Pathogens of Simuliidae (blackflies)

X. PATHOGENS OF SIMULIIDAE (BLACKFLIES) Marshall Laird Murray Colbo Jean Finney Joseph Mokry and Albert Undeen Research Unit on Vector Pathology Memorial University ofNewfoundland St. John's, Newfoundland, Canada A1C 5S7 105 41 9 a Ca i C 8 %D 0% "-4 "4 0 Is 0% - 0 -4. c 0 aa 00 1~-. 0% H- 10 0n 4.1 - 0 0s S. 0a %0 I.- 0% 0 41 0 4 -t 0% 0 H 0 z 0% c 0 0 z "a 0D ,l_ a 0% r4. -W 0 z '0 "0 0d 0 0 ".4ra4 9'0 4,4 I C~~~~~4 H H f c cn c: i > nc 0 0 4 -~~~~~~ 0 V0 0 -Ww O4 I 0 S d H c 2; .4 cn E :3 : 10 '0 c00 0 0 H 0 co "- c O ".4 0 -A. "4 C) 04 ".4 -A -'4 10 0 0 co O $1 0 * 0i 01 0 01, 0 .0 0 4 v 0 0 0.C to 4. .04.1 -A. 4) 4.1 go 0 0 01 .4 31313 31 i 4.1 p44-1 An ffi X C0aNu i 9 "-4 "4to0 04 0 fA 0 P4 106 0T% 0 ".4 0s '0 H4 0 .44 rIL H10 10 t 0 1004t %xC z L)l. 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"4 f a0 U. 0 0 I co . cO4 a "4 0 0 a 9:0 u 0 0 0 H "4 '0 "4 a m $4 w 014 0"-4 U I 0 "4 0 0 co 44 I 0 z '00 "4- "4 10 "4 :0 0 0 0 0 0 - '~ ~4i 0 1 :2:A : :2 A : : : : : 0 I c :~~~~~03 0.$~~~~~~4 '.4 r4 V ~~~~~~~ ~ H.1 co coCa cnI~~~~~~~~~~~~~~~~~~~~~~~0 114 0 C)00 044 0m '0$ 0 04 0 Is 10 "-414 44 '0-100 0 -4 -W 0 0 U. co H z.O 0 co 4 0 0 0C) 0 10 "4I 0 H r.4 0 4.' coPk I m u a0 0A4 0 00I 115 ABSTRACTS *Abdelnur, 0. M. (1968). The biology of some blackflies (Diptera: Simuliidae) of Alberta. Quaestiones entomologicae. 4: 113-174 Some 0-45% of blackfly larvae in rivers and 27-33% of those in creeks contain Microsporida of the genera Thelohania and Caudospora. Simulium venustum larvae and adults were parasitized by (Mesomermis) - Neomesomermis flumenalis (35-94% infection) and adult and larval Simulium vittatum harboured Gastromermis viridis (7-79%). Limnomermis sp. was recorded from S. arcticum, S. aureum, and S. tuberosum. *Bailey, C. H. (1977). Field and laboratory observations on a cytoplasmic polyhedrosis virus of blackflies (Diptera: Simuliidae). J. Invertebr. Pathol., i2: 69-73. Cytoplasmic polyhedrosis virus was recorded in Newfoundland from Cnephia mutata (up to 54% infection), Prosimulium mixtun/fuscum, Simulium tuberosum, S. venustum, and S. vittatum. With the exception of C. mutata, the incidence of infection was usually less than 1%, and never exceeded 5%. *Bailey, C. H. & Gordon, R. (1977). Observations on the occurrence and collection of mermithid nematodes from blackflies (Diptera: Simuliidae). Can. J. Zool., 55: 148-154. Prosimulium mixtun/fuscum and Simulium venustum are the major hosts of Neomesomermis flumenalis. Rates of infection in late instar larvae were 4.3 + 0.7% and 5.4 + 1.2% for these two hosts respectively. Nematode emergence were in two distinct peaks; one for the Prosimulium and the other for the first generation of S. venustum. *Bailey, C. H. et al. (1977). Laboratory culture of the free-living stages of Neomesomermis flumenalis a mermithid nematode parasite of Newfoundland blackflies (Diptera: Simuliidae). Can. J. Zool., 55: 391-397. 78.6% of female Neomesomermis flumenalis introduced to culture (under xenic conditions in containers with wet sand) reproduced. The influence of living and non-living factors on the success of culturing is discussed. Parasites from psiumer-breeding Simulium hosts developed nearly twice as fast aq those from winter-breeding Prosimulium hosts, at 10' C. *Batson, B. S. et al. (1976). An iridescent virus from Simulium sp. (Diptera: Simuliidae) in Wales. J. Invertebr. Pathol., 27: 133-135 The second iridescent virus recorded from blackflies was found in unidentified early instar blackfly larvae on the River Wsywyth from which Simulium variegatum. S. monticola and S. reptans were recorded. The organisms' intense lilac-blue opalescence in direct sunlight made it easy to distinguish a parasitized larvae from up to several thousand individuals attached to stones (whether these were examined in or out of the water). *Boemare, N. & Maurand, J. (1976). Investigations on respiratory metabolism of healthy and microsporidan-infected Simulium larvae. Bull. Soc. Zool. France 101: 377-385 Thelohania fibrata and Pleistophora debaisieuxi were recorded from Tetisimulium bezzii. *Bruder, K. W. (1975). The blackflies (Simuliidae: Diptera) of the Stony Brook Watershed of New Jersey with emphasis on parasitism by mermithid nematodes (Mermithidae: Nematoda). Dissert. Abstr. int. B., 35: 4925B. 116 Neomesomermis flumenalis showed an overall incidence of 5.287 larval parasitism in the watershed studied, with a range for individual sampling stations from 1.1% to over 11%. Six blackflies proved to be hosts for this species: Prosimulium magnum. P. fuscum/mixtum, Simulium tuberosum S. aureum and Cnephia mutata. Invasion by pre-parasitic juveniles was limited to early instar larvae. Two distinct host/parasite cycles were evident: a winter one (November through April) maintained by P. magnum and P. fuscuVn/mixtum, and a suer one (mid-April through October) maintained by S. tuberosum. No adults of the latter were parasitized, but females of Prosimulium spp. were. Carlsson, G. (1971). Parasites as means of biological control for Diptera of medical importance. C. -R. ler. Multicolloque europden de parasitologie Rennes, 1-4 September 1971, pp. 419-420. Investigations of blackflies in Scandinavia, North America and Africa revealed overall parasitism, mainly by mermithids, of about 5%. In western Kenya, what was probably a non-biting sibling of S. damnosum was abundant in eight of 28 larval habitats investigated. Mermithid parasitism ranged from 2-15% in three of the eight positive localities, last instar larvae being infected to a much higher degree than the earlier ones. Carlsson, G. (1971). Control of Diptera of medical importance by means of parasites, siblings, chemosterilants or predators. Round Table Conference convened as part of the C. -R. ler. Multicolloque europeen de parasitologie, Rennes, 1-4 September 1971, pp. 412-415. There was a consensus that there is an urgent need for integrated control in medical entomology, that this will demand international coordination and hopefully support as well, that blackflies stood in particular need of relevant research attention, and that an imediately suitable subject for experimentation would be the introduction of foreign species of mermithids, for example, from North America, against S. damnosum in Upper Volta. It was also felt that this major vector of onchocerciasis invited exposure to a broad complex of candidate pathogens, including microsporidans and fungi, under field conditions. *Colbo, M. H. (1974). Studies on the biology of the Simuliidae in Northeastern Australia with reference to their potential as vectors of pathogens. Ph.D. Thesis, Dept. of Parasitology, University of Queensland, Brisbane, Australia. Austrosimulium bancrofti harbouredPlistophorasp. and unidentified mermithids, the latter also being present in Simulium clathrinum S. ornatipes and S. nicholsoni which harboured microsporidan Thelohania sp. as well. *Condon, W. J. & Gordon, R. (1977). Some effects of mermithid parasitism on the larval blackflies Prosimulium mixtum/fuscum and Simulium venustum. J. Invertebr. Pathol., 29: 56-62 Histochemical studies on field-collected specimens of larval blackflies showed no significant differences in endocrine activity betweenmermithid-infected and uninfected P. mixtum/fuscum larvae of similar body dimensions. In S. venustum, mermithid parasitism significantly increased the nuclear DNA/RNA activity of the corpus allatum gland as well as the volume and amount of stored neurosecretory material in the corpus cardiacum gland. A marked decline in glycogen concentration and the amount of fat body tissue was evident in both infected simuliid species. Fat body nucleic acid activity was unaffected bymermithid parasitism. *Ebsary, B. A. & Bennett, G. F. (1975a). The occurrence of some endoparasites of blackflies (Diptera: Simuliidae) in insular Newfoundland. Can. J. Zool., 53: 1058-1062. 