This study was conducted during year 2011 in the farm of the Faculty of Agric., Moshtohor, Qualyubia. By cultivating varity tomato (Lycoprsicon esculentum Mill.) type (Elesa) and cucumber plant (Cucumis sativus L.) type (Alfa beta). Plants received three applications of insecticides, i.e., acetamiprid 20 % SP, dinotefuran 20 % SG and fenitrothion 50 % EC to evaluate the toxicity of the tested insecticides on and in tomato and cucumber fruits. This study studied also the level of these insecticides residues in soil under the treated plants.
The tested insecticides were tested against sucking pests i.e., whitefly (Bemisia tabaci), Jassids (Amereasca devastans), thrips (Thrips tabaci) and aphids (Aphis gosspyii).
Experiments were also directed to study also the side effects of the tested insecticides on some biochemical components in tomato and cucumber fruits and leaves i.e., total soluble solids (TSS), Vitamin C (V.C), titratable acidity, carbohydrate in fruits, total chlorophyll, nitrogen (N %), potassium (K %) and phosphor (P %) in leaves.
The obtained results may be summarized as follow:-
Ι. Field studies:
1. Pesticide residues on/in tomato and cucumber fruits grown in open field:
The obtained data represent the residues of tested insecticides on and in tomato and cucumber fruits. In general, insecticide residues at the initial (zero) time were the higher than 1, 3, 7 and 10 days after spraying by the tested insecticides acetamiprid, dinotefuran and fenitrothion where the residues were under the level of the codex MRL, for that the tomato and cucumber fruits could be used safely after three days, so, the initial time, 1, 3, 7 and 10 days after application in tomato fruits were 0.98, 0.51, 0.08, 0.02 and 0.01 ppm for acetamiprid, 0.83, 0.54, 0.14, 0.02 and 0.01 ppm for dinotefuran, 1.27, 0.64, 0.17, 0.05 & 0.005 ppm for fenitrothion.
The same trends of these data were occurred in the cucumber fruits by the same insecticides with the initial time, 1, 3, 7 & 10 days after treatments. The values were 1.26, 0.73, 0.07, 0.02 & 0.012 ppm for acetamiprid, 0.53, 0.39, 0.28, 0.03 & 0.008 ppm for dinotefuran, 3.02, 1.34, 0.04, 0.005 & 0.003 ppm for fenitrothion.
2. Insecticides resid ues in soil.
The residues of the tested insecticides acetamiprid, dinotefuran and fenitrothion in the soil took the same trend as that recorded for their effect on tomato and cucumber fruits. In tomato field, values reached at the initial (zero) time, 1, 3, 7 & 15 days after treatments 0.88, 0.79, 0.60 & 0.29 ppm for acetamiprid, 0.32, 0.27, 0.21 and 0.16 ppm for dinotefuran, 1.88, 1.70, 0.19 & 0.08 ppm for fenitrothion
Also, the similar data were in the case of cucumber where the residues were in the initial (zero) time, 1, 3, 7 & 15 days after spraying, 0.94, 0.88, 0.68 & 0.36 ppm for acetamiprid, 0.40, 0.37, 0.33 & 0.25 ppm for dinotefuran, 2.03, 1.90, 0.25 & 0.18 ppm for fenitrothion.
3. The reduction percent of sucking pest's infestation in tomato and cucumber fields.
Data concerning the effect of tested insecticides, acetamiprid and dinotefuran in comparison with Oraganophosphorus insecticide, fenitrothion for control sucking insects i.e., whitefly (Bemisia tabaci), jassid (Amereasca devastans), thrips (Thrips tabaci) and aphid (Aphis gosspyii) on tomato and cucumber plant control into fourth applications in tomato and cucumber fields. The percentages of population reduction of insects were calculated.
Data show the great role of tested insecticides in decreasing percent of infestation of tomato fruits by these pests. The mean percentages of reduction by acetamiprid insecticide were 95.6, 95.37, 95.4 & 95.9 % for whitefly (Bemisia tabaci), jassid (Amereasca devastans), thrips (Thrips tabaci) and aphid (Aphis gosspyii), respectively.
Also, the insecticide dinotefuran showed higher percentages of infestation reduction, to be 96.6, 96.37, 96.37 & 96.2 % for Bemisia tabaci, Amereasca devastans, Thrips tabaci and Aphis gosspyii, respectively. While, fenitrothion insecticide indicating less of percentages reduction where the values reached to 83.3, 81.95, 82.3 & 82.1 % for Whitefly, Jassid, thrips and Aphid, respectively.
Nearly same results were obtained in the percentages of infestation of these insects in case of cucumber fruits. The reduction percent of infestation by acetamiprid insecticides were 92.05, 94.4, 90.4 & 90.9 for whitefly (Bemisia tabaci), jassid (Amereasca devastans), thrips (Thrips tabaci) and aphid (Aphis gosspyii), respectively. Also, the insecticide dinotefuran showed higher percentages of infestation reduction to be 95.7, 95.12, 91.6 & 91.9 % for Bemisia tabaci, Amereasca devastans, Thrips tabaci and Aphis gosspyii, respectively. While, fenitrothion insecticide showed less reduction percentages where the values reached to to be 80.8, 80.97, 79.9 & 79.8 % for whitefly, jassid, thrips and aphid, respectively.
4. The percentage reduction of Coccinella sp & Chrysoperla carnea in tomato and cucumber fields.
Data show the effect of tested insecticides on the predator, ladybird beetles ( Coccinella sp .) on tomato and cucumber plants, in general.
The tested insecticides decreased the natural enemies, the mean reduction percentage of Coccinella sp. reached to 80.9 & 49.9 %, respectively, for acetamiprid, while 47.5 & 46.8 %, respectively, for dinotefuran, and 94.8 & 94.8 %, respectively for fenitrothion.
While the reduction percentages of Chrysoperla carnea in tomato and cucumber were 44.0 & 46.4 %, respectively by using acetamiprid, and 47.1 & 53.8 %, respectively by using with dinotefuran,and finaly 93.6 & 94.9 %, respectively, after treatment by fenitrothion.
5. Effect of the tested insecticides on TSS, V.C, Titratable acidity and Carbohydrate in tomato and cucumber fruits.
Data indicate the insignificant role of the tested insecticides acetamiprid, dinotefuran and fenitrothion on the total soluble solids (TSS), Vitamin C (V.C) and Carbohydrates in tomato. While, these insecticides had a significant increase in their effect on the titratable acidity, their values reached 0.63, 0.75 and 0.88 %, respectively, compared with 0.56 % in case of the control.
Also, the same trend of the results in tomato was occurred in the cucumber after treatment with acetamiprid, dinotefuran and fenitrothion where no significant effect on the total soluble solids (TSS), Vitamin C (V.C) and Carbohydrates. While, these insecticides had a significant increase in their effect on the titratable acidity. The values reached to 0.3 0.3 and 0.25 %, respectively, compared with 0.56 % in case of the control.
6. Effect of the tested insecticides on major nutrients (NPK) and Chlorophyll content in tomato and cucumber leaves.
Data indicate the significant role of tested insecticides in increasing the nitrogen content of leaves in tomato and cucumber than the untreated check. The nitrogen percentage were 2.8 & 3.2 % (untreated check in tomato and cucumber, respectively); 3.0, 2.6 and 2.4 % in cases of acetamiprid, dinotefuran, and fenitrothion in tomato, respectively, and 3.8, 3.9 and 3.7 % in the same application, respectively, in cucumber. While there was no significant effects from all treatments on phosphorous, potassium and carbohydrates content in tomato and cucumber when compared with the untreated check. |
