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.

     

Fungal and oomycete parasites of Chironomidae,Ceratopogonidae and Simuliidae (Culicomorpha,Diptera)

Members of the families Chironomidae (chironomids or non-biting midges), Ceratopogonidae (ceratopogonids or biting midges) and Simuliidae (simulids or blackflies) are ubiquitous dipterans of the infraorder Culicomorpha. They are extremely diversified in ecological strategies. Their larvae play major roles in aquatic food webs as detritivores or predators, whereas their adults can be general predators (Chironomidae), hemolymphagous or hematophagous predators (Ceratopogonidae and Simuliidae) or pollinators. Both larval and adult stages are commonly infected by bacteria, viruses, protists, nematodes, true fungi and oomycetes. These phylogenetically diverse assemblages of microorganisms can simultaneously infect multiple species of chironomids, ceratopogonids and simulids, and each host may become trophically interrelated with other hosts by sharing their parasites. Here, we review the information on fungal and oomycete parasites of these dipteran groups with special reference to the natural regulation of host populations, the impact of parasitism in food webs, and the potential of these parasites as biocontrol agents.     

Detection of Leishmania amazonensis and Leishmania braziliensis in Culicoides (Diptera,Ceratopogonidae) in an endemic area of cutaneous leishmaniasis in the Brazilian Amazonia

Biting midges in the genus Culicoides act as vectors of arboviruses throughout the world and as vectors of filariasis in Latin America, the Caribbean, and parts of Africa. Although Culicoides spp. are currently not considered to be vectors of Leishmania protozoa, the high abundance of biting midges in areas with active cutaneous leishmaniasis transmission points to the possibility of Culicoides infection by these pathogens. We used PCR to test captured Culicoides species for natural infection with Leishmania spp. We tested 450 Culicoides females, divided into 30 pools of 15 individuals each, as follows: nine pools of C. foxi (135 specimens), seven pools of C. filariferus (105), seven pools of C. insignis (105), five pools of C. ignacioi (75), and two pools of C. flavivenula (30). PCR confirmed the presence of Leishmania braziliensis DNA in C. ignacioi (0.14%), C. insignis (0.14%), and C. foxi (0.11); and Le. amazonensis DNA in C. filariferus (0.14%) and C. flavivenula (0.50%). We conclude that these Culicoides species can be naturally infected, but vector competence and transmission capability must be confirmed in future studies. Our results warrant further investigation into the role of these biting midge species in the leishmaniasis epidemiological cycle.     

Efficacy of the Entomopathogenic Fungus, Culicinomyces clavisporus against Larvae of the Biting Midge, Culicoides nubeculosus (Diptera: Ceratopogonidae)

Culicinomyces clavisporus, a fungal pathogen of a wide range of mosquito species, was investigated in relation to potential pathogenicity against Culicoides nubeculosus biting midge larvae. Seven different C. clavisporus strains were assayed. Each showed some degree of activity against C. nubeculosus larvae with LC₅₀ values of between 3.2×10^-5 and 1.1×10^-6 spores/mL; these effects occurred in dose-dependent manners and tended to be delayed until 72-96 h post treatment. The results are discussed in relation to incorporation of C. clavisporus into biocontrol programmes for Culicoides spp.     

基于光学显微镜和扫描电镜的新替库蠓成虫形态观察(双翅目： 蠓科)(英文)

【目的】通过发现更多的形态特征,以实现库蠓属Culicoides近似种的准确鉴定和区分。【方法】利用扫描电镜和光学显微镜观察新替库蠓Culicoides newsteadi Austen成虫的形态特征细节,包括具有重要鉴定意义的结构特征,如两性成虫的复眼、触角、触须、口器、中胸盾板、小盾板、翅、后足胫节、爪和生殖器等结构。【结果】发现新替库蠓雌成虫具有6种触角感器,包括腔锥感器、短毛形感器、长毛形感器、刺形感器、直锥形感器和弯直锥形感器;雌雄成虫的盾斑均呈卵形;雄成虫的阳基侧突端部具复杂分支。雌成虫的复眼连接处距离为1.3个小眼面;雌成虫大颚呈剑状,具14~17枚三角形齿;雄成虫后足胫节具16~19枚端梳。【结论】通过光学显微镜和扫描电镜获得的形态特征不仅为蠓科的分类和系统发育研究提供更多的信息,而且为流行病研究和疾控工作提供更多的帮助,进而为蠓科昆虫形态信息的数字化、立体化和网络化提供资料。     

