Page 16 - Volume 6, Issue 1, January 2013

© Benaki Phytopathological Institute
Kapaxidi 14
wooly bud stage when mites become ac-
tive, followed by a second spraying approx-
imately 10 days later when late-develop-
ing buds open. Papaioannou-Souliotis et al.
(1998) investigated the effect of some com-
monly used fungicides and insecticides on
phytoseiid populations in vineyards in four
regions of Greece.
There are no registered acaricides in
Greece for fig and pomegranate cultivations.
The cultivation of fig tree is traditional in
southern parts of mainland Greece and the
Aegean islands, yet yield loss due eriophyoid
infestation has been reported (Vachamid-
is and Vemmos, 2010). Pomegranate culture
has become popular during the last decade
in Greece. Aceria granati has been reported
to infest cultivations in northern Greece re-
cently (Koveos et al., 2010) but the possible
effect on yield is not yet determined.
Discussion
The economic importance of eriophyoid
mites has been estimated in some coun-
tries but the variability of environmental
conditions, cultural practices, cultivar fea-
tures and market standards make a gener-
alisation based on these studies difficult. A
number of eriophyoid species emerged as
economically important and their pest sta-
tus has been reconfirmed recently, mainly in
crops like citrus, apples, grapes, hazelnuts,
coconuts and tomatoes (Van Leeuwen et al.,
2010). In Greece, the economic importance
of eriophyoid mites as pests of orchards
and grapevine has not been much exploit-
ed. Most of them are considered occasion-
al pests whereas outbreaks often occur after
warm winters and springs with high rain-
falls. The change in control strategies main-
ly towards the use of fungicides lacking ac-
aricidal activity and of insecticides having a
detrimental effect on predatory mites might
cause outbreaks of rust mites and result in
the permanent pest status of the species
(Easterbrook, 1996; Croft and Slone 1998).
In addition, the climate change might be
important of future outbreaks of the erio-
phyoid mite pests.
In general, eriophyoid mites are suscep-
tible to most commonly used acaricides,
some insecticides and fungicides (especial-
ly sulphur). Τhe European Union review pro-
gramme of the existing active substances
under the Directive 91/414/EEC, resulted in
the reduction of the available substances
with acaricidal effect. The lack of registered
acaricides for some cultivations such as
pomegranate in Greece, may cause a prob-
lem in the future.
The main problem with the control of
eriophyoids is getting the compounds in
contact with the mites due to hidden life-
style of a number of important species.
Mites hiding in galls, blisters and buds are
not easily accessible. In these cases, an ac-
curate timing of the applications is crucial,
in order to reach the life stages that (tempo-
rarily) leave the hiding places, and can, only
at those times, be reached with pesticides.
That is why, in most cases, control is direct-
ed against the adults which are searching
for spots to induce their hiding places for
the immature life stages (gall mites) or for
existing shelters (bud mites) and for a lim-
ited time, few days or weeks. Hence, control
is best succeeded with acaricides providing
long residual activity. On the other hand,
rust mites have a more superficial lifestyle
on the underside of leaves, leaving them ex-
posed throughout their life cycle and result-
ing in easier control. In cropping systems
where eriophyoid mites cause economic
damage, such as apple and citrus orchards,
and Tetranychidae are also main pests, ap-
plication timing and product choice should
reflect concerns on the economic damage
of both species. (Van Leeuwen et al. , 2010).
The conservation of indigenous natural
enemies for controlling eriophyoid mites is
gaining more attention in the last decade
(Smith and Papacek, 1991). Morover, the
search for exotic natural enemies and re-
lease remains an option, in cases that local
predators fail or are less successful in con-
trolling these mite pests (Argov et al. , 2002).