Species Of Simulium Research Articles

The Simuliidae (Diptera) from Bougainville Island, Papua New Guinea.

Seven black fly species were identified, chiefly on the basis of reared adults, pupae and mature larvae collected from Bougainville Inland, Papua New Guinea. All were assigned to the genus Simulium Latreille s. 1. and were further classified into two subgenera, i.e., six species in Simulium (Morops) and one in Simulium (Gomphostilbia). S. (M.) noroense and S. (G.) hiroshii were newly recorded from Bougainville Island, and five other species were described as new species. Under the subgenus Morops, a new species-group was proposed.

Community Structure of Larval Black Flies (Diptera: Simuliidae) from the Avalon Peninsula, Newfoundland

This study, the last in a series, examines empirical relationships between the community structure of larval black flies from Newfoundland's Avalon Peninsula (Canada) and stream conditions. The primary emphasis is on spring and summer Simulium species. Principal component and correlation analyses were used to assess correlative relationships between species distribution and stream site variables. Fifty-five stream sites were sampled between May and August of 1987, 1988, and 1989. The spatial distribution of species examined was nonrandom and correlated with stream size (Simulium caledonense Adler & Currie, S. craigi Adler & Currie, S. tuberosum Lundström cytospecies AB, Prosimulium mixtum Syme & Davies) and proximity to lake outlets (S. tuberosum Lundström cytospecies FGH, S. vittatum complex Zetterstedt, S. decorum Walker). S. craigi, S. tuberosum AB, S. tuberosum FGH, and S. aureum Fries cytospecies C are reported from Newfoundland for the first time. Because this is the first cytotaxonomic investigation of the S. tuberosum complex from Newfoundland, notes on the cytology of the two sibling species are presented.

Induction of the prophenoloxidase-activating system of Simulium (Diptera: Simuliidae) following Onchocerca (Nematoda: Filarioidea) infection.

Trials were carried out to study the humoral immune response of blackflies to filariae following infection using the intrathoracic injection technique. An induced 66 kDa protein was abundant in the haemolymph of the European species Simulium ornatum following infection with bovine Onchocerca lienalis. This protein was apparently at higher concentrations in the haemolymph of sham-inoculated flies, i.e. flies that received sterile medium without the parasites. A molecule of the same size was also observed in the haemolymph of infected S. damnosum s.l. following infection with human O. volvulus or bovine O. ochengi. However, the level of this protein was lower in blackflies injected with microfilariae of bovine O. dukei. Unlike O. volvulus and O. ochengi this species is not transmitted by S. damnosum s.l. under natural conditions. No such reaction was observed if the African blackflies had received a sham inoculation. Feeding experiments with wild-caught nulliparous S. damnosum sl. on Onchocerca-infected cattle supported the results of the injection trials. The 66 kDa protein could only be found in the haemolymph of specimens infected via a blood meal. This 66 kDa molecule was identified as phenoloxidase. It appeared in the haemolymph due to the activation of the prophenoloxidase system following the filarial infection and we hypothesize that it may be sequestered by the parasites, as part of a non-self recognition system.

Natural Vectors of Three Bovine Onchocerca Species (Nematoda: Onchocercidae) and Seasonal Transmission by Three Blackfly Species (Diptera: Simuliidae) in Central Kyushu, Japan

Eleven blackfly species were examined in relation to the transmission of bovine onchocerciasis in central Kyushu, Japan. A total of 19,005 out of 47,746 females captured from June 1989 to June 1990 at two cattle sheds each in Oita and Kumamoto were dissected for their parities, infections with Onchocerca larvae, and intakes of Onchocerca microfilariae. Overall results showed that Simulium bidentatum (Shiraki), the predominant species, is a natural vector of the two bovine Onchocerca species, i.e., type I (O. sp.) in both localities and type II (probably O. gutturosa Neumann), in Oita, whereas S. kyushuense Takaoka and S. arakawae Matsumura serve as the primary vector of type III (O. lienalis Stiles) in Kumamoto and Oita, respectively. Simulium arakawae also plays a secondary role in the transmission of type I in Oita and of type III in Kumamoto. Despite the biting activities and microfilarial intakes observed throughout most of the entire year, the transmission of these bovine Onchocerca was restricted to the mild or warm months between May and November. The natural infections with mermithid, trematode, ciliates, and fungi occurred but their influence on the vector Simulium species was apparently small, if at all.

A new blackfly species of Simulium (Morops) from Solomon Islands, South Pacific (diptera: simuliidae).