Effect of vertebrate feces on the attraction of Culicoides (Diptera: Ceratopogonidae) in an Amazonian mangrove

Biting midges are of interest to public health because they play an important role as vectors of disease‐causing pathogens, as well as being a biting nuisance to humans and domestic animals. Although these insects are common in mangrove areas, they have not yet been studied in this ecosystem in the state of Maranhão (MA), Brazil. The objective of this study was to characterize the Culicoides community structure found in a mangrove swamp and verify if the use of vertebrate feces as bait interferes with their composition, richness, abundance, or seasonality. CDC light traps with vertebrate (chicken, ox, control, donkey, capuchin monkey and pig) feces baits were used to capture biting midges in a mangrove area of the Island of São Luís, MA. A total of 4,087 individuals representing 22 species of Culicoides were captured, the most abundant being C. (Oecacta) furens Poey (23.46%), C. (gr. Fluviatilis) leopoldoi Ortiz (21.58%), C. (Hoffmania) ignacioi Forattini (16.98%), C. (Hoffmania) maruim Lutz (13.85%), C. (Diphaomyia) iriartei Fox (10.57%), C. (Hoffmania) insignis Lutz (7.07%), and C. (gr. Limai) limai Barreto (3.03%). Species richness and abundance were higher when baits of capuchin monkey (15 species; 26.84% of the individuals) and pig (15; 25.3%) feces were used. The least attractive baits were donkey (12 species; 9.3%) and ox (nine species; 11.52%) feces. Biting midges were more abundant in the rainy season (67%), but richness was higher in the dry season (19 species). These results show that vertebrate feces may serve as olfactory cues and increase the attraction of biting midges to traps.     

Evaluation of Metarhizium anisopliae for the control of Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae), the principal vector of bluetongue virus in Australia

Four isolates of the entomopathogenic fungus Metarhizium anisopliae were tested for their potential to control the biting midge Culicoides brevitarsis, the principal vector of bluetongue virus in Australia. Adult C. brevitarsis died three to eight days after walking on paper substrate treated with 0.7 g/m² conidia of any of the isolates, indicating that M. anisopliae has potential as a surface treatment or topical application control strategy. Incorporation of the fungus into freshly excreted cattle dung at rates of between 0.25 and 1 g conidia/kg reduced the emergence of adult midges by up to 98.5% compared to untreated dung indicating that M. anisopliae has the potential to control C. brevitarsis larvae in cattle dung. Three of the isolates produced similar mortality rates on adult and immature C. brevitarsis while the fourth isolate produced lower, but still significant, mortality rates on adult and immature stages.     

Evaluation of light-emitting diodes as attractant for sandflies (Diptera: Psychodidae: Phlebotominae) in northeastern Brazil

Hoover Pugedo light traps were modified for use with green and blue-light-emitting diodes to trap phlebotomine sandflies in northeastern Brazil. A total of 2,267 specimens belonging to eight genera and 15 species were sampled. The predominant species were Nyssomyia whitmani(34.41%) and Micropygomyia echinatopharynx(17.25%).The green LED trap prevailed over the blue and control lights; however, no statistically significant difference could be detected among the three light sources. Even without statistical significance, we suggest using LEDs as an attractant for the capture of sandflies because of several advantages over the conventional method with incandescent lamps.     

