Role of etofenprox nanoformulation in suppression of the silver whitefly, Bemisia tabaci and its residue in eggplant fruits

Abstract

The normal formulation of etofenprox was developed to nanoformulation and used against the adults of silver whitefly, Bemisia tabaci in eggplant fields. Three concentrations of both the normal and nanoformulations were used. The concentrations of etofenprox nanoformulation were one-fifth of the normal formulation. The nanosize of etofenprox ranged from 225 to 489 nm. The loading capacity of etofenprox was 60.7 ± 5.7%. The obtained results showed that the LC 50 of the normal formulation was four times more than the nanoformulation. The LC 50 for the nanoformulation was 0.9 and 3.5 ppm for the normal formulation of etofenprox. This means that the nanoformulation of etofenprox was more effective than the normal. The residues of both nano and normal formulations were determined in eggplant fruits after three applications. The obtained results showed that the residue of nanoformulation after 1 hour of treatment was 0.51 ± 0.03 compared with 0.62 ± 0.03 mg · kg –1 ± SD in normal formulation. After 1 hour of treatment the residue of etofenprox was reduced to 0.11 ± 0.1 and 0.22 ± 0.02 mg · kg –1 ± SD in nano and normal formulations, respectively. The dissipation rates of both nano and normal formulations after 1 hour were 78.3 and 64.5%, respectively. The degradation rate ( K ) in nanoformulation and normal etofenprox was 1.33 and 0.73 mg · kg –1 ± SD, respectively. The residue half-life (LR 50 ) was 0.52 and 1 day, respectively. The preharvest interval (PHI) was 6 days for both nano and normal etofenprox formulations. The results confirmed that nanoetofenprox was more effective against B. tabaci adults, with lower persistence and lower residue than the normal formulation of etofenprox.