Enhance Systemic Resistance Significantly Reduces the Silverleaf Whitefly Population and Increases the Yield of Sweet Pepper, Capsicum annuum L. var. annuum

The silverleaf whitefly ( Bemisia tabaci ) is one of the most harmful insects attacking several economic plant crops worldwide, and it has developed a resistance toward several conventional insecticides. This study was conducted to estimate the impact of potassium phosphite (PK), effective microorganisms (EMs), and salicylic acid (SA) as plant inducers, and imidacloprid (IMI) as a synthetic insecticide on the systemic acquired resistance of sweet pepper ( Capsicum annuum var. annuum ) crop, whitefly population, and crop yield under greenhouse conditions. The treatment plots were sprayed with IMI, PK, EMs, SA, and water (control) on the 27th day after planting, and dinotefuran was applied when the whitefly-infestation ratio reached 3.00%. The enzymes responsible for the internal defence system, whitefly population, and crop yield were determined. Our results confirmed the idea that the PK, EMs, and SA may induce the synthesis of plant enzymes responsible for the internal defence system. The IMI, PK, EMs, and SA significantly suppressed the whitefly population compared with the control. Moreover, the reduction percentages of the whitefly population were significantly higher when using IMI and PK than EMs and SA. The IMI, PK, EMs, and SA improved the crop yield. It could be concluded that PK, EMs, and SA enhanced the systemic acquired resistance in sweet pepper crop causing high defence against the population of whitefly and might be a potent alternative to conventional insecticides and compatible with an integrated pest management program.