© Benaki Phytopathological Institute
Antonatos & Emmanouel
44
ulations in the European Union the use of
most of those has already been banned.
In recent years most of the research con-
cerning the chemical control of orthopter-
ans involves the use of pyrethroids (Ama-
rasekare and Edelson, 2004; Reinert
et al
.,
2001; Johnson, 1990; Olaifa, 1986; Ewen
et
al
., 1984; Mukeri and Ewen, 1984), neonico-
tinoids (Wilps
et al
., 2002; Tharp
et al
., 2000),
spinosins (Amarasekare and Edelson, 2004),
insect growth regulators (IGRs) (Weiland
et
al
., 2002; Amarasekare and Edelson, 2004)
and entomopathogenic organisms (Frank,
2009; Amarasekare and Edelson, 2004; Sie-
glaff
et al.
, 1998; Milner
et al.
, 1994; Moore
et
al
., 1992; Johnson and Pavlikova, 1986).
In the present study an attempt was
made to determine the toxic effect of vari-
ous insecticides, with different mode of ac-
tion, to nymphs and adults of the grasshop-
per
C. barbarus barbarus
under laboratory
conditions. In addition, the lethal time of
the 50% and 90% of the grasshopper popu-
lation by these insecticides was estimated.
Materials and methods
Biological material
The experiments were conducted with
nymphs (mixed population of 3
rd
and 4
th
in-
star) as well as with adults of
C. barbarus bar-
barus
. Nymphs of early instars (1
st
and 2
nd
)
were collectedby sweepnetting in a lowland
grassland area near Spata (Attica – Greece).
After the collection, the insects were trans-
ferred to the laboratory and reared in exper-
imental wood-framed cages (30 x 30 x 30
cm), 20-30 nymphs in each cage, at a tem-
perature of 25 ± 1°C, humidity 65 ± 5% and
a photoperiod 16: 8 light: dark (Lactin and
Johnson, 1995; De Faria
et al.
, 1999). Insects
were fed with vine leaves, placed in the cag-
es daily. Water was provided through a piece
of water soaked cotton placed on the bot-
tom of each cage. The adults were kept in
cages of same dimensions and fed also with
vine leaves until used in bioassays.
Insecticides
The insecticides that were used in bioas-
says with
C. barbarus barbarus
were imida-
cloprid 35% w/v (SC), alpha cypermethrin
10% w/v (EC) and spinosad 48% w/v (SC) for
both nymphs and adults. Two IGRs difluben-
zuron 25% w/w (WP) and azadirachtin 1%
w/v (EC) were tested on nymphs and lamb-
da cyhalothrin 9.43% w/w (CS) tested on
adults. The doses of the insecticides used in
the experiments were for imidacloprid 7.7gr
a.i./100lt water, for alpha cypermethrin 4gr
a.i./100lt water, for lambda cyhalothrin 1.2gr
a.i./100lt water, for spinosad 16.8gr a.i./100lt
water, for diflubenzuron 25gr a.i./100lt wa-
ter and for azadirachtin 2gr a.i./100lt water.
The concentrations of the insecticides so-
lutions were calculated based on the prod-
uct labels and were similar with those that
were used in agricultural practice against
Orthoptera or other insect pests.
Bioassays
To test the toxic effect of the insecticides
to
C. barbarus barbarus
nymphs and adults, a
water solution of each insecticide was pre-
pared (1.5 lt) using the above mentioned
doses. Fully expanded mature leaves of vine
(
Vitis vinifera
, cv Sultanina) were dipped
in each insecticide solution, removed and
dried at 30°C for 30-40 min (Amaraseka-
re and Edelson, 2004). Water treated leaves
were used as control. To keep the leaf turgid,
the stem was placed in a vial of water. Ev-
ery leaf was placed separately in a clear plas-
tic cage (1lt volume) bearing an opening at
the top covered with fine muslin. Eight indi-
viduals (4 males and 4 females), nymphs or
adults, of
C. barbarus barbarus
were placed
in each cage and remained under starvation
for 24 hours before their use in bioassays.
The treated leaf was kept in the cage for 48
hours and then was replaced with an un-
treated leaf every 48 hours, for 10 days. Wa-
ter was provided to the insects via a piece of
water soaked cotton placed at the bottom
of each cage. The toxicity of insecticides
was determined by the mortality of grass-
hoppers over the 10-day observation period
(Amarasekare and Edelson, 2004). Counting
