Advances in Disease Vector Research

I think the reader will agree that we have attained a good balance in Volume 6 between human-or animal-host and plant-host-related topics from outstanding research scientists. In Chapter 1, Frank Collins, Susan Paskewitz, and Victoria Finnerty explore the potential of recombinant DNA technology to distinguish indi vidual species and to establish phylogenetic relationships among member species in the Anopheles gambiae species complex, which includes the principal malaria vectors. Currently, relatively little is known about these morphologically identical species that are sympatric over most of their range but are not always equally involved in malaria transmission. With respect to individual species identification, the researchers have thus far described two DNA fragments, derived from the ribosomal DNA interge nic spacer region, that reliably distinguish five species in the complex by means of an RFLP visualized on a Southern blot. They have also described other species-specific fragments derived from a ribosomal DNA intron that could form the basis for a rapid dot blot assay. With respect to the phylogenetic relationships among member species in the complex, Collins, Paskewitz, and Finnerty focus on a comparison at the level of restriction site mapping and Southern analysis of the rDNA intergenic spacer regions. As expected, the two spacer regions near the coding region junctions are well conserved among the species, whereas the central regions tend to be highly variable among member species in the complex.

Contenu

1 Ribosomal RNA Genes of the Anopheles gambiae Species Complex.- The Anopheles gambiae Complex.- General Characteristics of Dipteran rDNA.- Anopheles gambiae rDNA: General Structure.- Intergenic Spacer Structure.- Intervening rDNA Sequences.- Applied Uses of rDNA.- Evolution of rDNA Within the Complex.- Summary.- References.- 2 Neuroendocrine and Midgut Endocrine Systems in the Adult Mosquito.- The Nervous System.- The Neuroendocrine System.- The Midgut Endocrine System.- Neuropeptide-Like Immunoreactivity in the Nervous System and Midgut Endocrine System.- Comparison of the Neuroendocrine and Midgut Endocrine Systems.- References.- 3 Gametocytemia and Infectiousness in Falciparum Malaria: Observations and Models.- Gametocytogenesis.- Patterns of Gametocytemia.- Circadian Rhythm.- Infectiousness Versus Gametocytemia.- Reservoir of Infection.- Immune Response.- Gametocytemia and Infectiousness in Mathematical Models of Malaria.- Conclusions.- References.- 4 Some Aspects of the Biology of Phlebotomine Sandfly Vectors.- Colonization.- Sandflies as Reservoirs and Vectors of Viruses.- Age Determination.- Sugar Feeding.- Species Groups and Complexes.- Chemically Mediated Behavior.- References.- 5 Vector-Spirochete Relationships in Louse-Borne and Tick-Borne Borrelioses with Emphasis on Lyme Disease.- The Behavior of Louse-Borne and Tick-Borne Spirochetes in Their Vectors.- The Behavior of Borrelia theileri in Its Tick Vectors.- The Behavior of the Lyme Disease Spirochete Borrelia burgdorferi in Its Tick Vectors.- The Relationship of Borrelia burgdorferi to Nonspecific Tick Vectors and Other Hematophagous Arthropods.- Borrelia burgdorferi: Subject of a Complex Development Cycle?.- Conclusion.- References.- 6 Distribution of Viruses and Their Nematode Vectors.- Nematode-Transmitted Viruses as Plant Pathogens.- Causal Agents.- Vectors.- Virus-Vector Associations.- Discussion.- References.- 7 Detecting Plant Viruses in Their Vectors.- Aphids.- Plant and Leafhoppers.- Nematodes.- Mites.- Fungi.- Beetles.- Other Vector Groups.- Concluding Remarks.- References.- 8 Insect-Borne Viruses of Rice.- Geographical Distribution.- Vector Species.- Vector-Virus Interactions.- Nucleic Acids and Proteins.- References.- 9 Homopteran Transmission of Xylem-Inhabiting Bacteria Alexander.- Historical Background.- Pathogens.- The Xylem Environment.- Vectors.- Epidemiology.- Summary.- References.- 10 Plant Pathogenic Spiroplasmas and Their Leafhopper Vectors.- Spiroplasmas and Their Habitats.- Leafhoppers That Transmit Spiroplasmas.- Transmission Terminology.- Spiroplasma citri.- Spiroplasma kunkelii.- Spiroplasma phoeniceum.- Spiroplasma-Leafhopper Relationships.- Concluding Remarks.- Summary.- References.- 11 Semipersistent Transmission of Viruses by Vectors with Special Emphasis on Citrus Tristeza Virus.- Viruses.- Vectors.- Virus-Vector Relationships.- Epidemiology and Control.- Principles of the Approaches to Control.- Conclusion and Summary.- References.