Host-parasite interactions between Acrididae (Orthoptera: Caelifera) and Parasitengona (Acari: Trombidiformes) in the southwestern Zagros Mountains, Iran

Abstract

Abstract Parasitengona mites (Acari: Trombidiformes) are common parasites of Orthoptera. Yet, we have limited knowledge on host-parasite interactions between these groups. Hence, in this study we investigate the interactions between these mites and their Acrididae hosts in the southwestern Zagros Mountains (Iran). Sampling was conducted at 22 stations, four times across two consecutive years (2020–2021). A total of 5,344 mite larvae were collected from 2,370 grasshoppers, representing 48 species, of which 1,137 individuals (48%) were parasitized. The mean number of mites per infested individual was 4.7; the maximum infestation observed was 103 Eutrombidium cf. trigonum larvae on Calliptamus barbarus . The most abundant mite species was E. sorbasiensis (4,282 larvae; 80%). Parasitism was sex-biased, with females more frequently infested than males (52% vs. 43%), likely due to larger body size. Mites exhibited preferences for specific attachment sites on their hosts, varying by mite species and host grooming behavior. Bipartite network analysis revealed a moderate degree of host specialization (H2′ = 0.38), and individual specialization indices (d′) indicated that most mite species were generalists. These findings suggest that while mites exploit a wide host range, infestation pressure is unevenly distributed and shaped by host traits, attachment-site preferences, and habitat quality, highlighting the importance of ecological and evolutionary factors in shaping host-parasite interactions.