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At least 505 records · Page 28Linked to original sources
PubMed1986

Dispersal of the parasitic ciliate Lambornella clarki: implications for ciliates in the biological control of mosquitoes.

Lambornella clarki (Ciliophora: Tetrahymenidae), an endoparasite of Aedes sierrensis (Diptera: Culicidae), is dispersed by infected adult mosquitoes. Invasion of the ovaries induces parasitically castrated females to exhibit oviposition behavior and thereby actively disperse ciliates through deposition into water. Oviposition behavior of infected females is prolonged and mimics that of normal gravid females in their first gonotropic cycle. Adults of both sexes also passively disperse ciliates by dying on water surfaces, and infected adults are more likely to die on water than uninfected adults. Ciliates dispersed by infected adults can infect larvae and form desiccation-resistant cysts. Parasite-induced dispersal by hosts, desiccation-resistant cysts, an active host-seeking infective stage, and high infection and mortality rates all indicate significant biological control potential for these and related ciliates against container-breeding mosquitoes.

Aedes↗
PubMed2004

Breast cancer risk and historical exposure to pesticides from wide-area applications assessed with GIS.

Pesticides are of interest in etiologic studies of breast cancer because many mimic estrogen, a known breast cancer risk factor, or cause mammary tumors in animals, but most previous studies have been limited by using one-time tissue measurements of residues of only a few pesticides long banned in the United States. As an alternative method to assess historical exposures to banned and current-use pesticides, we used geographic information system (GIS) technology in a population-based case-control study of 1,165 women residing in Cape Cod, Massachusetts, who were diagnosed with breast cancer in 1988-1995 and 1,006 controls. We assessed exposures dating back to 1948 (when DDT was first used there) from pesticides applied for tree pests (e.g., gypsy moths), cranberry bogs, other agriculture, and mosquito control on wetlands. We found no overall pattern of association between pesticide use and breast cancer. We found modest increases in risk associated with aerial application of persistent pesticides on cranberry bogs and less persistent pesticides applied for tree pests or agriculture. Adjusted odds ratios for these exposures were 1.8 or lower, and, with a few exceptions, confidence intervals did not exclude the null. The study is limited by uncertainty about locations of home addresses (particularly before 1980) and unrecorded tree pest and mosquito control events as well as lack of information about exposures during years when women in the study lived off Cape Cod and about women with potentially important early life exposures on Cape Cod who were not included because they moved away.

Aged↗
PubMed1979

Experimental hybridization of Coelomomyces dodgei and Coelomomyces punctatus.

Two closely related fungi, Coelomomyces dodgei and C. punctatus (Chytridiomycetes; Blastocladiales), showing considerable potential for mosquito control, have been hybridized. Both species have life cycles involving an obligate alteration of sexual and asexual generations between an intermediate copepod host and a definitive mosquito host, respectively. Hybridization was accomplished by making reciprocal crosses of gametes derived from infected copepods. In both cases, C. dodgei [unk] x C. punctatus [unk] and C. punctatus [unk] x C. dodgei [unk], zygotes infective for mosquito larvae were formed. Most sporangia produced by the hybrids in infected larvae were not typical of either parental species but resembled C. dodgei more than C. punctatus. Additionally, the majority of the sporangia formed in several larvae exhibited surface structures similar to C. lativittatus, indicating this species may be a naturally occurring hybrid of C. dodgei and C. punctatus. The experimental methods described provide a system to aid in the study of taxonomic relationships among closely related species of Coelomomyces, and furthermore they may contribute to the development of strains efficacious for mosquito control.

Journal Article↗
PubMed1991

Malathion and pyrethroid resistance in Culex quinquefasciatus from Cuba: efficacy of pirimiphos-methyl in the presence of at least three resistance mechanisms.

Use of malathion for mosquito control in Cuba for 7 years up to 1986 has selected for elevated non-specific esterase and altered acetylcholinesterase (AChE) resistance mechanisms in populations of the pest mosquito Culex quinquefasciatus Say. These mechanisms are still present in relatively high frequencies in the Havana area, despite the replacement of malathion by pyrethroid insecticides for the last 3 years in the mosquito control programme. Samples of Culex quinquefasciatus populations from within a 100 km radius of Havana had high levels of resistance to malathion and lower levels of resistance to propoxur, but there was little or no cross-resistance to the organophosphorus insecticide pirimiphos-methyl. Selection with malathion for twenty-two consecutive generations in the laboratory increased the level of malathion resistance to 1208-fold and propoxur level to 1002-fold, but the maximum level of pirimiphos-methyl resistance was only 11-fold. Pirimiphos-methyl is still operationally effective, despite the resistance mechanisms segregating, so this insecticide if used for control is unlikely to select either of the known resistance factors directly in the field population. Since 1986, pyrethroids have been used extensively, and low levels of pyrethroid resistance were detected in two of five field population samples tested. Malathion selection did not increase the level of pyrethroid resistance, which indicates that one or more distinct pyrethroid resistance factors are now being selected in the field populations of Culex quinquefasciatus.

