Laboratory evaluation of chlorpyrifos, bifenthrin, imidacloprid ...

Pak. Entomol. Vol. 28, No.2, 2006
LABORATORY EVALUATION OF CHLORPYRIFOS, BIFENTHRIN, IMIDACLOPRID,
THIAMETHOXAM AND FLUFENOXURON AGAINST MICROTERMES OBESI (ISOPTERA:
TERMITIDAE)
Sohail Ahmed and Muhammad Farhan
Department of Agri. Entomology, University of Agriculture, Faisalabad
ABSTRACT
Laboratory evaluation of chlorpyrifos 40 EC, bifenthrin 10 EC, imidacloprid 50 SC, thiamethoxam 70WS
and flufenoxuron 10 DC on mortality of Microtermes obesi in soils from Faisalabad, Layyah and Chakwal
was carried out. Termites collected from sugarcane fields were exposed to the soil treated with various
concentrations of the insecticides and mortality of the termites was observed until all the exposed
individuals were dead. There was no difference in mortalities expressed as LT 50 in min and hrs in three
soils. Mortality decreased with decrease in concentrations of the insecticides. Topical application showed
the similar trend as was observed in the method of insecticide mixed soil.
INTRODUCTION
Fungus growing termites of the family Termitidae
are the most troublesome in agricultural crops. They
feed on the dead organic material such as crop
residues, mulches and soil organic matter (humus)
(Anonymous, 2001a). Termite’s fauna of Pakistan
consists of 50 species, of these nine termite species
belonging to Termitidae were recorded as pests of
agricultural crops in Pakistan. Microtermes obesi
and Eremotermes paradoxalis were found damaging
the sugarcane fields at Gojra, Lahore, and Qaderpur
in Punjab (Akhtar and Shahid, 1993).
Despite many safe and simple practices of termites’
management including cultural and biological
control, queen removal, plant resistance natural
products physical barriers and baiting systems being
proposed but insecticides are still plying a key role
for the termites control. Chemicals like chlorpyrifos,
thiodan cypermethrin, carbosulfan and triazophos
have been recommended (Kumawat, 2001; Rana et
al. 2001). Imidacloprid, thiamethoxam, fipronil and
bifenthrin in different formulations have been found
effective for the control of different species of
termites (Annonymous, 2001 a, b; Delgarde et al.,
2002a,b; Singh and Singh, 2002; Ahmed et al.,
2005a,b; Remmen and Su, 2005).
The major constraint in termites’ management
through these new chemicals appears to be whether
are these effective in all situation and on various
type of soils.
Hu (2005) demonstrated a delayed mode of activity
and nonrepellency of indoxacarb and fipronil against
the two termite species Reticulitermes flavipes
(Kollar) and Coptotermes formosanus Shiraki. There
is no published information about the use of
imidacloprid, thiamethoxam and flufenoxuron as
soil application in Pakistan.
The present studies evaluated laboratory efficacy of
chlorpyrifos 40 EC, bifenthrin 10 EC, imidacloprid
50 SC, thiamethoxam 70WS and flufenoxuron 10
DC on mortality of Microtermes obesi in soils from
Faisalabad, Layyah and Chakwal.
MATERIALS AND METHODS
Collection of termites
Subterranean termites (M. obesi) were collected
from the agricultural fields in and around the campus
of University of Agriculture, Faisalabad. Workers of
each species of at least 3rd instar (as determined by
size) were collected within 3 days of the beginning
of the experiment.
Research work was carried out in the Termites
Management Laboratory, Department of Agri.
Entomology, University of Agriculture, Faisalabad.
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Pak. Entomol. Vol. 28, No.2, 2006
Insecticides
Following five insecticides were used in the
bioassay of termites,
1. Chlorpyrifos 40EC
2. Bifenthrin 10EC
3. imidacloprid 50SL
4. Thiamthoxam 70WSC
5. Flufenoxuron 10DC
1000 ppm, 500 ppm, 250 ppm, 125 ppm, 62.5 ppm,
31.25 ppm, 15.62 ppm and 7.81 ppm solutions of
these insecticides were prepared in order to evaluate
their effects against Microtermes obesi.
