Biology Reference
In-Depth Information
Family
TARSONEMIDAE
Phytonemus pallidus
(Banks) (
1123
)
syn.
Tarsonemus pallidus
Banks
Cyclamen mite
A major pest of greenhouse ornamentals, including
African violet (
Saintpaulia hybrida
), azalea
(
Rhododendron
),
Begonia
, busy lizzie (
Impatiens
),
Cyclamen, Gerbera, Gloxinia
, ivy (
Hedera
), Japanese
aralia (
Fatsia japonica
),
Pelargonium, Petunia
and
Verbena
. In favourable situations infestations also
survive on outdoor plants. Distinct biological races
are associated with Michaelmas daisy (
Aster
) and
strawberry -
Phytonemus pallidus asteris
and
P. pallidus fragariae
, respectively. Virtually
cosmopolitan. Widely distributed in Europe.
Small, elliptical, light brown to whitish mites with a
distinct head-like gnathosoma, short, needle-like
chelicerae and pronounced sexual dimorphism; the hind
legs of females are clawless and those of males broadly
elaborated and often inwardly flanged.
Hemitarsonemus tepidariorum
(Warburton)
Fern mite
Recorded in Costa Rica, England and the USA as a pest
of ferns, including hen & chick fern (
Asplenium
bulbiferum
), Polystichum and
Pteris
in greenhouses.
DESCRIPTION
Adult female:
0.23 mm long; pale yellowish brown;
body elongate-oval, the gnathosoma longer than broad
and with the palps directed forwards.
Adult male:
0.15-0.16 mm long; pale yellowish brown; hind leg
with a broad triangular tooth on the inner margin of the
tibia and a prominent tarsal claw; tibia and tarsus both
longer than femur.
Egg:
0.11-0.12 mm long; oval and
whitish.
Larva:
similar to adult, but smaller and 6-
legged.
DESCRIPTION
Adult female:
0.25 mm long; light brown and
translucent; body oval-elongate and somewhat barrel-
shaped; gnathosoma longer than broad, with the palps
directed forwards; hind legs very thin, each bearing a
long, whip-like seta.
Adult male:
0.2 mm long; light
brown and oval-bodied; hind legs broad, each with a
very large femur bearing a rounded inner flange and
terminating in a strong claw.
Egg:
0.125 × 0.075 mm;
elliptical, semitransparent and whitish.
Larva:
whitish,
with hind part of body triangular; 6-legged.
LIFE HISTORY
The mites breed continuously throughout the year, with
a succession of overlapping generations, and
infestations are encouraged by warm, dark and humid
conditions. Eggs are laid singly or in small groups close
to the tips of the fronds (within the shelter of the furled
leaflets or pinnae) or at the top of the rhizome between
the scales. The eggs hatch within a few days at normal
greenhouse temperatures but their development is
greatly protracted in cool conditions. The larvae feed for
1-2 weeks before entering the quiescent nymphal stage.
Adults appear 3-4 days later. Adults and larvae feed on
the youngest tissue, imbibing sap from the surface cells
which then collapse. All developmental stages and both
sexes occur in abundance throughout the summer but
winter populations consist mainly of adult females and
eggs.
1123
DAMAGE
Infested leaves are speckled with brown, attacked
fronds becoming distorted and discoloured. The growth
of heavily infested plants is severely checked.
1123
Cyclamen mite (
Phytonemus pallidus
) damage to leaf
of
Fatsia
.
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