of four habitat types were sampled. The fourth instar larvae of Cx. pipiens pallens collected in each habitat type were tested for resistance to five insecticides according to a WHO bioassay. A total of 7,281 mosquito larvae were collected, of which 399 (5.48%) were categorized as Anopheles mosquito larvae (An. sinensis), 6636 (91.14%) as culicine larvae (Cx. pipiens pallens, Cx. tritaeniorhynchus, Cx. halifaxii, and Cx. bitaeniorhynchus), 213 (2.93%) as Armigeres larvae, and 33 (0.45%) as Aedes larvae (Aedes albopictus). In addition, a total of 1,149 mosquito pupae were collected. Culex larvae were distributed in all habitats investigated. Tukeys HSD analysis showed that roadside drainages were the most productive habitat type for Culex larvae. Armigeres species were found only in drains, Aedes only in water tanks, and Anopheles in water that was comparatively clear and rich in emergent plants. Bioassay showed that the maximum resistance level of Cx. pipiens pallens was to deltamethrin, while it was lowest to plifenate. The productivity of various mosquitoes in different habitat types is very heterogeneous. It is particularly important to modify human activity and the environment to achieve effective mosquito vector control. For effective larval control, the type of habitat should be considered, and the most productive habitat type should be given priority in mosquito abatement programs.

Polyphosphate kinase of Lysinibacillus sphaericus and its effects on accumulation of polyphosphate and bacterial growth

Lysinibacillus sphaericus produces parasporal crystal proteins (Bin toxins) that are specifically toxic to Culex and Anopheles mosquito larvae. It has long persistence in mosquito breeding sites due to the recycle of spores in mosquito cadaver and certain environments. This bacterium is unable to metabolize sugar (except N-acetylglucosamine) but can use proteinaceous materials. Previous studies have shown that inorganic polyphosphate (polyP) is essential for cell growth and responses to nutritional stringencies and environmental stresses and branched-chain amino acids (BCAAs) are useful intracellular signals for bacterial adaption to nutritional environments. However, relatively little is known about the role of polyP and the regulation link between polyP and BCAAs in nutritional limitation adaptation in a bacterium incapable of polysaccharide utilization. Here, a primary enzyme involved in polyP biosynthesis, polyphosphate kinase (PPK), was identified from L. sphaericus, and the polyP accumulation in different nutritional media was investigated. Furthermore, a ppk null mutant and the ppk-complemented strain were constructed and the effect of deletion on cell growth, polyP accumulation and expression of BCAAs biosynthetic genes (ilvBHC) was surveyed. The result showed that deletion of ppk resulted in a deficiency in polyP accumulation rather than cell growth in Luria-Bertani (LB) medium. Further studies demonstrated that the cell growth was evidently retarded and the ilvBHC expression was significantly reduced when ppk mutant was transferred from LB to limited-amino acid (LA) medium and that these phenotypes were significantly restored in the ppk-complemented strain. These results suggested that PPK plays a role in polyP accumulation and expression of genes involved in BCAAs biosynthesis, providing a hint for further understanding of the role of PPK in nutritional limitation in L. sphaericus.

English

The laboratory evaluation of larvicidal activities of some bacteria namely; Pseudomonas aeruginosa, Bacillus polymyxa and and Bacillus subtilis was assessed against the second and fourth instar of Anopheles arabiensis collected from South West Nigeria. Concentrations ranging from 1.3 x 107cfu/mL to 6.5 x 107 cfu/mL were tested on the larvae for a period of 48 h.  The disparity in the activities was monitored with B. subtilis displaying the highest activity in both the second and fourth instar with LC50 of 0.865 and 2.361 mg/mL respectively. P. aeruginosa showed LC50 of 1.931 and 4.205 mg/mL while the least activity was recorded in B. polymyxa with LC50 of 5.776 and 7.403 mg/mL. There were significant differences in the LC50 value of the bacteria on the tested instars. Values obtained from the fourth instar group were significantly different from those obtained from the second instar group in all the treatments. Finding from this study show that B. subtilis may be a potential biocontrol agent of A. arabiensis, the main malaria vector in Nigeria.   Key words: Biocontrol, larvicidal activities, Anopheles mosquito larvae, malaria.