Ultrastructure of mediodorsal setae in biting midge larvae of the genus Atrichopogon Kieffer with notes on their biological significance (Diptera: Ceratopogonidae)

The ultrastructure of the strong mediodorsal setae in terrestrial stage IV larvae of Atrichopogon (Meloehelea) oedemerarum and A. (M.) meloesugans was examined using light, scanning and transmission electron microscopy. Serrated setae placed on prominent processes are distributed in pairs on all thoracic and abdominal segments. Setae are innervated by a single dendrite and their surface has no pores. The trichogen cell is not retracted from the setal lumen on completion of the hair-forming process but fills the mediodorsal seta also when the larval cuticle is fully sclerotised. Such a phenomenon was previously reported in terrestrial larvae of the genus Forcipomyia. We suggest that the mediodorsal setae described in Atrichopogon are plesiotypic mechanoreceptors for the subfamily Forcipomyiinae. They are preserved in the truly terrestrial larvae of Atrichopogon, but modified to secretory setae in the genus Forcipomyia. Both genera bearing distinct mediodorsal setae have developed functional tracheal gills, unknown in other biting midges.     

Descriptions of a new species and the pupae of two known species of Culicoides Latreille (Diptera: Ceratopogonidae) from India

Pupa, and adult male and female of Culicoides pseudosimilis n. sp., and pupae of two known species, C. selangorensis Wirth & Hubert, and C. dryadeus Wirth & Hubert, are described and illustrated. An identification key to the Indian species of Clavipalpis and Shermani species group of male Culicoides is also provided.     

Occurrence of Culicoides spp. (Diptera: Ceratopogonidae) in Tunisia, with emphasis on the bluetongue vector Culicoides imicola

Following the bluetongue (BT) outbreaks in Tunisia from 1999 to 2002, BTV (bluetongue virus) serotype 2 was isolated; however, no entomological investigation was performed. In the study presented here, we assessed the Culicoides species populations (particularly C. imicola) in proximity to the BT outbreaks locations, both as a retrospective analysis and to update the list of Culicoides species present in Tunisia. The insects were caught using light traps and the species identification was performed according to the standard entomological methods. This study reveaaled the presence of significant numbers of C. imicola in all the tested locations. In addition, we reported a new Culicoides species for the Tunisian fauna C. punctatus.     

The dying of the light: crepuscular activity in Culicoides and impact on light trap efficacy at temperate latitudes

The light trap is the tool of choice for conducting large‐scale Culicoides (Diptera: Ceratopogonidae) vector surveillance programmes. Its efficacy is in doubt, however. To assess this, hourly changes in Culicoides activity over the 24‐h diel were determined comparatively by way of light trapping and aerial sweeping, and correlated against light intensity. In the Netherlands, sweeping around cattle at pasture revealed that, in early summer, Culicoides are active throughout the diel, and that their abundance peaks during the crepuscular period and falls to a low during the brightest hours of the day. By contrast, the light trap was able to accumulate Culicoides only at night (i.e. after illuminance levels had dropped to 0 lux and midge activity had begun to decline). Although Culicoides chiopterus and species of the Culicoides obsoletus complex were similarly abundant around livestock, they differed critically in their hours of peak activity, being largely diurnal and nocturnal, respectively. This polarity helps to explain why, routinely, the C. obsoletus complex dominates light trap collections and C. chiopterus does not. Inability to accumulate Culicoides at light intensity levels above 0 lux means that, at ever‐higher latitudes, particularly beyond 45° N, the progressive northward lengthening of the twilight period will have an increasingly adverse impact upon the efficacy of the light trap as a vector surveillance tool.     

