[Edited_by_A._Ciancio,_C.N.R.,_Bari,_Italy_and_K.(Bookos.org)

IPM OF CITRUS PESTS IN GREECE
35
A food attractant, mainly a compound that releases ammonia, is added in the
pesticide solution.
The timing of spray applications is determined by monitoring medfly population
with traps, which are hanged on citrus trees a few weeks before fruits begin to
mature. The monitoring of adult population may take place at field or region scale.
Trap networks for monitoring C. capitata population have been installed and
operate in some areas of Greece by the Regional Plant Protection Services so
forecasting of infestation is possible based on trap captures and environmental
conditions and warnings are released to the growers when necessary. Although
treatment application thresholds against medfly have not been established at
national level, those suggested by Katsoyannos (1996a) are applied in many cases
(20 adults/trap/week in autumn on clementines approaching ripeness, 40–50
adults/trap/week in autumn on oranges (pre-ripe and ripe stages), 10
adults/trap/week in spring on late ripening varieties).
When no monitoring is performed, sprayings are performed when the fruits reach
maturity whereas the number of applications depends on the region, the season and
the variety of citrus fruits. A spray program for orange and mandarin, which was
recommended by the Ministry of Rural Development and Food in the past and can
be applied even today, if using other insecticides, involves the following actions:
(a) For bait spraying, the first application is carried out 15 days before fruit
ripening and is repeated at 5–7 days intervals. The spray solution consists of 2%
protein (as an attractant) and 0.3% dimethoate or fenthion or 0.5% malathion. It is
applied on hedges and bushes in the perimeter of the orchard, on the interior and
the upper part of the trees, mainly on branches that do not bare fruits (b) For cover
spaying, the first application is carried out at the beginning of ripening and spraying
may be repeated after 20 days depending on the prevailing enviromental conditions
and the time of fruit harvest. The spray solution consists of 0.03% dimethoate or
fenthion or other organophosphorate insecticides (Anonymous, 1973).
In most of the orange cultivated areas in Greece the bait sprayings applied for the
control of Bactrocera oleae (Gmelin) also contribute to a significant reduction of
the medfly populations (Economopoulos, 1996). The same attractants (salt of
protein hydrolysates) as those for the medfly have been used in bait sprays for B.
oleae together with organophophorate insecticides. Applications start early in the
summer and they are continued until the end of autumn (Broumas, 1994).
In some cases, spray solutions are applied on an artificial medium such as a
gunny placed on a parallelepiped plastic plate which is hanged on trees branches
(Economopoulos, 1996). Laboratory experiments by Mavrikakis, Remboulakis,
and Economopoulos, (2003) showed that a type of a paper surface (Vioryl) baited
with a water solution of protein hydrolysate (6%) had a better “attract and kill”
performance on medfly than the gunny surface baited with the same food lure. The
insecticide (active ingredient) used as a killing agent was spinosad in a proportion
of 0.04% v/v and it was effective for a time period more than 5 weeks.
Some of the former mentioned insecticidal active substances used for the control of
medfly have been withdrawn after being re-evaluated (Directive 91/414/EEC) in
the E.C. (fenthion, malathion). Currently, the insecticides which are authorized
for use against medfly in Greece include Beauveria bassiana (mandarin),