Interaction between mosquito-larvicidal Lysinibacillus sphaericus binary toxin components: Analysis of complex formation

The two components (BinA and BinB) of Lysinibacillus sphaericus binary toxin together are highly toxic to Culex and Anopheles mosquito larvae, and have been employed world-wide to control mosquito borne diseases. Upon binding to the membrane receptor an oligomeric form (BinA2.BinB2) of the binary toxin is expected to play role in pore formation. It is not clear if these two proteins interact in solution as well, in the absence of receptor. The interactions between active forms of BinA and BinB polypeptides were probed in solution using size-exclusion chromatography, pull-down assay, surface plasmon resonance, circular dichroism, and by chemically crosslinking BinA and BinB components. We demonstrate that the two proteins interact weakly with first association and dissociation rate constants of 4.5×103M−1s−1 and 0.8s−1, resulting in conformational change, most likely, in toxic BinA protein that could kinetically favor membrane translocation of the active oligomer. The weak interactions between the two toxin components could be stabilized by glutaraldehyde crosslinking. The cross-linked complex, interestingly, showed maximal Culex larvicidal activity (LC50 value of 1.59ngmL−1) reported so far for combination of BinA/BinB components, and thus is an attractive option for development of new bio-pesticides for control of mosquito borne vector diseases.

Bioactivity, Qualitative and Quantitative Components of Alstonia Boonei Leaf Extracts on Anopheles Mosquito Larvae in Nigeria

Malaria the most common disease in Africa is transmitted by the bites of female Anopheles mosquito. Different control measures have been applied to combat the spread of this infection including biological control measures. Our research focused on the use of water, ethanol and methanol extracts of a local medicinal plant; Alstonia boonei for 24 hours in vitro on different instars of mosquito larvae. The qualitative and quantitative components of these plants were also determined. The highest mortality was recorded in the ethanol treated larvae. Lethal concentration (LC) at LC50 and LC75 varied with the different extracts and instars. Phytochemical screening showed the presence of some chemicals that are insecticidal such as tannins, saponin and alkaloids. The quantitative components of these chemicals were also seen to vary significantly. Conclusively, our study revealed that the use of Alstonia boonei as vector control agents can reduce the spread of malaria infection.

Ecology of Malaria Vectors in a Rainforest Suburban Community of Nigeria

The ecology of malaria vectors in a suburban community of Umudioka,Dunukofia Local Government Area (LGA), Anambra State was studiedbetween May and July 2009. Umudioka is an agrarian community in therainforest zone of Nigeria and it is situated between longitude 6085´E andLatitude 6010´N of Equator. Mosquito larvae were collected from groundwater pools, discarded old tyres and domestic water containers using ladles, bowls, sieves and specimen bottles. Indoor biting and resting adultmosquitoes were collected from 30 houses using pyrethroid-based insecticide knockdown method (PKC). Discarded tyres yielded the highest number of mosquito larvae 204 (54.84%) but ground pool yielded the highest number of Anopheles mosquito larvae 117 (31.45%). Of 263 adults mosquitoes collected from inside houses, 243 (92.40%) were from houses with ceilings and 20 (7.60%) from houses without ceilings. Of the 3 mosquito species collected indoors, A. gambiae 156 (59.3%), had the highest number with a room density of 5.2 mosquitoes/room/night. Ground water pools sustained by streams, tap overflows and flooding due to heavy rainfall patterns of the area, were the most favourable breeding ground for malaria vectors in the area.Key words: Malaria, Mosquito, Vectors, Ecology, Suburban, Community.

Evaluation of pesticidal properties of Euphorbia tirucalli L. (Euphorbiaceae) against selected pests

Euphorbia tirucalli L. (Euphorbiaceae) was evaluated against a number of pests to assess its pesticidal properties. Using various bioassays, it was established that its latex is effective against the bean aphid (Brevicoryne brassicae) and Anopheles mosquito larvae (Anopheles Gambiae and A. fenestus) as well as a number of nematodes. It, however, fell short of obtaining economic threshold levels with the diamond back moth (Plutella xylostella) and others like Purex spp. Its usefulness as a plant-based remedy was underscored but it was observed that a lot remains to be established like its toxicity to non-target organisms, its residual levels at harvest and long term effect to the environment among others, in order to allow public use and commercialization. Its potential as a plant-based pesticide was observed pending extraction of active ingredients from its latex.

