Potential mechanical vectors of Trypanosoma evansi in the Canary Islands, Spain

Abstract

Mechanical transmission by hematophagous insects, mainly large dipterans, is the main mode of transmission of African trypanosomes in herbivores out of Africa (Desquesnes et al., 2013). Trypanosoma evansi was detected in a dromedary camel in the Canary Islands (Spain) in 1997 (Gutiérrez et al., 1998). Few studies have been completed on its vectors in Spain, however, Stomoxys calcitrans was considered as responsible for the transmission of T. evansi in an affected area of the island of Gran Canaria (Rodríguez et al. 2014). Within the framework of the COMBAT project, a study of the possible vectors of Trypanosomes in the Canary Islands has been implemented. During 7 days every three months for 1 year, two models of traps, Vavoua and NZI (ZeroFly®), were used for sampling vectors in the islands of Gran Canaria (5 locations, 15 traps), Lanzarote (3 locations, 9 traps) and Fuerteventura (2 locations, 6 traps) according to geoclimatic and farm locations. Insects caught were identified and postprandial individuals were kept for subsequent DNA analysis, through metabarcoding (MBC). A total of 17,077 S. calcitrans (3,359 in Lanzarote, 5,539 in Fuerteventura and 8,179 in Gran Canaria), 1 Tabanus cordiger (in Fuerteventura), 25 Pseudolynchia canariensis (16 in Gran Canaria, 8 in Fuerteventura and 1 in Lanzarote) and 16,911 individuals of the genus Musca (3,250 in Fuerteventura, 3,403 in Gran Canaria and 10,258 in Lanzarote) have been trapped. In addition, approximately 40 postprandial insects from different locations have been stored for further DNA analysis in MBC. Results confirm the major role S. calcitrans could play in the transmission of T. evansi; the potential role of other species such as T. cordiger and P. canariensis would require further sampling and blood meal analyses to confirm this hypothesis.