scholarly journals Etudes préliminaires sur les préférences de site d'oviposition de Culicoides imicola

2009 ◽  
Vol 62 (2-4) ◽  
pp. 108
Author(s):  
Gert J. Venter ◽  
S. Boikanyo
Keyword(s):  
Light Trap ◽  
Oviposition Preference ◽  
Petri Dish ◽  
Additional Treatment ◽  
African Horse Sickness ◽  
Culicoides Species ◽  
Direct Sunlight ◽  
Culicoides Imicola ◽  
Oviposition Sites ◽  
Chloride Concentrations

Light trap collections have shown that Culicoides imicola, con­sidered a vector of both African horse sickness and bluetongue viruses is the most widespread and abundant livestock-associated Culicoides species in South Africa. Despite this, relatively little is known about the biology of this Culicoides species. A labora­tory study was undertaken to clarify the oviposition preference of C. imicola. Field collected midges were fed on defibrinated ovine blood. Blood engorged females were offered a choice of differently treated oviposition surfaces. The artificial oviposition device consisted of a plastic Petri dish (35 mm diameter) with a double layer of filter paper on top of tamped-down moist cotton-wool at the bottom of the holding container. This provided an even surface on which eggs could be laid. Salt (sodium chloride) concentrations varying from 0.003 to 3.0 g/10 mL and infusions of sheep, horse, zebra and bovine dung were compared. In an additional treatment, engorged females were given a choice between oviposition surfaces heated to 22°C and 25°C. All treat­ments were done in duplicate. Flies were kept at 23.5°C and the first eggs were usually deposited after three days. Results showed that C. imicola preferred oviposition sites with a salt concentra­tion below 0.06 g/10 mL. Extracts of horse dung were preferred and increased the notion that horses are the preferred host of C. imicola. It was also found that there was a preference for the 25°C surface, which supports the idea that C. imicola will rather oviposit in areas heated by direct sunlight than in shaded areas.

scholarly journals Surveillance entomologique de la fièvre catarrhale ovine en Algérie

2009 ◽  
Vol 62 (2-4) ◽  
pp. 141 ◽  
Author(s):  
M. Djerbal ◽  
Jean-Claude Delecolle
Keyword(s):  
African Horse Sickness ◽  
Culicoides Species ◽  
Old World ◽  
Culicoides Imicola ◽  
Virus Serotype ◽  
Weak Activity ◽  
June July ◽  
First Time ◽  
Second Period

Culicoides imicola is the major Old World vector of the arbovi­ruses that caused African horse sickness and bluetongue (BT). BT was observed for the first time in Algeria in 2000. BT virus serotype 2 (BTV-2) was then reported, whereas BTV-1 was incriminated in 2006. Various Culicoides species were captured during the trapping campaigns of 2003 and 2006 carried out by Delécolle and Baldet, and those of 2007 and 2009 carried out by the present team. The 2007/2009 campaigns covered two periods (March-April and June-July) and samples were collected in 28 departments of Algeria. More C. imicola were caught in the second period (June-July). Although a weak activity and sometimes absence of C. imicola were observed in some depart­ments, BTV-1 was reported in these areas. It seems likely that other species of Culicoides are incriminated in the transmission of BTV in the country. The 2007/2009 campaigns revealed 10 new Culicoides species, which, added to the 37 species identi­fied by Delécolle and Baldet in the 2003/2006 campaigns, bring the total of known species in Algeria to 47.

scholarly journals The occurrence of Culicoides species, the vectors of arboviruses, at selected trap sites in Zimbabwe

2015 ◽  
Vol 82 (1) ◽  
Author(s):  
Stuart J.G. Gordon ◽  
Charlotte Bolwell ◽  
Chris Rogers ◽  
Godfrey Musuka ◽  
Patrick Kelly ◽  
...  
Keyword(s):  
Bluetongue Virus ◽  
Light Trap ◽  
Abundant Species ◽  
Climatic Conditions ◽  
African Horse Sickness ◽  
Successful Development ◽  
Natural Region ◽  
Culicoides Imicola ◽  
Virus Serotype ◽  
Culicoides Enderleini

A study of the distribution of Culicoides species was conducted by establishing 12 light trap sites over five rainy seasons between 1998 and 2003 covering all the geo-climatic natural regions of Zimbabwe. In total, 279 919 specimens of Culicoides were trapped over a total of 163 trapping nights. The highest median counts of Culicoides per trapping night were recorded in natural region III, which has climatic conditions conducive to the successful development of the larvae. Culicoides imicola, the major vector of bluetongue and African horse sickness viruses in Africa, was found to be the most abundant species (80.4%), followed by Culicoides enderleini (5.9%) and Culicoides milnei (5.2%). This study identified 10 species of Culicoides that had not been previously described in Zimbabwe, including Culicoides loxodontis and Culicoides miombo, which are members of the C. imicola complex. A total of 23 994 Culicoides midges were collected from five trap sites in Harare, Zimbabwe, with the dominant species, C. imicola, representing 91.6% of the total collection. Seventeen arboviruses were isolated from these midges, 15 of which were bluetongue virus. The predominant bluetongue virus serotype was serotype 11, followed by serotypes 1, 8, 12 and 15. Bluetongue virus serotypes 1, 2, 8, 10, 12, 15, 16 and 18, detected in this study, had not been previously reported in Zimbabwe.