117 Gastromermis viridiss Isomermis wisconsinensis and Neomesomermis flumenalis were recovered from blackfly larvae in 59 of 198 streams sampled on the Avalon Peninsula and elsewhere on the island of Newfoundland, along the Trans-Canada Highway. N. flumenalis proved the most important mermithid parasite of Newfoundland blackflies. Simuliidae in 40 of the streams harboured microsporidans - Thelohania bracteata, T. fibrata. Pleistophora simulii, Caudospora simulii and C. brevicauda. The two last species were collected from overwintering blackfly larvae. Both overwintering and summer larvae from 14 streams harboured the fungus Coelomycidium simalii. The blackfly hosts from which one or more of these parasites were recorded are: Prosimulium fuscuD/mixtum, Cnephia mutata, Simulium corbis, S. latipes, S. tuberosum, S. venustum and S. vittatum. Twelve other species of blackfly which were examined proved negative for endoparasites. *Ebsary, B. A. & Bennett, G. F. (1975b). Studies on the bionomics of mermithid nematode parasites of blackflies in Newfoundland. Can. J. Zool., 53: 1324-1331. Neomesomermis flumenalis primarily parasitizes larval simuliids, Prosimulium fuscum/ mixtum, during the winter months, and Simulium venustum (and to a lesser extent other summer simuliids) in early spring (May and June). Data extrapolated from late instar larvae and pupae indicated that less than 0.03% and 0.06% of adults of P. fuscuWmixtum and S. venustum respectively were parasitized. The apparent host specificity of N. flumenalis is attributed to the close synchrony of its life cycle with that of those blackflies overwintering as larvae and developing at temperatures of 12'C and below (actual infection occurred from 4-12°C). Male mermithids outnumbered females in Prosimulium hosts, the reverse being true for S. venustum. When only a single mermithid was present in blackfly larvae, the parasite was always a female; when more than one worm was present in a blackfly larva, the mermithids were usually males. *Edwrds, A. J. (1975). Parasitism of blackflies (Simuliidae) by mermithid nematodes at the beginning of the rainy season in the Ivory Coast. OCCGE Mimeogr. document No. 9/Oncho/Rap., 75, pp. 33, Bouake, Ivory Coast. Unidentified nematodes are recorded from larval Simulium damnosum. S. adersi, and S. unicornutum, one example of the last-named species being definitely parasitized by a mermithid. The field site was on the N'Zi River, near Fetekro. *Ezenwa, A. 0. et al. (1974). Microsporidan infection of Simulium damnosum in West Africa. J. Parasitol., 60: 975. Thelohania fibrata identified from Simulium damnosum near Lamto, Bandama River, Ivory Coast. *Federici, B. A. (1976). Pathology and histochemistry of a Densonucleosis Virus in larvae of the blackfly, Simulium vittatum. 9th Ann. Mtg. Soc. Invertebr. Pathol. & 1st Internatl. Collog. Invertebr. Pathol. (Kingston, Ontario, Canada, 29 August - 2 September 1976), and Proceedings. pp. 341-342 A probable Parvovirus recorded from Simulium vittatum Colorado River, near Bullhead, California. Figueros, M., H. et al. (1977). Post-prandial transportation and maintenance of Simulium ochraceum infected with Onchocerca volvulus. Amer. J. Trop. Med. Hyg., 26: 75-79 Factors affecting the survival of adult blackflies (Simulium ochraceum) during long- distance transportation, include "the parasite load (protozoa, fungi and/or mermithids) within the flies . . . ". 118 *Finney, J. R. (1975). The penetration of three simuliid species by the nematode Reesimermis nielseni. Bull. Wld Hlth Org., 52: 235 The mosquito mermithid Romanomermis culicivorax under still water conditions in glass cavity plates did penetrate larvae of Simulium venustum (ex Newfoundland), also S. decorum and S. vittatum (ex Georgia, USA). Finney, J. R. (1976a). The in vitro culture of the mermithid parasites of mosquitoes and blackflies. 9th Ann. Mtg. Soc. Invertebr. Pathol. & 1st Internatl. Collog. Invertebr. Pathol. (Kingston, Ontario, Canada, 29 August - 2 September 1976), and Proceedings, p. 225. Preparasites of Romanomermis culicivorax have developed best in Grace's insect tissue culture media together with foetal calf serum, growth and differentiation continuing for six weeks and leading to the production of females (only) lacking a developed trophosome. This fact indicates nutritional deficiency in the culture medium, a question consequently receiving continuing study. Finney, J. R. (1976b). The in vitro culture of mermithid parasites of blackflies and mosquitoes. J. Nematol., 8: 284. Best results for Romianomermis culicivorax