The effect of physical water quality and water level changes on the occurrence and density of <i>Anopheles</i> mosquito larvae around the shoreline of the Koka reservoir, central Ethiopia

Abstract. Entomological studies to determine the effect of the physical characteristics of mosquito larval breeding water bodies and reservoir water level changes on the occurrence of Anopheles mosquito larvae were conducted in two villages at Koka reservoir in central Ethiopia between August and December 2007. Of the two study villages, Ejersa is located close to the reservoir, and Kuma is 5 km away from it. Data on the type, number and physical characteristics of Anopheles larval breeding habitat, species composition and densities of anopheles mosquitoes in and around the study villages were investigated and recorded. Meteorological and reservoir water level data were compared with availability of Anopheles larval breeding sites and densities. Entomological data, derived from weekly larval collections, showed that Anopheles pharoensis Theobald, Anopheles gambiae s.l. Giles, Anopheles coustani Laveran and Anopheles squamosus Theobald were breeding in the study area. The mean larval density of An. gambiae s.l. in this study was higher in slightly turbid and shallow aquatic habitat than in turbid and relatively deep aquatic habitat. The density of An. pharoensis in habitat with floating vegetation and with relatively shady conditions was significantly higher than that of less shaded aquatic habitat and greater emergent vegetation. There was also a positive correlation between the occurrence of Anopheles larvae with the water and daily minimum atmospheric temperature. Similarly at Ejersa, over the sampling period, there was a positive correlation between falling reservoir water levels and the number of positive breeding habitats. These results confirm that physical characteristics of the water bodies play an important role in the species composition, total Anopheles larval count, and the density of Anopheles mosquitoes. Suitable breeding habitat in the vicinity of the reservoir village was strongly associated with the reservoir. This is particularly important for An. pharoensis and An. gambiae s.l. which are important vectors of malaria in the area.

English

Malaria is the most important vector-borne disease in tropical and sub-tropical countries. Although, different control measures like use of insecticide-impregnated mosquito nets and curtains, chemotherapy and others are in place, so far, malaria eradication has proved impossible in affected areas. Therefore, any measure that attempts to fight the parasite or its vector (Anopheles spp.) would be of help. In this experiment, we assessed the efficacy of Euphorbia tirucalli latex both as a herbal mosquito remedy and larvicide against Anopheles fenestus Giles and Anopheles gambae Giles in a semi-natural environment. Our results indicate that E. tirucallilatex can bring about total mortality of Anopheles species larvae at the highest dilution used of 1: 250 in 5 days. LT 50 and LT 90 for the same dilution were attained at 12 and 36 h respectively. Latex was active only for eight days which is typical for herbal biocides, whose advantage is that they do not accumulate in the environment. It is concluded that E. tirucalli latex has a high efficacy against Anopheles mosquito larvae and could eventually be considered for adoption as a plant based mosquito larvicide, after further research.   Key words: Euphorbia tirucalli, Anopheles spp., latex, larvicide, malaria, efficacy.

A Study of the Essential Oils of Four Sudanese Accessions of Basil (Ocimum basilicum L.) Against Anopheles Mosquito Larvae

Problem statement: Certain basil essential oils were claimed to have a larvicidal activity towards mosquito's larvae. To test this claim the essential oils of four accessions of basil grown in Sudan were selected and tested for Anopheles larvae. Malaria is the major health problem in the Sudan and the whole country is now considered endemic, with varying degrees, about 35,000 deaths every year due to malaria. Anopheles mosquito is the major vector of malaria disease in Sudan. Search for larvicidal active compound(s) is one of several attempts to fine effective and affordable ways to control this mosquito. To determine the toxic effects of basil essential oils extracted by steam distillation against Anopheles larvae. Approach: For the larvicidal bioassay, three concentrations (100, 300, 500 ppm) of essential oil solutions of four basil accessions were prepared; 1 mL of ethanol was used to solubilize the oil in water (999 mL). In each concentration of oil solution were inserted 20 larvae (third instars). A set of controls using 0.1% ethanol and untreated sets of larvae in (tap) water, were also run for comparison. Data were evaluated through regression analysis, from the regression line; the LC50 values were read. The active ingredients were separated and/ or identified by TLC, IR and GC-MS. Results: Larvicidal activity of the essential oils is varied, lasted for about 9 h and thereafter decreased, LC50 values ranging from 190-300 ppm. Linalool, geraniol and eugenol are active components of basil essential oil against Anopheles larvae. Two accessions were caused 100% mortality at a concentration range 300-500 ppm for 3 h. Conclusion: These results indicated that basil essential oils have larvicidal activity towards Anopheles larvae. Therefore, could be affordable way to control this mosquito.

