Influence of latitude, host body size and host body weight on helminth species richness and abundance in two Neotropical marsupials

Parasite species richness can be influenced by intrinsic and extrinsic factors of their hosts, such as host body size and latitude. Although these factors have been studied for several taxa, few studies have investigated them for helminths of wild mammals. The aim of this study was to evaluate the influence of host body size, body weight and latitude on the species richness and abundance of the helminths of <i>Didelphis aurita</i> and <i>Didelphis albiventris.</i> Data on helminths and the geographic coordinates of the collection localities of the hosts were obtained from the Collection of Wild Mammal Reservoirs and the database of the Laboratory of Biology and Parasitology of Wild Mammal Reservoirs. The influences of latitude and host body size and body weight on helminth species richness (HSR) and helminth abundance were analysed using linear regressions. We evaluated the effect of latitude on helminth species composition using redundancy analysis followed by ANOVA. The HSR ranged from 1 to 9 for <i>D. aurita</i> and from 1 to 7 for <i>D. albiventris</i>. We found a positive relationship between latitude and total HSR for <i>D. aurita</i> (<i>p</i> = 0.012). The ANOVA revealed the influence of latitudinal variation on the species composition variation of helminths only for <i>D. aurita</i> (<i>p</i> = 0.001). With respect to body size, we did not find a significant relationship between this variable and HSR or abundance for either species. However, we found a positive relationship between host body weight and helminth abundance for <i>D. aurita</i> (<i>p</i> = 0.004). We conclude that the increase in latitude was an explanatory factor for the increasing HSR along infracommunities, contradicting the general pattern of increasing species with decreasing latitude observed in free-living species. Moreover, host intrinsic factors may be more relevant to endoparasite occurrence and development than latitude because they directly influence the parasite niche.