and Neomesomermis flumenalis were obtained using a combination of Grace's tissue-culture medium and Schneider's Drosophila medium modified by the addition of foetal calf serum. After 22 days, preparasites of both mermithids had developed to a stage comparable with that of a three-day nematode in vivo with R. culicivorax having reached a length of 6-7 mm and N. flumenalis 8-9 mm. Fredeen, F. J. H. (1970). Sexual mosaics in the blackfly Simulium arcticum (Diptera: Simuliidae). Can. Entomol., 102: 1585-1592. Four adult Simulium arcticum (two presumed intersexes, and two apparently normal males) were parasitized by Hydromermis sp. *Garris, G. I. & Noblet, R. (1975). Notes on parasitism of black flies (Diptera: Simuliidae) in streams treated with Abate. J. Med. Entomol., 12: 481-482. Immature blackflies were collected near Pageland, South Carolina, in connexion with chemical control studies. Simulium sp., S. venustum S. verecundum S. tuberosum andCnephia sp. yieldedmermithids. One collection site exhibited 38.6% parasitism in S. venustum in March and 19.7% in April. In the latter month, 27% parasitism was recorded at the same site for S. verecundum. Microsporidan infections were widespread, the blackflies parasitized being Simulium sp., S. vittatum. S. verecundum S. venustum S. tuberosum, Prosimulium spp. and P. magnum. The procedure for storing the material prevented further identification of these organisms, but Coelomycidium simulii was reported from Simulium sp.,S. S. tuberosum, S. notiale Cnephiasp. The incidence of parasites did not appear significantly affected by temephos. Golini, V. I. (1975). Simuliidae (Diptera) of Rendalen, Norway, I. Eusimulium rendalense n.sp. and E. fallisi n.sp. feeding on ducks. Ent. scand., 6: 229-239. Four of 470 adult female Eusimulium rendalense and E. fallisi proved to harbour nematodes. *Golini, V. I. (1977). Simuliidae (Diptera) of Rendalen, Norway. III. Females of the Eusimulium rendalense complex infected withmermithids (Nematoda). Can. 755-758. One female Eusimulium rendalense and three E. fallisi, among nearly 470 simuliids captured from Anas boschas in Norway, were found naturally infected with mermithid nematodes. Two of these infected flies had fully fed on avian blood. The nematodes may be a species of the Gastromermis boophthorae complex Welch and Rubtzov. 119 Gordon, R. et al. (1976). Endocrine relations between larval Diptera and their mermithid parasites. 9th Ann. Mtg Soc. Invertebr. Pathol. & 1st Internatl Collog. Invertebr. Pathol. (Kingston, Ontario, Canada 29 August - 2 September 1976), Proceedings pp. 268-271. The endocrine system of overwintering larval Prosimulium mixtuVfuscum did not appear affected by mermithid parasitism. The latter, though, significantly affected DNA/RNA activity of the corpus allatum, as well as the volume and amount of neurosecretory material in the corpus cardiacum of Simulium venustum. Endocrine dysfunction in S. venustum constitutes a stressful effect of parasitism, explicable in terms of the nematode's more rapid development in the summer host than in the winter one. Studies were done to ascertain whether the insect growth regulator methoprene interfered with development of Reesimermis nielseni a mermithid parasite of larval mosquitos. Infectivity of preparasites and parasitic development were not affected by its application and host mortality was increased to approximately 1007. in methoprene-treated infected mosquitos. *Hansen, E. L. & Hansen, J. W. (1976). Parasitism of Simulium damnosum by Romanomermis culicivorax. IRCS Medical Science: Environmental Biology and Medicine; Experimental Animals; Microbiology, Parasitology and Infectious Diseases; Social and Occupational Medicine, 4: 508. Simulium damnosum larvae were penetrated by Romanomermis culicivorax in the laboratory at Bouake, Ivory Coast, and development of the worm in this abnormal host was demonstrated. Infections took place both in still water and in a recirculation system with moving water. *Eazard, E. I. & Oldacre, S. W. (1975). Revision of Microsporida (Protozoa) close to Thelohania with descriptions of one new family, eight new genera, and 13 new species. United