High host specificity of obligate ectoparasites

Abstract 1. Host specificity is the degree to which a parasite species occurs in association with a host species. 2. The degree to which obligate ectoparasites are host specific has been debated, but effects of sampling contamination were usually not addressed. Data from a controlled mammal–ectoparasite survey were used to assess host specificity of an obligate group of ectoparasites – streblid bat flies. 3. Host–parasite associations were categorised as primary or non‐primary. Non‐primary host associations were evaluated against primary associations via proportional comparison. 4. Results indicate that host specificity was high, exceeding previous reports. Natural host transfers were rare. 5. Non‐primary host associations were almost completely explained by disturbance transfers during sampling of the host or by contamination upon sampling the parasite. These conclusions likely hold for other taxa of obligate parasites.