Ecological determinants of prevalence of the male-killing bacterium Arsenophonus nasoniae Garrido Bautista, Jorge Norte, Ana Cláudia Moreno Rueda, Gregorio Nadal Jimenez, Pol Blowfly Cyanistes caeruleus Endosymbiont Male-killing Nasonia vitripennis Protocalliphora azurea This work was financed by projects from the NERC (NE/I01067X/1) and BBSRC (BB/S017534/1) supporting the work of Pol Nadal-Jiménez; projects from the Fundação para a Ciência e a Tecnologia (UIDB/04292/2020; UIDP/04292/2020; LA/P/0069/2020) to Ana Cláudia Norte; and projects from the Spanish Ministries of Economy and Competition (CGL2017-84938-P), Science and Innovation (PID2022-136400NB-I00) and Consejería de Universidad, Investigación e Innovación de la Junta de Andalucía (A-RNM-48-UGR20) to Gregorio Moreno-Rueda. Jorge Garrido-Bautista was supported by an AUIP mobility grant and by a pre-doctoral contract (FPU18/03034) from the Spanish Ministry of Education. Ana Cláudia Norte was supported by the transitory norm contract DL57/2016/CP1370/CT89. Male-killing bacteria are found in a broad range of arthropods. Arsenophonus nasoniae is a male-killing bacterium, causing a 80% reduction of the male progeny in infected Nasonia vitripennis wasps. Although the discovery of A. nasoniae dates from the early 80′s, knowledge about the biology and ecology of this endosymbiont is still scarce. One of these poorly studied features is the ecological factors underlying A. nasoniae incidence on its Nasonia spp. hosts in different geographical locations. Here, we studied the prevalence of A. nasoniae in Iberian wild populations of its host N. vitripennis. This wasp species is a common parasitoid of the blowfly Protocalliphora azurea pupae, which in turn is a parasite of hole-nesting birds, such as the blue tit (Cyanistes caeruleus). We also examined the effects of bird rearing conditions on the prevalence of A. nasoniae through a brood size manipulation experiment (creating enlarged, control and reduced broods). Both the wasp and bacterium presence were tested through PCR assays in blowfly pupae. We found A. nasoniae in almost half (47%) of nests containing blowflies parasitized by N. vitripennis. The prevalence of A. nasoniae was similar in the two geographical areas examined (central Portugal and southeastern Spain) and the probability of infection by A. nasoniae was independent of the number of blowfly pupae in the nest. Experimental manipulation of brood size did not affect the prevalence of A. nasoniae nor the prevalence of its host, N. vitripennis. These results suggest that the incidence of A. nasoniae in natural populations of N. vitripennis is high in the Iberian Peninsula, and the infestation frequency of nests by N. vitripennis carrying A. nasoniae is spatially stable in this geographical region independently of bird rearing conditions. 2026-01-29T07:56:07Z 2026-01-29T07:56:07Z 2024-02-10 journal article Garrido-Bautista, J., Norte, A. C., Moreno-Rueda, G. & Nadal-Jiménez, P. (2024). Ecological determinants of prevalence in the son-killer bacterium Arsenophonus nasoniae. Journal of Invertebrate Pathology, 203: 108073. https://doi.org/10.1016/j.jip.2024.108073 https://hdl.handle.net/10481/110438 10.1016/j.jip.2024.108073 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ embargoed access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier