The Efficacy of different insecticides against Aphis gossypii (Hemiptera: Aphididae) and the determination of Emamectin Benzoate and Acetamiprid residue levels on greenhouse cucumber

Many aphids attack cucumbers in the greenhouse and reduce their quality and quantity. Various varieties of greenhouse aphid species, particularly Aphis gossypii Glover, are responsible for considerable damage to cucurbits and vegetables, including cucumbers, tomatoes, watermelons, melons, etc. In addition, these insects can transmit many plant viruses from infected plants to healthy ones.

This study was conducted in the cucumber greenhouses of the three provinces of Sistan and Baluchestan, western Azerbaijan, and southern Kerman by a randomized complete block design with five treatments and four replicates. The efficiency of Emamectin benzoate 4.8% + Acetamiprid 6.4% EC at a ratio of 1.5/1000 and 2 /100 was compared with Flonicamid (Teppeki 50 WG) at a ratio of 0.25 /100, Primicarb (DF 50%) at a ratio of 0.7 /1000, Dichlorvos (EC 50%) at a ratio of 0.5 /1000, and the control (water spraying). The sampling was done one day before and 3, 7, and 14 days after treatment. The Henderson-Tilton formula was used to calculate the efficiency of the pesticides. And the means were compared by Tukey's test and SAS software. In the second part of this study, to measure the pesticide residues, 11 samples (one sample from each both different doses were collected three times: 3, 6, 8, 13, and 15 days after spraying, while one sample was taken as a control with no treatment) were collected in West Azerbaijan Province and transferred to the Pesticide Residues Reference Laboratory in the Pesticide Research Department. The samples were crushed, homogenized, and prepared. The organic phase obtained in the process was used for the cleanup stage and then centrifuged. Furthermore, residual pesticide content was identified and quantified by optimizing the operating conditions of the LC-MS/MS instrument. Finally, a comparison of the calculated levels with the national MRLs was made to determine the level of the toxin residues present in the product.

The results showed the following on the third day after spraying:The concentration of Emamctin benzoate + Acetamiprid treatment in Sistan and Baluchestan province was 2/1000 (77. 30 ± 4.6%). The concentration of Imamctin Benzoate + Acetamiprid insecticides in the Western Azerbaijan province was 2/1000 and 1.5/1000, and the concentration of Flonicamid was 95.02 ± 2.35, 94.42 ± 1.07, and 91.68 ± 3.65% respectively. Subsequently, Emamectin benzoate + Acetamiprid in the concentration of 2/1000 with an efficiency of 100% performed better than the others. The examination of the pesticide residues in the insecticide-treated cucumbers showed that the residues of Emamectin benzoate in all the samples sent after harvest were so low that LC-MS/MS was not able to detect it both quantitatively and qualitatively. Although the Acetamipride residue was 0.058 and 0.063 mg/kg respectively in both treatments on the third day after spraying, the level was below the permissible limit. Moreover, it was not detectable from the sixth day after spraying.