Stabling and the protection of horses from Culicoides bolitinos (Diptera: Ceratopogonidae), a recently identified vector of African horse sickness

2000 ◽  
Vol 90 (6) ◽  
pp. 509-515 ◽  
Author(s):  
R. Meiswinkel ◽  
M. Baylis ◽  
K. Labuschagne
Keyword(s):  
South Africa ◽  
Light Trap ◽  
African Horse Sickness ◽  
High Wind ◽  
Wind Speeds ◽  
Culicoides Imicola ◽  
Fold Reduction ◽  
Suppressant Effect ◽  
Open Structures ◽  
Trap Catches

AbstractThe stabling of horses at night reportedly offers protection from African horse sickness and the most significant vector of the disease, Culicoides imicolaKieffer, has been shown to be exophilic. In certain high-lying regions of South Africa, however, C. bolitinos Meiswinkel, may be the major vector of the disease but its entry behaviour into stables is unknown. Accordingly, in the eastern Free State province of South Africa, light trap catches of C. bolitinos inside stables and outside, were compared. Two horse-baited stables, one traditional, and one modern, were used and combinations of stable (old/new), ceiling fans (on/off) and accessibility to Culicoides (stable doors open/closed or windows gauzed/ungauzed) were investigated as treatments. A total of 111,452 Culicoides of 26 species was collected on 60 trap nights; C. bolitinos was dominant (89.1% overall) with C. imicola second in abundance (2.9%). Outside catches were greater on warmer, drier, evenings but were suppressed by high wind speeds. Catches of C. imicola inside stables with doors open, or with windows ungauzed, were less than the numbers captured outside. In contrast, more C. bolitinos were caught in open stables than outside, i.e. open structures may protect horses from the exophilic C. imicola, but may increase attack rates from the endophilic C. bolitinos. The closing of doors and the gauzing of windows, however, led to a 14-fold reduction in numbers of C. bolitinos and C. imicola entering stables. A well-gauzed ‘traditional’ stable was as effective as a closed ‘modern’stable. Ceiling fans had no suppressant effect.

scholarly journals Oviposition site attraction of Aedes albopictus to sites with conspecific and heterospecific larvae during an ongoing invasion in Medellín, Colombia

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Talya Shragai ◽  
Laura Harrington ◽  
Catalina Alfonso-Parra ◽  
Frank Avila
Keyword(s):  
Open Field ◽  
Aedes Albopictus ◽  
Competitive Exclusion ◽  
Oviposition Preference ◽  
Ecological Niches ◽  
Low Density ◽  
Larval Competition ◽  
Field Cage ◽  
Main Hypothesis ◽  
Oviposition Sites

Abstract Background Aedes aegypti and Aedes albopictus are two globally invasive vectors with similar ecological niches. Encounters between them can result in either competitive exclusion or stable co-existence, but it is unclear what drives these variable outcomes. Larval competition in favor of Ae. albopictus is a main hypothesis for the competitive exclusion of Ae. aegypti observed in some regions. However, the role of oviposition preference in determining the degree of competitive larval interactions in the field is not well understood. In this study, we used a combination of mark-release-recapture methods with ovitraps in the open-field and a semi-field cage to test whether gravid Ae. albopictus seek oviposition sites in response to the presence, species, and density of either conspecific or heterospecific Ae. aegypti larvae in the aquatic habitat. We conducted our study in Medellín, Colombia, where Ae. aegypti is a long-term resident and Ae. albopictus is a recent invader. Results In the open-field and semi-field cage experiments, gravid Ae. albopictus showed strong preference for ovitraps with larvae over those without. They consistently preferred ovitraps with higher density of conspecific (Ae. albopictus) larvae and low density of heterospecific (Ae. aegypti) larvae over traps with no larvae or high density of heterospecific (Ae. aegypti) larvae. In the semi-field cage experiment, traps with low density of Ae. albopictus were not preferred more or less than any other trap, but in the open-field experiment they were preferred over traps without larvae. Conclusions We demonstrate, through open-field and semi-field cage experiments, that Ae. albopictus are more attracted to oviposition sites with larvae and that the combination of species and density of larvae influence attraction. This demonstrated preference could increase interspecific larval competition as Ae. albopictus actively seek containers with conspecific and heterospecific larvae. Any resulting competition with Ae. aegypti may favor one species over the other and alter the distribution or abundance of both. Because these species vary in vectorial capacity and insecticide resistance, effects of interspecific competition could ultimately impact arbovirus transmission rates and the success of vector control efforts.

