Edwin I. Hazard
United States Department of Agriculture
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Edwin I. Hazard.
Journal of Invertebrate Pathology | 1985
A.W. Sweeney; Edwin I. Hazard; M.F. Graham
Abstract Experiments conducted in Australia are described which show that there is an intermediate host involved in the life cycle of an Amblyospora sp. infecting the mosquito, Culex annulirostris. Microsporidian spores produced in the cyclopoid copepod, Mesocyclops albicans, are infectious to laboratory colony C. annulirostris larvae and produce developmental stages identical to those of natural Amblyospora infections in this mosquito. These larval infections result in uninucleate spores in progeny mosquitoes which, in turn, are infectious to M. albicans. Subsequent studies conducted with Amblyospora, copepods, and mosquitoes in the United States to replicate and reconfirm results obtained in Australia were successful. This is the first substantiated evidence of the involvement of intermediate hosts in the life cycles of microsporidia, and the discovery now provides us with information needed to evaluate these organisms as biological control agents for mosquitoes and other disease vectors.
Journal of Invertebrate Pathology | 1977
John D. Knell; George E. Allen; Edwin I. Hazard
Abstract A new species of Microsporida, Thelohania solenopsae , is described from the red imported fire ant, Solenopsis invicta . The Thelohania infections are localized in the fat body of workers. Meronts causing infections of progeny are found in the ovaries of queens. Spores occur only in adult ants and only vegetative stages are present in larvae and pupae. Both uninucleate octospores (eight spores within a pansporoblast membrane) and binucleate free spores (spores developing in isolation) are formed.
Journal of Invertebrate Pathology | 1984
Edwin I. Hazard; John W. Brookbank
Abstract Stages of merogony and sporogony are illustrated in photomicrographs of lacto-aecto-orcein stained smears of an undescribed species of Amblyospora in male Culex salinarius larvae. Karyogamy was observed to take place in diplokaryotic meronts followed by an unusual meiosis-like process in young sporonts. Karyogamy was confirmed by DNA measurements in the nuclei of meronts. DNA measurements at mingling indicate that tetrads may not be formed during “pachytene.” Therefore, structures previously reported to be synaptonemal complexes and meiotic configurations of chromosomes may not actually represent true pachytene chromosomes. It is further shown that karyogamy has been either misplaced or overlooked by numerous investigators and that the behavior of chromosomes during the meiosis-like process was misinterpreted by previous researchers studying chromosomes in microsporidian sporonts.
Journal of Invertebrate Pathology | 1988
A Sweeney; Maureen Graham; Edwin I. Hazard
Abstract A new species of Microspora, Amblyospora dyxenoides, is described. This parasite has three sporulation sequences: two in Culex annulirostris, the mosquito host, and one in Mesocyclops albicans, the intermediate copepod host. Diplokaryotic meronts in larval oenocytes persist to the adult stage and form binucleate spores in females which are responsible for transovarial transmission to larval progeny. Unlike other described species of Amblyospora, binucleate spores may also form in adult male mosquitoes. Diplokaryotic cells infect the oenocytes of some male and female larvae which hatch from transovarially infected egg batches. These larvae survive to the adult stage after which binucleate spores develop in the females to initiate another transovarially transmitted cycle. In other male and female larvae which hatch from infected egg batches the parasite invades fat body tissue where it undergoes meiosis during a complex sporulation sequence resulting in the formation of eight haploid meiospores within a sporophorous vesicle. Fat body infected larvae usually die in the 4th instar. Larval meiospores are responsible for horizontal transmission to M. albicans copepods in which the parasite develops in ovarian tissue to form another kind of uninucleate spore. These infections ultimately lead to death of the copepods and the spores are infectious per os to C. annulirostris larvae. The first mosquito stages resulting from these infections are small cells with a single large nucleus relative to the cytoplasm. It appears that the parasite then returns to the diploid state by cytoplasmic fusion (plasmogamy) of uninucleate gametes to form binucleate cells which later adopt the diplokaryotic arrangement and invade larval oenocytes to complete the life cycle.
Journal of Invertebrate Pathology | 1985
Edwin I. Hazard; Tokuo Fukuda; James J. Becnel
Abstract Gametogenesis and plasmogamy of gametes is documented in light and electron microscopy of Hazardia milleri, Culicospora magna, and an undescribed microsporidium in Aedes aegypti, using three mosquito hosts in experimental infection studies. Events taking place during gametogenesis and plasmogamy were similar in all three species studied. However, merogonial and sporogonial sequences differed among the three species. Gametes of C. magna and a Microsporidium sp. in A. aegypti were structurally different from those of H. milleri in that they contain an unusual nipple-like structure on one end. The function of this structure was not ascertained. C. magna was successfully transmitted to healthy Culex restuans larvae exposed to spores in well water, but infections were higher when larvae were exposed to spores in filtered field water taken from breeding sites. The presented evidence of the production and union of gametes is the first documentation of gametogenesis and plasmogamy in species of microsporidia. The realization of sexual cycles in some species raises important questions concerning the present classification of the Microspora.
Journal of Invertebrate Pathology | 1971
Edwin I. Hazard; Clifford S. Lofgren
Abstract Studies of the host-parasite relationships of a Nosema in four species of mosquitoes showed that the primary sites of infection were: (1) Anopheles quadrimaculatus —accessory glands, brain, fat body, gut, Malpighian tubules, muscle, nerve ganglia, rectum, ventral diverticula, and the ventriculus; (2) Culex quinquefasciatus —fat body, gut, and Malpighian tubules; (3) Culex salinarius —fat body, gut, Malpighian tubules, and muscle; and (4) Aedes aegypti —brain and nerve ganglia. The variation in susceptibility of tissues in host species is interesting and illustrates the danger of differentiating Microsporidia solely on the basis of the sites of the infection in hosts. Since anopheline mosquitoes appear to be the primary hosts, the parasite might be useful in control programs for anopheline mosquitoes and/or the interruption of development of plasmodia in the female mosquito. The taxonomic placement is also discussed.
Journal of Invertebrate Pathology | 1970
Edwin I. Hazard; K.E Savage
The morphology and the developmental stages of a new species of Stempellia (Nosematidae) in Culex pilosus (Culicidae) are described. The diagnostic characters are compared with those of Stempellia magna, the only other described member of the genus Stempellia in mosquitoes. The host-parasite relationships of Stempellia lunata sp. n. and S. magna are discussed.
Journal of Invertebrate Pathology | 1971
Darrell W. Anthony; Harold C. Chapman; Edwin I. Hazard
Abstract A scanning electron microscope was used to study the sporangia of at least 6 species of Coelomomyces from 9 species of mosquitoes. The scanning micrographs obtained of (1) Coelomomyces punctatus from Anopheles quadrimaculatus , (2) C. dodgei from A. crucians , (3) C. quadrangulatus from A. crucians , (4) C. macleayae from Aedes triseriatus , (5) C. pentangulatus from Culex erraticus , (6) C. sp., probably pentangulatus , from Culex peccator , (7) C. psorophorae from Psorophora howardii , (8) C. near psorophorae from Culiseta inornata , (9) from Aedes sollicitans , and (10) from Aedes taeniorhynchus showed morphological differences in the surface microstructure of the sporangia of most species.
Critical Reviews in Microbiology | 1992
Victor Sprague; James J. Becnel; Edwin I. Hazard
Archive | 1977
Edwin I. Hazard; Victor Sprague