© Benaki Phytopathological Institute
Toxicity of insecticides to
Calliptamus barbarus barbarus
49
tion and it was the most toxic insecticide
to the grasshopper nymphs and adults in
the laboratory experiments. However, un-
der field conditions its application may not
have exactly the same effect as spinosad
undergoes rapid decomposition by sun-
light when it is on the leaf surface of plants.
Photolysis is the main degradation mech-
anism of spinosad. Its half-life ranges from
2.61 to 6.31 days depending on the species
of plant on which has been applied (DPR,
1995a, DPR, 1995b). Our results on both the
speed of action and the toxicity of spinosad
are in agreement with the study of Amar-
asekare and Edelson (2004) on
M. differentia-
lis
nymphs.
Imidacloprid exhibited very high toxicity
and speed of action on the experiments with
C. barbarus barbarus
nymphs and adults. The
mortality of the grasshoppers caused by the
application of imidacloprid and its speed
of action were lower than those caused by
spinosad and similar to those caused by al-
pha cypermethrin. Tharp
et al.
(2000) report-
ed that the LD
90
of imidacloprid to 4
th
instar
nymphs of
Melanoplus sanguinipes
Fabrici-
us (Orthoptera: Acrididae) was 93 ppm. In
the present study 89% mortality of 3
rd
and
4
th
instar nymphs of
C. barbarus barbarus
was achieved over 10 days with a concen-
tration of 77 ppm of this insecticide. Moreo-
ver, Wilps
et al.
(2002) reported high mortal-
ity (90%) of individuals of
C. italicus
in field
experiments using low dose of imidacloprid
(7.5 gr a.i./ha).
The results of the laboratory bioassays
showed that from the insecticides tested
at the labeled use rates, spinosad had the
most toxic effect and required the least time
to control nymphs and adults of
C. barbar-
us barbarus
. Imidacloprid and alpha cyper-
methrin exhibited also high toxicity. Howev-
er, it must be mentioned that the exposure
of the grasshopper’s individuals to the in-
secticides under laboratory conditions is
not the same as in field conditions and con-
sequently the actual mortality in the field
may be different.
Literature cited
Amarasekare, K.G. and Edelson, J.V. 2004. Effect of
temperature on efficacy of insecticides to differ-
ential grasshopper (Orthoptera: Acrididae).
Jour-
nal of Economic Entomology
, 97(5): 1595-1602.
Antonatos, S.A., Emmanuel, N.G. and Fantinou, AA.
2013. Effect of temperature and species of plant
on the consumption of leaves by three species
of Orthoptera under laboratory conditions.
Eu-
ropean Journal of Entomology
, 110(4): 605-610.
Aragón, P., Coca-Abia, M.M., Llorente, V. and Lobo,
J.M. 2013. Estimation of climatic favourable ar-
eas for locust outbreaks in Spain: integrating
species’ presence records and spatial informa-
tion on outbreaks.
Journal of Applied Entomolo-
gy
, 137(8): 610-623.
Bei-Bienko, G.Ya. and Mishcheno, L.L. 1963.
Locusts
and grasshoppers of the U.S.S.R. and adjacent
countries
(Translated from Russian). Part 1, Israel
program for scientific translations, 400 p.
Table 4.
Lethal time of 50% (LT
50
) and 90% (LT
90
) of adults of
Calliptamus barbarus barbarus
when exposed for 48 hours to grapevine leaves treated with different insecticides.
Treatment
Slope (b) ±
S.E.
LT
50
α
(Days)
95% confidence
limits
LT
90
α
(Days)
95% confidence
limits
df
X
2
P
Spinosad
2,49
±
0,26 0,97 0,66 – 1,25 3,18
2,66 – 3,89 78 107,00 0,016
β
Imidacloprid 1,24
±
0,18 3,90 3,12 – 4,71 41,82 24,91 – 104,28 78 33,75 1,000
Alpha cyper-
methrin
1,86
±
0,21 5,40 4,45 – 6,64 26,43 17,17 – 59,19 78 155,46 <0,0001
β
Lambda cyhalo-
thrin
1,37
±
0,23 12,51 8,80 – 28,26 107,41 40,54 – 1471,18 78 155,01 <0,0001
β
α: LT
50
and LT
90
are considered different when the 95% confidence limits fail to overlap
β: Heterogeneity factors were used in the calculation of confidence