Ecological aspects of mosquitoes (Diptera: Culicidae) in an Atlantic forest area on the north coast of Rio Grande do Sul State,Brazil

Mosquito diversity was determined in an area located on the southern limit of the Atlantic Forest on the north coast of Rio Grande of Sul State. Our major objective was to verify the composition, diversity, and temporal distribution of the mosquito fauna, and the influence of temperature and rainfall. Samplings were performed monthly between December, 2006 and December, 2008, in three biotopes: forest, urban area, and transition area, using CDC light traps and a Nasci vacuum. A total of 2,376 specimens was collected, from which 1,766 (74.32%) were identified as 55 different species belonging to ten genera. Culex lygrus, Aedes serratus, and Aedes nubilus were dominant (eudominant) and constant throughout samplings. The forest environment presented the highest species dominance (D_S=0.20), while the transition area showed the highest values of diversity (H'=2.55) and evenness (J'=0.85). These two environments were the most similar, according to the Morisita‐Horn Index (I_M‐H=0.35). Bootstrap estimates showed that 87.3% of the species occurring in the region were detected. The seasonal pattern showed a greater abundance of mosquitoes between May and October, indicating the period to intensify entomological surveillance in that area.     

First report of Culicoides boyi (Diptera: Ceratopogonidae) in France

Culicoides boyi Nielsen, Kristensen & Pape 2015 (Diptera: Ceratopogonidae), described in Denmark in 2015, is reported in France. This species is closely related to Culicoides pulicaris (Linnaeus 1758) and can only be distinguished from this species by a subtle variation in spot wing pattern and by calculation of maxillary palpal ratio.     

The Mondrian matrix: Culicoides biting midge abundance and seasonal incidence during the 2006–2008 epidemic of bluetongue in the Netherlands

During the northern Europe epidemic of bluetongue (BT), Onderstepoort‐type blacklight traps were used to capture Culicoides Latreille (Diptera: Ceratopogonidae) biting midges weekly between November 2006 and December 2008 on 21 livestock farms in the Netherlands. Proven and potential vectors for the bluetongue virus (BTV) comprised almost 80% of the midges collected: the Obsoletus complex, constituting C. obsoletus (Meigen) and C. scoticus Downes & Kettle (44.2%), C. dewulfi Goetghebuer (16.4%), C. chiopterus (Meigen) (16.3%) and C. pulicaris (Linnaeus) (0.1%). Half of the 24 commonest species of Culicoides captured completed only one (univoltine) or two (bivoltine) generations annually, whereas multivoltine species (including all BTV vectors) cycled through five to six generations (exceeding the one to four generations calculated in earlier decades). Whether this increment signals a change in the phenology of northern Europe Culicoides or simply is an adaptive response that manifests during warmer episodes, thus heightening periodically the incursive potential of midge‐borne arboviruses, remains to be clarified. Culicoides duddingstoni Kettle & Lawson, C. grisescens Edwards, C. maritimus Kieffer, C. pallidicornis Kieffer and C. riethi Kieffer are new records for the biting midge fauna of the Netherlands. It is suggested that C. punctatus (Meigen) be added to the European list of vector Culicoides.     

Laboratory Culture and Life History of Heleidomermis magnapapula in Its Host, Culicoides variipennis (Diptera: Ceratopogonidae)

The mermithid parasite Heleidomermis magnapapula was maintained in larvae of the midge Culicoides variipennis for 20 months in enamel pans containing nutrient-rich water and polyester pads as a substrate. Inseminated female mermithids were introduced to the pad surface when the host was in the late second or early third-instar. Host larvae were harvested from the pans 9 days after exposure and held in tap water for nematode emergence. Preparasite yield was positively correlated with female nematode size and averaged 1,267 preparasites/female. Male and female nematodes emerged an average of 12.2 and 13.4 days after host exposure, respectively. Supplemental host food (Panagrellus) during the final days of parasitism did not alter time of emergence. Parasites emerging singly were 64% females, whereas superparasitized hosts yielded males (up to nine/host). Nematode carryover into the adult midge normally occurred at a level of 0.5-2.5%. Parasite load (nematodes/ parasitized individual) in midge adults was lower than that of larvae from the same cohort, and adult midges were more likely to harbor female parasites. Exposure of fourth-instar host larvae resulted in higher levels of adult parasitism (up to 17%).