Description of the Pupa of Culicoides crucifer Clastrier (Diptera: Ceratopogonidae)

The pupa of Culicoides crucifer Clastrier is described, illustrated and photomicrographed by using binocular microscope and phase-contrast microscopy from material collected in an artificial container in Manaus, Brazil. The pupa shows features typical of pupae occurring in calm and clean waters, and it is compared with its similar congeners of the subgenus Haematomyiidium, Culicoides annuliductus Wirth and Culicoides debilipalpis Lutz.     

A new Culicoides (Diptera:Ceratopogonidae) of the subgenus Diphaomyia from Peru

A new species of Culicoides of the subgenus Diphaomyia, Culicoides jurbergi Felippe-Bauer, is described and illustrated based on female specimens collected biting man and with light traps in Peruvian Amazonia. The species is compared with its similar congener mirsae Ortiz.     

Effects of seawater components on immature Culicoides molestus (Skuse) (Diptera: Ceratopogonidae)

Abstract Following analysis of beach sites and an indication that seawater components might influence larval occurrence, we studied the impact of increasing salinity and seawater concentration on survival of fourth-instar larvae of the canal biting midge, Culicoides molestus . While NaCl had little effect on immature survival, increasing the concentration of seawater increased mortality prior to the adult stage. Seawater at three and four times the normal concentration killed all immatures. Artificial elevation of seawater concentration in the sandy substrate preferred by larvae, therefore, has the potential to reduce immature midge survival. Diet also affected survival, with higher mortality of immatures that were fed fish-food flakes compared with those that were fed live nematodes.     

A new Culicoides from the Amazonian region, Brazil (Diptera: Ceratopogonidae)

A new Neotropical species of biting midge Culicoides (Haematomyidium), C. kampa Felippe-Bauer, Veras & Castellon, is described and illustrated based on female specimens from the Amazonian Region.     

Five new species of Culicoides (Diptera: Ceratopogonidae) of the Nansei Islands.

Five new species of Culicoides of the Nansei Islands are described: C. sasai sp.n. from Amami-oshima Is., C. toshiokai sp.n. from Ishigaki Is., C. iriomotensis sp.n. from Iriomote Is., C. flavipunctatus sp.n. from Yonaguni Is., and C. yaeyamaensis sp.n. from the latter three islands. C. toshiokai sp.n. and C. iriomotensis sp.n. are tree-hole breeders, such as C. dendrophilus Amosova, which is common in similar habitats extending from Okinawa to Honshu.     

Interactions between dung beetles (Coleoptera: Scarabaeidae) and the arbovirus vector Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae)

Abstract  The potential for dung beetles to reduce populations of the biting midge and arbovirus vector Culicoides brevitarsis in bovine dung was studied in the Hunter Valley, New South Wales (NSW) between 1999 and 2003 using natural populations of insects. Preliminary work to develop experimental procedures showed that: a few C. brevitarsis could survive in buried dung; dung beetles and C. brevitarsis coming to dung were unaffected by a background of shade-cloth used experimentally to prevent dung burial; the most abundant dung beetle, Onthophagus gazella L. and C. brevitarsis oviposition occurred concurrently in the first 2 d after dung deposition, and the potential for interaction between dung beetles and C. brevitarsis was greatest in open pasture adjacent to trees where cattle congregate at night. Laboratory experiments on dung burial showed that C. brevitarsis numbers decreased as numbers of dung beetles increased or as the dry weight of dung decreased due to burial. This was seldom reflected in the field where, although significant burial occurred experimentally in 9 of 20 trials over 3 years, a significant decline in C. brevitarsis numbers attributable to burial only occurred once. C. brevitarsis numbers in the field were lower in unburied dung in 70% of trials. Differences were significant twice and were considered the result of dung disturbance. In the laboratory, decreasing numbers of C. brevitarsis were related to three characteristics of disturbance: the flattening, spreading and reduction in wet weight of the dung. Evidence of C. brevitarsis activity throughout coastal NSW suggests that, while C. brevitarsis numbers may be modified by dung beetles, the interaction is insufficient to prevent their increase, spread and ability to transmit viruses to livestock.     

Cell lines from Culicoides variipennis (Diptera: Ceratopogonidae) support replication of bluetongue virus

Cell lines have been developed from 2-day-old embryos of the biting midge, Culicoides variipennis (Diptera: Ceratopogonidae). In North America C. variipennis is the primary insect vector of bluetongue virus (BTV), an orbivirus that causes disease of ruminants. The C. variipennis (CuVa) cells, grown in Schneider's Drosophila medium, consist primarily of a fibroblast-like cell type. CuVa cells are very hardy. They can grow over a wide range of temperature and pH and adapt to growth in minimal essential medium. BTV replicates to high titer (7.5-8.0 log10 50% tissue culture infectious doses/ml) in CuVa cells over a wide range of temperatures (19 degrees to 37 degrees C) without inducing any significant cytopathic effects. The highest BTV titers were obtained in CuVa cells grown at 25 degrees and 32 degrees C. Cells from C. variipennis can be useful for many diverse investigations.     

