Oribatida

Roczen-Karczmarz, M. & Tomczuk, K., 2016, Oribatid mites as vectors of invasive diseases, Acarologia 56 (4), pp. 613-623 : 617-618

Oribatida as intermediate hosts of tapeworms

Interest in oribatid mites acting as intermediate hosts began to rise with the Stunkard study (1934; 1937), who discovered that they are intermediate hosts and vectors of the tapeworm Moniezia expansa . Since then other researchers have shown that oribatid mites are also hosts for other tapeworms of the Anoplocephalidae family. A comprehensive list of anoplocephalids and their intermediate and definitive hosts was compiled by Denegri (1993). He listed 127 mites species which belong to 27 families. He assigned them to 27 tapeworms species belonging to the family Anoplocephalidae . There are several scientists who are involved in exploring oribatids in respect of their role as intermediate hosts ( Xiao and Herd 1992; Schuster et al. 2000; Denegri et al. 2002; McAloon 2004; Akrami et al. 2007; ElMehlawy 2009; Schuster and Coetzee 2012; Ire et al. 2013; Żbikowska-Zdun and Koczara 2013). There was an attempt at studying the growth of oncosphere in mites ( Xiao and Herd 1992; Schuster et al. 2000; Denegri et al. 2002; Akrami et al. 2007; Schuster and Coetzee 2012). Furthermore, a number of new species of oribatids that participate in life cycles of tapeworms were described ( Haq et al. 1999; Schuster et al. 2000; Denegri et al. 2002; McAloon 2004; Shimano 2004; Akrami et al. 2007; Schuster and Coetzee 2012). The list created by Denegri (1993) might be extended by additional items with respect of oribatids participating in the life cycle of tapeworms of the Anoplocephalidae family. In his review, Denegri (1993) considered the state of research until 1991. The Table 2 presents Oribatida species examined by scientists after 1991 and those that were not found in Denegri’s review.

Scientists have also undertaken to find oribatid mites acting as intermediate hosts for other cestodes. Thysanosoma actinoides ( Cestoda: Anoplocephalidae ) parasitizes domestic and wild herbivores. Allen (1973) confirmed that T. actinoides requires two intermediate hosts. In his investigation he tried to infect sheep and goats directly by supplying egg capsules. Egg capsules were usually obtained from the intestinal contents of infected sheep or from rectal fecal samples. Allen (1973) discovered that some egg capsules were resistant to artificial gastric juice and would probably pass through the gastrointestinal tracts of mammals without releasing the oncospheres. Some of these were fed in- tact while others were fed after having been mashed to release all or part of the oncospheres. Tapeworms did not appear in the final host so he collected invertebrates on range known or suspected to be infectious. These were: psocopterous insects, beetles, ants, grasshoppers, tyroglyphid mites, oribatid mites, also foot lice, sheep keds and biting lice. Previously he fed the egg capsules to invertebrates and ectoparasites. Although the eggs of the cestodes were ingested, no larval stages developed in those hosts. T. aetinioides larvae developed and supported development of the larval stages only in psocid body cavities. Cysticercoids from psocids have the appearance of stages infective to a definitive host. Then he fed of these forms directly to tapewormfree lambs. No tapeworm infections were produced in any of lambs ( Allen 1959, 1973). Allen (1973) postulated that psocids in which they found the cestode larvae are the first intermediate hosts and that the obligate hosts are either other species of psocids or other groups of insects closely related phylogenetically to them.

Denegri et al. (2002) analyzed the role of oribatid mites as intermediate hosts of T. actinoides . They experimentally infected Zygoribatula striassima (Family: Oribatulidae ) and Oribatella spp . (Family: Oribatellidae ) with larval stages of T. actinoides . The percent of infected mites ranged from 1.3 to 7.3%. Cysticercoids found in oribatid mites were not completely developed and not infective due to the lack of primordial suckers ( Denegri et al. 2002).

Oribatid mites are also the first intermediate host of Mesocestoididae family tapeworms. Cysticercoids, which are produced in oribatid mites, are ingested by the second intermediate host (small mammals, birds, reptiles, amphibians), where tetrathyridia are formed in the body cavity ( Zale´sny and Hildebrand 2012; Cho et al. 2013; Tokiwa et al. 2014). Soldatova (1944) claimed to have successfully infected oribatid mites with tapeworm eggs of Mesocestoides lineatus , but did not have enough cysticercoids to complete the life cycle experimentally. Later Webster (1948), James (1968), Kugi (1983) tried to infect oribatid mites and other invertebrates with eggs of Mesocestoides . They attempted to determine the existence of the first intermediate host of Mesocestoides . Unfortunately, all studies were not successful.