الفهرس 
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Abstract
The present study is to through light on role of some insecticides (chemical insecticides (a.i.chlorphyrifos) Dursban® 48% EC, spinosyns group (a.i.spinosad) Tracer® 24% SC and insect growth regulator (a.i.lufenuron) Match® 5% EC) against insect attacking cotton cultivation under Egyptian conditions as follows:
I-Effect of treatment with chlorphyrifos ,spinosad and lufenuron insecticides on 2ndlarval instar of S.littoralis:
The mortality percentage was recorded to calculate the LC50 and LC90 values.
1- The obtaind results showed that the LC25 values were 2.21, 8.1 and 0.0005 ppm for the insecticides chlorphyrifos, spinosad and lufenuron, respectively.
2- Also the LC50 values were 6.25, 29.86 and 0.015 ppm for chlorphyrifos, spinosad and lufenuron, respectively.
3- Moreover the LC90 values were 44.96, 355.98 and 9.38 ppm for the compounds chlorphyrifos, spinosad and lufenuron, respectively.
II- The biochemical effects for tested insecticides:
The biochemical parameters for tested insecticides at LC25were studied on some bio-components namely acetylcholinesterase: (AchE), glutathione s-Transferase: (GST), chitinase, phenoloxidase, aspartate (AST) and alanine (ALT) aminotransferases, α- Esterase (α- Est), total protein and protein electrophoresis for laboratory strain.
• The results can be summarized as follows:
1-Effect of insecticides on acetylcholinesterase (AchE):
The enzyme activity of acetylcholinesterase in insect treated with chlorphyrifos and lufenueon recorded increase in enzyme activity by change value 50% and 200% in comparion with control, respectively.
2- Effect of insecticides on glutathione s-transferase (GST):
The enzyme activity of glutathione s-transferasein insect treated with chlorphyrifos recorded increase in enzyme activity by change value (22.78%).While, decrease was recorded in treated insect with lufenuron and spinosad by change value (-7.12% and -35.88%), respectively in comparison with control.
3- Effect of insecticides on chitinase:
The enzyme activity of chitinase in insect treated withspinosad and lufenuron showed significant increaseby change value (8.50%) and (14.96%), respectively. The LC25of chlorphyrifos caused nonsignificant change with value (9.16%) in comparison with control.
4- Effect of insecticides on phenoloxidase:
The enzyme activity of phenoloxidase in insect treated with spinosad and lufenuron caused significant decrease by change value (-7.02%) and (-33.27%), respectively. The LC25 of chlorphyrifos caused nonsignificant change value (-0.44%) in comparison with control.
5- Effect of insecticides on aspartate amino transferases ( AST ):
The enzyme activity of aspartate amino transferases( AST ) in insect treated with spinosad and lufenuron led to significant increase by change value (35%) and (57.22%), respectively. Whereas the LC25of chlorphyrifos caused significant decrease by change value (-84.18%) in comparion with control.
6- Effect of insecticides on alanine amino transferases ( ALT ):
The enzyme activity of alanine amino transferases ( ALT ) in insect treated with spinosad and lufenuron caused significant increase by change value (38.09%) and (388.19%), respectively. The LC25of chlorphyrifos led to nonsignificant change value ( -5.45%) in comparison with control.
7- Effect of insecticides on α-esterases (α-EST):
The enzyme activity of α-esterases(α-EST) in insect treated with spinosad and lufenuron caused increase significant change value (8.68%) and (91.88%), respectively. Whereas the LC25 of chlorphyrifos decrease significantly the activity by change value (-40.19%) in comparion with control.
8- Effect of insecticides on Total protein:
Chlorphyrisand lufenuron reduced significantly the enzyme activity of total protein in insect treated with them by change value (-12.95%) and (-38.69%), respectively. The LC25 of spinosad caused nonsignificant increase by change value (1.31%) in comparion with control.
9- Fractionation of protein patterns:
SDS – PAGE was used to analyze the total body proteins of 2nd instar larval of S. littoralis treated with LC25 . Control and different treatments were separated into 56 different bands according to their relative frequencies Rf values, and molecular weights (MW). Samples of electrophoresis were carried out for three different insecticides namely chlorphyrifos ,spinosad and lufenuron which used to treat insects.
