Mosquitos of the Culex pipiens complex offer unique opportunities for study of the mechanisms that separate populations and of the possible advantages of the blood-feeding habit. C. pipiens is a polytypic species in which there are at least three major adaptations to environment. The tropical quinquefasciatus (fatigans) is a generalized blood-feeder dependent on the year-round availability of a variety of hosts. The obligate blood-feeding pipiens form of the temperate zone appears to be adapted to feeding upon nesting birds. The autogenous molestus form is essentially non-blood-feeding. Additional variants are present in different parts of the world.The variety of devices that serve to separate these different populations pose difficult problems for the taxonomist.

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PubMed1966

Lethal effects of synthetic juvenile hormone on larvae of the yellow fever mosquito, Aedes aegypti.

Emergence of adult mosquitoes is blocked after the addition of 1 part of crude synthetic juvenile hormone to 100,000 parts water. Development is arrested at stages ranging from pupae to fully formed pharate adults incapable of escaping from the pupal exuvium. Fourth-stage larvae just prior to metamorphosis are most sensitive: 40 percent were killed after being exposed for 1 dayto 1 part juvenile hormone in 2 million parts water. The active material also inhibits the hatching of mosquito eggs.

Aedes↗

PubMed1966

The functional anatomy of the copulatory apparatus of male Culex pipiens (Diptera: Culicidae).

Explore the source record for details and available documents.

Animals↗

PubMedDate not supplied

Suppression of transmission of malaria through source reduction: antianopheline measures applied in Israel, the United States, and Italy.

To provide a conceptual basis applicable to future antimalarial efforts, we sought to identify the sources of success in three notable campaigns that were consummated largely before DDT became available. A variety of measures directed against the aquatic stages of the anopheline vectors provided the main strategy for the antimalarial programs in Palestine/Israel, Italy, and the Tennessee River Valley of the United States. Source reduction-the modification or elimination of aquatic habitats to reduce mosquito breeding-was applied extensively and proved decisive. In all three regions, transmission of malaria was reduced to the point of extinction. Effective measures against anopheline larvae, in particular through source reduction, depend upon locally derived ecologic concepts that can be adapted to each vector species and applied continuously without limit of time. An integrated control program based on the long-term application of such measures can suppress transmission of malaria in edemic areas, as well as contain episodes of locally increased transmission of malaria.

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PubMedDate not supplied

A new tick-borne encephalitis-like virus infecting New England deer ticks, Ixodes dammini.

To determine if eastern North American Ixodes dammini, like related ticks in Eurasia, maintain tick-borne encephalitis group viruses, we analyzed ticks collected from sites where the agent of Lyme disease is zoonotic. Two viral isolates were obtained by inoculating mice with homogenates from tick salivary glands. The virus, which was described by reverse transcriptase polymerase chain reaction and direct sequencing of the amplification products, was similar to, but distinct from, Powassan virus and is provisionally named "deer tick virus." Enzootic tick-borne encephalitis group viruses accompany the agents of Lyme disease, babesiosis, and granulocytic ehrlichiosis in a Holarctic assemblage of emergent deer tick pathogens.

Animals↗

PubMedDate not supplied

Wild primate populations in emerging infectious disease research: the missing link?

Wild primate populations, an unexplored source of information regarding emerging infectious disease, may hold valuable clues to the origins and evolution of some important pathogens. Primates can act as reservoirs for human pathogens. As members of biologically diverse habitats, they serve as sentinels for surveillance of emerging pathogens and provide models for basic research on natural transmission dynamics. Since emerging infectious diseases also pose serious threats to endangered and threatened primate species, studies of these diseases in primate populations can benefit conservation efforts and may provide the missing link between laboratory studies and the well-recognized needs of early disease detection, identification, and surveillance.

Animals↗

PubMedDate not supplied

Genospecies diversity of Lyme disease spirochetes in rodent reservoirs.

To determine whether particular Borrelia burgdorferi s.l. genospecies associate solely with rodent reservoir hosts, we compared the genospecies prevalence in questing nymphal Ixodes ticks with that in xenodiagnostic ticks that had fed as larvae on rodents captured in the same site. No genospecies was more prevalent in rodent-fed ticks than in questing ticks. The three main spirochete genospecies, therefore, share common rodent hosts.

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PubMedDate not supplied

A focus of deer tick virus transmission in the northcentral United States.

We screened salivary glands from adult deer ticks collected near Spooner and Hayward, Wisconsin, to determine whether deer tick virus, a recently described flavivirus, occurs with other tickborne agents in the upper Midwest. Intraacinar inclusions suggestive of replicating virus were detected in 4 (4.6%) of 87 ticks. The virus was isolated by suckling-mouse inoculation.

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PubMedDate not supplied

Competence of American robins as reservoir hosts for Lyme disease spirochetes.

To explore the competence of American robins as a reservoir for Lyme disease spirochetes, we determined the susceptibility of these birds to tickborne spirochetes and their subsequent infectivity for larval vector ticks. Robins acquired infection and became infectious to almost all xenodiagnostic ticks soon after exposure to infected nymphal ticks. Although infectivity waned after 2 months, the robins remained susceptible to reinfection, became infectious again, and permitted repeated feeding by vector ticks. In addition, spirochetes passaged through birds retained infectivity for mammalian hosts. American robins become as infectious for vector ticks as do reservoir mice, but infectivity in robins wanes more rapidly.

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PubMedDate not supplied

Enzootic transmission of deer tick virus in New England and Wisconsin sites.

To determine whether rodents that are intensely exposed to the deer tick-transmitted agents of Lyme disease, human granulocytic ehrlichiosis, and human babesiosis are also exposed to deer tick virus (DTV), we assayed serum samples from white-footed mice (Peromyscus leucopus) and meadow voles (Microtus pennsylvanicus) in sites densely infested by deer ticks. To conduct serosurveys, we developed an enzyme-linked immunosorbent assay (ELISA) and Western blot assay by cloning, expressing, and purifying a portion of the DTV envelope glycoprotein (DTV rE) for use as test antigen. Sera from mice and voles trapped in Massachusetts, Rhode Island, and Wisconsin were screened by ELISA for IgG reactive to DTV rE. Samples that were positive or borderline by ELISA were subsequently analyzed by immunoblotting. Samples reactive in both assays were considered to be positive. Three percent of 264 mouse samples collected from sites in Rhode Island, 3.8% of 52 samples from mice trapped in Wisconsin, and 3.9% of 282 samples collected from mice trapped on Nantucket Island, MA were positive. No samples from either Great Island, MA, or voles from any study site were reactive. A reverse transcriptase-polymerase chain reaction yielded molecular evidence of DTV infecting questing adult deer ticks in sites where seroreactive mice were trapped, but not from ticks collected where serologic evidence of virus perpetuation was absent. White-footed mice appear to be exposed to DTV in certain sites where other deer tick-borne agents perpetuate. This virus may be maintained in the same enzootic cycle.

Animals↗

PubMedDate not supplied

Enhanced development in nature of larval Anopheles arabiensis mosquitoes feeding on maize pollen.

To determine whether pollen produced by maize (Zea m. mays) may contribute to the development of larval Anopheles gambiae complex mosquitoes, the main African vectors of malaria, we correlated duration of larval development, pupation success, and size of the resulting adults with degree of access to this potential nutriment. Maize pollen is abundant during the wet season on the surface of water near maize plantings in a malaria-endemic region of Ethiopia, and larval Anopheles arabiensis readily ingest these particles in nature. Larvae develop to the pupal stage more rapidly, more frequently, and produce larger adults where maize pollen is abundant than do those that have little access to this food. The force of transmission of malaria in sub-Saharan Africa might be reduced if maize plantings were excluded from the immediate vicinity of homes or, perhaps, if pollen of such maize were to express entomotoxins.

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PubMedDate not supplied

Sylvatic transmission of arboviruses among Bornean orangutans.

Wild populations of nonhuman primates live in regions of sylvatic arbovirus transmission. To assess the status of arbovirus transmission in Bornean forests and the susceptibility of wild orangutans to arboviral infection, blood samples of wild orangutans, semi-captive orangutans, and humans were examined. Samples were tested by plaque reduction neutralization test for antibodies to viruses representing three families (Flaviviridae, Alphaviridae, and Bunyaviridae), including dengue-2, Japanese encephalitis, Zika, Langat, Tembusu, Sindbis, Chikungunya, and Batai viruses. Both wild and semi-captive orangutan groups as well as local human populations showed serologic evidence of arbovirus infection. The presence of neutralizing antibodies among wild orangutans strongly suggests the existence of sylvatic cycles for dengue, Japanese encephalitis, and sindbis viruses in North Borneo. The present study demonstrates that orangutans are susceptible to arboviralinfections in the wild, although the impact of arboviral infections on this endangered ape remain unknown.

Animals↗

PubMedDate not supplied

[Detection of natural foci of babesiosis and granulocytic ehrlichiosis in Russia].

The use of microscopy, infection of golden hamsters and the polymerase chain reaction made it possible to find out that about 30% of common red-backed voles (Clethrionomys glareolus), inhabiting the taiga forests of the southern part of the Western Urals (the Chusovskoi district of the Perm region), were infected with Babesia microti and simultaneously (a third of them) with Ehrlichia (Cytoecetes) phagocytophila, the causative agent of granulocytic ehrlichiosis. The sequencing of 18S rDNA of strain "Mys", isolated in Russia, revealed its identity to American B. microti strain GI, pathogenic for humans. The main vector supporting the circulation of B. microti in the natural foci in the region where these investigations were conducted was, seemingly, the tick Ixodes trianguliceps, Thus, for the first time the data proving the presence of reservoir hosts infected with B. microti and granulocytic E. phagocytophila, pathogenic for humans, in Russia were presented.

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