Agriculture Reference
In-Depth Information
within a couple of hours; they are then capable of
transmitting the disease to healthy plants.
Aceria lycopersici
(Wolffenstein)
Tomato erineum mite
This widely distributed tropical and subtropical
pest occurs in greenhouses in various parts of
Europe, especially on aubergine and tomato. It
induces the development of whitish, hairy
patches (erinea) on the leaves, petioles and
stems, and causes most damage under hot,
dry conditions. The mites inhabiting these
erinaceous galls are vermiform, 0.15-0.20 mm
long, with equal numbers (c. 60) of tergites and
sternites (cf. tomato russet mite,
Aculops
lycopersici,
below).
DESCRIPTION
Adult
0.18-0.20mm long, whitish, elongate and
slender-bodied;
hysterosoma
subdivided into nu-
merous tergites and sternites;
prodorsal shield
setae
directed backwards.
Acalitus essigi
(Hassan)
Blackberry mite
This species is widely distributed and sometimes
common on cultivated and wild blackberry. The
mites do not damage the leaves (cf. raspberry
leaf & bud mite,
Phyllocoptes gracilis,
p. 259) but
cause a characteristic uneven ripening of infested
fruits, the basal drupelets of which remain hard
and greenish-red to red whilst the rest mature,
a condition known as 'red-berry' disease. The
incidence of 'red-berry' tends to increase as
the season progresses, with late-maturing fruits
the most severely affected. Physiological factors
may cause uneven ripening of blackberries, but
not necessarily of the basal drupelets, and af-
fected areas often become softened (a clear indi-
cation that mites are not the cause).
Aculops lycopersici
(Massee)
Tomato russet mite
This mite is an important pest of tomato; other
cultivated hosts include aubergine, potato and
sweet pepper. In temperate regions, such as
Europe, the pest occurs in glasshouses and
breeds continuously without a dormant stage. In-
festations lead to significant bronzing of leaves
and stems; damaged areas often also crack
and become distorted. Symptoms usually
first appear at the base of plants and gradually
spread upwards. Most significant damage occurs
on tomato; leaves may desiccate and drop
off, and infested plants are often killed. The
free-living mites are pale yellowish-brown,
0.15-0.18 mm long and wedge-shaped, with
about 27 broad tergites and 60 narrow ster-
nites (cf. tomato erineum mite,
Aceria
lycopersici,
above, which is a far less important
pest).
BIOLOGY
Mites hibernate in various sheltered situations
on host plants, and become active in the early
spring. They then move to the new shoots to feed
and breed amongst the hairs on the leaves and
petioles. Later, the mites migrate to the opening
blossoms and will eventually become established
around the base of the developing fruits, shel-
tered by the remains of the calyxes; here, they
feed on the basal drupelets. There are several
overlapping generations annually. Populations
diminish rapidly in the autumn, and survivors
eventually overwinter.
Aculus schlechtendali
(Nalepa)
Apple rust mite
This mite is a widely distributed and generally
common pest of apple; occasionally, the mites
also occur on pear (cf. pear rust mite,
Epitrimerus piri,
p. 258). Although implicated in
causing leaf bronzing and fruit russeting in apple
orchards, large numbers of mites can be toler-
DESCRIPTION
Adult mite
0.16-0.18 mm long, whitish and ver-
miform;
prodorsal shield setae
long and directed
backwards.
