PORTFOLIO

In this project, we aim to develop the first skin microbial preventive treatment of animals against biting insects, thereby reducing their impact and improving animal health. We focus on biting midges (Ceratgopogonidae, genus Culicoides, ‘no-see-ums’) which are of huge veterinary importance, mainly as vectors of disease agents, such as e.g. bluetongue virus (sheep, cattle) and African horse sickness virus, but also as causative agents of nuisance (also for humans) and insect bite hypersensitivity. Like mosquitoes, biting midges are attracted to their host by carbon dioxide released in their breath and by the body odours these hosts emit. These body odours are mainly produced by skin bacteria, and differences in attractiveness between individuals to mosquitoes is mediated by these volatiles released from the skin.
We aim at identifying sheep skin bacteria that repel biting midges and also bacteria that attract biting midges. We will take skin bacterial and odour samples of several sheep of different breeds. The odour samples will be used to determine the attractiveness of each individual to biting midges and linked to the skin bacterial profile of each animal. Bacterial species correlated with the most and least attractive animals will be isolated, cultured, and tested for repellency and attractiveness to biting midges. Finally, we will apply the repellent bacteria to sheep to reduce their attractiveness to biting midges. In addition, attractive bacteria will be used in traps to increase the capture of biting midges.

Management of the human skin microbiome has gained a lot of interest with several success stories. In contrast, microbiome management of animal skin has gained very little attention. The effect of the application of skin bacteria on animals is probably more successful than in humans because they do not wash and thereby remove the treatment. To reach our goal, we combine a set of multidisciplinary techniques from the fields of vector entomology, microbiology and veterinary medicine.
In the recent past, there were large outbreaks of diseases caused by Culicoides-transmitted viruses in Central Europe, such as bluetongue and Schmallenberg virus. Costs incurred by these viruses include direct (production losses, animal deaths, and veterinary treatment) and indirect (surveillance, restrictions on animal movement, preventive vaccination and treatment with insecticides, vector monitoring) ones. The project will contribute to reduce biting by midges and reduce the impact of midges-borne diseases by using cheap and ecologically friendly means. It could also trigger corresponding research in other livestock or companion animal species.

By sequencing we analyzed the skin bacterial composition from three different breeds of sheep from different farms. Interstingly the farm on which the sheep lived had a larger influence on the diversity and composition of the bacteria then sheep breed and body part. We isolated and cultivated these skin bacteria and tested a subset for their effect on biting midges. We identified at least one bacterial species that can inhibit midges from feeding in an artificial setup. Next we will see if we can use these bacteria to protect sheep from getting bitten.

Verhulst, N.O., Spitzen, J., Boulanger, N. (2018). Impact of skin microbiome on attractiveness to arthropod vectors and pathogen transmission, in: Boulanger, N. (Ed.), Skin and Arthropods. Academic Press, London, pp. 55-82;
Verhulst, N.O., Umanets, A., Weldegergis, B.T., Maas, J.P.A., Visser, T.M., Dicke, M., Smidt, H., Takken, W. (2018). Do apes smell like humans? The role of skin bacteria and volatiles of primates in mosquito host selection. The Journal of Experimental Biology, 221, jeb.185959.

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