Persistence and dissipation kinetics of novaluron 9.45% + lambda-cyhalothrin 1.9% ZC insecticides in tomato crop under semi-arid region

In recent decades, fate studies of pesticides have been a topic of interest worldwide due to human health concerns tomato, contain abundant nutritional phytochemicals and lycopene which is known for antioxidant. Tomato is susceptible to many pest, so to overcome from these pests many insecticides are used, leaving residual effects on the crop. So to find out the persistence, the present study was carried out to investigate the residual levels and dissipation behaviour of novaluron 9.45% + lambda-cyhalothrin 1.9% ZC in tomato crop during Rabi session of 2017-18 in randomized block design. The first spray of insecticide was done at fruit formation stage and second spray at 10-day interval at recommended dose @43.31 g a.i. ha-1 and double of recommended dose @86.62 g a.i. ha-1. The residue of novaluron determined by HPLC (high-performance liquid chromatography) on 0 day (two hours after spraying) was 0.154 ppm at lower dose and 0.234 ppm at higher dose. The residue of lambda-cyhalothrin determined by GC ECD (gas chromatography electron capture detector) at 0 day (two hours after spraying) was 0.451 ppm at lower dose and 0.849 ppm at higher dose. The deposition of novaluron 9.45% +  lambda-cyhalothrin 1.9% ZC was gradually decreased with increasing days after spraying (DAS). The mean initial deposition of the pesticide novaluron and lambda-cyhalothrin was recorded as 0.154 mg/kg, 0.451 mg/kg, respectively, at the recommended dose @43.31 g a.i. ha-1 while at double of recommended dose @86.62 g a.i. ha-1 novaluron and lambda-cyhalothrin, the mean initial deposition of 0.234 mg/kg and 0.849 mg/kg was recorded, respectively. The residue of the novaluron and lambda-cyhalothrin was at BDL (below determination level) (0.01 and 0.05 ppm) on 5th and 7th day, respectively, at lower dose (x), whereas at higher dose (2x) it was below determination level on 7th and 10th day, respectively. In soil samples, the residue levels were at below the determination level (0.01 mg/kg) for novaluron and (0.05 mg/kg) for lambda-cyhalothrin at both doses. The half-life DT50 of novaluron and lambda-cyhalothrin in the tomato fruit was found to be 2 days at recommended dose (X) @43.31 g a.i. ha-1 for both the pesticide and at double of the recommended dose @86.62 g a.i. ha-1 it was 3 and 2 days, respectively.