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Feasibility of wing beat sound trap for the control of mosquito vectors.

Early observations suggested that the female sound was a possible cause of mating. Attempts had been made for introduction of female wing beat sound for removal male mosquitoes from the population for the control purpose. The traps emitted female wing beat sound, were set on black clothes as a swarm marker, could collect a large number of male Cx. tritaeniorhynchus in Japan. Those traps were later improved with introduction of two attractants, hamster and dry ice. Consequently, two systems were adopted for efficiency trapping of males and females. A cylinder trap with 350 Hz of wing beat frequency was introduced for male Cx. tritaeniorhynchus collection, while the cage trap with 530 Hz was for female collection. The traps were set every other days after sun set for three weeks in a paddy field. Although there was no decrease of population density, the reduction of parous rate was evident. For future effective control, it may suggest the need to distribute more wing beat sound traps to cover all larva breeding paddy field and near by blood sources. On the other hand, other control methods should be integrated.

Animals↗

Small scale field trial with polystyrene beads for the control of mosquito breeding.

Mosquito breeding sites confined within four walls as cesspits were selected to carry out the trial with expanded polystyrene beads for the control of mosquito breeding. A comparative study between the use of the beads and oil has also been carried out. Results revealed the superiority in effectiveness of beads over oil for the control of mosquito breeding. Mosquito catches from cesspits treated with polystyrene beads dropped to zero soon after application of the beads and remained so throughout five months observation period.

Animals↗

Flatworm control of mosquito larvae in rice fields.

We describe some flatworms (some in the genus Mesostoma) that kill mosquito larvae and may account for the variability in the population densities of Culex tarsalis and Anopheles freeborni in rice fields. When mosquito larvae brush against these worms, the larvae immediately become paralyzed and die. When C. tarsalis larvae are placed inside floating cages that exclude flatworms (50-micromter mesh), there is a fourfold increase in the their survival. Rice fields that have abundant mosquito populations lack flatworms. Most such fields have only recently been turned over to rice production, suggesting that the flatworms have difficulty dispersing to new fields but, once established, are able to overwinter and control mosquitoes for the subsequent years of rice production.

Agriculture↗

Source reduction in Florida's salt marshes: management to reduce pesticide use and enhance the resource.

Source reduction as part of an integrated pest management program is a cornerstone of the American Mosquito Control Association's Pesticide Environmental Stewardship Program Strategy Document to reduce pesticide risk. Since the early 1980s, Florida has made important strides in implementing environmentally sound source reduction strategies in salt marshes while managing them for both mosquito control and natural resource enhancement. The political mechanism for this progress has been interagency cooperation through the Florida Coordinating Council on Mosquito Control and its Subcommittee on Managed Marshes. Challenges in accomplishing source reduction continue because both public and private lands are involved. Public lands include those owned by federal (e.g., U.S. Fish and Wildlife Service, National Park Service), state (Florida Department of Environmental Protection), and local governments, and they have a diversity of management objectives. This diversity adds to the challenge facing mosquito control agencies in providing mosquito control services while protecting and enhancing the environment.

Conservation of Natural Resources↗

Laboratory evaluation of a Helicosporidium sp. (Protozoa: Helicosporida) as an agent for the microbial control of mosquitoes.

A Helicosporidium sp. isolated from diseased larvae of Culex pipiens L. in Egypt was assessed for its microbial control potential against mosquito larvae. Dose infectivity and dose mortality of the pathogen was determined for each larval instar of Cx. pipiens. Helicosporidium sp was infectious to Aedes caspius (Pallas), C. antennatus (Becker), C. perexiguus Theobald, and Culiseta longiareolata (Macquart). Using 24-hr exposures of first instar larvae to a range of concentrations between 50 and 5 x 10(3) spores/ml, Cx. antennatus and Cx. perexiguus were more susceptible than Cx. pipiens, Ae. caspius and Cs. longiareolata with LC50's of 5 x 10(2), 5 x 10(2), 1.6 x 10(3), 1.4 x 10(3), and 1.7 x 10(3), respectively. Current experiments shown that Helicosporidium spores were tolerant of freezing and storage at 5 degrees C, but not to desiccation. Production trails indicated that up to 6.2 x 10(8) spores could be routinely produced in individual cotton leaf worms, Spodoptera littolaris (Boisd) (Lepidoptera: Noctuidae).

