Larva Immersion and Square Dip method
Lambda-cyhalothrin
H. armigera larval mortality of 100, 100, 100, and 90% mortality turned into at field rate (5.0 x 10-4g. a.i/ml) of the insecticide for Goffa-Sawla, Upper-Awash, Werer, and Gewane population, respectively. Four times the decrease dose from the recommended rate (1.25 x 10-4g. a.i/ml) led to 100% mortality on Gofa-Sawla populace, which turned into higher than field rate dose-mortality (90%) of Gewane and two times lower dose rate mortality percent (96%) Upper-Awash and (86.7%) of Werer population (Table 1). In the squared dip technique the field rate lambda-cyhalothrin (5.0 x 10-4g. a.i/ml) led to 100, 100, 96.7, and 93.3% mortality on Goffa-Sawla, Upper-Awash, Werer, and Gewane populations, respectively (Table 1). The four-times decrease dose (1.25 x 10-4 g. a.i/ml) precipitated 100% mortality even as the eight-times decrease dose (2.5 x 10-5a.i/ml) 93.3%) mortality at the Goffa-Sawla population even as handiest 83.3% mortality turned into recorded for Werer to two times-decrease doses (2.5 x 10-4g. a.i/ml) and 90% mortality of the Upper-Awash populace to field rate dose of Gewane population (Table 1).
Both bioassay techniques showed Goffa-Sawla population was significantly different (P<0.05) from Werer, Upper-Awash, and Gewane populations without any overlap of 95% CL. The result suggests the Goffa Sawla populace is a lot greater touchy to lambda-cyhalothrin as compared to different populace. (Table 2).
This takes a look at discovered that variation in the degree of susceptibility to lambda-cyhalothrin exists in H armigera collected from different locations. Both bioassay techniques confirmed that the examined population had a low degree of resistance to lambda-cyhalothrin. The Gewane population has a better resistance ratio in comparison to different examined populations. Several studies have indicated the development of resistance in H armigera for pyrethroids. A low degree of resistance to lambda-cyhalothrin became suggested via way of means of Karaagac et al. (2013) from Turkey and Avilla and González-Zamora (2010) in Spain. Other research suggested slight to high-degree resistance (Hussain et al. (2014) and high-degree resistance (Duraimurugan & Regupathy, 2005) of H. armigera to pyrethroids. This locating evaluation with Geremew et al. (2004) who discovered in larva immersion and squared dip methods.
Table 1. Percent of mortality of 3rd instar H. armigera larvae in different concentration of lambda-cyhalothrin 5% EC 72 hours after treatment with larva immersion bioassay and 48 hours after treatment in squared dip bioassay (29+ 20C & 48+4% RH) on Gofa Sawla, Upper Awash, Werer and Gewane populations (N=30).
larva immersion
|
squared dip
|
Concentration (μl/ml)
|
Percent mortality
|
Concentration (μl/ml)
|
Percent mortality
|
Gofa Sawla
|
Upper Awash
|
Werer
|
Gewane
|
Gofa Sawla
|
Upper Awash
|
Werer
|
Gewane
|
2
|
100
|
100
|
100
|
90.0
|
2
|
100
|
100
|
96.7
|
93.3
|
1
|
100
|
96.7
|
86.7
|
70.0
|
1
|
100
|
90.0
|
83.3
|
73.3
|
0.5
|
100
|
83.3
|
70.0
|
53.3
|
0.5
|
100
|
76.7
|
63.3
|
53.3
|
0.25
|
83.3
|
63.3
|
46.7
|
26.7
|
0.25
|
93.3
|
56.7
|
46.7
|
33.3
|
0.12
|
66.7
|
40.0
|
23.3
|
13.3
|
0.12
|
73.3
|
36.7
|
23.3
|
16.7
|
0.0625
|
50.0
|
23.3
|
10.0
|
6.7
|
0.0625
|
56.7
|
20.0
|
10.0
|
3.3
|
0.03125
|
16.7
|
10.0
|
10.0
|
3.3
|
0.03125
|
23.3
|
6.7
|
3.3
|
3.3
|
Control
|
6.7
|
0
|
6.7
|
3.3
|
Control
|
3.3
|
3.3
|
6.7
|
6.7
|
Table 2. Comparative toxicity of lambda-cyhalothrin 5% EC to H. armigera populations in larva immersion and squared dip study.
