Pest Mosquitoes Research Articles

Ecology of Insect Communities in Nontidal Wetlands

Published research about wetland insects has proliferated, and a conceptual foundation about how wetland insect populations and communities are regulated is being built. Here we review and synthesize this new body of work. Our review begins with a summary of insect communities found in diverse wetland types, including temporary pools, seasonally flooded marshes, perennially flooded marshes, forested floodplains, and peatlands. Next, we critically discuss research on the population and community ecology of wetland insects, including the importance of colonization strategies and insect interactions with the physical environment, plants, predators, and competitors. Results from many of the experimental studies that we review indicate that some commonly held beliefs about wetland insect ecology require significant reevaluation. We then discuss the importance of wetland insect ecology for some applied concerns such as efforts to manage wetland insect resources as waterfowl food and development of ecologically sound strategies to control pest mosquitoes. We conclude with a discussion of wetland conservation, emphasizing insect aspects.

Ecology of insect communities in nontidal wetlands.

Published research about wetland insects has proliferated, and a conceptual foundation about how wetland insect populations and communities are regulated is being built. Here we review and synthesize this new body of work. Our review begins with a summary of insect communities found in diverse wetland types, marshes, forested floodplains, and peatlands. Next, we critically discuss research on the population and community ecology of wetland insects, including the importance of colonization strategies and insect interactions with the physical environment, plants, predators, and competitors. Results from many of the experimental studies that we review indicate that some commonly held beliefs about wetland insect ecology require significant reevaluation. We then discuss the importance of wetland insect ecology for some applied concerns such as efforts to manage wetland insect resources as waterfowl food and development of ecologically sound strategies to control pest mosquitoes. We conclude with a discussion of wetland conservation, emphasizing insect aspects.

Evaluation of Inoculative Releases of Toxorhynchites splendens (Diptera: Culicidae) in Urban Environments in Florida

Inoculative releases of Toxorhynchites splendens (Wiedemann) were conducted of the cities of Sarasota, Tallahassee, Panama City, and Panama City Beach, FL, in 1989 and 1990. In 1989, painted 473-ml little black jars were used to monitor T. splendens oviposition. T. splendens larvae were found in 88–100% of the jars within 3 wk of release periods but were never recovered at longer intervals. Significantly fewer eggs of pest mosquitoes were recovered from a site receiving both ultralow volume (ULV) applications of malathion and T. splendens than the site receiving ULV alone. In 1990, although 45% of the artificially placed jars were colonized by T. splendens at both sites following releases, natural container colonizations were below 10%. Apparent predation of resident pest mosquitoes by T. splendens within the little black jars over the entire 1990 study was not statistically significant.

Color and Height Affects Oviposition Site Preferences of Toxorhynchites splendens and Toxorhynchites rutilus rutilus (Diptera: Culicidae) in the Laboratory

Oviposition site preferences of two predatory mosquitoes, Toxorhynchites splendens (Wiedemann) and Toxorhynchites rutilus rutilus (Coquillet), were compared in the laboratory using eight oviposition cup colors affixed 0 and 1 m from the cage floor. T. splendens females preferred to oviposit in black containers. Secondary preferences were for dark red and brown rather than green, blue, orange, yellow, or white containers. Substantial oviposition occurred in containers of all colors except white and yellow. Over 96% of all eggs were deposited at ground level. T. r. rutilus females had a stronger preference for ovipositing in black containers but did deposit eggs in red, blue, and brown containers at ground level. More than 25% of all eggs were deposited 1 m from the cage Roorduring choice tests. Oviposition by T. r. rutilus rarely took place in containers painted white, yellow, orange, and green. On the basis of these results, T. splendens appears to be the better candidate for mosquito control in heavily urbanized areas where discarded containers on the ground serve as developmental habitat for pest mosquitoes. T. r. rutilus appears to be the better candidate for treeholes. It is suggested that consistent means of comparing the characteristics of Toxorhynchites species for biological control programs be developed.

What Role for Insecticides in Vector Control Programs?

Vector-borne diseases including dengue, yellow fever, Japanese encephalitis, malaria, leishmaniasis, and filariasis remain severe public health problems in most of the countries in which they are endemic. In some cases, their incidence is increasing and they are spreading to new geographic areas. For a number of the infections, the most effective manner of controlling their transmission is through control of their vectors. However, in some instances, such as dengue and Chagas' disease, there is no alternative. Most countries that are endemic for vector-borne diseases maintain vector control services, and most large tropical and semitropical cities also have pest control programs, mainly against pest mosquitoes. Virtually all of the vector and pest control programs depend on the use of insecticides formulated as larvicides, adulticides, baits, or insecticide impregnated bed nets. For many years, the development of new insecticides for use in public health programs was encouraged and supported by multilateral and bilateral health agencies, including the implementation of field trials in endemic areas. Due to the development of insecticide resistance, toxicologic and environmental considerations, and the cost of development and of registration, the number of compounds available for use has declined while the number of new insecticides submitted for laboratory and field trials to the World Health Organization has dwindled even more. The recrudescence of vector-borne diseases, the rapid pace of urbanization, lagging development of environmental services in many tropical cities, and difficulties encountered in ensuring the community's cooperation in its own protection through environmental measures make imperative the continued availability of pesticides for public health use. Since only the pesticide manufacturing industry has the combination of technical and financial resources to promulgate the research and development of new pesticides and pesticide groups, it is suggested that governments, bilateral, and multilateral organizations explore the manner in which they can assist industry in the development of new compounds and guarantee the continued availability of effective and safe pesticides for vector-control programs.