Soil sampling
Soil samples from 3 Districts (Faisalabad, Layyah
and Chakwal) were collected. The soil was sifted
through a 30-mesh screen and moisture was
determined with the help of Oven Wet and dry
method. More amount of water was added up to 50%
of water holding capacity of soil to avoid mortality
of termites due to dehydration.
Two types of bioassay were carried out.
a. Mixing insecticide concentrations in soil
Toxicity tests were done in Petri dishes of 8.75 cm
dia containing 10g sifted soil, strips of sugarcane
having dimension 1.5 x 6 cm. were placed in each
Petri plate to keep the termites alive. Experimental
units were oven dried for 24 h for solvent
evaporation. Control units were treated with acetone
only. 40 workers of termites were released in the
Petri dishes having treated and untreated soils. These
dishes were placed under controlled conditions
28 + 2 0 C and 80 + 5% r.h. in a growth chamber.
Termites were examined after every 2 hours up to 12
hours, later, and then after each 24 hours until 100%
mortality occurred.
b. Direct exposure by Micro applicator
0.1 µl (microlitre) drop of different concentrations
was applied to the thorax of the termites by using
Burkard Micro Applicator. The termites after
treatment were put into the Petri dishes containing
filter paper moistened with distilled water. Mortality
was noted after 24 hours of treatment.
Statistical Analysis
Probit analysis (Polo-Pc) was used to make
toxicological inferences.
RESULTS
Table 1 shows LT 50 values of different
concentrations of chlorpyrifos, bifenthrin,
imidacloprid and thiamethoxam on Microtermes
obesi in soils from Faisalabad, Chakwal and Layyah.
LT 50 values of different concentrations of
chlorpyrifos and bifenthrin were in minutes while
imidacloprid and thiamethoxam showed LT 50 values
in hours. These values increased with decline in
concentrations. However, small difference was
found in LT 50 values of four insecticides in three
soils. For example, 198, 222 and 227 min were
values at 7.81 ppm of chlorpyrifos in soils from
Faisalabad, Chakwal and Layyah. Bifenthrin
differed from chlorpyrifos as 222, 136 and 123 were
values in these soils. There was no difference in
LT 50 values of imidacloprid and thiamethoxam in
three soil types.
Topical application of different concentrations of
chlorpyrifos, bifenthrin, imidacloprid and
thiamethoxam did not show difference in LT 50
values recorded in case of when these were applied
in the soils. To some extent these values were less in
control treatment (Table 2).
The lethal time of flufenoxuron to kill 50%
population of Microtermes obesi was high (3.62 to
11) as Chakwal than at two other places (2.5 to 7).
However direct exposure to flufenoxuron showed
similar pattern as was observed in case of other four
insecticides (Table 3).
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Pak. Entomol. Vol. 28, No.2, 2006
Table 1. LT 50 values of different concentrations of chlorpyrifos, bifenthrin, imidacloprid and
thiamethoxam on M. obesi in soils from Faisalabad, Chakwal and Layyah
chlorpyrifos bifenthrin imidacloprid thiamethoxam
Mins. Mins. Hrs Hrs.