A new blackfly species, Simulium (Morops) kerei sp. nov. is described based on male and pupal specimens collected from the Solomon Islands, South Pacific. This species is placed in the farciminis-group by the pupal gill consisting of 1 inflated, horn-like filament and 4 slender filaments. This species is unique in possessing the parameral hooks in the male genitalia which are absent in all the Papua New Guinean Morops species. From the known species of the farciminis-group, this species is easily distinguished by the absence of the distinct hair crest on the male fore basitarsus, and in the pupa by the plate-like terminal hooks, all terga well-sclerotized, and the normal, wall-pocket-shaped cocoon covering whole of the thorax and abdomen. This is the first record of the farciminis-group of the subgenus Morops from the Solomon Islands.

Blood-feeding host preferences of the isomorphic species Simulium venustum and S. truncatum.

Animal-baited traps, using fox, mink, rabbits and ducks, were used in host preference experiments in two habitats (Beach and Woods). A generalized linear model of blood-feeding host preference is presented to test for significant differences between the isomorphic species Simulium venustum and Simulium truncatum. The S. truncatum population peaked before that of S. venustum. On any given day the two species divided their blood-feeding efforts among the different hosts in the same proportions. On the Beach, fox was the preferred host at the beginning of the season, but by the end of the season flies fed with equal frequency on the fox and the mink. In the Woods fox remained the preferred host throughout the season (late May to early July). Possible reasons for these feeding trends are discussed.

The Salivary Gland Chromosomes of the Black fly Simulium (Simulium) singtamense (Diptera: Simuliidae).

Standard maps of polytene salivary gland chromosomes of black fly species Simulium (Simulium) singtamense have been prepared. It revealed normal simuliid complement of n=3 chromosomes. Two homologues of each polytene chromosomes are tightly synapsed and are provided with identifiable centromeres. First two chromosomes are metacentric while the third one is submetacentric. Characteristic landmarks of polytene chromosomes such as Balbiani Ring, nucleolar organiser, puff and characteristic banding patterns have been described and compared with those of congeneric species.

The Simuliidae (Diptera) of Sri Lanka. Descriptions of additional species of Simulium (Simulium), with a key for Sri Lankan species in the subgenus and a checklist for the country

This is the fifth and final paper in a series treating the Simuliidae of Sri Lanka, and it contains a checklist of the species in the country. In this paper are described three new species of Simulium (Simulium): all stages of Simulium subpalmatum and Simulium cruszi (except the larva) and the male and pupa of Simulium paranubis. The female, male, and pupa of Simulium (Simulium) consimile and S. (S.) striatum are redescribed and the larva of S. (S.) consimile is described for the first time. Taxonomic comparisons are made with related species and keys are provided to separate the eight Sri Lankan species in the subgenus.

Flow patterns around cocoons and pupae of black flies of the genusSimulium (Diptera : Simuliidae)

Flow patterns around structurally different cocoons and pupae of five species ofSimulium Latreille are described. Three features of the flow pattern common to all cocoons are; 1) a solenoidal vortex around the cocoon, 2) upward flow anterior (downstream) to the cocoon, and 3) one or two pairs of spiral-shaped vortices, which either touch or envelop the fill filaments of the pupa. The solenoidal vortex and the upward-spiralling, downstream vortices are common features of flow patterns around most bluff bodies submerged in a boundary layer. The proximity of the vortices to the fill filaments of all pupae suggests that these vortices are associated with gaseous exchange at the gill filaments.

Development of microfilariae of two bovine Onchocerca species in blackflies in Japan.

Injections of blackflies with two types of bovine Onchocerca microfilariae (so far regarded as different stages of O. gutturosa) obtained from engorged Simulium spp. and umbilical skins of a slaughtered cattle in Oita, Japan, were carried out to determine whether they can develop in blackflies to the third-stage larvae (L3). As a result, one type of microfilariae (i.e., long, slender and with uncoiled tail) developed in S. arakawae to the short L3 (478 μm long), while another type (short, thick and with a strongly coiled tail) developed to the elongate L3 (1, 100-1, 230 μm long) in two other Simulium species. Morphometric analysis of these L3 shows that the former type microfilariae are likely to include O. lienalis, whereas the latter represent an undescribed species, readily distinguishable from O. gutturosa and O. gibsoni so far reported from Japanese cattle.

Infections of blackflies (Diptera: Simuliidae) with three types of zoonotic Onchocerca larvae in Oita, Japan

Wild female blackflies were collected at five cattle sheds in Oita, southern Japan, where a human zoonotic onchocerciasis had occurred. Among the eight Simulium species captured, S. bidentatum was predominant, followed by S. arakawae. Natural infections with filarial larvae were found in 10.5-20% of the parous S. bidentatum collected at three cattle sheds, and also in 6% of the parous S. arakawae captured at one cattle shed. Only one infected S. arakawae harbored two third-stage larvae in the thorax while the others had 1-4 either first-or second-stage larvae in the thorax. Third-stage larvae obtained from wild flies maintained alive for 6-9 days after being collected are distinguished into three types of Onchocerca : type I recovered from S. bidentatum, S. arakawae and S. aokii is probably new, having an elongated body length (1, 075-1, 380 pm), and types II and III, recovered from S. bidentatum and S. arakawae respectively, are each indistinguishable from O. gutturosa and O. lienalis. It is suggested that due to its anthropophily as well as zoophily S. bidentatum is the most probable vector of zoonotic Onchocerca (either type I or II) which may be acquired by humans in the western suburbs of Oita.

