327
specialised for exploiting ephemeral habitats. To this end they have evolved a specialised dispersing deutonymph stage, the hypopus, which has an attachment organ
and is often transported by a larger animal in an example of phoresy (see also Sect.
9.5). Thus intimate associations with larger arthropods or even vertebrates have
evolved in several groups, and in at least four astigmatan lineages these lifestyles
have gone further and can be considered parasitic:
1. Hemisarcoptoidea contains a few species in the Hemisarcoptidae which have
been recorded as haematophagous parasite of beetles or scale insects. These
mites have even been employed in pest control against scale insects and one
hemisarcoptid has been used as a model organism for how parasitism may have
evolved from phoresy (Holte et al. 2001; see also Sect. 9.5). Some
Winterschmidtiidae have been recorded feeding on the paralysed prey of a wasp,
or on the larva or the pupa of the wasp itself. The entire superfamily can be dated
back to a record of Winterschmidtiidae in Miocene (ca. 16 Ma) Chiapas amber
(Mexico) (Türk 1963).
2. Members of the Glycyphagoidea are thought to have been originally associated
with vertebrate nests (OConnor 1994). The families Pedetopodidae,
Chortoglyphidae, Echimyopodidae and some Glycyphagidae have deutonymphs
which parasitize the hair follicles of rodents causing dermatitis. Some glycyphagids are again thought to induce dermatitis in people handling food products
(see also above). There is no fossil record.
3. All members of the family Hypoderatidae, the only family of the Hypoderatoidea,
have deutonymphs which parasitise the subcutaneous tissues of birds (e.g. Pence
et al. 1997) and (rarely) desert rodents. The deutonymph is the only stage of the
lifecycle which acquires food—i.e. adults do not feed—and can engorge themselves to increase their body volume by up to 1000 times, for a mechanism see
Alberti et al. (2016). There is no fossil record and many extant species are only
known from the deutonymph.
4. Psoroptida are a putatively monophyletic assemblage of three superfamilies:
Pterolichoidea and Analgoidea (feather mites), and Sarcoptoidea (fur mites). An
important characteristic of this group is that they have lost the deutonymph stage
of the lifecycle and are transferred from host to host by direct contact. Psoroptid
mites typically feed on oils or sebaceous secretions and can be considered parasites in that their presence can damage the plumage or fur. Some psoroptids
infect the respiratory tract of the host and others burrow into the upper layer of
the skin. Classic examples here would be mange mites, causing hair loss in dogs,
and scabies mites inducing itching in humans. Possible feather mite eggs
described from the Cretaceous (ca. 115 Ma) Crato Formation of Brazil (Martill
and Davis 1998) were rejected as unconvincing by Proctor (2003). The oldest
psoroptid is thus a putative fur mite (Fig. 9.4d)—now thought to belong to the
family Apotomelidae—from Miocene (ca. 16 Ma) Dominican amber (Poinar
Jr 1988).
9 Chelicerates as Parasites
specialised for exploiting ephemeral habitats. To this end they have evolved a specialised dispersing deutonymph stage, the hypopus, which has an attachment organ
and is often transported by a larger animal in an example of phoresy (see also Sect.
9.5). Thus intimate associations with larger arthropods or even vertebrates have
evolved in several groups, and in at least four astigmatan lineages these lifestyles
have gone further and can be considered parasitic:
1. Hemisarcoptoidea contains a few species in the Hemisarcoptidae which have
been recorded as haematophagous parasite of beetles or scale insects. These
mites have even been employed in pest control against scale insects and one
hemisarcoptid has been used as a model organism for how parasitism may have
evolved from phoresy (Holte et al. 2001; see also Sect. 9.5). Some
Winterschmidtiidae have been recorded feeding on the paralysed prey of a wasp,
or on the larva or the pupa of the wasp itself. The entire superfamily can be dated
back to a record of Winterschmidtiidae in Miocene (ca. 16 Ma) Chiapas amber
(Mexico) (Türk 1963).
2. Members of the Glycyphagoidea are thought to have been originally associated
with vertebrate nests (OConnor 1994). The families Pedetopodidae,
Chortoglyphidae, Echimyopodidae and some Glycyphagidae have deutonymphs
which parasitize the hair follicles of rodents causing dermatitis. Some glycyphagids are again thought to induce dermatitis in people handling food products
(see also above). There is no fossil record.
3. All members of the family Hypoderatidae, the only family of the Hypoderatoidea,
have deutonymphs which parasitise the subcutaneous tissues of birds (e.g. Pence
et al. 1997) and (rarely) desert rodents. The deutonymph is the only stage of the
lifecycle which acquires food—i.e. adults do not feed—and can engorge themselves to increase their body volume by up to 1000 times, for a mechanism see
Alberti et al. (2016). There is no fossil record and many extant species are only
known from the deutonymph.
4. Psoroptida are a putatively monophyletic assemblage of three superfamilies:
Pterolichoidea and Analgoidea (feather mites), and Sarcoptoidea (fur mites). An
important characteristic of this group is that they have lost the deutonymph stage
of the lifecycle and are transferred from host to host by direct contact. Psoroptid
mites typically feed on oils or sebaceous secretions and can be considered parasites in that their presence can damage the plumage or fur. Some psoroptids
infect the respiratory tract of the host and others burrow into the upper layer of
the skin. Classic examples here would be mange mites, causing hair loss in dogs,
and scabies mites inducing itching in humans. Possible feather mite eggs
described from the Cretaceous (ca. 115 Ma) Crato Formation of Brazil (Martill
and Davis 1998) were rejected as unconvincing by Proctor (2003). The oldest
psoroptid is thus a putative fur mite (Fig. 9.4d)—now thought to belong to the
family Apotomelidae—from Miocene (ca. 16 Ma) Dominican amber (Poinar
Jr 1988).
9 Chelicerates as Parasites