Animals↗

[Application of a mermithid nematode for the control of mosquito larvae in natural conditions].

Field tests were carried out with the Romanomermis culicivorax nematode (Ross and Smith, 1976) for the control of 3 mosquito species--Anopheles albimanus (Wiedeman, 1821): Culex nigripalpus (Theobald, 1901); and Uranotaenia saphirina (Oster-Sacken, 1868)--in 10 natural reservoirs. The infective nematodes were disseminated in doses of 1 x 10(3) preparasites/m2 of surface area. Increased infestation indices were observed with values ranging from 1.2 to 3.4; mortality percentages fluctuated between 70 and 97% depending on the mosquito species found in the reservoirs. In those reservoirs containing specimens of the 3 species, anophelines showed more susceptibility to parasite infection; culicines showed a lower susceptibility in general. Mosquito larva populations were significantly reduced in the treated reservoirs.

Animals↗

A review of current salt marsh management issues in Florida.

For the past decade, salt marsh management in Florida has been a central issue in attempts to reconcile mosquito control and natural resource interests. Progress has been made in trying to maintain effective mosquito control while protecting and enhancing salt marsh resources primarily due to: 1) efforts by the Florida Coordinating Council on Mosquito Control and its Subcommittee on Managed Marshes, which are committees comprised of agencies responsible for wetlands resources, those mandated to provide mosquito control, and research institutions; and 2) funding of research to investigate ecosystem effects of marsh management techniques. Research and management experience have demonstrated that Rotational Impoundment Management (RIM) and rotary ditching can provide ecologically sound source reduction benefits. Salt marsh ownership, management of state lands and mariculture remain controversial salt marsh management issues.

Animals↗

Prevention of mosquito nuisance among urban populations in Burkina Faso.

This paper addresses the problems of mosquito control in urban areas of Burkina Faso. The main objectives are to examine relevant socio-cultural aspects in relation to a mosquito control intervention using a biolarvicide with main emphasis on local perceptions of mosquito nuisance and existing practices of mosquito control, including the cost of protective measures at household level. This is the report of an inter-disciplinary research project carried out in the two major towns of Burkina Faso, Bobo-Dioulasso and Ouagadougou, in 1999 and 2000, respectively. Both quantitative and qualitative methods were used in the ethnographic part of the study. Two questionnaire surveys were conducted in both study areas: one prior to the intervention (n=1083) and the other after the intervention of the treatments with bio-larvicide (n=956). In addition, 70 in-depth interviews and 17 focus group discussions (FGDs) were conducted. The findings show that mosquitoes are considered an important problem in the urban areas, both as a nuisance and a health risk and that the local population is very active in applying mosquito control measures at the household level. The intervention project was received positively by the local population with a decline in the perceived level of annoyance. The causal relationship between mosquitoes and malaria is clear, but the explanatory framework of the relationship between mosquitoes and other diseases is still under debate. The most common prevention methods are mosquito coils and aerosol spray, even though bed nets are perceived to be the most efficient and effective method. The investments in coils and aerosol sprays alone would mean an increase of 40% in the national figures for health expenditure at household level.

Adolescent↗

[Reevaluation of the biological control of vector mosquitoes using predatory larvae of Toxorhynchites mosquitoes].

Attempts to control mosquito-borne disease using predatory mosquitoes such as Toxorhynchites larvae have led to indefinite results for many years, mainly because of the lack of adequate species or strains of Toxorhynchites. Recent improvements of natural and artificial matings of adults in the laboratory and of mass breeding of larvae, however, have made it possible to establish laboratory colonies of most Toxorhynchites species whenever and wherever necessary. Effects of biological control by releasing large numbers of Toxorhynchites mosquitoes should be reevaluated from a new concept of comparing the usual chemical insecticides with the living and flying "insecticides" which cause no environmental pollution.

Animals↗

Development of a method for heterologous gene expression in Enterobacter amnigenus, a potential host for the biological control of mosquito larvi.