The Role of Biological Control of Mosquitoes in Integrated Vector Control

An integrated approach for the control of mosquitoes and the diseases they transmit will better enable sustainable control while helping to circumvent some of the problems associated with the use of conventional insecticides. Environmental methods and biological control are alternatives to chemical control and are key components of the integrated strategy. The use of vertebrate and invertebrate predators and entomopathogens as biological control agents and their role in integrated control programs is reviewed with emphasis on fish, Toxorhynchites mosquitoes, Notonecta species, predatory copepods, entomopathogenic bacteria, and the fungus Lagenidium giganteum. The successful implementation of these organisms will depend on an in-depth understanding of the ecology of both the targeted species and the biological control agents to be used. Thorough geographic reconnaissance will also be essential for the successful abatement of pest and vector mosquitoes. The success and sustainability of future programs, especially in developing countries, will rely not only on the use of the most appropriate technologies but also on the direct participation of the affected communities. Possible undesirable effects of biological control are also reviewed.

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.

Resistance spectra and allelism of chlorpyrifos resistance factors in Culex quinquefasciatus populations from colombo and Dar-es-Salaam

The induction of resistance in the urban pest mosquito, Culex quinquefasciatus, to chlorpyrifos and chlorfenvinphos and the cross-resistance spectra of these selected lines to propoxur and a number of organophosphate insecticides was studied. Distinct genetic factors governing intermediate (R1 ) and high (R2) levels of larval resistance to organophosphates were found to be allelic according to the single locus, multiple allele hypothesis. Adults were less susceptible to malathion and fenitrothion after larval selection with chlorpyrifos, but the degree of resistance was found to be much less than that in the larvae. The implications of these results for the control of C. quinquefasciatus in Dar-es-Salaam, Tanzania, is discussed.

Mosquito and copepod host range tests with Coelomomyces psorophorae (Blastocladiales, Chytridiomycetes)

—An extensive survey for natural pathogens and parasites of mosquitoes as prospective biological control agents was carried out in Israel. Coelomomyces (Class, Chytridiomycetes; Order, Blastocladiales), a fungal genus of which all but a few members are specific to mosquitoes, was not known to be present in Israeli waters. Therefore, mosquito and copepod host-range tests were conducted with Coelomomyces psorophorae obtained from abroad, in order to test the desirability of introducing Coelomomyces as a contribution to mosquito control. Acanthocyclops viridis, a cosmopolitan copepod relatively common in Israel, was duly infected with Coelomomyces psorophorae. However, the infectivity of Israel’s most common pest mosquitoes (Culex pipiens complex) proved low.

水質汚濁が原因と思われるアカイエカの大発生例とその防除対策

1. In the late spring of 1968,nuisance and biting problems by an unusually great number of adult mosquitoes took place in a suburban area of Kagamigahara City, Gifu Prefecture, Central Japan. Through a request of the city authorities, a series of field investigations were made on the population dynamics of the pest mosquitoes. Chemical and environmental control measures were also planned. 2. A pool which was receiving most of the raw wastes of a starch and woolen factories was found to be the main breeding source of the bothering mosquitoes. This pool was located at the river beach neighboring the residential quarter and had an extent of approximately 80 ares and an average depth of 0.2 meters. Population density of mosquito larvae and pupae at the station P selected in the pool was estimated by the removal method, and age structure of these aquatic stages was also analyzed. Imaginal population size in the residential district about 200 meters apart from the breeding source was estimated with light trap collections. These investigations were continued on the weekly basis during the period from June to November, 1968. 3. As the results, it was known that the overall species composition of mosquitoes of this area was very unusual for such a typical suburban habitat surrounded by many paddy fields; more than 90 percent of the collected adults and larvae were the house mosquitoes, Culex pipiens pallens Coquillett. This uncommonness was further ascertained by the comparison with the results of our mosquito surveys simultaneously performed in other two areas with similar topographical features. For the correct identification of the species, examinations were made of ommatidial number in females as well as DV/D value in males randomly sampled from the above "C. pipiens pallens" population. The results revealed that the autogenous house mosquito, C. pipiens molestus, was not intermixed. 4. Population dynamics of the C. pipiens pallens was studied by analyzing the seasonal change of larval population size and age structure. It was presumed that the adults had four definite peaks of emergence in late June, mid and late July, and early August on the bases of precursory ageing in the larval population. The actual number of adults collected by light traps and the above presumption were proven to be in good agreement. 5. Details of the control measures taken to cope with the outbreak were described, and several problems in the planning of insecticide application along with the merit and demerit of the environmental control of the pest mosquitoes, particularly of the construction of drainages, were discussed in relation to the pollution of inland water.