Aerosols↗
PubMed1993

Mosquitocidal toxins of bacilli and their genetic manipulation for effective biological control of mosquitoes.

The identification, cloning, and characterization of protein toxins from various species of bacilli have demonstrated the existence of mosquitocidal toxins with different structures, mechanisms of action, and host ranges. A start has been made in understanding the polypeptide determinants of toxicity and insecticidal activity, and the purification of toxins from recombinant organisms may lead to the elucidation of their X-ray crystal structures and the cloning of brush border membrane receptors. The results of cloning mosquitocidal toxins in heterologous microorganisms show the potential of expanding the range of susceptible mosquito species by combining several toxins of different host specificity in one cell. Toxins have been expressed in new microorganisms with the potential for increasing potency by persisting at the larval feeding zone. The powerful tools of bacterial genetics are being applied to engineer genetically stable, persistent toxin expression and expand the insecticidal host ranges of Bacillus sphaericus and Bacillus thuringiensis strains. These techniques, together with modern formulation technology, should eventually lead to the construction of mosquitocidal microorganisms which are effective enough to have a real impact on mosquito-borne diseases.

Animals↗
PubMed2026

Genomic profiling of digestion related enzymes in Anopheles aquasalis a major coastal neotropical malaria vector.

Digestive genes are fundamental for the development and survival of mosquitoes and can serve as a target for the development of strategies for mosquito control or vector-borne disease prevention. Genes related to digestion were identified in the genome of the neotropical malaria vector Anopheles aquasalis by similarity. We used reciprocal BLAST with annotated digestion proteins for Anopheles gambiae. Orthology and evolutionary analyses were performed using MEGA with a bootstrapped phylogenetic tree constructed by the neighbor-joining method, and copy number variation was measured by the standard deviation of the average copy number in each gene family. We identified 241 genes related to digestion in An. aquasalis: 56 genes related to carbohydrate digestion, 51 genes for lipid digestion, and 134 genes for protein digestion. Phylogenetic relationships with other anophelines show that An. aquasalis genes are closely related to those of neotropical mosquitoes Anopheles darlingi and Anopheles albimanus. Orthologous gene clusters are conserved in important families of all four species. Some of these conserved genes are of interest for studies on controlling mosquito vectors, such as larvicidal toxin receptor genes, alpha-amylase, alpha-glucosidase, and maltase; important target genes for transmission-blocking vaccines, such as aminopeptidase N1 and carboxypeptidase B; and the major intestinal serine proteases, such as trypsins and chymotrypsins, which can positively or negatively affect Plasmodium development in the midgut. These data provide a better understanding of digestion-related genes in American anopheline mosquitoes and may support further fundamental and applied studies aimed at malaria control.

Animals↗
PubMed1987

Ground and aerial application of the asexual stage of Lagenidium giganteum for control of mosquitoes associated with rice culture in the Central Valley of California.

A series of ground and aerial applications of Lagenidium giganteum, a facultative fungal parasite of mosquito larvae, was made in rice fields and associated habitats in the Sacramento Valley, CA. Initial trials using ground applications of the fungus in 400 m2 plots indicated that asexually competent mycelium from 30 liters of fermentation beer per hectare was sufficient to control Culex tarsalis in rice field habitats. Two multi-hectare applications using a Micronair Atomizer were made at rates of mycelium from either 20 or 30 liters of fermentation beer per hectare. The lower application rate resulted in 40% confirmed infection of Cx. tarsalis and Anopheles freeborni sentinel larvae, while the higher application rate resulted in greater than 90% initial mortality of sentinel Cx. tarsalis and An. freeborni and 65% Aedes melanimon sentinel mortality. This was accompanied by a 10-fold decrease in indigenous populations of the 2 former species.

Agriculture↗
PubMed2003

Mosquito coil emissions and health implications.

