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Vector Populations (vector + population)
Selected AbstractsSynergist efficacy of piperonyl butoxide with deltamethrin as pyrethroid insecticide on Culex tritaeniorhynchus (Diptera: Culicidae) and other mosquitoe speciesENVIRONMENTAL TOXICOLOGY, Issue 1 2009M. R. Fakoorziba Abstract Continuous and indiscriminate use of pesticides, especially in tropical countries for public health or agriculture purpose, has led many vector populations to become resistant to organochlorides, organophosphates, and even to carbamates and pyrethroids. Development of resistance by a vector population has been one of the reasons for the failure of the control measures in many countries. This investigation demonstrates the efficacy of piperonyl-butoxide (PBO) with deltamethrin, as pyrethroid insecticide, against the field-collected mosquitoe larvae of five species, Aedes aegypti, Anopheles culicifacies, An. stephensi, An. vagus, and Culex quinqufasciatus, and two morphological variants of Cx. tritaeniorhynchus (type A from grand pools of Mysore city and type B from rice fields of Mandya district). For testing the synergistic effect of PBO, stock solutions of deltamethrin and PBO were mixed in 1:6 ratio. The synergistic ratio and the percent suppression in deltamethrin tolerance were calculated by using LC50 values. From the results, it is clear that, PBO is an effective synergist with deltamethrin against all of species undertaken in this investigation. So, it is suggested that PBO is a good synergist in this area for decreasing the use of pesticides in environment in vector control. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] Novel strategies targeting pathogen transmission reduction in insect vectors: Tsetse-transmitted trypanosomiasis controlENTOMOLOGICAL RESEARCH, Issue 4 2007Brian L. WEISS Abstract Insect vectors are essential for the transmission of important human diseases such as malaria, leishmaniasis, Chagas and sleeping sickness. Insects are also responsible for the transmission of agricultural diseases that affect livestock and crops. Traditionally, control of the vector populations has been an effective disease management strategy. Recently, vector control strategies have been fortified by research in insect biology and in insect,pathogen interactions as well as by the development of transgenic technologies. In addition to insect population reduction methods, disease control via selective elimination of pathogens in insects can now be explored. Here we explore the tsetse vectors of African trypanosomes and describe the application of recent knowledge gained in their symbiotic, reproductive and vectorial biology to develop novel disease control strategies. [source] Synergist efficacy of piperonyl butoxide with deltamethrin as pyrethroid insecticide on Culex tritaeniorhynchus (Diptera: Culicidae) and other mosquitoe speciesENVIRONMENTAL TOXICOLOGY, Issue 1 2009M. R. Fakoorziba Abstract Continuous and indiscriminate use of pesticides, especially in tropical countries for public health or agriculture purpose, has led many vector populations to become resistant to organochlorides, organophosphates, and even to carbamates and pyrethroids. Development of resistance by a vector population has been one of the reasons for the failure of the control measures in many countries. This investigation demonstrates the efficacy of piperonyl-butoxide (PBO) with deltamethrin, as pyrethroid insecticide, against the field-collected mosquitoe larvae of five species, Aedes aegypti, Anopheles culicifacies, An. stephensi, An. vagus, and Culex quinqufasciatus, and two morphological variants of Cx. tritaeniorhynchus (type A from grand pools of Mysore city and type B from rice fields of Mandya district). For testing the synergistic effect of PBO, stock solutions of deltamethrin and PBO were mixed in 1:6 ratio. The synergistic ratio and the percent suppression in deltamethrin tolerance were calculated by using LC50 values. From the results, it is clear that, PBO is an effective synergist with deltamethrin against all of species undertaken in this investigation. So, it is suggested that PBO is a good synergist in this area for decreasing the use of pesticides in environment in vector control. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] Climate change effects on physiology and population processes of hosts and vectors that influence the spread of hemipteran-borne plant virusesGLOBAL CHANGE BIOLOGY, Issue 8 2009TOMÁS CANTO Abstract Plant virus diseases constitute one of the limiting factors to the productivity of agriculture. Changes in host plants and insect vector populations that might result from climate change (their geographical distribution range, their densities, migration potential and phenology) could affect the spread of plant viruses. At the individual level, alterations in plant physiological processes that are relevant to their molecular interactions with viruses, like changes in metabolism, leaf temperature, and their effects on some processes, like the temperature-sensitive antiviral resistance based in RNA silencing, can also influence the ability of individual plants to control viral infections. In order to assess the impact that climate change may have on the incidence and spread of hemipteran-borne plant viruses, its potential effects on virus/plant interactions and hemipteran insect vectors, as well as other operating processes, which could exacerbate or mitigate them, are identified and analyzed in this review. [source] West Nile virus may have hitched a ride across the Western United States on Culex tarsalis mosquitoesMOLECULAR ECOLOGY, Issue 8 2010TONY L. GOLDBERG West Nile virus spread rapidly from east to west across North America, despite the north-south migratory flyways of its avian hosts. In this issue, Venkatesan & Rasgon (2010) present new data on the population genetics of Culex tarsalis, the dominant West Nile virus vector in the Western United States, suggesting that patterns of mosquito gene flow may better reflect the virus's expansion from the Midwest to the Pacific than patterns of bird movement. These findings suggest a more significant role for vector dispersal in arboviral range expansion than has previously