The Potential of Two Biopesticides in Controlling Tomato yellow leaf curl virus in Pepper Plants

Tomato yellow leaf curl virus (TYLCV) is one of the most destructive plant pathogens worldwide, severely limiting the growth and productivity of tomato and pepper crops. In this study, the efficacy of two commercial biopesticides namely: ChitoGold (CHTG) and Bio-act (BA) in controlling TYLCV infection in sweet pepper was evaluated. TYLCV-infected pepper plants were treated with either distilled water, CHTG, or BA, and several parameters related to induced resistance were assessed. Visual inspections revealed that TYLCV symptoms appeared on untreated plants at 15–20 days post-virus inoculation (dpvi). In contrast, symptoms expression was delayed by 7 and 10 days in CHTG- and BA-treated infected plants, respectively. Furthermore, both treatments resulted in milder TYLCV symptoms, with BA showing a more pronounced suppressive effect. Consistently, TYLCV- DNA accumulation was significantly reduced in CHTG- and BA-treated plants compared with untreated controls, with BA exerting a stronger inhibitory response. Induced resistance to TYLCV in pepper was associated with enhanced plant growth, increased proline and total phenolic contents, elevated activities of phenylalanine ammonia-lyase (PAL) and peroxidase (POX), and upregulation of the defense-related genes PR-1 and PR-10, particularly in BA-treated plants. Overall, these findings demonstrate that both ChitoGold and Bio-act are promising biocontrol agents against TYLCV infection in pepper, with Bio-act showing superior antiviral efficacy.