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At least 1,387 records · Page 77Linked to original sources
PubMed2005

Impact of a screen barrier on dispersion behavior of Homalodisca coagulata (Hemiptera: Cicadellidae).

The recent incursion of the sharpshooter Homalodisca coagulata (Say) (Hemiptera: Cicadellidae), a vector of the plant pathogenic bacterium Xylellafastidiosa, into southern California has caused new epidemics of plant diseases. The potential of H. coagulata to spread throughout the state and disseminate disease has encouraged the development of techniques to limit further spread of the vector and to manage disease epidemics where the insect already exists. We evaluated a unique tactic to curtail the immigration of H. coagulata into high-value crops, including nursery stock, where they can be spread via commercial transportation throughout the state and into disease-susceptible vineyards. This tactic consists of a 5-m-high screen barrier surrounding the crop that is impenetrable to H. coagulata. We examined H. coagulata orientation and flight direction when placed near or on the screen barrier, and determined the proportion of insects that flew over it. When released midway between a barrier and adjacent vegetation 71.5% of H. coagulata flew away from the barrier and in the direction of the vegetation; whereas 29.5% flew in the direction of the barrier. Of the total number of H. coagulata released, 7.5% flew over the barrier. When placed on the barrier, H. coagulata generally climbed up an average of 1.16 m before flying away from the structure. Of the total number of H. coagulata placed on the barrier, 6% flew over it. These results suggest that a screen barrier can be a part of a management strategy to reduce number of H. coagulata in high-value crops.

Animal Migration↗
PubMed1982

The Australian brown dog tick Rhipicephalus sanguineus as an experimental parasite of cattle and vector of Anaplasma marginale.

Experiments were done to explore the possible relationship between cattle, Australian dog ticks (Rhipicephalus sanguineus) and Anaplasma marginale. Calves' ears were exposed to larval, nymphal and adult ticks on 8, 9 and 7 occasions, respectively. The immature instars fed readily, but the adults attached very poorly to calves. Transtadial transmission of A. marginale was achieved on 6 occasions from 9 attempts: ticks infected as larvae or nymphs were able to transmit at the subsequent stage or stages. Transovarial transmission was not achieved. Six calves supported more than one infestation of ticks. Attached ticks caused the calves no apparent discomfort and calves developed no noticeable skin reactions. An abattoir survey of 200 hides detected no R. sanguineus.

Anaplasma↗
PubMed1965

Anopheles balabacensis balabacensis identified as vector of simian malaria in Malaysia.

The mosquito Anopheles balabacensis balabacensis has been identified as a natural vector of at least two species of simian malaria in the monsoon forests of the northern Malay States. This mosquito is also a serious vector of human malaria from Viet Nam to northern Malaya. This is the first report of a mosquito which transmits both human and simian malaria in nature.

Animals↗
PubMed1996

Genetically engineered resistance to dengue-2 virus transmission in mosquitoes.

The control of arthropod-borne virus diseases such as dengue may ultimately require the genetic manipulation of mosquito vectors to disrupt virus transmission to human populations. To reduce the ability of mosquitoes to transmit dengue viruses, a recombinant Sindbis virus was used to transduce female Aedes aegypti with a 567-base antisense RNA targeted to the premembrane coding region of dengue type 2 (DEN-2) virus. The transduced mosquitoes were unable to support replication of DEN-2 virus in their salivary glands and therefore were not able to transmit the virus.

Aedes↗
PubMedDate not supplied

Flea-borne rickettsioses: ecologic considerations.

Ecologic and economic factors, as well as changes in human behavior, have resulted in the emergence of new and the reemergence of existing but forgotten infectious diseases during the past 20 years. Flea-borne disease organisms (e.g., Yersinia pestis, Rickettsia typhi, R. felis, and Bartonella henselae) are widely distributed throughout the world in endemic-disease foci, where components of the enzootic cycle are present. However, flea-borne diseases could reemerge in epidemic form because of changes in vector-host ecology due to environmental and human behavior modification. The changing ecology of murine typhus in southern California and Texas over the past 30 years is a good example of urban and suburban expansion affecting infectious disease outbreaks. In these areas, the classic rat-flea-rat cycle of R. typhi has been replaced by a peridomestic animal cycle involving, e.g., free-ranging cats, dogs, and opossums and their fleas. In addition to the vector-host components of the murine typhus cycle, we have uncovered a second typhuslike rickettsia, R. felis. This agent was identified from the blood of a hospitalized febrile patient and from opossums and their fleas. We reviewed the ecology of R. typhi and R. felis and present recent data relevant to the vector biology, immunology, and molecular characterization and phylogeny of flea-borne rickettsioses.

Animals↗
PubMed2001

Chemistry and specifications of pesticides.