Larva immersion
|
Location
|
N
|
LC50 μl/ml
|
95% CL
(lower-upper)
|
LC90 μl/ml
|
95%CL
(lower-upper)
|
The fit of probit analysis
|
RR
|
Slope + SE
|
χ2 (df)
|
P
|
Gofa-Sawla
|
180
|
0.074
|
(0.057 -0.094)
|
0.260
|
(0.192- 0.415)
|
2.36+ 0.333
|
2.778 (4)
|
0.5957
|
_
|
Upper Awash
|
180
|
0.153
|
(0.118 - 0.199)*
|
0.693
|
(0.476 - 1.226)
|
1.96 + 0.250
|
0.512 (4)
|
0.9723
|
2.07
|
Werer
|
180
|
0.264
|
(0.199 - 0.361)*
|
1.419
|
(0.886 -3.022)
|
1.75+ 0.236
|
2.15 (4)
|
0.7089
|
3.57
|
Gewane
|
180
|
0.498
|
(0.364 - 0.763)
|
2.870
|
(1.578 - 8.204)
|
1.69 + 0.256
|
0.622 (4)
|
0.9606
|
6.73
|
Squared dip
|
Location
|
N
|
LC50 μl/ml
|
95% CL
(lower-upper)
|
LC90 μl/ml
|
95%CL
(lower-upper)
|
The fit of probit analysis
|
|
RR
|
Slope + SE
|
χ2 (df)
|
P
|
|
Gofa-Sawla
|
180
|
0.060
|
(0.044 -0.075)
|
0.193
|
(0.144 - 0.306)
|
2.52+0.384
|
0.976 (4)
|
0.9134
|
_
|
Upper Awash
|
180
|
0.194
|
(0.147 -0.258)*
|
1.007
|
(0.657-1.969)
|
1.80 +0.237
|
0.113 (4)
|
0.9985
|
3.25
|
Werer
|
180
|
0.302
|
(0.230 - 0.41)*
|
1.505
|
(0.949-3.162)
|
1.84 +0.249
|
0.168 (4)
|
0.9967
|
5.03
|
Gewane
|
180
|
0.447
|
(0.334 - 0.651)*
|
2.338
|
(1.364-5.869)
|
1.78 +0.261
|
0.797 (4)
|
0.9389
|
7.45
|
N= total number of larva used for probit analysis, LC50 = median lethal concentration, LC90= the lethal concentration which killed 90% of the test H. armigera population, 95% CL= the lower and the higher confidence limits at which the LC50 and LC90 value can fall at 95% probability, SE= standard Error, χ2 =Chi-square, RR (Resistance Ratio) = LC50 of the field population / LC50 of Goffa-Sawla population, superscript denoted astric*=the collected H. armigera populations were not significantly different (P<0.05) among each other in their susceptibility to lambda-cyhalothrin insecticide.
Deltamethrin
H. armigera populations of Werer, Upper-Awash, Goffa-Sawla, and Gewane populations exposed to different concentrations of deltamethrin 2.5% EC experienced a varying level of mortality. At field rate (3 x 10-4g. a.i/ml) deltamethrin gave 100, 93.3, 86.7, and 80.0% mortality 72 hours after larvae were immersed for Goffa-Sawla, Upper-Awash, Gewane, and Werer populations, respectively. In squared dip method at field rate (3.0 x 10-4 g. a.i/ml) deltamethrin gave 100, 90, 83.3 and 80.0% larval mortality after 48 hours in square dip method of Goffa-Sawla, Upper-Awash, Gewane, and Werer population, respectively (Table 3). The field-collected H. armigera larva from Goffa-Sawla experienced 100% mortality at two times lower doses (1.5 x 10-4 g. a.i/ml) of deltamethrin which was higher than the field rate mortality of Werer, Upper-Awash, and Gewane populations, respectively (Tables 3).