An integrative plasmid containing a 1.3 kb fragment of chromosomal DNA from Enterobacter amnigenus was constructed. The Omega fragment encoding spectinomycin/streptomycin resistance was cloned into the unique BglII site of the resulting plasmid, and the interrupted fragment was transferred via plasmid pMAK705 by electroporation into E. amnigenus with a selection for spectinomycin resistance. Cointegrants were resolved to generate an E. amnigenus strain that expressed spectinomycin resistance, but grew as rapidly as the parental strain. The cloned fragment encodes a putative homologue of the proW gene of Escherichia coli that is not essential for E. amnigenus growth. The integrative plasmid is now available to introduce any heterologous DNA into the E. amnigenus chromosome, for the construction of promoter-probe vectors for the studies of gene regulation, or to construct plasmids suitable for the isolation of secretion signals. Immediate applications of this system will include the expression and secretion of crystal toxins from bacilli for the biological control of mosquito larvae infected with the bacterial host.

ATP-Binding Cassette Transporters↗

Evaluation of Methoprene (Altosid) and Diflubenzuron (Dimilin) for control of mosquito breeding in Tezpur (Assam).

Insect growth regulators (IGRs) namely, Isopropyl (E-E)-(RS)-11-methoxy-3,7,11-trimethyldodeca-2, 4-dinoate (Methoprene) and 1-(4-cyclophenyl)-3-(2,6-diflerobenzoyl) urea (Diflubenzuron) were evaluated against mosquito larvae in laboratory as well as in different breeding habitats in Tezpur, Assam. LC90 values of diflubenzuron against Culex quinquefasciatus and Aedes albopictus were 0.0022 and 0.0027 ppm respectively, while it was 0.0027 and 0.0022 ppm respectively in case of methoprene. However, LC50 values of both the IGRs were almost same in case of Ae. albopictus and Cx. quinquefasciatus (varies between 0.0009 and 0.0011 ppm). In case of methoprene, maximum mortality was observed in pupal stage though the exposure was given in all the cases to the III instar larvae. Field trials were conducted in cemented drains, small ponds and ditches. At 0.2 ppm (0.020 kg/ha) both diflubenzuron and methoprene were found to eliminate 92-96 per cent Culex and Anopheles larvae. Methoprene and diflubenzuron were found equally effective for control of mosquito breeding in different breeding habitats and provide better efficacy than conventional larvicides and biocides.

Aedes↗

Key premises, a guide to Aedes aegypti (Diptera: Culicidae) surveillance and control.

The population densities of Aedes aegypti Linneaus in four towns in Trinidad were studied using standard house-to-house inspections of all water-holding containers to determine whether persistently positive containers and premises existed over a three-month period in the wet season, from May to July 2002. From a total of 1503 houses inspected, 223 were positive with 41 persistently positive over the three month period and classified as 'key premises'. The definition of the term key premises is described and the rationale for its utilization discussed. A total of 24,439 containers was inspected from Santa Margarita (6407), Mt Lambert (5709), St Augustine (5384) and Curepe (6939) of which 1.3% or 334 containers were positive for A. aegypti larvae and pupae. A total of 16,507 immatures of A. aegypti were retrieved from these containers which comprised 17 container types but when these were ranked according to productivity levels, only water drums (average 53.5%), buckets (22.2%), tubs and basins (8.0%), water tanks (5.4%), brick holes (4.2%) and tyres (2.0%) were significant (P < 0.001) producers. The role that key premises play in the introduction and re-infestation of A. aegypti-free communities is described and illustrated. These results suggest that A. aegypti control programmes could be more cost effective and sustainable by concentrating efforts on key premises and key containers to control mosquito densities and Dengue transmission while reducing manpower needs and insecticide use.

Aedes↗

Comparative use of bendiocarb and DDT to control Anopheles pseudopunctipennis in a malarious area of Mexico.