Chromocentre polymorphism in polytene chromosomes of Simulium costatum (Diptera: Simuliidae)

The polytene chromosomes of the black fly species Simulium (Nevermannia) costatum are joined at the centromeres in a strongly heterochromatic chromocentre. Examination of the larval salivary gland chromosomes revealed two populations with a unique polymorphism for attachment to the chromocentre involving all centromeres. All three homologous pairs of chromosomes are polymorphic for centromeres that do not join to the chromocentre. Samples from one of these populations were large enough for thorough study. In this population, the attachment polymorphism is in Hardy-Weinberg equilibrium for two of the centromeres and was in the same frequency for 2 successive years of sampling. The polymorphism could be either primary, retained from an ancestral nonchromocentric state, or secondary, evolving independently or introduced via hybrid introgression. The evolution of chromocentres is discussed in the context of species in the Simulium vernum group.Key words: black fly, polytene chromosome, chromocentre, polymorphism, evolution.

Natural infections of Simulium bidentatum (diptera: simuliidae) with larvae of Onchocerca SPP., in relation to a human zoonotic onchocerciasis in Oita, Japan.

A total of 579 wild female flies belonging to eight species of Simulium were collected on human baits, in relation to the transmission of a human zoonotic onchocerciasis found in Oita, Japan. Simulium bidentatum was the most dominant species. Natural infections with filarial larvae were found in 11 of 449 S. bidentatum (or 6.5% of the parous flies) and in 1 of 23 S. aokii (or 10% of the parous flies). All the infected flies had 1-4 either first-, second-or early third-stage larvae in the thorax. Examination of third-stage larvae shows that S. bidentatum is infected with at least two species of Onchocerca. Our result represents the first record of natural Onchocerca infections in Japanese Simuliidae, and also suggests the possibility of S. bidentatum as the potential vector of zoonotic Onchocerca spp. to humans.

Cloning and characterization of a species-specific repetitive DNA sequence from Onchocerca armillata

Two clones, pOA1 and pOA5, have been isolated from a genomic DNA library prepared from pools of Onchocerca armillata adults in the plasmid vector pUC12. In dot-blot hybridisations, these two clones do not cross-hybridise significantly with total genomic DNA from O. volvulus, O. gutturosa, O. ochengi, O. gibsoni, O. lienalis, bovine, human, Culicoides nubeculosus, Simulium species or Brugia pahangi, but do hybridise with as little as 100 pg of DNA from two separate geographic isolates of O. armillata. The sequence of pOA1 and pOA5 has been determined and found to contain a repetitive DNA sequence 147 bp in length. These clones can be used as specific and sensitive DNA probes for the identification of O. armillata capable of identifying a single L3 larva.

The Simuliidae (Diptera) of Sri Lanka. Descriptions of species in the subgenera Eusimulium and Gomphostilbia of the genus Simulium

This paper on the Simuliidae of Sri Lanka provides notes on Simulium (Eusimulium) aureohirtum and describes three new species of Simulium (Gomphostilbia): Simulium krombeini, Simulium ela, and Simulium dola. The females of S. (G.) pattoni and Simulium (Gomphostilbia) ceylonicum comb.n. are redescribed and the males, pupae, and larvae are described for the first time. Keys are provided for separating the subgenera of Simulium and the species of Gomphostilbia in Sri Lanka. Some taxonomic comparisons are made with related Oriental species and a few biological notes are given.

Rearing black flies (Diptera: Simuliidae) in the laboratory: mass-scale in vitro membrane feeding and its application to collection of saliva and to parasitological and repellent studies.

A highly efficient, mass-scale in vitro membrane feeding system for black flies is described that has proven effective for 5 Simulium species exhibiting a wide range of blood-feeding preferences. Factors affecting feeding rate, such as type of membrane or blood used, addition of ATP, age of flies, and temperature differential, were examined for the species tested. Nearctic black flies could be stored at a cool temperature (ca. 7 °C) for up to 20 days with no significant decrease in feeding rates, while cool storage was detrimental to S. damnosum s.l., a tropical species. Saliva was collected from females as they fed on various nonblood sources such as tissue culture media, saline solutions, or distilled water. Repellent activity was evaluated for 6 commercial formulations of deet by using a “free-choice” system and counting actual bites through the membrane. Percent reduction of biting activity increased as the percentage of deet in the repellent increased. Attempts to infect simuliid females per os with 3 vertebrate pathogens— Onchocerca lienalis, Leucocytozoon smithi , and vesicular stomatitis virus (New Jersey serotype)—resulted in successful recovery of infective forms from the flies.