• Treatment with chlorphyrifos:
Treatment of laboratory strain with chlorphyrifos at LC25 caused the appearance of several specific protein bands, the bands are ( 1 , 3 , 7 , 8 , 10 , 11 and 12) with Rf (0.022 , 0.238 , 0.361 , 0.388 , 0.436 , 0.555 and 0.648 and) MW (192.243 , 54.113 , 39.623 , 36.461 , 32.538 , 28.636 , and 25.401 KDa), respectively, were characteristic bands compared with control sample lane 1.
• Treatment with spinosad:
Treatment of laboratory strain with spinosad at LC25 caused the appearance of several specific protein bands No. (2, 6 , 9 , 10 , 12 , 15 , 17 and 19) with Rf (0.035 , 0.225 , 0.344 , 0.396 , 0.436 , 0.608 , 0.775 and 0.859) and MW (169.434 , 54.826 , 41.978 , 35.562 , 32.538 , 26.902 , 20.719 and 17.75 KDa), respectively, which were characteristic bands compared with control sample lane 1.
• Treatment with lufenuron:
Treatment of laboratory strain with lufenuron at LC25led to appearance of several specific protein bands No.( 2 , 5 , 7 , 10 , 13 , 15, 17 and 20 ) with Rf (0.062, 0.142 , 0.235 , 0.393 , 0.442 , 0.633 , 0.761 and 0.956) and MW (130.062 , 73.531 , 54.041 , 36 , 32.239 , 25.901 , 21.188 and 14.313 KDa), respectively, were characteristic bands compared with control sample lane 1.
Finally, the treatment with insecticides led to detection of new bands, and disappeared some bands in comparison to control. It can be concluded that treatment with insecticides have strong efficacy on the soluble protein in the body of insects.
III- Toxicological studies on the field strains:
Four field strains of spodoptera littoralis were collected from four Egyptian governorates (KafrAl-Sheikh, Beheira, Gharbia and Beni Suef) to determine the susceptibility and monitoring resistance for the tested insects to some insecticides namely (chlorphyrifos , spinosad and lufenuron) compared with a laboratory susceptible strain. This experiment was done to determine the strain with the highest resistance ratio based on the median lethal concentration LC50.
1-The efficacy of the tested insecticides to the field strains of S.littoralis:
• Responses of spodoptera littoralis field strain collected from Gharbiya governorate:
According to the toxicity index (Ti), the efficacy of the insecticides was arranged in descending order as follows: spinosad and lufenuron>chlorphyrifos in cotton season 2015.While, lufenuron> spinosad>chlorphyrifos in cotton season 2016 and 2017 with toxicity index (T.i) values 100, 100 and 2.06 in season (2015) 100, 48.27 and 0.58 in season (2016) 100, 54.84 and 0.46 in season (2017) ,respectively.
• Responses of spodoptera littoralis field strain collected from Beheira governorate:
According to the toxicity index (Ti), the efficacy of the insecticides was arranged from highest to lowest effect as spinosad> lufenuron>chlorphyrifos in cotton season 2015, 2016 and 2017 with toxicity index (T.i) values 100, 64.89 and 1.68 in season (2015) 100, 71.74 and 1.29 in season (2016) 100, 97.99 and 1.38 in season (2017) ,respectively.
• Responses of spodoptera littoralis field strain collected from Kafr Al-sheikh governorate:
According to the toxicity index (Ti), the efficacy of the insecticides was arranged descendingly from highest to lowest effect as spinosad>lufenuron>chlorphyrifos in cotton season 2015.Whereas, spinosad>lufenuron>chlorphyrifos in cotton season 2016 and 2017 with toxicity index (T.i) values 100, 72.22 and 1.98 in season (2015) 100, 70.22 and 0.69 in season (2016) 100, 91.71 and 0.83 in season (2017) ,respectively.
• Responses of spodoptera littoralis field strain collected from Beni Suef governorate:
According to the toxicity index (Ti), the efficacy of the insecticides was arranged from highest to lowest effect as lufenuron>spinosad>chlorphyrifos in cotton season 2015, 2016 and 2017 with toxicity index (T.i) values 100, 44.74 and 0. 97 in season (2015) 100, 71.29 and 1.29 in season (2016) 100, 66.67 and 1.21 in season (2017), respectively.
