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At least 19 recordsLinked to original sources
PubMed1989

[Aegla platensis Schmitt, 1942 (Decapoda: Anomura) a predator of immature stages of Simuliidae (Diptera: Culicomorpha)].

For the first time, preferential predation of larvae and pupae of Simuliidae by the crustacean, Aegla platensis Schmitt, 1942, was observed in the field and in the laboratory. Field observations and collections were done in the Carpintaria stream, Dois Irmãos, Country Rio Grande do Sul, Brazil. The possibility of using this freshwater crab in an integrated control of Simuliidae is discussed.

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PubMed1977

A synopsis of the nematodes occurring in blackflies (Diptera: Simuliidae).

Larvae, pupae, and adult blackflies (Simuliidae) are capable of harbouring several groups of nematodes. Multiple parasitism involving nematodes of the same or different species, or various developmental stages of the same nematode may also occur. Thus, blackflies can serve as paratenic, intermediate, or definitive hosts of nematodes. The present study reviews the literature pertaining to the association between nematodes and Simuliidae and provides a key to various groups of nematodes found in blackflies. Emphasis is placed on the commoner filarial and mermithid nematodes, but several other unusual and rare roundworm parasites are also discussed.

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PubMed1992

Biological transmission of vesicular stomatitis virus (New Jersey) by Simulium vittatum (Diptera: Simuliidae).

Simulium vittatum females were shown to be competent vectors for the New Jersey serotype (VSNJ) of vesicular stomatitis virus (Camp Verde strain). Seventy percent of females infected intrathoracically transmitted infectious virions in their saliva after a 10-d incubation period. When infected with virus per os, 63% of the flies tested were positive at day 10, and 45% of flies infected in this manner also secreted virus in their saliva by day 9 or 10 after infection. When ingested by S. vittatum females, VSNJ virus readily replicated and increased from a mean baseline titer of 1.2 x 10(4) pfu per fly to 3 x 10(4) pfu per fly on day 10. An eclipse phase was demonstrated between approximately 18 and 48 h postinfection. This experimental evidence supports the hypothesis that black flies play a major role in the epizootic transmission of VSNJ. This is also the first confirmed example of biological transmission of an arbovirus by a member of the Simuliidae.

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PubMed1989

Assessment of a silhouette trap for sampling zoophilic blackflies (Diptera: Simuliidae).

A collapsible animal-type silhouette trap was designed to catch zoophilic female blackflies (Diptera: Simuliidae) which feed on the head or ventral surface of cattle. The trap was assessed for its ability to sample attacking blackflies by comparison with simultaneous manual catches from a bait cow, in an enzootic bovine onchocerciasis area in North Wales. In thirteen 1-hour collections, the trap provided a representative sample of the blackfly population in terms of the relative abundance of species. There was a strong correlation between the catch sizes from both methods (r = +0.73), and the body site feeding preferences for all species were similar with both trap and cow. There was no significant difference between the Onchocerca spp. infection rates of flies caught by either method.

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PubMed1992

[Small-scale evaluation of the efficacy of growth-regulating insecticides on larvae of the Simulium damnosum complex (Diptera: Simuliidae)].

The efficacy of insect growth regulators was assessed in small scale tests on larvae of the Simulium damnosum complex (Diptera: Simuliidae) in the Ivory Coast. Three compounds [OMS 2015 (triflumuron), OMS 3009 (teflubenzuron), OMS 3013 (chlorfluazuron)] belong to the group of benzoylphenyl-urea substitutes; these IGR's are supposed to inhibit chitin synthesis. Two other compounds are Juvenile Hormone Analogs (JHA's) (OMS 3007 and OMS 3019). The last compound (OMS 3010) is a phenoxycarbamate. The first three compounds had a low efficacy on blackfly larvae, which is consistent with the literature data for another compound of this group: diflubenzuron. The other three compounds (OMS 3007, OMS 3010 and OMS 3019) were much more efficient, OMS 3010 and OMS 3019 showing high activity at low concentrations. These results would justify further studies on the effect of larval age and exposure parameters, and eventually full scale river tests.

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PubMed1989

The development of Onchocerca ochengi in surrogate temperate Simuliidae, with a note on the infective larva.

Laboratory reared nulliparous female flies of six temperate species of Simuliidae were examined for their susceptibility to infection with Onchocerca ochengi by intrathoracic injection of cryopreserved skin microfilariae obtained from cattle in Mali. Three species (S. equinum, S. ornatum and S. erythrocephalum) supported development to the infective stage, one species (S. variegatum) allowed partial development and the remaining two species (S. reptans and S. aureum) were insusceptible to infection. The most suitable surrogate vectors were S. equinum and S. ornatum which had survival rates of 44% and 49%, proportions of microfilariae developing to third stage larvae of 6.4% and 3%, and infection rates with infective larvae of 13.5% and 14% respectively. O. volvulus infective larvae, produced by intrathoracic microfilarial injection in S. ornatum, were 586-760 microns (mean 687 microns) long and were significantly shorter (p less than 0.02) than the O. ochengi infective larvae (645-880 microns, mean 756 microns). No constant differences in the posterior or anterior morphology, or in the acid phosphatase staining patterns between O. ochengi and O. volvulus, were seen. These results raise the possibility that the presence of O. ochengi in a population of infective larvae from vector flies in endemic onchocerciasis zones might be identifiable on the basis of their length alone.