The state of Sinaloa has one of the highest and most persistent malaria transmission levels in Mexico. Due to this situation, with resistance of the vector Anopheles pseudopunctipennis Theobald to DDT, the carbamate insecticide bendiocarb was evaluated as an alternative to DDT for residual house-spraying in village-scale trials during 1985-87. Application rates of the active ingredient per square metre of sprayable surface (ai/m2) were 0.4 g bendiocarb 80% wettable powder (80WP) and 2 g DDT 75% WP. Both insecticides failed to control mosquito populations. Human-bait mosquito densities were not altered as a result of insecticide spraying and human-bait collected mosquito mortality rates were low, suggesting little pre-biting insecticide contact due to avoidance or insufficient resting time indoors. Lower densities of indoor-resting mosquitoes were observed with DDT as opposed to bendiocarb treated houses. Anopheline mortality was higher (98-100%) when exposed for 1 h to 1% bendiocarb in standard WHO susceptibility tests and wall bioassays. Mortality-rates of 15-48% due to 1 h exposure to 4% DDT indicated that this insecticide may continue to be partially effective. House curtain and mark-recapture mosquito studies indicated that DDT produced higher excito-repellency than bendiocarb, as reflected by more mosquito landings but lower feeding rates, shorter resting period and earlier exit time from DDT sprayed houses. In the absence of insecticide, more than 50% of blood-fed An.pseudopunctipennis females exited from houses within 2-4 h of release, showing exophilic behaviour. The outdoor/indoor density ratio indicated that the majority were exophagic. These behavioural characteristics limit the usefulness of any residual insecticide against An.pseudopunctipennis.

Aerosols↗

Oviposition attractancy of bacterial culture filtrates: response of Culex quinquefasciatus.

Oviposition attractants could be used for monitoring as well as controlling mosquitoes by attracting them to lay eggs at chosen sites. In the present study, culture filtrates of seven bacterial species were tested for their attractancy against gravid females of Culex quinquefasciatus. When their oviposition active indices (OAI) were studied, the culture filtrates of Bacillus cereus and Pseudomonas fluorescens exhibited oviposition attractancy (OAI = > 0.3) at 100 ppm and the OAI were respectively 0.70 and 0.47. Culture filtrates of B. thuringiensis var. israelensis (wild type), B. t. var. israelensis (mutant) and B. sphaericus showed attractancy at 2000 ppm with OAI of respectively 0.71, 0.59 and 0.68. However, the OAI of B. megaterium as well as Azospirillum brasilense was 0.13 (at 2000 ppm), which was less than 0.3 required to be considered them as attractants. When the oviposition attractancy of the bacterial culture filtrates were compared with that of a known oviposition attractant, p-cresol (at 10 ppm), the culture filtrates of B. t. var. israelensis (wild type) and B. cereus were found to be more active than p-cresol, respectively with 64.2 and 54.3% oviposition.

Animals↗

[Experimental study of larval efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (fish-Poecilidae)].

Experimental study of efficiency of Gambusia affinis holbrooki (GIRARD, 1859) (Fish-Poecilidae). Gambusia affinis is a culiciphage fish which was introduced in Tunisia in 1929 to control mosquito larvae. In the present study, we confirm, under laboratory conditions, the good efficacy of Gambusia affinis against mosquito larvae. The consumption of larvae decreases with the evolution of larvae instars and increases, for the same instar, in relation with the fish size. In fact, the size of the prey is related to the predator's size: fish belonging to the length class [20-24 mm] prefer IIIrd instar, fish from class length [25-29 mm] prefer pupae and IVth instar. The trophic test shows that G. affinis has a clear preference for Culicidae larvae, except fish belonging to the 2 length classes [35-39 mm] and [40-44 mm] for which Culicidae and Ephemeroptera have similar preference. In addition, at high temperature (30 degrees C), Gambusia affinis has a higher efficiency.

Animals↗

Organochlorine pesticide and polychlorinated biphenyl residues in selected fauna from a New Jersey salt marsh--1967 vs. 1973.

More than a half million pounds of DDT were applied to control mosquitoes in salt marsh estuaries of Cape May County, New Jersey, from 1946 to 1966. The use of DDT was discontinued in the County after 1966. In 1967, mean concentrations of DDT and metabolites ranged from 0.63 to 9.05 ppm in aquatic fauna, but by 1973 mean residue levels had decreased 84 to 99 percent among nine species. DDE was still present at reduced levels in nearly all samples in 1973, but other DDT isomers had mostly disappeared. Dieldrin was detected only in clapper rails, and residue levels decreased during the period. Mean concentrations of PCB's increased in the clapper rail, remained the same in the fiddler crab and mud snail, and decreased in the sheepshead minnow, mummichog, striped killifish, and salt marsh snail. Small amounts of mirex, toxaphene, cis-chlordane (and/or trans-nonachlor), oxychlordane, and HCB were detected in a few specimens.

Animal Population Groups↗