Biology Reference
In-Depth Information
Family ERIOPHYIDAE (gall mites and rust
mites)
ACER
Aculops acericola Nalepa
Sycamore gall mite
Although sometimes considered a gall-forming species,
this mite is merely an inquiline in erinea produced
on sycamore ( Acer pseudoplatanus ) by Eriophyes
psilomerus (p. 408). The mites are c . 0.12 mm long with
about 23 abdominal tergites; microscopically, therefore,
the two species are readily distinguishable.
Many different species of eriophyid mite are associated
with ornamental plants, some forming galls or bronzing
the leaves but others existing merely as inquilines or as
leaf vagrants. Most species mentioned in the following
account are indigenous to northern Europe but some are
relatively new arrivals, having been introduced along
with their host plants from other parts of the world. The
nomenclature for eriophyid mites is very confusing,
with many species referred to in the literature under two
or more specific if not subspecific names. Confusion at
generic level is also widespread. As a result it is often
difficult, if not impossible, to assign correctly an
observed plant symptom to any particular species,
subspecies or race of mite. These problems are
exacerbated by the occurrence in eriophyid galls of
inquilines, which are not the gall-forming species.
Further difficulties arise in those eriophyids exhibiting
deuterogeny (two or more structural female forms - a
winter form or 'deutogyne' and a summer form or
'protogyne'). In this topic, to reduce confusion and to
aid correct cross-reference to names used in other
publications, species are catalogued under their main
host plants rather than in any taxonomic order. Apart
from occasional reference to colour, size and form,
taxonomic descriptions of the mites have been
excluded. Although most, if not all, of the more
important pest species are included, the following
account is far from exhaustive, there being many others
on ornamental plants, especially shrubs and trees. Also,
various galls are known that cannot be attributed with
certainty to any particular species of mite.
Artacris cephaloneus (Nalepa) ( 1073-1074 )
Maple bead-gall mite
A generally abundant species, responsible for the
development of pimple-like bead galls on the leaves of
maple ( Acer ) and sycamore ( A. pseudoplatanus ).
Female mites overwinter in sheltered situations on the
shoots and become active in the early spring. They then
invade the expanding foliage, each initiating the
development of numerous galls. These galls occur from
April onwards, and change from green to red as they
mature. The galls are often present in very large
numbers, particularly on young trees, but are generally
harmless. Breeding continues in the galls throughout the
summer, although many galls will be found on
examination to be empty. The causal mites are
c . 0.16 mm long and slender-bodied, with about
65 abdominal tergites and sternites, and a pair of
backwardly directed setae arising from tubercles on the
hind margin of the prodorsal shield.
1073
1074
1073 Young galls of maple bead-gall mite ( Artacris
cephaloneus ) on leaves of Acer campestre .
1074 Mature galls of maple bead-gall mite ( Artacris
cephaloneus ) on leaf of Acer campestre .
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