The LC50 values suggests that Werer, Upper-Awash, and Gewane populations have been now no longer extensively distinctive amongst every different, however (P<0.05) from the Goffa-Sawla population with no overlapping 95% CL (Table 4). Probit analysis showed that the Werer population is 8.79 times and Gewane populations 6.45 times more resistant to the susceptible Goffa-Sawla population in larva immersion technique (Table 4). And, in square-dip technique the Werer and Gewane 9.25 and 7.55 more resistant to the susceptible Goffa-Sawla population (Table 4).
According to the resistance grouping of Torres-Vila et al. (2002a, b) H. armigera in Middle Awash, Ethiopia showed a low level of resistance to deltamethrin. Deltamethrin has been wont to control H. armigera and sucking pests in cotton for a protracted time. Recently, because of dreath of the ultra-low volume (ULV) formulation, the emulsify concentrate (EC) formulation of deltamethrin has been applied like ULV by mixing with a little volume of water to save a lot of of time and labor (Personal communication). Such misuse of an insecticide against H. armigera, may led to choice of resistant forms of the pest population. Development of low to high-level resistance in several strains of H. armigera for deltamethrin reported by Faheem et al. (2013) and Hussain et al., (2014) in Pakistan.
Table 3. Percent of mortality of 3rd instar H. armigera larvae in different concentrations of deltamethrin 2.5% EC 72 hours after treatment with larva immersion bioassay and 48 hours after treatment in squared dip bioassay(29 + 20C & 48 + 4% RH) on Gofa-Sawla, Upper Awash, Werer and Gewane population (N= 30).
larva immersion
|
squared dip
|
Concentration (μl/ml)
|
Percent mortality
|
Concentration (μl/ml)
|
Percent mortality
|
Gofa Sawla
|
Upper Awash
|
Werer
|
Gewane
|
Gofa Sawla
|
Upper Awash
|
Werer
|
Gewane
|
3
|
100
|
93.3
|
80.0
|
86.7
|
3
|
100
|
90.0
|
80.0
|
83.3
|
1.5
|
100
|
76.7
|
56.7
|
66.7
|
1.5
|
100
|
76.7
|
50.0
|
60,0
|
0.75
|
93.3
|
50.0
|
30.0
|
43.3
|
0.75
|
96.7
|
56.7
|
23.3
|
33.3
|
0.375
|
76.7
|
26.7
|
13.3
|
20.0
|
0.375
|
76.7
|
40.0
|
3.3
|
6.7
|
0.1875
|
53.3
|
13.3
|
3.3
|
6.7
|
0.1875
|
56.7
|
20.0
|
3.3
|
3.3
|
0.09375
|
30.0
|
3.3
|
0
|
0
|
0.09375
|
26.7
|
6.7
|
0
|
0
|
0.046875
|
13.3
|
0
|
0
|
0
|
0.046875
|
6.7
|
0
|
0
|
0
|
Control
|
3.3
|
6.7
|
6.7
|
6.7
|
Control
|
6.7
|
6.7
|
0
|
6.7
|
Table 4. Comparative toxicity of deltamethrin 2.5% EC to H. armigera populations in larva immersion and squared dip study.
Larva immersion
|
Location
|
N
|
LC50 μl/ml
|
95% CL
(lower-upper)
|
LC90 μl/ml
|
95%CL
(lower-upper)
|
The fit of probit analysis
|
RR
|
Slope + SE
|
χ2 (df)
|
P
|
Gofa-Sawla
|
150
|
0.143
|
(0.104- 0.246)
|
0.572
|
(0.430- 0.966)
|
2.59 + 0.563
|
0.517 (3)
|
0.915
|
_
|
Upper Awash
|
150
|
0.690
|
(0.533 - 0.890)*
|
2.690
|
(1.863 - 4.894)
|
2.17 + 0.313
|
0.433 (3)
|
0.933
|
4.83
|
Werer
|
150
|
1.257
|
(0.980 - 1.690)*
|
4.814
|
(3.146 - 9.990)
|
2.20 + 0.331
|
0.044 (3)
|
0.998
|
8.79
|
Gewane
|
150
|
0.922
|
(0.717 -1.207)*
|
3.633
|
(2.446 - 7.017)
|
2.15 + 0.314
|
0.203 (3)
|
0.977
|
6.45
|
Squared dip
|
Location
|
N
|
LC50 μl/ml
|
95% CL
(lower-upper)
|
LC90 μl/ml
|
95%CL
(lower-upper)
|
The fit of probit analysis
|
|
RR
|
Slope + SE
|
χ2 (df)
|
P
|
Gofa-Sawla
|
150
|
0.155
|
(0.097 - 0.234)
|
0.515
|
(0.391 - 0.870)
|
2.74 + 0.626
|
0.884 (3)
|
0.829
|
_
|
Upper Awash
|
150
|
0.563
|
(0.400 - 0.758)
|
3.111
|
(1.970 - 7.063)
|
1.727 + 0.287
|
0.104 (3)
|
0.9913
|
3.63
|
Werer
|
150
|
1.435
|
(1.137- 1.899)*
|
4.712
|
(3.199- 9.103)
|
2.48 + 0.371
|
1.689 (3)
|
0.639
|
9.25
|
Gewane
|
150
|
1.171
|
(0.935- 1.504)*
|
3.751
|
(2.643- 6.632)
|
2.53 + 0.359
|
0.865 (3)
|
0.834
|
7.55
|
N= total number of larva used for probit analysis, LC50 = median lethal concentration, LC90= the lethal concentration which killed 90% of the test H. armigera population, 95%CL= the lower and the higher confidence limits at which the LC50 and LC90 value can fall at 95% probability, SE= standard Error, χ2 =Chi-square, RR (Resistance Ratio) = LC50 of the field population / LC50 of Goffa-Sawla population, superscript denoted astric*=the collected H. armigera populations were not significantly different (P<0.05) among each other in their susceptibility to deltamethrin insecticide
Alphacypermethrin
Alphacypermethrin caused 100% H. armigera larva mortality at field rate (1.0 x 10-3g. a.i/ml) on Werer, Upper-Awash, and Gewane populations in both bioassay methods (Table 5). Subsequent dilutions of the insecticide resulted in lower percent mortality of larva to alphacypermethrin (Tables 5).
Probit analysis Goffa-Sawla population was significantly different (P <0.05) from Werer, Upper-Awash, and Gewane populations with non-overlapping 95% CL (Table 6). The resistance ratio in the range of 1.86-1.93 in the larval immersion method (Table 6) and 1.76-1.94 in the square dip techniques (Table 6). The level of resistance to alphacypermethrin was comparatively lower compared with other compounds of the pyrethroids group (lambda-cyhalothrin and deltamethrin) tested.
Alphacypermethrin insecticide is applied one time during peak squaring and flowering period. That could be the reason for a high level of H. armigera mortality compared to other insecticides evaluated in this study. Alphacypermethrin is a newer insecticide in the study areas and has not been widely used compared to the other tested insecticides. Alpha-cypermethrin, a third-generation pyrethroid is now one of the top-selling insecticides globally (BASF Chemical Company, 2014). Therefore, alphacypermethrin could be used for the resistance management program as one of the insecticides in the alternation scheme.
Table 5. Percent of mortality of 3rd instar H. armigera larvae in different concentrations of alphacypermethrin 100G/L 72 hours after treatment with larva immersion bioassay and 48 hours in squared dip bioassay (29 + 20C 48+4% RH) on Gofa Sawla, Upper Awash, Werer and Gewane populations (N=30).