A survey of the mosquitoes of Guam in two periods in 1948 and 1949 and its epidemiological implications.

Summary and ConclusionsTwo surveys of the mosquitoes of Guam in the post-World War II period have provided new data of value to persons concerned with mosquito control and epidemiological investigations on diseases of man.In these studies two species of mosquitoes are recorded from Guam for the first time: Aedes albopictus and Anopheles subpictus indefinitus. The latter record is the first of an Anopheles imported and established in the Central Pacific Area. It is felt that both of these species were introduced in the period following 1945, but there is no indication of the way in which this occurred.Interpretation of data on the biology of the adult stage of the 11 species now known from Guam, coupled with a review of their known disease vector abilities, has permitted a re-evaluation of the relative potential importance of the various species as vectors of human disease. It is concluded that as vectors of Japanese B encephalitis the following species should be kept under surveillance: Culex quinquefasciatus, Culex annulirostris marinae, Aedes vexans nocturnus, Aedes albopictus and Aedes pandani. Laboratory tests for encephalitis viruses on 20,361 mosquitoes representing 6 species have been negative. For dengue fever only Aedes albopictus would be suspected as a vector at this time. This opinion is influenced by the almost complete disappearance of Aedes aegypti, possibly due to earlier intensive control activities. Because of the habits of Anopheles subpictus indefinitus, the possibility of autochthonous malaria is believed to be minimal. It is felt that nocturnal filariasis might well be introduced and become endemic through the vector activities of Culex quinquefasciatus.A sample of 2,261 larval collections have been analyzed as to larval habitats, association of various species and monthly distribution of sources. It is concluded that the majority of domestic pest and potential disease vector mosquitoes have come from sources directly attributable to the activities of man, namely, domestic water receptacles and domestic and military refuse. It is suggested that any program for mosquito control on Guam should be aimed at the detection and correction or elimination of these mosquito sources. In the immediate vicinity of heavily populated areas, inspection and abatement of mosquito sources in ground pools and water collections in plants and coconut shells would be an important adjunct to this program during and immediately following the rainy season.

Biology of a Pest Mosquito Common in New Guinea1

Among the more important mosquitoes affecting the health of natives and newcomer alike in New Guinea and adjacent islands is Aedes scutellaris scutellaris (Walker). Its characteristics as a pest alone class this as a mosquito of importance. The fact that this is a bold and persistent feeder during daylight causes it to be noticed more than other furtive species that feed after dark. This mosquito was especially annoying at army installations during the early stages of construction and was always a greater or lesser problem as the amount of rainfall was more or less. Opportunity to study this species was afforded at Oro Bay, New Guinea, and near Bosnek, Biak, in the Schouten Group during 1944 and 1945.[2][1] [1]: #fn-2

Observations on the Abatement of Pest Mosquitoes with DDT Residual Sprays

During the investigations on the use of DDT (1-trichloro2,2-bis (p-chlorophenyl) ethane) for the control of mosquitoes, which were conducted in the vicinity of the Stuttgart Army Air Field at Stuttgart, Ark., in the summer of 1944, observations were made on the value of DDT residual sprays as a method of abating the nuisance of pest mosquitoes, such as the Psorophora spp. Studies by Gahan et al. (1, 2) had shown that these sprays were effective against Anopheles quadrimaculatus Say and other mosquitoes when applied to their diurnal resting places. As a result of the alternate drying and reflooding of the surrounding rice fields, enormous numbers of Psorophora mosquitoes invaded the cantonment area of the Stuttgart Army Air Field during the summer of 1944. The annoyance was so great that it became necessary to resort to daily treatment of all halls and corridors in the hospital building by power spraying of regulation Army issue insecticide containing Thanite (a thiocyanate). This situation was undesirable because it disrupted the regular hospital routine and tied up manpower and equipment needed for other mosquito-control work, and because of the rather disagreeable odor produced by the spray. In July a 10 per cent DDT emulsion was applied to the screens on all entranceways and windows with an ordinary decontamination-type spray cylinder. This spray was made from a basic concentrate consisting of 25 per cent of DDT, 7 per cent of Triton X-100 (an aralkyl polyether alcohol), and 68 per cent of xylene. (Less than 2 gallons of liquid were used to treat

The Pest Mosquito Problem in the Minneapolis-St. Paul Metropolitan Area*

Following some 10 years of subnormal precipitation, the return of normal conditions and then of excessive precipitation in the season of 1938 caused widespread interest in the pest mosquito problem in Minnesota.

Pest Mosquito Control in Alabama Under C. W. A.

Pest Mosquito Control in Alabama Under C. W. A.