States Department of Agriculture/Agricultural Service Technical Bulletin No. 1530, 104 pp. Pegmatheca simulii is described from larval Simulium tuberosum near Gainesville, Florida. *Hurtter, D. M. & Moorhouse, D. E. (1976). Sexual mosaics and mermithid parasitism in Austrosimulium bancrofti (Tayl.) (Diptera: Simuliidae). Bull. Entomol. Res., 65: 549-553. Six intersexes of Austrosimulium bancrofti, also some normal flies, harboured mermithid larvae in Queensland. Mermithids were also reported in adult A. pestilens and Simulium nicholsoni. *Lacey, L. A. & Mulla, M. S. (1977). Evaluation of Bacillus thuringiensis as a biocide of blackfly larvae (Diptera: Simuliidae). J. Invertebr. Pathol., 30: 46-49. In this Californian study, 13 strains of Bacillus thuringiensis were bioassayed against late-instar Simulium vittatum. All 13 strains caused significant blackfly mortality. Laird, M. (1975). Recent progress towards innovative procedures for vector control. Proc. 14th Ann. Mtg. Northwest Mosquito & Vector Control Assn., Vancouver, B.C., 8-10 October 1974, pp. 1-10. This review includes a summary of recent research concerning candidate blackfly biocontrol agents. 120 Le Berre, R. (1971). Parasitisme de Simulium damnosum par Mermithidae. C.-R. ler Multicolloque europden de parasitologie, Rennes, 1-4 September 1971, pp. 426-429. Mermithid-parasitized larvae of S. damnosum were found in rivers of Senegal, Mali, Upper Volta, Ivory Coast, Togo, and People's Republic of Benin. Eighty per cent. of nulliparous S. damnosum females were parasitized by mermithids on the Okpara River in Benin, and 507, on the River Monongo in Ivory Coast. Levchenko, N. G. (1975). §ew breeding grounds of microsporidiosis of blood-sucking mosquitoes and blackflies detected in Southeast and Central Kazakhstanj7 Izv. Akad. Nauk Kazakhsk. SSR (Biol.), Alma-Ata, No. 4, 48-50. (In Russ.) Thelohania sp. was found in about 6.6% of larval blackflies of the Bolshaya Bugun River and some 2-207. of those in the Djabagli and Aksu Rivers. In the Djungarski Alatayu, Plistophora sp. and Thelohania sp. parasitized from 107.-30% of the blackfly larvae sampled. The hosts are not named, and the species of Microsporida remain to be determined. *Levchenko, (1977). §iiew species of microsporidans, Thelohania assovi sp.nov. (Microsporida, Nosematidae), from larvae of blackfliesj7 Parazitologiva, 11: 272-275. (In Russ.) Thelohania assovi is described from a larval population of Odagmia sp. from mountain rivers of Tien-Shan and southeastern Kazakhstan. Up to 20% larval parasitism is recorded. *Levchenko, N. G. & Issi, I. V. (1973). 7Microsporida of blood-sucking Arthropoda] (In Russ.) In: Regulators of Numbers of Blopdsucking Flies in the Southeast of KazakhstanDubitskii, A. M. et al., eds., Institute of Zoology, Kazakh Academy of Sciences, Alma-Ata pp. 42-64 (an English translation of this book is currently in preparation at the National Institutes of Health, National Medical Library, Bethesda, Maryland, USA). Plistophora simulii is recorded from larvae and pupae of the blackfly Odagmia sp. from the River Turgen, and P. turgenica is described from the same host and locality. *Lewis, D. J. Bennett, G. F. (1975). The blackflies (Diptera: Simuliidae) of insular Newfoundland. III. Factors affecting the distribution and migration of larval simuliids in small streams on the Avalon Peninsula. Can. J. Zool., 53: 114-123. Neomesomermis flumenalis is recorded from Prosimulium fuscum/mixtum, Simulium latipes, and S. venustum. Thelohania fibrata was present in S. latipes and S. venustum. and Plistophora simulii in S. tuberosum and S. venustum. The last-mentioned host also harboured Thelohania bracteata, Thelohania sp. and Coelomycidium simulii. These parasites were found to be of little or no significance as factors affectimg the distribution and migration of simuliid larvae, vith respect to which, current, velocity substrate type, and water depth were important. Likhovoz, L. K. (1975).