larva immersion
|
squared dip
|
Concentration (μl/ml)
|
Percent mortality
|
Concentration (μl/ml)
|
Percent mortality
|
Gofa Sawla
|
Upper Awash
|
Werer
|
Gewane
|
Gofa Sawla
|
Upper Awash
|
Werer
|
Gewane
|
1.5
|
100
|
100
|
100
|
100
|
1.5
|
100
|
100
|
100
|
100
|
0.75
|
100
|
100
|
96.7
|
100
|
0.75
|
100
|
93.3
|
96.7
|
90.0
|
0.375
|
100
|
90.0
|
83.3
|
83.3
|
0.375
|
100
|
80.0
|
83.3
|
76.7
|
0.1875
|
90.0
|
73.3
|
73.3
|
63.3
|
0.1875
|
86.7
|
76.7
|
66.7
|
56.7
|
0.09375
|
76.7
|
60.0
|
53.3
|
46.7
|
0.09375
|
70.0
|
60,0
|
53.3
|
43.3
|
0.046875
|
56.7
|
43.3
|
40.0
|
30.0
|
0.046875
|
53.3
|
36.7
|
36.7
|
26.7
|
0.0234375
|
26.7
|
16.7
|
16.7
|
10.0
|
0.0234375
|
23.3
|
16.7
|
16.7
|
10,0
|
Control
|
0
|
0
|
6.7
|
6.7
|
Control
|
10.0
|
0
|
3.3
|
6.7
|
Table 6. Comparative toxicity of alphacypermethrin 100G/L to H. armigera populations in larva immersion and squared dip study.
Larva immersion
|
Location
|
N
|
LC50 μl/ml
|
95% CL
(lower-upper)
|
LC90 μl/ml
|
95%CL
(lower-upper)
|
The fit of probit analysis
|
RR
|
Slope + SE
|
χ2 (df)
|
P
|
Gofa-Sawla
|
180
|
0.043
|
(0.031 - 0.055)
|
0.157
|
(0.114- 0.265)
|
2.28 + 0.366
|
0.992 (3)
|
0.803
|
_
|
Upper Awash
|
180
|
0.070
|
(0.051- 0.091)*
|
0.335
|
(0.232 - 0.591)
|
1.88 + 0.261
|
2.039 (4)
|
0.729
|
1.62
|
Werer
|
180
|
0.080
|
(0.057 - 0.107)*
|
0.471
|
(0.310 - 0.922)
|
1.66 + 0.236
|
0.978 (4)
|
0.913
|
1.86
|
Gewane
|
180
|
0.083
|
(0.078 - 0.133)*
|
0.459
|
(0.318 - 0.806)
|
1.97 + 0.256
|
2.62 (4)
|
0.620
|
1.93
|
Squared dip
|
Location
|
N
|
LC50 μl/ml
|
95% CL
(lower-upper)
|
LC90 μl/ml
|
95%CL
(lower-upper)
|
The fit of probit analysis
|
|
RR
|
Slope + SE
|
χ2 (df)
|
P
|
|
Gofa-Sawla
|
180
|
0.049
|
(0.036 - 0.063)
|
0.186
|
(0.134 - 0.320)
|
2.21 + 0.347
|
1.666 (3)
|
0.664
|
_
|
Upper Awash
|
180
|
0.079
|
(0.055 -0.107)*
|
0.528
|
(0.338- 1.096)
|
1.55+ 0.228
|
1.648 (4)
|
0.8001
|
1.62
|
Werer
|
180
|
0.086
|
(0.062 -0.115)*
|
0.516
|
(0.336-1.029)
|
1.65 + 0.234
|
0.977 (4)
|
0.9133
|
1.76
|
Gewane
|
180
|
0.095
|
(0.100- 0.185)*
|
0.852
|
(0.527- 1.871)
|
1.61+ 0.226
|
0.743 (4)
|
0.9459
|
1.94
|
N= total number of larva used for probit analysis, LC50 = median lethal concentration, LC90= the lethal concentration which killed 90% of the test H. armigera population, 95%CL= the lower and the higher confidence limits at which the LC50 and LC90 value can fall at 95% probability, SE= standard Error, χ2 =Chi-square, RR (Resistance Ratio) = LC50 of the field population/LC50 of Goffa-Sawla population, superscript denoted astric*=the collected H. armigera populations were not significantly different (P <0.05) among each other in their susceptibility to alphacypermethrin insecticide