Burning mosquito coils indoors generates smoke that can control mosquitoes effectively. This practice is currently used in numerous households in Asia, Africa, and South America. However, the smoke may contain pollutants of health concern. We conducted the present study to characterize the emissions from four common brands of mosquito coils from China and two common brands from Malaysia. We used mass balance equations to determine emission rates of fine particles (particulate matter < 2.5 microm in diameter; PM(2.5)), polycyclic aromatic hydrocarbons (PAHs), aldehydes, and ketones. Having applied these measured emission rates to predict indoor concentrations under realistic room conditions, we found that pollutant concentrations resulting from burning mosquito coils could substantially exceed health-based air quality standards or guidelines. Under the same combustion conditions, the tested Malaysian mosquito coils generated more measured pollutants than did the tested Chinese mosquito coils. We also identified a large suite of volatile organic compounds, including carcinogens and suspected carcinogens, in the coil smoke. In a set of experiments conducted in a room, we examined the size distribution of particulate matter contained in the coil smoke and found that the particles were ultrafine and fine. The findings from the present study suggest that exposure to the smoke of mosquito coils similar to the tested ones can pose significant acute and chronic health risks. For example, burning one mosquito coil would release the same amount of PM(2.5) mass as burning 75-137 cigarettes. The emission of formaldehyde from burning one coil can be as high as that released from burning 51 cigarettes.

Air Pollution, Indoor↗
PubMed1994

A device for monitoring and control of mosquitoes by behaviour manipulation.

A trap was designed and fabricated for capturing mosquito larvae based on their behavioural responses to food and light. The larvae upon entering the trap died ultimately due to asphyxiation. Maximum success was achieved with Aedes aegypti larvae in lesser water volumes. The usefulness of the device for studying the response of mosquito larvae and aquatic organisms to chemicals, baits, light, various stimuli and possible pest/vector monitoring and management in aquatic eco-system is discussed.

Aedes↗
PubMed1953

The 1952 outbreak of encephalitis in California; vector control aspects.

The emergency vector control measures used during the summer of 1952 were designed to supplement the normal mosquito control programs of mosquito abatement districts. The emergency measures were aimed at destruction of adult vector mosquitoes in populated areas as contrasted to normal programs which consist of elimination of breeding places or destruction of the aquatic stages of mosquitoes. Experience during 1952 clearly demonstrated the limitations of present techniques for coping with adult mosquitoes and pointed up the need for better understanding of the factors controlling survival of Culex tarsalis over the winter months, as well as the need for better methods of measuring the prospect of a large number of infected vector mosquitoes early enough in the year to permit the establishment of preventive rather than palliative measures.

Animals↗
PubMed2001

[Disease vector control strategy in the French army].

Disease vector control is a major priority for the Medical Health Corps of the French Armed Forces which maintains around 23,000 troops in tropical areas and is involved in numerous military and humanitarian missions throughout the world. Control strategy includes both general and personal control measures. Personal control measures include wearing permetherin-impregnated combat uniforms, application of repellents to the skin, and use of deltamethrin-impregnated bednets. General measures are implemented in facilities and in the environment. Measures in facilities include not only physical deterrents such as screens on openings and air-conditioning but also application of chemical insecticides to walls, curtains, and screening. Environmental measures include control of larval deposits and elimination of potential breeding areas. Low-volume wide-area spraying of imagocides is a supplemental option used in case of disease outbreak. For units stationed in tropical areas, command and surveillance of vector control operations is under the responsibility of the mosquito control committee which includes personnel from the affected field unit. Strategies are chosen in function of local climate and operational conditions. The efficacy of vector control programs is assessed annually by reviewing the incidence in armed forces personnel of the main vector-transmitted diseases: malaria, dengue fever, and leishmaniasis. Documentation and training are dispensed to all units stationed in tropical areas. To ensure that knowledge of military physicians remains current, three courses on malaria control are offered each year at the Tropical Medicine Institute of the Armed Forces Health Corps (Le Pharo) in Marseille. Field research conducted in collaboration with military or civilian organizations independent of the Armed Services Health Corps makes it possible to keep chiefs of staff informed of state-of-the art vector control measures adapted to use by personnel on assignment or mission in tropical areas.

Animals↗
PubMedDate not supplied

[Experience in the control of the mosquito Culex pipiens molestus Forsk. In Leningrad].

Systematic control of mosquitoes (C. p. molestus) has begun in Leningrad since 1968 when undertaken inspections revealed mosquitoes and their aquatic stages in 21.8% of basements. All hatching sites of mosquitoes were registered and sanitary, hydrotechnical and destroying measures were carried out there. During the period of 1968 to 1973 the basements were cleaned, in 509 of them hydroisolation was made and many were dried. Anually chemical treatment of basements was undertaken and for 6 years the treated area amounted to 6.00000 m2. As a result, the percentage of flooded basements decreased from 25.8 to 7.1% and the hatching sites of mosquitoes--from 21.8% to 9.1%. The total population of mosquitoes decreased 43 fold.

