Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/biocon Perspective Microbiomes are integral to conservation of parasitic arthropods Kelly A. Speer a,b,c, ⁎ , Nolwenn M. Dheilly d,e , Susan L. Perkins f,g a Richard Gilder Graduate School, American Museum of Natural History, New York, NY 10024, United States of America b Center for Conservation Genomics, Smithsonian National Zoological Park and Conservation Biology Institute, Washington, DC 20008, United States of America c Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, United States of America d School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, United States of America e Unité Génétique Virale de Biosécurité, ANSES, Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail—Laboratoire de Ploufragan- Plouzané, Ploufragan, France f Sackler Institute of Comparative Genomics, American Museum of Natural History, New York, NY 10024, United States of America g Division of Science, City College of New York, New York, NY 10031, United States of America ARTICLE INFO Keywords: Host–parasite interactions Vector competence Parasite microbiome Microbiome–environment interactions Extinction risk ABSTRACT Parasitic arthropods have not typically been included in conservation and management strategies, possibly because the most well-known blood-feeding arthropods are associated with human and livestock disease. However, the vast majority of parasitic arthropods pose no threat to human health and instead contribute to the overall stability of communities to which they belong. The loss of parasitic arthropod biodiversity likely has repercussions for host health, population density, and community structure. The need for parasitic arthropod conservation is urgent given they represent the majority of parasitic animal biodiversity and environmental change is expected to pose a significant threat to their survival. We urge that microbial associations of hos- t–parasitic arthropod assemblages be considered in conservation efforts. Parasitic arthropods are dependent on their microbial associates for development, nutrient acquisition, immune function, and reproduction. The mi- crobiome also mediates the interactions between a parasitic arthropod and a host, and the role of a parasitic arthropod in vectoring pathogens to its host. The microbiome may therefore represent a “weak link” that in- creases the susceptibility of parasitic arthropods to environmental change. Fundamental knowledge is missing, precluding assessment of this complex association between microbes and parasitic arthropods. We highlight broad areas of future research that focus on building primary knowledge, developing experimental protocols and novel statistics, and leveraging new techniques to increase the resolution at which we can examine microbial communities of parasites. Conservation of parasitic arthropods that accounts for microbiota will likely be more effective at maintaining parasite biodiversity and at controlling arthropod-vectored disease emergence. 1. Introduction Though often overlooked, global parasite biodiversity is threatened by environmental change and declining host biodiversity (Gómez et al., 2012; Rocha et al., 2016; Carlson et al., 2017). Indeed, all species are hosts for parasitic organisms, supporting a remarkable diversity of parasitic species, and the loss of these parasite species from ecosystems may have unforeseen negative consequences (Gómez et al., 2012; Stringer and Linklater, 2014; Wood and Johnson, 2015; Dougherty et al., 2016). Climate change-induced habitat alteration alone is ex- pected to cause a global loss of 5–10% of parasite diversity by 2070, with ectoparasites experiencing greater extinction risk than en- doparasites (Carlson et al., 2017). Parasites with high host specificity, a complex life cycle, or narrow environmental preferences will be impacted most severely (Cizauskas et al., 2017). As arthropods com- prise the majority of classified animal life on earth (Giribet and Edgecombe, 2012) and the majority of parasitic animals are arthropods (Weinstein and Kuris, 2016), extinction of parasitic arthropod species represents a significant threat to biodiversity. Parasites are most commonly viewed as hurdles along the path to- wards conservation of free-living host species, rather than the target of conservation efforts themselves (Stringer and Linklater, 2014; Dougherty et al., 2016). However, increasing evidence shows that parasites contribute to healthy host immune response, host population regeneration, ecological network stability, and nutrient cycling (Gómez et al., 2012; Hatcher et al., 2012; Wood and Johnson, 2015; Dougherty et al., 2016). For example, in humans, infection with some helminth parasites modulates the immune response and eases the effects of https://doi.org/10.1016/j.biocon.2020.108695 Received 23 August 2019; Received in revised form 22 June 2020; Accepted 26 June 2020 ⁎ Corresponding author at: Richard Gilder Graduate School, American Museum of Natural History, New York, NY 10024, United States of America. E-mail address: speerkelly@gmail.com (K.A. Speer). Biological Conservation 250 (2020) 108695 Available online 01 August 2020 0006-3207/ © 2020 Elsevier Ltd. All rights reserved. T