[On combined parasitizing of mermithids and microsporida inlarvae of blackfliesj7 Med. Parazitol. Parazit. Bolez-ni 44: 230-233. (In Russ.) *Liu, T. P. & Davies, D. M. (1973a). Ultrastructure of the frozen-etched polar filament in a microsporidan Thelohania bracteata (Strickland, 1913). Can. J. Zool., 51: 217-219. The polar filament of Thelohania bracteata has eight coils and possesses a double membrane. Fractured faces of each layer of this membrane bear many particles arranged in net-like pattern. This pattern distinguishes the polar filAment membrane from the spore membrane and other cytomembranes. The polar filament possesses a central tubular structure which is ringed by 12 microcylinders arranged symmetrically. The significance of these observations is discussed. 121 *Liu, T. P. & Davies, D. M. (1973b). Ultrastructural architecture and organization of the spore envelope during development in Thelohania bracteata (Strickland, 1913) after freeze- etching. J. Protozool., 20: 622-630. The mature spore coat is composed of numerous microfibres running parallel to the spore surface and possesses an outer and inner limiting membrane. The convex face of the outer limiting layer is granular and the convex face of the inner limiting layer bears many particles and long narrow depressions. The concave face of the inner limiting layer carries many stud-like projections complementary to the depressions on the convex face. The concave face subunits are apparently arranged in a hexagonal pattern. Changes in size of these projections, depressions, and subunits are presumably related to spore maturation. Maurand, J. (1975). Les Microsporidies des larves de Simulies. Ann. Parasitol., 50: 371-396 Ten microsporidan parasites of the genera Nosema Pleistophora. Thelohania Stempellia, Octosporea Weiseria and Caudospora are known as parasites of Simuliid larvae. All are intimate intracellular parasites which increase larval life span and respiratory rate. An acid mucosubstance rich in -SH groups appear during sporogeny of various species of Thelohania, Pleistophora and Stempellia. *Mokry, J. E. & Finney, J. R. (1977). Notes on the mermithid parasitism of Newfoundland blackflies, with the first record of Neomesomermis flumenalis from adult hosts. Can. J. Zool., 55: 1370-1372. Twenty-six of 221 female Prosimulium mixtum emerging from field-collected pupae were found to be parasitized by mermithids, but all 187 males examined were free from infection. The nematodes identified were Neomesomermis flumenalis (66.6%), Isomermis sp. (26.7%), and Gastromermis viridis (6.7%). Forty-three (22.2%) of 194 female Simulium venustum were parasitized. While all 134 males examined were unparasitized, three of 60 male pupae of S. venustum contained mermithids. The nematodes recovered from S. venustum were Hydromermis sp. (75%), G. viridis (12.5%), and N. flumenalis (12.5%). *Molloy, D. & Jamnback, H. (1975). Laboratory transmission of mermithids parasitic in blackflies. Mosq. News, 35: 337-342. As earlier demonstrated by another author, preparasitic Neomesomermis flumenalis were shown to parasitize larval blackflies by direct penetration of the integument. Laboratory transmission rates of about 807% for first instar Simulium vittatum larvae and 407. for second instars were achieved in a running water system, the presence of detritus being held important in maximizing infection, as it favoured retention of tm preparasitic nematodes at the blackfly breeding site. *Molloy, D. & Jamnback, H. (1977). A larval blackfly control field trial using mermithid parasites and its cost implications. Mosq. News, 37: 104-108. Treatment of a small stream with Neomesomermis flumenalis preparasites resulted in blackfly larval infection rates of up to 71.4%. Simulium venustum larvae were mre readily parasitized than S. vittatum. It was estimated that to achieve 90% parasitism in a 2.5 metre wide stream, approximately 3.6% x109 preparasites would have to be applied per mile (1.6 ki) of stream, the cost being prohibitive at this time. Mondet, B. & Poinar, Jr., G. 0. (1976). Recent developments on mermithid parasitism of Simulium dmnosum in West Africa. 9th Ann. Mtg. Soc. Invertebr. Pathol. &1st Internatl. Collog. Invertebr. Pathol. (Kingston, Ontario, Canada, 29 August - 2 September 1976), Proceedings, pp. 232n@5. 122 Representations of the genera Gastromermis, Isomermis and Mesomermis parasitized Siouliua damnosum and other associated blackflies in West Africa. One of these, a species of Gastromermis (G. philipponi - see Mondet et al. 1977) possesses a unique caudal appendage which breaks off during entry into the host. *Mondet, B. et al. (1976). Etude du parasitisme des simulies (Diptera) par des Mermithidae (Nematoda) en Afrique de l'Ouest. I. Observations preliminaires sur on cours d'eau temporaire de savanne. Cah. O.R.S.T.O.M. Ser. med. Parasitol., 14: 141-149. Five species of mermithids are now known from West African simuliids, including Simulium damnosum, but none of them show close host specificity. These preliminary observations ascribe the mermithids to the genera Neomesomermis, Gastromermis, and a new species (Mondet & Poinar corrected these identifications subsequently to Mesomermis Gastromermis, and Isomermis in their 1976 paper quoted below). The new species (Isomermis) in an isolated population of S. damnosum females achieved 75-80% infections of nulliparous specimens, and 20-35% of the entire population. Mondet, B. et al. (1977a). Etude du parasitisme des simulies (Diptera) par des Mermithidae (Nematoda) en Afrique de l'Ouest. III. Elevage de Isomermis sp. et infestation en laboratoire de Simulium damnosum. Cah. O.R.S.T.O.M. Ser. Ent. med. Parasitol., 15: 265-269. Mondet, B. et al. (1977b). Etude du parasitisme des simulies (Diptera, Simuliidae) par des Mermithidae (Nematoda) en Afrique de l'Ouest. II. Description de deux nouvelles especes de Gastromermis. Can. J. Zool., 55: 1275-1283. Gastromermis philipponi is described from larval Simulium damnosum. S. cervicornutum and S. adersi in Ivory Coast, and Gastromermis leberri is described from S. damnosum. S. cervicornutum, and S. hargreavesi in Mali and Upper Volta. *Muu, L. T. (1977). On the identity of the microsporidan parasites of Odagmia ornata (Meig.) (Diptera, Simuliidae). Vestn. Ceskoslov. spol. zool., 41: 45-51. On the basis of year-long studies of Odagmia ornata pathogens in Czechoslovakia this paper contends that five species of Thelohania and two of Pleistophora described as new from Simulium ornatum in southern England (by Gassouma, 1972 - see reference under Bailey et al. in Roberts & Strand, 1977) are referable to known species; Gassouma's Thelohania minuta and T. avacuolata being referable to T. bracteata (Strickland, 1913), his T. bertrami and T. canningi with T. varians (Leger, 1894), his T. simulii with T. fibrata (Strickland, 1913), his Pleistophora tillingbournei to P. simulii (Lutz & Splendore, 1904) and his P. leasei to P. debaisieuxi (Jirovec). *Man, E. A. et al. (1976). §xRerimentation with a fungus of the class Entomophthorales upon Simuliidae and Blepharoceridiaj Izv. Akad. Nauk Kazakhsk. SSR (Biol.), Alma-Ata, No. 5, pp. 12-15. (In Russ.) A new fungus referred to the Family Entomophthorales is recorded in this preliminary description from larval blackflies of the genera Prosimulium Eusimulium, and Tianshanella. The organism is not assigned to genus and species, which will be done in a subsequent paper. Nolan, R. A. (1975). Physiological studies with the fungus Saprolegnia megasperma isolated from the freshwater nematode Neomesomermis flumenalis. Can. J. Bot., 53: 3032-3040. Saprolegnia megasperma is recorded for the first time from Neomesomermis flumenalis and indeed from any freshwater nematode. It is pointed out that such microorganisms could affect the degree of success of mermithid introductions for biocontrol. 123 *Nolan, R. A. & Lewis, D. J. (1974>. Studies on Pythiopsis cymosa from Newfoundland. Trans. Br. mycol. Soc., 62: 163-179. Pythiopsos cymosa is recorded from a pupa of Prosimulium fuscum. Morphological and physiological studies are described, as was an unsuccessful attempt to infect larval blackflies in the laboratory (mingled Prosimulium fuscuumixtum and Cnephia mutata) by means of cysts of this fungus. Rubtov, I. A. (1971). Mermithids, entomophagous agents of blackflios and mosquitoes. C. -R. ler Multicolloque europden de parasitologie, Rennes, 1-4 September 1971, pp. 430. On prevailing knowledge, mermithids appear superior as candidate biocontrol