Diversity and breeding sites of mosquitoes (Diptera, Culicidae) potentially vectors of arboviruses in Belgian equestrian farms

Poster (2012, October 08)

This study aims to determine the potential importance of the livestock farms, especially equestrian, to welcome and favor the proliferation of certain species of mosquito responsible for transmission of ... [more ▼]

This study aims to determine the potential importance of the livestock farms, especially equestrian, to welcome and favor the proliferation of certain species of mosquito responsible for transmission of arboviruses. The study of biodiversity of Culicidae in the horse farms in Belgium is carried out on species sampled at 64 biotopes in six stations study. Five surveys were realized during 2011 (June, July, August and October) and one in 2012 (June). The morphotaxonomic and molecular study of mosquitoes collected showed the presence of ten species: Culisata annulata Schrank, 1776; Anopheles claviger s.s. Meigen, 1804; An. maculipennis s.s. Meigen, 1818; An. messae Falleroni, 1926; Culex pipiens molestus Forskal, 1775; Cx. pipiens pipiens Linné, 1758; Cx. torrentium Martini, 1925; Cx. hortensis hortensis Ficalbi, 1889; Cx. territans Walker, 1856 and Coquillettidia richardii Ficalbi, 1889. Among the 24893 individuals examined in 2011, Cx. pipiens sl and Cx. torrentium represent 68.00% and 22.38% respectively of total harvest. These last species with Cs. annulata, are dominants and ubiquitous in all the horse farms visited. The species of the genus Anopheles have strong ecological requirements and are therefore associated with some special habitats; other species however have a strong ability to adapt and therefore attend a wide variety of biotopes (Cx. pipiens, Cx. torrentium and Cs. annulata). At the horse farms, water troughs and ponds are the most favorable habitats for larval development of Culicidae. The species potentially vectors of arboviruses that can cause problems in epidemiological equestrian farms are Cx. pipiens sl, Cx. torrentium and Cs. annulata. [less ▲]

Laboratory and field preliminary tests of Metarhizium anisopliae formulated with neem oil (Suneem) against Anopheles gambiae sl adult emergence

Poster (2012, October 08)

Metarhizium anisopliae have shown great potential for the control of malaria vectors. However, their ability to control aquatic stages of anopheline vectors with conidial formulation is need. In ... [more ▼]

Metarhizium anisopliae have shown great potential for the control of malaria vectors. However, their ability to control aquatic stages of anopheline vectors with conidial formulation is need. In laboratory condition (25°C and 76%RH), we formulated M. anisopliae with emulsifian neem oil (Suneem 1%) before application on An. gambiae larvae at 4, 6, 8, 10 and 12 % (v/v) to determine the LD90. We applied in semi-field environment, the LD90 of the formulation into artificial vats on the Anopheles gambiae sl larvae collected from many breeding sites at dry and rain seasons. In laboratory condition, the LD 50 was 4.4 x 10^6 spores/ml and the LD90 was not obtained 24 after exposure. The probite line equation was Y=1.61 x – 0.55 and R²= 0.9793. The LD 50 was 3.1 x 10^6 and the LD90 was 5.3 X 10^6 spores/ml 48 h after exposure. The probite line equation was then Y= 1.69 x + 1.79 and R²= 0.9757. Microscope magnifying revealed also the fungal attack via cuticle and mycelia germination one dead larvae and pupae. In semi-field environment, treatment revealed that, at 5.3 x 10^6 spores/ml, the formulation has a great emergence inhibition of mosquito adult formation. No significant difference was observed between dry and rain season application of M. anisopliae on the larvae. Therefore, a combination of M. anisopliae with Suneem may provide a more sustainable management strategy for malaria vectors control at the larval stages. [less ▲]

Livestock farms in Belgium shelter they the mosquitoes (Diptera, Culicidae) potentially vectors of arboviruses?