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PubMed1976

A simplified membrane technique for feeding blackflies (Diptera: Simuliidae) on blood in the laboratory.

In order to overcome the difficulties of colonizing Simuliidae in the laboratory, a membrane system has been developed which was successfully used to feed Simulium vittatum and S. verecundum on out-dated human whole blood. Thirty-seven (41.1%) of 90 S. vittatum and 4 (8.6%) of 46 S. verecundum took blood meals in 6 trials. The membrane system was also shown to be more effective and consistent in providing blood meals compared with the use of laboratory animals.

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PubMed1986

Acquired resistance to Onchocerca lienalis infections in Simulium ornatum Meigen and Simulium lineatum Meigen following passive transfer of haemolymph from previously infected simuliids (Diptera, Simuliidae).

This study describes experiments which demonstrate the presence of a parasite-induced or derived factor in the haemocoel of Onchocerca lienalis-infected simuliids. Haemolymph, when transferred from previously infected donor flies to previously untreated recipient flies, using fine glass needles, confers protection against a subsequent challenge to the recipients. In three trials using Simulium ornatum sl. or S. lineatum, significant levels of protection in 'immunized' compared to 'challenge control' groups were achieved (84% and 81% with S. ornatum sl. and 85% with S. lineatum). This is despite the fact that the worm burdens of the infected donor groups in the three trials were very different (means of 33.1 and 3.4 larvae/fly with S. ornatum sl. and 1.6 larvae/fly with S. lineatum). The use of sham-operated and bentonite-inoculated control groups demonstrate that this effect is not merely a non-specific reaction to trauma, but is probably parasitic in its derivation. The use of double infections separated by 4 days shows that the donor flies have themselves probably acquired resistance to O. lienalis. Frequency distributions of O. lienalis burdens in individual flies show that there is a shift from a normal to a skew distribution when comparing 'challenge control' flies with 'immunized'. This possible acquired resistance could have important implications in the transmission of forest and savanna human onchocerciasis by the Simulium damnosum complex.

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PubMed1988

The vectoral role of several blackfly species (Diptera: Simuliidae) in relation to human onchocerciasis in the Sierra Parima and Upper Orinoco regions of Venezuela.

Experimental and natural infections with Onchocerca volvulus were studied in several anthropophilic blackfly species present in the endemic area of the Upper Orinoco region of Venezuela. When fed on four different Yanomami volunteers in the Sierra Parima, the total infection rate was 31.4% for Simulium guianense in comparison with 7.5% for S. limbatum. The proportion of ingested microfilariae that entered the thorax during the first 24 hours and completed development to the infective stage was also much lower in the latter than in the former species. There was no larval development of O. volvulus in S. antillarum, but one female harboured in its head six infective larvae of a zoonotic filaria. When S. oyapokense s.l. was fed on an infected volunteer in the Upper Orinoco most flies ingested few microfilariae, and further development reached only the L1 stage. Natural infection and infectivity rates for S. guianense in two localities of the Sierra Parima were 0.2-4.0% and 1.3-10.2%, respectively, more than 50% of the L3 larvae being in the head. The corresponding data for S. oyapockense s.l. in the Upper Orinoco were 0.1-0.5%, although the only L3 larva found did not correspond to O. volvulus. It is suggested that S. guianense is the main vector of onchocerciasis in the Sierra Parima and that S. limbatum could play a secondary role. Simulium oyapockense s.l. replaces them in the Upper Orinoco and may maintain a degree of transmission, but its epidemiological importance remains to be assessed.

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PubMed1992

Studies on environmentally-induced colour variation in Simulium sirbanum (Diptera: Simuliidae) using a portable rearing system.

Previous studies on the morphological identification of adult female Simulium damnosum s.l. have involved use of colour characters. To determine the degree to which these qualitative characters are influenced by the physical environment, a portable rearing system was constructed. Wild-caught female flies and flies emerging from pupae maintained at ambient temperatures or above showed entirely pale antennae, fore-coxae, wing-tufts and hairs on the scutellum and ninth abdominal tergite, as is normal for S. sirbanum. Adults reared from larvae at below ambient temperatures were also pale, except for the antennae which were dark in all specimens. Adult females emerging from pupae maintained at below ambient temperatures were entirely pale up to the fourth day of emergence and mostly with dark antennae. The biological significance and the implications to the morphological identification of the savannah species of the S. damnosum complex in West Africa are discussed.

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PubMed1991

Life cycle of Simulium jenningsi (Diptera: Simuliidae) in southern West Virginia.

The life cycle of Simulium jenningsi Malloch was compared at two study sites representing the largest and smallest streams (New River and Indian Creek, respectively) where this species is known to breed in southern West Virginia. Larvae first appeared in March, and the first generation emerged in April, followed by two to four more generations by September. A few larvae and adults persisted in autumn, then the population overwintered in the egg stage. There were considerable differences in life cycle at the two study sites. In the New River, emergence of the first generation was 2-3 wk earlier, there were five generations rather than three, and the last larvae of the season persisted 1 mo later as compared with Indian Creek. Warmer temperature and higher quality food in the New River are probable explanations for differences in life cycle. Effective pest management of this species will require larviciding at frequent intervals (1-2 wk) from April through September in many streams over a broad geographic area because of the species' nonsynchronous life cycle, occurrence in different size streams, and strong dispersal ability.

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