Animals↗
PubMedDate not supplied

[Evaluation of isolates and a new granular formulation of Bacillus sphaericus Neide for control of mosquitoes].

Nineteen Bacillus sphaericus Neide strains obtained in Brazil were evaluated in addition to a standard strain (2362) supplied by Pasteur Institute. Most strains were more efficient than the standard, and seven of them caused mortality equal to or higher than 80%, at a low concentration (7 x 10(2) spores/ml). Strain ESALQ MS6 was selected for formulation, since it showed better yield in liquid culture medium (3 x 10(9) CFU/ml). The G4 granular formulation was tested in artificial rearing sites, consisting ofplastic buckets containing 10 L water and twenty 3rd-instar larvae of Culex quinquefasciatus Say (Diptera: Culicidae). The efficiency of formulation was compared against a commercial product, at three different concentrations. Evaluations were taken every 24h, at seven and 18 days after inoculation, with subsequent replacement of larvae in the bucket. The G4 formulation was similar to the commercial product, and controlled 100% of the larvae at the concentrations tested; however, the granules remained at the surface for a longer period. In tannery effluent treatment ponds, the G4 formulation at a concentration of 2 kg/ha reduced the number of larvae by 21%, 47%, 85%, and 94%, after 1, 3, 7, and 15 days, respectively.

Animals↗
PubMed1985

Micro-lipid-droplet encapsulation of Bacillus thuringiensis subsp. israelensis delta-endotoxin for control of mosquito larvae.

The crystal delta-endotoxin of Bacillus thuringiensis subsp. israelensis is less toxic to larvae of Anopheles freeborni than to larvae of Aedes aegypti. However, when solubilized crystal was used, larvae from both species showed similar sensitivities. This effect presumably was due to the differences in feeding behavior between the two mosquito larvae when crystal preparations are used. A procedure is described whereby both crystal and solubilized B. thuringiensis subsp. israelensis toxin were emulsified with Freund incomplete adjuvant, with retention of toxicity. The use of Freund incomplete adjuvant also allowed one to assay the solubilized toxin at a low nanogram level. Furthermore, coating the toxin with lipophilic material altered the buoyancy of the toxin and reversed the sensitivities of the two mosquito larvae toward the B. thuringiensis subsp. israelensis toxin. This difference in buoyancy was determined by using an enzyme-linked immunosorbent assay that was specific for the toxic peptides. These data indicate that economically feasible buoyant formulations for the B. thuringiensis subsp. israelensis crystal can be developed.

Aedes↗
PubMed1991

Vector population responses to control interventions.

In 1981, Kenyan authorities attempted eradication of tsetse (Glossina pallidipes) from the Lambwe valley, by sequential aerial spraying of endosulfan. Fly populations were reduced by over 99.9% in the main habitats, but recovered to their original levels within one year. In 1986, an Argentine research team attempted local elimination of domestic Triatominae (Triatoma infestans) in an area of Santiago del Estero. House infestation rates were reduced to an apparent zero, but recovered to pre-control levels in two years. In Sri Lanka, a combination of mosquito control with active case detection and treatment reduced malaria incidence to just 17 cases in 1964. Interruption of the programme then saw case incidence return to over 500,000 by 1969. These three examples-from African trypanosomiasis, South American Chagas disease and malaria-all illustrate the same process. Vector populations, infestation rates, and rates of disease transmission, can be reduced. The real problem is not in achieving the initial reduction, but in subsequently either driving the disease to extinction or maintaining it below acceptable levels. And this problem takes us beyond the simple analysis of interventions, into the complex realms of population behaviour set in its political, social and economic context. It seems that we have been too rarely concerned to plan and implement the long term surveillance and selective interventions that are required to translate initial gains into real success. In biological terms, we tend to ignore the complexity and robustness of vector populations and disease transmission cycles, especially their varied capacity to recover from interference. Moreover, in socio-political terms, a reduced problem-even one representing potential for future catastrophe-tends to claim less priority than present problems, even though premature redeployment of resources may abnegate gains already achieved. The problem is strongly compounded by methods of economic analysis where the benefits of avoiding future problems are strongly discounted in favour of short-term temporary gains. This paper seeks to open discussion on these long-term planning issues.

Animals↗