agents to, for example, microsporidans or fungi; they should be able to be used practically in the near future, particularly because human manipulation could overcome their limited natural distribution. Claims that mermithids usually enter blackfly larvae perorally or "from the outside by using an onchostyle", also that these worms can exterminate blackfly populations from large rivers. Indicates existing knowledge of about 60 species of mermithids parasitizing blackflies, the most important genera being Mesomermis Isomermis and Gastromermis. Rubtsov, I. A. (1975). some goals of the studies of mermithids for biological control of blackfliesj7 Parazitologiia, 9: 299-300. (In Russ.) The paper advocates analysis of the haemolymph of mermithid-infected blackfly larvae towards identification of substances necessary for the creation of an artificial culture medium; and recommends exploitation of the cultivation of simuliid fat body tissue as a medium for in vitro growth. Recommends EM investigations of the system of such organs-and tissues as stichosomes, trophosomes, longitudinal chords and cuticles. RUVP (1972). First Biannual Report, Research Unit on Vector Pathology, Memorial University of Newfoundland, 31 December 1972. (Mimeogr.) 14 pp. RUVP (1973a). Second Biannual Report, Research Unit on Vector Pathology, Memorial University of Newfoundland, 30 June 1973. (Mimeogr.) 15 pp. RUVP (1973b). Third Biannual Report, Research Unit on Vector Pathology, Memorial University of Newfoundland, 31 December 1973. (Mimeogr.) 19 pp. .RUVP (1974). Fourth Biannual Report, Research Unit on Vector Pathology, Memorial University of Newfoundland, 30 June 1974. (Mimeogr;) 44 pp. RUVP (1975). Annual Report, Research Unit on Vector Pathology, Memorial University of Newfoundland. (Mimeogr.) 29 pp. RUVP (1976). Annual Report, Research Unit on Vector Pathology, Memorial University of Newfoundland. (Mimeogr.) 50 pp. These documents, widely distributed and available on request, detail the progress of investigations undertaken at the Memorial University of Newfoundland's Research Unit on Vector Pathology, and by consultants working in a project, supported by the International Development Research Centre, conducted jointly with the Institut de Recherches sur l'Onchocercose (Organisation.de Coordination et de Coopdration pour la Lutte contre les Grandes End6mies), Bouakd, Ivory Coast. 124 *Streett, D. A. (1977). Microsporidan infection in the blackfly Simulium vittatum. 10th Ann. Mtg. Soc. Invertebr. Pathol., East Lansing, Mich., 21-26 August 1977. Abstracts of Pa ers. 7. Amblyospora sp. is reported from 2% of a larval population of Simulium vittatum in Ohio, the primary site of infection appearing to be the fat body. *Unde,on, A. H. & Nolan, R. A. (1977). Ovarian infection and fungal spore oviposition in the blackfly Prosimulium mixtum. J. Invertebr. Pathol., 30: 97-98. An undetermined fungus is recorded from Prosimulium mixtum near St. John's Newfoundland, and some stages of its life history are described. 10.8X of 398 females exhibited fungal spores in their ovaries and lacked eggs altogether; the remainder were gravid. Caged flies deposited sporangia during what would otherwise have been the act of oviposition, upstream dispersal for which could lead to the maintenance of the pathogen population in a stream. *Weiser, J. (1976). The Plistophora debaisieuxi Xenoma. Z. Parasitenk., 48: 263-270. Syncytial and neoplastic xenomas were differentiated for (Plistophora) debaisieuxi in Odagmia ornata in Czechoslovakia. *Weiser, J. & Zizka, Z. (1975). Stages in sporogony of Plistophora debaisieuxi Jirovec (Microsporida). Acta Protozoologica, 14: 185-194. (Plistophora - Pleistophora debaisieuxi) was studied in Odagmia ornata in Czechoslovakia, and its sporogony is described in detail. Wenk, Von P. (1976). Koevolution von Ubertrlger und Parasit bei Simuliiden und Nematoden. Z. anpew. Ent., 82: 38-44. Dispersal of mermithids takes place in surviving blackfly adults (most parasitized larvae dying at the exit of the worms before pupation), when females of the latter fly upstream to oviposit, the parasite thus compensates for downstream riverinm drift.