Poster (2012, August 23)

Although no major arbovirus which mosquitoes are responsible for its transmission has been recorded in Belgium in recent decades, environment and climate change, current and future, could favor the ... [more ▼]

Although no major arbovirus which mosquitoes are responsible for its transmission has been recorded in Belgium in recent decades, environment and climate change, current and future, could favor the emergence of vector-borne diseases in the country, by inducing changes on Culicidae populations. This study aims to determine the potential importance of agricultural environments, and especially livestock farms, to welcome and favor the proliferation of certain species of mosquito responsible for transmission of arboviruses. A taxonomic inventory was conducted in 2008 (III, VI and X) and 2009 (V and IX) in ten cattle farms, and in 2010 (X) in ten stables located in Belgium. The harvest of mosquitoes is based on larval sampling at the level of 14 biotopes such as water troughs, used tires, abandoned utensils and temporary puddles or not. The morphotaxonomic study of larvae and genitalia has allowed to identify eight species in 18 study stations. These are Anopheles claviger Meigen, 1804 ; A. maculipennis s.l. Meigen, 1818 ; Culiseta annulata Schrank, 1776 ; Cs. morsitans Theobald, 1901 ; Culex modestus Ficalbi, 1889 ; Cx. torrentium Martini, 1925 ; Cx. territans Walker, 1856 and Cx. pipiens s.l. L., 1758. Of the 1843 individuals examined in 2009, Cx. pipiens s.l. represents 79.98% of the total harvest; however, Cx. modestus represents only 0.92%. Used tires form the most favorable habitat for larval development of Culicidae. Therefore, despite the low diversity of mosquito observed within the livestock environments, they represent a significant risk for the reproduction of some potential vectors of arboviruses. In addition, some larval habitats constitute very favorable sites for proliferation of mosquito, causing a real problem of nuisance for animals of farms. [less ▲]

Breeding sites of main Bluetongue virus vectors in Belgian cowshed

Poster (2012, August)

Bluetongue (BT) is an emerging vectorborne disease of ruminants that was reported in August 2006 in northern Europe. Since 2007, BT virus (BTV) serotype 8 continued its spread across Europe and caused ... [more ▼]

Bluetongue (BT) is an emerging vectorborne disease of ruminants that was reported in August 2006 in northern Europe. Since 2007, BT virus (BTV) serotype 8 continued its spread across Europe and caused considerable economic losses. This observation indicates possible overwintering of the vector from year to year. The biological vectors of BTV are biting midges of the genus Culicoides. Breeding sites of bluetongue vector species have been found near farms (e.g. silage residues) and in neighboring meadows (e.g. cattle dung) but never inside sheds. We conducted a study in five cattle farms in Belgium during February–October 2008. Three samplings were performed and each soil sample collected inside cowsheds was incubated to enable adult midges to emerge. Among 15 soil biotopes sampled, only one showed the emergence of adult Culicoides biting midges: dried dung adhering to walls inside animal enclosures and resulting to the partial removal of used animal litter. It was a breeding site for the C. obsoletus/C. scoticus complex. Physico-chemical characteristics showed that midges of this complex are more prevalent in soil samples with a high carbon:nitrogen (C:N) index. So Culicoides biting midges are able to complete their life cycle in animal enclosures. We identified a breeding site for the primary BTV vector in a cowshed in northern Europe. These observations could explain the persistence of BTV from year to year despite fairly harsh winters. Hygienic measures on farms could reduce biting midges populations and so improve efficacy of vaccination campaigns against BT in Europe. [less ▲]

Effect of reduced water supply on aphid physiology : A proteomic approach on peach-aphid interaction

Poster (2012, August)

Investigation of lectins as competitors of virus in aphids and potentiality in viral disease transmission

Poster (2012, August)

Volatile organic compounds released by barley roots attract wireworms

Poster (2012, August)

Wireworms, the soil dwelling larvae of click beetles, are pests of many crops worldwide. Alternatives to insecticide treatments are needed for integrated management strategies. Our work consists in ... [more ▼]

Wireworms, the soil dwelling larvae of click beetles, are pests of many crops worldwide. Alternatives to insecticide treatments are needed for integrated management strategies. Our work consists in elucidating the role of barley (Hordeum vulgare L.) root-emitted volatile organic compounds (VOC) on the orientation behaviour of Agriotes sordidus Illiger wireworms (Fig. 1). Using dual choice olfactometers, we have evaluated the attractiveness of baits ranging from barley roots themselves to one isolated root-emitted volatile organic compound. [less ▲]

Characterization of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) overwintering sites

Poster (2012, August)

Originally introduced as a biological control agent, the multicoloured Asian ladybeetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), has become an invasive pest throughout Europe and North ... [more ▼]