Larvicidal effects of paw paw (Carica papaya) aqueous extract on mosqiuto vectors

As part of local sourcing for control of malaria in Nigeria, the larvicidal effect of Carica papaya extract against larvae of Anopheles and Culex mosquitoes and the rate of decay of the extract in aqueous solution was investigated. The leaf extract was found to achieve a 100% mortality rate of the Anopheles mosquito larvae at the concentration of 0.06 mg/ml. A much higher concentration (0.10 mg/ml) was required to achieve the same mortality rate for Culex larvae. The lethal strength of the solution decreased with time of storage, loosing its larvicidal property on the 18th day of storage. The study suggests that Carica papaya extract could act as effective larvicide if appropriate bio-degradation controlled system capable of maintaining the release of the active ingredients for a longer period is developed.. International Journal of Natural and Applied Sciences Vol. 2 (4) 2006: pp. 417-420

Status of malaria in the Kingdom of Bahrain: a 10-year review.

Malaria was eradicated in Bahrain about 20 years ago. However, because of a large immigrant population, cases of imported malaria continued to be seen. This paper presents an evaluation of the data from 1992 to 2001 to assess the levels of indigenous and imported malaria cases and the potential for reemergence of malaria transmission in the country. Epidemiologic and parasitologic data on confirmed malaria cases during the review period were analyzed. Data on vector breeding activity were also analyzed to determine the potential for reemergence of local transmission. From 1992 to 2001, 1,572 cases of malaria were reported. All were imported malaria cases. There was a consistent decline in the number of cases, from 282 (the peak level) in 1992 to 54 in 2001. Eighty-four percent (1,318/1,572) of infections were contracted as a result of travel to or previous domicile in five countries, namely India, Pakistan, Sri Lanka, Bangladesh and Sudan. Plasmodium vivax was the etiologic agent in 85.6% (1,346/1,572) of cases, with Plasmodium falciparum accounting for 14% (220/1,572). During this period, the percentage of examined breeding sites where Anopheles mosquito larvae were identified remained fairly constant, ranging between 0.05% and 0.1%. From 1992 to 2001, there was a consistent decline in the number of imported malaria cases in Bahrain. There were no cases of locally acquired malaria during this period. The low level of vector breeding spots with Anopheles mosquito larvae suggests that the potential for reemergence of local transmission remains low.

Growth of Anopheles mosquito larvae on dietary microbiota in aquatic surface microlayers.

Hydrophobic organic matter accumulates under the surface film of water bodies to form the surface microlayers. Heterotrophic microorganisms use this organic matter for growth, and they, in turn, are fed upon by Anopheles mosquito larvae and other animals. From laboratory experiments we show that two species of mosquito larvae, Anopheles gambiae and An.quadrimaculatus, grew most rapidly where surface microlayers were present and, especially, where labile dissolved organic matter was added to promote growth of microorganisms. The importance of microorganisms was confirmed by the addition of gentamicin antibiotic, which suppressed the microbiota and reduced the growth of larvae feeding on surface microlayers. Anopheles larvae grew well on a suspension of finely ground fish food to which the antibiotic had been added, showing that reduced growth was not due to gentamicin itself. Because sub-surface microorganisms are the components of the larval diet that most affect growth, we discuss their relevance to strategies for larval control of Anopheles mosquitoes.

Uric Acid in Anopheles Mosquitoes (Diptera: Culicidae): Effects of Collarless, Stripe, and White Mutations

Anopheles mosquito larvae and pupae often have a layer of white pigment visible beneath the transparent cuticle on the dorsum of the abdomen and thorax. This pigment occurs in granules that are highly concentrated in ameboid-shaped cells of the parietal fat body. Mutations that affect the pattern or abundance, or both, of this pigment in A. albimanus Wiedemann and A. gambiae Giles are characterized by differences in the abundance of uric acid, whose levels range from 1.86 to 3.13 μg per larvae in individuals of 4 phenotypes having white pigmentation. Uric acid concentrations are higher in A. albimanus stripe + individuals which also have the most prominent white pigment. Two other mutants, A. gambiae collarless and A. albimanus white eye, contain no detectable uric acid nor any white pigment. None of the mutants examined has reduced xanthine dehydrogenase activity nor altered XDH electrophoretic mobility. We suggest that the prominent white pigment is precipitated uric acid contained within specialized fat-body cells similar to urocytes. We discuss the genetic basis of mutants affecting uric acid deposition, and the pleiotropic effects of the eye-color mutations such as white.