Characteristics of Culicoides (Diptera, Ceratopogonidae) breeding places near Salisbury, Rhodesia

Abstract. 1. A survey of Culicoides breeding places was made around Salisbury. Out of forty species caught in light traps, only nineteen were reared from breeding places.
2. The seven most abundant species with their characteristic sites were C.pycnostictw in mud around water bodies, especially dams; C.nivosus very prevalent around puddles rich in organic matter: C. distinctipennis along drainage canals intermediate in organic matter; C.gulbenkiani in cow dung especially on damp soil; Caccraensis gp. only in rot holes and tree forks; Cschultzei gp. along streams and drainage canals in mud rather poor in organic matter; C.tropi-calis in drainage canals very low in organic matter; C.imicola possibly breeds widely dispersed mainly in a rich mixture of organic matter and damp soil, with cow pats and edges of water bodies being marginal.
3. The prevalent species are believed to breed all year round. Preponderance of females in the breeding places was found in C.pycnostictus, C.nivosus and C.accraensis gp. while the reverse was true in C.distinctipennis and C.gulbenkiani. The preponderance of males as indication of proximity to breeding sites is thus probably questionable.     

Occurrence of immature Culicoides molestus (Skuse) (Diptera: Ceratopogonidae) in relation to habitat characteristics

Abstract Analysis of beach sites on the Gold Coast, Australia, found that 14 physical and chemical habitat characteristics differed significantly between sites where numerous immatures of the canal biting midge, Culicoides molestus (Skuse), were found and sites where no midge immatures occurred. Five of the chemical factors found to reliably distinguish C. molestus habitat are major components of seawater, while another, electrical conductivity, is related to the concentration of seawater components. Calcium was the only one of the six primary components of seawater that was not a statistically significant correlate of C. molestus habitation by sand analysis. It is likely that a causative variable in occurrence of immatures is the concentration of seawater present in canals, because larvae are found where seawater component concentration is low in relation to uninhabited sites of similar appearance.     

The swarming behaviour of the Scottish biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae)

Abstract.

• 1 Swarms of Culicoides impunctatus males were examined in the field in Scotland. Most swarms were close to midge emergence/breeding grounds over a variety of vegetation, some of which clearly acted as swarm markers. Low light (0–1000 lux) and still/humid conditions favoured swarming.
• 2 Swarm size ranged between less than 10 and more than one thousand midges. The modal size was 200 individuals. The smallest swarms were usually columnar in shape and the larger swarms ovoid.
• 3 Midges behaved individually within swarms, moving in an elliptical manner characteristic of other dipterans in swarms.
• 4 Swarms were classified as either ‘persistent’ or ‘transient’ in terms of their shape, size and stability. Wind was the most influential factor in disrupting swarms.
• 5 Swarms were confirmed as mating sites for C.impunctatus.

     

Modelling the Northward Expansion of Culicoides sonorensis (Diptera: Ceratopogonidae) under Future Climate Scenarios

Climate change is affecting the distribution of pathogens and their arthropod vectors worldwide, particularly at northern latitudes. The distribution of Culicoides sonorensis (Diptera: Ceratopogonidae) plays a key role in affecting the emergence and spread of significant vector borne diseases such as Bluetongue (BT) and Epizootic Hemorrhagic Disease (EHD) at the border between USA and Canada. We used 50 presence points for C. sonorensis collected in Montana (USA) and south-central Alberta (Canada) between 2002 and 2012, together with monthly climatic and environmental predictors to develop a series of alternative maximum entropy distribution models. The best distribution model under current climatic conditions was selected through the Akaike Information Criterion, and included four predictors: Vapour Pressure Deficit of July, standard deviation of Elevation, Land Cover and mean Precipitation of May. This model was then projected into three climate change scenarios adopted by the IPCC in its 5^th assessment report and defined as Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5. Climate change data for each predictor and each RCP were calculated for two time points pooling decadal data around each one of them: 2030 (2021–2040) and 2050 (2041–2060). Our projections showed that the areas predicted to be at moderate-high probability of C. sonorensis occurrence would increase from the baseline scenario to 2030 and from 2030 to 2050 for each RCP. The projection also indicated that the current northern limit of C. sonorensis distribution is expected to move northwards to above 53°N. This may indicate an increased risk of Culicoides-borne diseases occurrence over the next decades, particularly at the USA-Canada border, as a result of changes which favor C. sonorensis presence when associated to other factors (i.e. host and pathogen factors). Recent observations of EHD outbreaks in northern Montana and southern Alberta supported our projections and considerations. The results of this study can inform the development of cost effective surveillance programs, targeting areas within the predicted limits of C. sonorensis geographical occurrence under current and future climatic conditions.