Originally introduced as a biological control agent, the multicoloured Asian ladybeetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), has become an invasive pest throughout Europe and North America in the last few years. Although its effectiveness to control aphid and coccid populations was impressive, some negative impacts appeared rapidly, notably on human health. Indeed, to protect themselves from cold temperatures, H. axyridis individuals move inside dwellings and buildings and form large aggregations in concealed portions of structures to overwinter. The aggregating beetles are responsible for some annoyances due to, on one hand, the number of individuals inside homes and, on the other hand, the hemolymph secretions they release when they are disturbed, which can cause allergic reactions. In order to highlight the specific features of infested houses, we investigated a large number of overwintering sites in Wallonia between 2007 and 2011. These sites were characterized through a survey sent to homeowners confronted to invasion problems. This survey was mainly focused on a general description of the infested house (type, colour, infested floor(s), building material), the orientation of the colonized rooms and the position of the beetles’ cluster. The collected data indicate that H. axyridis preferentially selects isolated brick houses with red or white fronts to take shelter. Aggregations are mostly located at the first floor, essentially inside south, west or southwest oriented rooms. Furthermore, ladybeetles generally gathered into wooden windows frames facing south, west or southwest and to a lesser extent, in the upper corners of walls presenting the same orientation. All these results contribute to improve the knowledge on the aggregative behaviour of H. axyridis and could promote the development of more specific and efficient management methods to prevent massive infestations into dwellings, such as artificial shelters or trapping systems located at the outside of buildings. [less ▲]

Identification of bacteria community associated with earthworm gut

Poster (2012, July 26)

The role of earthworms in soil fertility and transformation of organic waste was regulary cited to be of first importance. Associated to these macro-invertebrates, a large diversity of micro-orgnisms are ... [more ▼]

The role of earthworms in soil fertility and transformation of organic waste was regulary cited to be of first importance. Associated to these macro-invertebrates, a large diversity of micro-orgnisms are found indirectly in their closed environment or directly in their gut. Functional aspects of these interactions and symbiosis in relation with soil characteristics and fertility rates are poorly developed. Here, the micro-organisms diversity and potential related functions of earthworm gut were investigated using a proteiomic approach for both protein and micro-organism identifications. Microbial community investigation was detected by proteomic approach based on bidimensional electrophoresis coupled with mass spectrometry using Matrix Assisted Laser Desorption Ionisation – time of flight (Maldi-Tof). Diversity of gut associated bacterial communities was discussed. Indeed, application of particular crop production practices such as crop residue management at the field level could regulate the gut bacterial communities in earthworm but also microbials in soils. Agricultural systems had to consider the microbial and associated organisms in the soil to enhance fertlility and crop production in sustainable ways. [less ▲]

Impact of Myzus persicae infestation on the volatile emission of Arabidopsis thaliana Col-0.

Poster (2012, July 22)

Being members of complex communities, plants often emit a wide range of volatile organic compounds to defend themselves against insect invasions. Although many studies exist on insect-induced plant ... [more ▼]

Being members of complex communities, plants often emit a wide range of volatile organic compounds to defend themselves against insect invasions. Although many studies exist on insect-induced plant volatile emission, most of them either compare the influences of various herbivore species on one plant species or the impact of a given herbivore on several host plant species. Moreover, informations related to the influence of insect density as well as the infestation duration are still needed. Here, we showed that a sucking insect – Myzus persicae (green peach aphid) induced the volatile emission from Arabidopsis thaliana Columbia wild-type (A.thaliana Col-0) under laboratory conditions based on results obtained by solid-phase micro-extraction coupled with gas chromatography - mass spectrometry (SPME-GC/MS). The released volatile blend was discussed in relation to related biosynthesis pathways and functions. These included terpenoids, green leaf volatiles, alcohols and isothiocyanate. The qualitative and overall proportion of volatile components differed depended on the number and residence duration of aphids on leaves. By studying the effects of sucking insect stresses to plant, we not only aim to contribute to the fundamental understanding of the emission of volatile components in the interaction between plants and pests, but also to provide standardised and easy to use assays to assess A.thaliana volatile changes according to cross stresses, including both biotic and abiotic ones in ongoing experiments. [less ▲]