Culicoides species composition and environmental factors influencing African horse sickness distribution at three sites in Namibia

Acta Tropica ◽  
2016 ◽  
Vol 163 ◽  
pp. 70-79 ◽  
Author(s):  
Danica Liebenberg ◽  
Stuart Piketh ◽  
Karien Labuschagne ◽  
Gert Venter ◽  
Telane Greyling ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Species Composition ◽  
African Horse Sickness ◽  
Culicoides Species ◽  
Factors Influencing

scholarly journals Culicoides species abundance and potential over-wintering of African horse sickness virus in the Onderstepoort area, Gauteng, South Africa

2014 ◽  
Vol 85 (1) ◽  
Author(s):  
Gert J. Venter ◽  
Karien Labuschagne ◽  
Daphney Majatladi ◽  
Solomon N.B. Boikanyo ◽  
Carina Lourens ◽  
...  
Keyword(s):  
South Africa ◽  
Species Abundance ◽  
Winter Period ◽  
Infection Prevalence ◽  
African Horse Sickness ◽  
African Horse Sickness Virus ◽  
Pcr Assay ◽  
Culicoides Imicola ◽  
The Mean ◽  
Polymerase Chain

In South Africa, outbreaks of African horse sickness (AHS) occur in summer; no cases are reported in winter, from July to September. The AHS virus (AHSV) is transmitted almost exclusively by Culicoides midges (Diptera: Ceratopogonidae), of which Culicoides imicola is considered to be the most important vector. The over-wintering mechanism of AHSV is unknown. In this study, more than 500 000 Culicoides midges belonging to at least 26 species were collected in 88 light traps at weekly intervals between July 2010 and September 2011 near horses in the Onderstepoort area of South Africa. The dominant species was C. imicola. Despite relatively low temperatures and frost, at least 17 species, including C. imicola, were collected throughout winter (June–August). Although the mean number of midges per night fell from > 50 000 (March) to < 100 (July and August), no midge-free periods were found. This study, using virus isolation on cell cultures and a reverse transcriptase polymerase chain reaction (RT-PCR) assay, confirmed low infection prevalence in field midges and that the detection of virus correlated to high numbers. Although no virus was detected during this winter period, continuous adult activity indicated that transmission can potentially occur. The absence of AHSV in the midges during winter can be ascribed to the relatively low numbers collected coupled to low infection prevalence, low virus replication rates and low virus titres in the potentially infected midges. Cases of AHS in susceptible animals are likely to start as soon as Culicoides populations reach a critical level.

scholarly journals Identification and Distribution of Species Culicoides spp. (Diptera: Ceratopogonidae) of Broiler in Banda Aceh

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
Rusli Rusli ◽  
Muhammad Hanafiah
Keyword(s):  
Disease Control ◽  
Light Trap ◽  
Culicoides Species ◽  
Average Distribution ◽  
Number Species ◽  
Banda Aceh

A research has been done to identify the distribution of Culicoides species in Banda Aceh. Culicoides samples were collected by using modified Center for Disease Control (CDC) Miniatur Light Trap. All Culicoides samples has choice a small measured, were identified morfologically. The result showed that the number species Culicoides has caught in Ulee Kareng are: C. huffi, C. arakawae and C. shultzei, whereas in Alue Naga are C. huffi and C. shultzei. The distribution of species Culicoides in Ulee Kareng are: C. huffi has 22, C. arakawae 13 and C. shultzei 11. The average distribution of Culicoides in Alue Naga are C. huffi has 11 and C. shultzei has 4 .

scholarly journals A moth odorant receptor highly expressed in the ovipositor is involved in detecting host-plant volatiles

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Rui-Ting Li ◽  
Ling-Qiao Huang ◽  
Jun-Feng Dong ◽  
Chen-Zhu Wang
Keyword(s):  
Plant Volatiles ◽  
Host Plants ◽  
Odorant Receptor ◽  
Oviposition Preference ◽  
Egg Laying ◽  
Host Plant Volatiles ◽  
Helicoverpa Assulta ◽  
Electrophysiological Responses ◽  
Or Gene ◽  
Oviposition Sites

Antennae are often considered to be the nostrils of insects. Here, we sequenced the transcriptome of the pheromone gland-ovipositor complex of Helicoverpa assulta and discovered that an odorant receptor (OR) gene, HassOR31, had much higher expression in the ovipositor than in antennae or other tissues. To determine whether the ovipositor was involved in odorant detection, we co-expressed HassOR31 and its co-receptor, HassORco, in a Xenopus oocyte model system, and demonstrated that the OR was responsive to 12 plant odorants, especially Z-3-hexenyl butyrate. These odorants elicited electrophysiological responses of some sensilla in the ovipositor, and HassOR31 and HassORco were co-expressed within ovipositor sensilla. Two oviposition preference experiments showed that female moths lacking antennae still preferentially selected oviposition sites containing plant volatiles. We suggest that the expression of HassOR31 in the ovipositor of H. assulta helps females to determine precise egg-laying sites in host plants.

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