Faisalabad
C 1 (1000 ppm) 9 10 1.17 2.39
C 2 (500 ppm) 13 17 1.81 2.61
C 3 (250 ppm) 19 22 2.41 4.10
C 4 (125 ppm) 33 30 3.48 5.81
C 5 (62.5 ppm) 66 69 5.33 6.89
C 6 (31.25 ppm) 118 105 8.11 8.38
C 7 (15.62 ppm) 175 154 10.3 11.5
C 8 (7.81 ppm) 198 222 11.7 17.9
C 9 (Control) 251 298 232 298
Chakwal
C 1 (1000 ppm) 10 15 1.26 2
C 2 (500 ppm) 17 20 1.73 2.63
C 3 (250 ppm) 22 26 2.47 3.63
C 4 (125 ppm) 30 34 3.66 4.92
C 5 (62.5 ppm) 69 44 5.71 5.43
C 6 (31.25 ppm) 105 54 7.32 8
C 7 (15.62 ppm) 154 94 9.35 10
C 8 (7.81 ppm) 222 136 11.2 14
C 9 (Control) 298 221 276 222
Layyah
C 1 (1000 ppm) 11 15 1.38 1.85
C 2 (500 ppm) 13 25 1.97 2.67
C 3 (250 ppm) 20 28 2.71 3.09
C 4 (125 ppm) 29 39 3.63 3.56
C 5 (62.5 ppm) 59 45 5.77 4.38
C 6 (31.25 ppm) 90 54 8.92 6.05
C 7 (15.62 ppm) 138 105 11.3 9.27
C 8 (7.81 ppm) 227 123 14.2 10.6
C 9 (Control) 289 266 245 274
Table 2. LT 50 values of chlorpyrifos, bifenthrin, imidacloprid and thiamethoxam for M. obesi
workers by direct exposure
Concentrations chlorpyrifos bifenthrin Imidacloprid thiamthoxam
Mins, Mins. Hrs Hrs
C 1 (1000 ppm) 7 13 1.50 1.15
C 2 (500 ppm) 10 18 2.21 1.66
C 3 (250 ppm) 13 27 3.21 2.41
C 4 (125 ppm) 19 40 6.34 3.45
C 5 (62.5 ppm) 33 57 8.41 5.04
C 6 (31.25 ppm) 53 76 10.4 6.89
C 7 (15.62 ppm) 66 100 27.9 8.21
C 8 (7.81 ppm) 79 140 31.8 9.00
C 9 (Control) 195 149 132 133
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Pak. Entomol. Vol. 28, No.2, 2006
Table 3. LT 50 values (hrs) of different concentrations of flufenoxuron 10 DC for M. obesi in treated
soil and in direct exposure
Soil
Concentrations Faisalabad Chakwal Layyah
C 1 (1000 ppm) 2.51 3.62 2.85 1.32
C 2 (500 ppm) 3.23 5.10 3.48 1.80
C 3 (250 ppm) 4.73 7.26 4.45 2.37
C 4 (125 ppm) 7 11 6.37 3.60
C 5 (Control) 98 133 132 132
Direct exposure
DISCUSSION
Chlorpyrifos 40 EC at 1000 ppm was found to be the
most effective insecticide against M. obesi with LT 50
ranging between 9 to 15 min in all the soils. The
LT 50 increases with the decrease in concentration.
Our results are in confirmation with the results of Su
et al. (1987) who stated that mortality of termites
exposed to chlorpyrifos 40 EC typically occurred
within the first 24h of exposure. No penetration was
observed in all the concentrations of chlorpyrifos 40
EC. Su et al. (1995) reported that the termite species
did not penetrate sand containing more > 100ppm of
chlorpyrifos 40 EC. Su and Scheffrahn (1990)
reported that termite did not fully penetrate the
treated sand at high concentration due to high
mortality. Bifenthrin 10EC was not penetrated by
Reticulitermes flavipes at any thickness through the
sand treated with 1ppm (Hu, 2005). Imidcloprid
50SL and thiamethoxam 70WS caused the mortality
in M. obesi but their efficacy did not match with
chlorpyrifos 40 EC and bifenthrin 10EC.
Imidachloprid 50SL was more efficient than
thiamethoxam 70WP and flufenoxuron 10DC. These
results are in agreement to that of Almeida and
Alves (1999) who reported that imidacloprid had
better efficacy against termites. However, Remmen
and Su (2005) reported that actara 70WS was found
to be more toxic against C. formosanus and
Reticulitermes flavipes. Cascade 10DC was found to
be least effective for the control of termites,
nevertheless, at high concentration no penetration
was observed but at lower concentration the termite
species penetrated into the soil.
Topical application of the insecticides on the
termites showed the following order of efficacy:
chlorpyrifos > bifenthrin > flufenoxuron >
thiamethoxam > imidacloprid.
In nutshell, it is nearly difficult to achieve a
homogenous concentration of these insecticides in
the soil. It is unknown how these treatments may
affect field population of termites. Future
investigations include field studies to determine
application of the insecticides per volume basis of
the soil.
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