2- Resistance ratio (RR) of the tested insecticides to the field strains of S.littoralis:
According to Torres-vila et al, (2002) for classification of resistance categories (RR < 2 consider susceptible , RR 2-10 low resistance , RR 11-30 moderate resistance , RR ˃ 30 highly resistance ) it canbe deduce from obtained results that the S.littoralis in both Gharbiya, Beheira, Kafr Al-Sheikh and Beni Suef governorates didn,t show found any resistance to spinosad insecticide in season 2015 , 2016 and 2017, except Kafr Al-Sheikh governorate in season 2017 which was found to be low resistance. While, in case lufenuron insecticide in season 2015, 2016, 2017 were found to be low resistance except Beni Suef governorate in season 2015 which was found to be susceptible and Kafr Al-Sheikh governorate in season 2017 was found to be moderate resistance. While , in case chlorphyrifos insecticide in season 2015 , 2016, 2017were found to low resistance except Gharbiya governorates didn,t show found any resistance in season 2015 and Kafr Al-Sheikh governorate in season 2016 and 2017 were found to be moderate resistance.
3-Resistance percentage (Rp) of the tested insecticides to the field strains of s.littoralis:
According to Roush and Miller, (1986) was calculated as follows:
Resistance percentage = [100 – (Mr / Ms X 100)]
The values of resistance percentage (RP) from Gharbiya governorate showed the highest values of RP with chlorphyrifos in seasons 2016
and 2017 with values ( 59.37 , 81.98)% ,respectively.
• The values of resistance percentage (RP) from Beheira governorate indicated that the highest values of RP were obtained with lufenuron in season 2016 and 2017 with values (57.57 , 55.12)% and chlorphyrifos in season 2016 and 2017 with values (67.63 , 64.38)% , respectively.
• The values of resistance percentage (RP) from Kafr Al-Sheikh governorate revealed that the highest values of RP were obtained with lufenuron in season 2016 and 2017 with values (61.77 , 63.57)% and chlorphyrifos in season 2016 and 2017 with values (86.51 , 95.67)% ,respectively.
• The values of resistance percentage (RP) from Beni Suef governoratere found that the highest values of RP were obtained with chlorphyrifos in season 2017 with value (58%) .
4-Resistance coefficient (Rc) of the tested insecticides to the field strains of s.littoralis:
According to Wegoreket al., (2011) resistance coefficient was calculated as follows: Resistance Cofficient (RC)= LC95/recommended field concentration RC ≤ 1 lack of resistance RC=1.1-2 low resistance RC=2.1-5 medium resistance RC = 5.1-10 high resistance RC ≥ 10 very high resistance.
• The resistance coefficient values for spinosad were (0.04 & 0.18& 0.23), (0.16 & 0.21 & 0.24), (0.17 & 0.13, 0.32) and (0.18 & 0.26 & 0.31) for Gharbiya, Beheira, Kafr Al-Sheikh and Beni Suef governorates, respectively, i.e. show lack of resistance.
• In the case of lufenuron both Gharbiya, Beheira, Kafr Al-Sheikh and BeniSuef governorates show lack of resistance to lufenuron in cotton season 2015 on resistance coefficient (RC) values were (0.84 & 0.81 & 0.13 & 0.70), respectively. And in season 2016show lack of resistance in Gharbiya and Beni Suef governorates with values (0.63 & 0.38), respectively. while in Beheira and Kafr Al-Sheikh governorates show low resistance and the values were (1.32&1.41) and in season 2017 for Gharbiya governorate show lack of resistance with value 0.88 ,while Beheira, Kafr Al-Sheikh and Beni Suef governorates show medium resistance with values (3.87&2.71&2.14), respectively.
• In the case of chlorphyrifos both Gharbiya, Kafr Al-Sheikh and Beni Suef governorates show lack of resistance to chlorphyrifos in cotton season 2015, 2016 and 2017 on resistance coefficient (RC) and the values were (0.08 & 0.29 & 0.36 ), (0.19 & 0.94 &
0.57 ) and (0.20 & 0.31 & 0.20) in 2015,2016 and 2017 for Gharbiya, Kafr Al-Sheikh and Beni Suef governorates, respectively. While in Beheira governorate show lack of resistance in season 2015&2016 with values 0.21and 0.22, respectively. Resistance coefficient show low resistance with value 1.22 in season 2017.