Occurrence of Simulium (Edwardsellum) damnosum s.l. (Diptera: Simuliidae) in nine river systems in Kenya.

Six river systems in Kenya were found to harbor Simulium damnosum Theobald s.l. Two CDC light traps, during 12-h overnight collections at the Isiukhu and Nzoia rivers, caught 3 and 116 adult S. damnosum s.l., respectively. Searches for aquatic stages of S. damnosum s.l. in the 9 river systems produced 15 species of Simulium. Simulium damnosum s.l. is reported here for the 1st time from the Lusumu (0°19′N, 34°35′E) and Nzoia (0°35′N, 34°48′E) rivers.

Seasonal Abundance of Anthropophilic Simuliidae from the Adirondack Mountains of New York State and Effectiveness of an Experimental Treatment Program Using Bacillus thuringiensis var. israeliensis

A 154-km2 study area near Loon Lake, Town of Franklin, Franklin County, N.Y., was used for sampling the nuisance activity and seasonal occurrence of anthropophilic Simuliidae within the Adirondack Park. Black flies were monitored at 47 sites on a biweekly or weekly basis throughout two consecutive flight seasons. Population data were acquired from over 1,800 10-min aerial, sweep-net collections of black flies swarming around stationary human collectors from 17 May–6 August 1982 and from 2 May–2 September 1983. Thirteen species in four genera of black flies were represented in combined collections of over 171,000 females. Of the 13 species collected, 12 represent new black fly distribution records for Franklin County, N.Y. Intensity and duration of predominant species' seasonal flight patterns were monitored and compared. In addition, mean numbers of black flies captured inside and outside a partially overlapping area that had been experimentally treated with Bacillus thuringiensis var. israeliensis ( Bti ) were compared on a weekly and seasonal basis. Despite evidence of effective control of several Simulium species, the application of Bti did not result in the control of anthropophilic Prosimulium .

THE SEASONAL ACTIVITY OF HEMATOPHAGOUS DIPTERA ATTACKING CATTLE IN INSULAR NEWFOUNDLAND

AbstractA cattle-baited (C-B) trap and a Trueman–McIver (T-M) segregating CO2 trap provided information on seasonal abundance, host-seeking activity, and blood-feeding of biting-flies near St. John's, Newfoundland. A total of 19 682 biting-flies (26 species) were collected (C-B trap = 11 407; T-M trap = 8275) from 26 May to 16 September 1982. Black-flies (Simuliidae) comprised 94.1% of the total sample (C-B trap = 10 747; T-M trap = 7773). Mosquitoes (Culicidae), biting midges (Ceratopogonidae), and tabanids (Tabanidae) comprised the remainder. Blood-fed flies represented 54.7% of the total catch in the C-B trap, but the proportion varied considerably among species. Black-fly activity was concentrated in June and July, though flies were also collected in May, August, and September. Prosimulium mixtum was the predominant species in June and Simulium venustum/verecundum complex was the major pest in July. Prosimulium mixtum was most active from mid-morning to late-afternoon, with little evening activity. Simulium venustum/verecundum complex showed 2 peaks of activity, one in the morning and another in the early evening. A few P. mixtum and S. venustum/verecundum complex were active after dark. Captures from the T-M and C-B traps were compared to test the reliability of the T-M trap as an indicator of activity of biting-flies attracted to cattle. Significant correlations (P < 0.001) between the number of flies collected in the 2 traps were found for P. mixtum and S. venustum/verecundum complex. Remaining species were taken in numbers too low for analysis.

Observations on the Limnological Factors Associated with Three Species of the Simulium jenningsi Group (Diptera:Simuliidae) in New York State

A survey of three species of Simulium (S. jenningsi, S. luggeri and S. fibrinflatum) was conducted from April to October, 1978, in the Adirondacks and Finger Lakes region of New York State. These species were distributed within the study area as follows: S. fibrinflatum, Adirondacks; S. luggeri, Finger Lakes region: and S. jenningsi, both areas. All three were found from June through September. Of the 21 limnological parameters studied, the most important in separating the species were pH and ionic concentration of the water. Simulium fibrinflatum occurred in mildly acidic to neutral, dilute streams whereas S. luggeri occurred in basic, rich streams. Simulium jenningsi was found in both types of streams.