been appreciated, and they highlight the value of molecular genetic studies of insect vector populations for understanding epidemiology and disease ecology. [source] Insecticide resistance in vector mosquitoes in ChinaPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2006Feng Cui Abstract Because of their special behaviour, physiology and close relationship with humans, mosquitoes act as one of the most important vectors of human diseases, such as filariasis, Japanese encephalitis, dengue and malaria. The major vector mosquitoes are members of the Culex, Aedes and Anopheles genera. Insecticides play important roles in agricultural production and public health, especially in a country with a huge human population, like China. Large quantities of four classes of insecticides, organochlorines, organophosphates, carbamates and pyrethroids, are applied annually to fields or indoors in China, directly or indirectly bringing heavy selection pressure on vector populations. The seven major species of vector mosquito in China are the Culex pipiens L. complex, C. tritaeniorhynchus Giles, Anopheles sinensis Wied., A. minimus Theobald, A. anthropophagus Xu & Feng, Aedes albopictus (Skuse) and Ae. aegypti L., and all have evolved resistance to all the above types of insecticide except the carbamates. The degree of resistance varies among mosquito species, insecticide classes and regions. This review summarizes the resistance status of these important vector mosquitoes, according to data reported since the 1990s, in order to improve resistance management and epidemic disease control, and to communicate this information from China to the wider community. Copyright © 2006 Society of Chemical Industry [source] New 16Sr subgroups and distinct single nucleotide polymorphism lineages among grapevine Bois noir phytoplasma populationsANNALS OF APPLIED BIOLOGY, Issue 2 2009F. Quaglino Abstract Bois noir (BN) is an insect-transmitted grapevine yellows disease caused by phytoplasmas belonging to the stolbur subgroup 16SrXII-A. In Italy, increasing prevalence of stolbur phytoplasma strains in vineyards suggests progressive spread of the disease and potential for heavy impacts on the wine industry. In this study, we investigated the genetic diversity of stolbur phytoplasma strains in BN phytoplasma populations. Nucleotide sequences of 16S rRNA genes from stolbur phytoplasma strains affecting vineyards in the Lombardy region of Italy and stolbur phytoplasma 16S rDNA sequences retrieved from GenBank were subjected to virtual restriction fragment length polymorphism analysis. Calculation of virtual restriction similarity coefficients revealed the presence of new subgroups in group 16SrXII (stolbur phytoplasma group). Representative strains of confirmed new subgroups 16SrXII-F (XII-F) and XII-G and tentative new subgroups XII-A1 through XII-A19, XII-H, XII-I, and XII-J as well as known subgroup XII-A were from grapevines; strains representing three additional tentative new subgroups (XII-K, XII-L and XII-M) were from other plant hosts. Nucleotide sequence alignments identified no less than nine genetically distinct 16S rDNA single nucleotide polymorphism lineages from grapevine, indicating a high degree of genetic heterogeneity within BN phytoplasma populations. The findings open new opportunities for in-depth studies of the distribution of grapevine-associated 16SrXII phytoplasma strains in weeds, insect vector populations and grapevines from vineyards located in different geographic areas. [source] Breeding for resistance to whitefly-transmitted geminivirusesANNALS OF APPLIED BIOLOGY, Issue 2 2002MOSHE LAPIDOT Summary Geminiviruses comprise a large and diverse family of viruses that infect a wide range of important monocotyledonous and dicotyledonous crop species and cause significant yield losses. The family Geminiviridae is divided into three genera, one of which is Begomovirus. Species of this genus are transmitted by the whitefly Bemisia tabaci in a persistent, circulative manner and infect dicotyledonous plants. Severe population outbreaks of B. tabaci are usually accompanied by a high incidence of begomoviruses. During the last two decades, there has been a worldwide spread of the B biotype of B. tabaci, accompanied by the emergence of whitefly-transmitted geminiviruses. Control measures in infected regions are based mainly on limitation of vector populations, using chemicals or physical barriers. However, under conditions of severe whitefly attack, none of these control measures has sufficed to prevent virus spread. Thus, the best way to reduce geminivirus damage is by breeding crops resistant or tolerant to the virus, either by classical breeding or by genetic engineering. A number of begomoviruses have been the subject of much investigation, due to their severe economic impact. This review considers the most severe viral diseases of four major crops (tomato, bean, cassava and cotton). The approaches taken to breed for resistance to these viral diseases should provide a perspective of the issues involved in breeding for begomovirus resistance in crop plants. [source] Transgenic mosquitoes and malaria transmissionCELLULAR MICROBIOLOGY, Issue 3 2005George K. Christophides Summary As the malaria burden persists in most parts of the developing world, the concept of implementation of new strategies such as the use of genetically modified mosquitoes to control the disease continues to gain support. In Africa, which suffers most from malaria, mosquito vector populations are spread almost throughout the entire continent, and the parasite reservoir is big and continuously increasing. Moreover, malaria is transmitted by many species of anophelines with specific seasonal and geographical patterns. Therefore, a well designed, evolutionarily robust and publicly accepted plan aiming at population reduction or replacement is required. The task is twofold: to engineer mosquitoes with a genetic trait that confers resistance to malaria or causes population suppression; and, to drive the new trait through field populations. This review examines these two issues, and describes the groundwork that has been done towards understanding of the complex relation between the parasite and its vector. [source] | ||||||||||