© Benaki Phytopathological Institute
Hajjar & Al-Masoud
64
dry for 3 h. Control tubes were treated with
distilled water. Five replicates of glass tubes
per insecticide treatment were used. Twen-
ty adults of
T.
cacoeciae
, which were 24 hours
old, were transferred to each treated tube af-
ter drying, using a fine feather. The tubeswere
then sealed using cotton previously dipped
in 50% honey solution and were kept in an
incubator at 26 ±2°C, RH 75 ±5% RH and 16:8
L:D cycle. After 24 h of exposure to the dry
insecticide residues, the effect on adult mor-
tality was recorded. The classification system
of the International Organization for Biolog-
ical Control (IOBC) was used for the classifi-
cation of the insecticide toxicity as: harmless
(<30%mortality, Class 1); slightly harmful (30-
79% mortality, Class 2); moderately harmful
(80-99% mortality, Class 3); or harmful (>99%
mortality) (Hassan
et al.,
2000).
Sublethal effect on parasitism
Sublethal effect on parasitism were as-
sessed on adult females of
T.
cacoeciae
,
which had survived the 24 h exposure to
insecticide residues (bistrifluron 10% EC;
pyriproxyfen 10% EC; matrine 0.6% EC;
azadirachtin 1.0% EC, and control). Females
were placed in glass tubes (2.5 x 20 cm), 6 in-
dividuals per tube, along with 100 ± 10 eggs
of
E. cautella
, which were glued on card-
board tape (1cm
2
). The females were provid-
ed with food through a cotton wool, which
had been dipped in 50% honey solution,
and served also as a closure of the tubes.
Five tubes (replicates) were used per insec-
ticide treatment and the control and were
kept at 26 ±2°C, RH 75 ±5% RH at a 16:8 L:D
cycle. The eggs of
E. cautella
were removed
from the glass tubes after 24 h exposure to
the parasitoids and placed in labeled Pe-
tri dishes corresponding to the replicates,
in the incubator. After 9 days of incubation,
the number of parasitized eggs was counted
and parasitism ratios of the insecticide treat-
ments were compared with the control. The
IOBC classification (Hassan
et al.,
2000) was
used for the classification of insecticide tox-
icity and the data were corrected using the
Abbott’s formula (Abbott 1925).
Sublethal effects on parasitoid
longevity
Sublethal effect of insecticides on para-
sitoid longevity was also assessed on adult
females which survived 24 h exposure to
the insecticide treatments. Female individ-
uals were placed individually in clean glass
tubes sealed with cotton wool, which had
been dipped in 50% honey solution, and
were incubated as described before. Five
tubes (replicates) per insecticide treatment
and the control were used. Longevity of the
parasitoid as number of days until death was
recorded.
Persistence effects on parasitoid
mortality
The persistence effect of insecticides, ap-
Table 1.
List of insecticides used in the study.
Insecticides
Class
Recommended
application rate
(ml/L)
Manufacturing company
Cypermethrin (Hi power10% EC)
Pyrethroid
0.50
Sulphur mills limited- India
Deltamethrin (Flotron 2.5% EC)
Pyrethroid
0.35
Sulphur mills limited- India
Malathion (Sulmathion 57% EC) Organic phosphorus
0.75
Sulphur mills limited- India
Phenthoate (Peston 50% EC)
Organic phosphorus
0.80
Astrachem - Saudi Arabia
Methomyl (Metho900 SP)
Carbamate
0.20
BASF Corporation – Germany
Carbosulfan (Marshal 25% WP)
Carbamate
0.50
Astrachem - Saudi Arabia
Bistrifluron (Hanaro 10% EC)
(IGR)
1.00
Astrachem - Saudi Arabia
Pyriproxyfen (Muligan 10% EC)
(IGR)
0.75
Parabolan- Spain
Matrine (Kingbo 0.6% EC)
Plant Extract
2.00
Beijing Kingbo Biotech- China
Azadirachtin (Amen 1.0% EC)
Plant Extract
2.50
Ecopheosides – India