This report presents the conclusions of a WHO Expert Committee commissioned to make recommendations on specifications for pesticides used in public health, with a view to promoting the manufacture and use of high-quality products that are both effective against susceptible vectors of disease and acceptable in terms of safety. These specifications serve mainly for purchase and quality-control purposes, but may also be useful for product registration by WHO Member States. The text includes an outline of the objectives and achievements of the WHO Pesticide Evaluation Scheme (WHOPES) and an overview of recent trends in pesticide usage in the various WHO regions. Analytical methods and quality control of pesticides in developing countries are discussed, and the Committee's recommendations for specifications for various types of pesticides are presented. The Committee also considered pesticide containers and packaging, marking and storage, as well as the problems of disposal of unusable pesticides and their containers. Recommendations for continued collaboration between WHO and other organizations are summarized, as are the Committee's more general recommendations for WHO's future work in the area of pesticides. Annexed to the report are the Committee's recommendations for changes to existing specifications and methods, for new pesticides and formulations, and for new methods.

Agrochemicals↗
PubMed2003

Human zoonotic cutaneous leishmaniasis and associated sand flies (Diptera: Psychodidae) in Sheikh Atiya village, southern Sinai, Egypt.

Zoonotic cutaneous leishmaniasis is endemic in Sinai Peninsula. Human cases were recorded from the northern Sinai, however little was known about the disease in southern Sinai. During entomological surveys conducted southern Sinai in summers of 1997-1999, a clinically confirmed ZCL case was encountered for the first time in Sheikh Atiya village in June 1999. The parasite was isolated and identified as L. major using cellulose acetate electrophoresis. A total of 784 phlebotomine sand flies were collected. Sand fly species composition at Sheikh Atiya village showed that P. papatasi and P. alexandri were the most abundant species in the area and each comprises about 47 % of the flies collected. P. sergenti and P. kazeruni occurred in very low numbers. All the female flies dissected (N = 304) were negative for any Leishmania-like flagellates. When the identified isolate was inoculated in the footpads of a clean laboratory colonized Acomys cahirinus dimidiatus, a lesion was developed on the site of inoculation 9 months post injection. The role of P. alexandri and A. c. dimidiatus in transmission of leishmaniasis in southern Sinai remains questionable. Environmental factors contributed to the appearance of ZCL in the area are discussed.

Adult↗
PubMedDate not supplied

[An experimental study of the effect of different biologically active substances on the susceptibility of mosquitoes to the causative agent of malaria. 2. Herbicides and fungicides].

The feasibility was determined of influencing Ae. aegypti sensitivity to bird malaria agent P. gallinaceum by sublethal concentrations of herbicides (ordram and propanide) and fungicides (fundozol and blue vitriol) introduced into the larvae habitation medium or into the imago feed. No stable changes in the infectivity of test female individuals, as compared to the control, have been observed. Specific action of the group of preparations under study has been noted. It has been shown that the use of herbicides causes a decrease in some parameters of the vector potential (survival and aggressiveness) of the survived insects, however, it is accompanied by a tendency towards enhanced invasion by malaria plasmodia. The treatment of larvae with fungicides has less effect on the viability of the imago and their reaction to the prey, however, unlike herbicides, fungicides are associated with a tendency towards reduced Ae. aegypti sensitivity to P. gallinaceum. When fungicides are added to the imago feed the indexes of test female individuals infectivity do not differ from the control ones.

Aedes↗
PubMedDate not supplied

[Visceral leishmaniasis in Central Asia and Kazakhstan].

At present sporadic foci of visceral leishmaniasis (VL) are encountered mainly in the natural foci. The natural foci of VL are situated mainly in valleys and foothills. In southern areas of the Turkmen SSR the majority of cases were registered in small settlements situated near wells in interbarkhan lowerings. The reservoir of pathogen here may be Vulpes vulpes and dogs and the most likely vector is Phlebotomus turanicus. In Kazakhstan cases of VL are encountered in the thickets of the Syr-Darya floodlands in Kzyl-Orda Province, where the natural reservoir of the pathogen are Canis aureus L. and Vulpes corsac, and the vector is P. smirnovi. Synanthropic foci in Dzhambul and Chimkent, where dogs were most likely the source of the infection and P. longiductus was the vector, are at present inactive. The maps have been plotted where landscape dissemination of mosquitoes (VL vectors) is compared to places of habitation of Canis aureus L. and VL incidence in humans at peaks of the disease endemia. Medical personnel should be on the look-out for VL on the whole territory with VL natural foci.

Animals↗
PubMedDate not supplied

[Ecological approaches to the study of natural-focus diseases].

Changes in the epidemiology and epizootiology of diseases with natural foci due to anthropogenic influence on biosphere necessitate thorough studies of ecological specific features of agents, carriers and vertebral hosts reflecting their adaptation to various natural geographical and social conditions. The attention should be focussed on geographical variability of agents, changes in populations of arthropod carriers and their feeders, monitoring of natural territorial complexes and scientifically grounded prognosis for diseases with natural foci.

Animals↗