Agriculture Reference
In-Depth Information
EXAMPLES: Androlaelaps casalis (poultry litter
mite); Varroa jacobsoni, a parasite of honey
bees.
covering the idiosoma, and either undivided or
subdivided transversely into two; females with a
large metasternal shield; pedipalpal tarsus with
a specialized three-pronged apotele. Parasitid
mites are especially numerous in the soil leaf-
litter layer, the family including both detritus-
feeding and predatory species.
EXAMPLES: Parasitus spp., including some that
are abundant in mushroom beds.
4. Family PARASITIDAE
Oval (although sometimes somewhat pointed
anteriorly), usually heavily sclerotized, reddish-
brown or yellowish-brown mites; dorsal shield
ORDER IXODIDA (TICKS)
A major group of blood-sucking external para-
sites, associated with vertebrates (but not fish)
and known collectively as ticks; includes the
largest of all mites (adults of some species are up
to 30 mm or more in length when fully engorged
with blood from the host). Gnathosoma with a
well-developed hypostome, armed with numer-
ous barb-like teeth; ocelli present or absent.
economic importance, some being vectors of the
organisms that cause, for example, the arboviral
disease Lyme disease and the rickettsial diseases
louping ill and Q fever.
EXAMPLE: Ixodes ricinus (sheep tick).
2. Family ARGASIDAE (soft ticks)
1. Family IXODIDAE (hard ticks)
Ticks usually without a distinct scutum;
gnathosoma placed ventrally and visible from
above only during the larval stage; coxae without
spurs; body oval or rounded. Soft ticks are para-
sites of bats and birds, and are of considerable
economic importance.
EXAMPLE: Argas persicus (fowl tick).
Idiosoma partly (in males almost entirely)
covered dorsally by a sclerotized, leathery
scutum; gnathosoma clearly visible from above
(unless tick fully engorged); body oval or
pyriform. Several species are of considerable
ORDER PROSTIGMATA
Adults usually weakly sclerotized and most rang-
ing from 0.1 to 1.0 mm in length, although some
species are considerably larger; stigmata, when
present, located between the chelicerae or
dorsally on the propodosoma; chelicerae either
chelate or needle-like but sometimes reduced;
pedipalps usually 3- to 5-segmented, the tibia
and tarsus often forming a distinct 'thumb-claw';
ocelli present or absent. This is the main group of
phytophagous mites and includes many impor-
tant pests, some of which are vectors of plant
virus diseases; superfamilies are indicated below
but not defined.
Superfamily ERIOPHYOIDEA (gall mites)
1. Family PHYTOPTIDAE (p. 255)
Minute, vermiform (worm-like) mites up to
0.2mm long; two pairs of legs, located anteriorly;
propodosoma forming a shield-like structure
(the prodorsal shield) which bears three or four
setae (Fig. 168a); hysterosoma elongated and
annulated; feather-claws (see Fig. 169a) simple.
Includes gall-forming and free-living species.
EXAMPLE: Phytoptus avellanae (filbert bud
mite).
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