Efficient synthesis of mosquitocidal toxins in Asticcacaulis excentricus demonstrates potential of gram-negative bacteria in mosquito control.

The control of mosquitoes with chemical insecticides pollutes the environment and leads to resistance in mosquito populations. Bacterial control of mosquito larvae with Bacillus sphaericus and Bacillus thuringiensis subsp. israelensis, which produce protein toxins, has proved useful, safe, and nonpolluting. These bacteria do, however, suffer from disadvantages, including rapid setting, UV sensitivity, and lack of persistance of spores, proteolysis of toxins, narrow host range, and high production costs. Here we show that the Gram-negative bacterium Asticcacaulis excentricus is a promising host for delivering toxins to mosquito larvae. Plasmid-transformed A. excentricus cells expressing the binary toxin of B. sphaericus exhibited toxicity to Culex and Anopheles mosquito larvae similar to that of the high-toxicity strains of B. sphaericus which produce several toxins. A. excentricus has potential advantages as a larvicide compared with the bacilli, especially persistance in the larval feeding zone, resistance to UV light, lack of toxin-degrading proteases, and low production costs.

Molecular cloning of the 130-kilodalton mosquitocidal delta-endotoxin gene of Bacillus thuringiensis subsp. israelensis in Bacillus sphaericus

A 3.7-kilobase (kb) XbaI fragment harboring the cryIVB gene (L. Thorne, F. Garduno, T. Thompson, D. Decker, M. A. Zounes, M. Wild, A. M. Walfield, and T. J. Pollock, J. Bacteriol. 166:801-811, 1986) which encoded a 130-kilodalton (kDa) mosquitocidal toxin from a 110-kb plasmid of Bacillus thuringiensis subsp. israelensis 4Q2-72 was cloned into pUC12 and transformed into Escherichia coli. The clone with a recombinant plasmid (designated pBT8) was toxic to Aedes aegypti larvae. The fragment (3.7 kb) was ligated into pBC16 (tetracycline resistant [Tcr]) and transformed by the method of protoplast transformation into Bacillus sphaericus 1593 and 2362, which were highly toxic to Anopheles and Culex mosquito larvae but less toxic to Aedes larvae. After cell regeneration on regeneration medium, the Tcr plasmids from transformants (pBTC1) of both strains of B. sphaericus were prepared and analyzed. The 3.7-kb XbaI fragment from the B. thuringiensis subsp. israelensis plasmid was shown to be present by agarose gel electrophoresis and Southern blot hybridization. In addition, B. sphaericus transformants produced a 130-kDa mosquitocidal toxin which was detected by Western (immuno-) blot analysis with antibody prepared against B. thuringiensis subsp. israelensis 130-kDa mosquitocidal toxin. The 50% lethal concentrations of the transformants of strains 1593 and 2362 against A. aegypti larvae were 2.7 X 10(2) and 5.7 X 10(2) cells per ml, respectively. This level of toxicity was comparable to the 50% lethal concentration of B. thuringiensis subsp. israelensis but much higher than that of B. sphaericus 1593 and 2362 (4.7 X 10(4) cells per ml) against A. aegypti larvae.(ABSTRACT TRUNCATED AT 250 WORDS)

Data and Observations on the Natural Reduction of Anopheles Mosquito Larvae in Certain Environments

Data and Observations on the Natural Reduction of Anopheles Mosquito Larvae in Certain Environments

THE EFFECT OF OIL UPON ANOPHELES MOSQUITO LARVAE

Journal Article THE EFFECT OF OIL UPON ANOPHELES MOSQUITO LARVAE Get access HOWARD WHIPPLE GREEN, A.B., S.B. HOWARD WHIPPLE GREEN, A.B., S.B. Sanitary Engineer Bureau of Statistics and Research, Cleveland Health CouncilCleveland O. Search for other works by this author on: Oxford Academic PubMed Google Scholar American Journal of Epidemiology, Volume 4, Issue 1, 1 January 1924, Pages 12–22, https://doi.org/10.1093/oxfordjournals.aje.a119290 Published: 01 January 1924 Article history Received: 01 September 1923 Published: 01 January 1924