Optimised triangular pheromone traps for multi-season monitoring of Tuta absoluta in protected tomato systems

The invasive tomato leafminer Tuta absoluta has become a major constraint to tomato production worldwide, and intensive insecticide use against this pest increases production costs and environmental risks. Robust and cost-effective monitoring tools are therefore essential to support integrated pest management (IPM) and reduce pesticide dependence. We systematically evaluated the performance of triangular pheromone traps under different deployment parameters and protected cultivation systems, aiming to develop a standardised monitoring protocol for T. absoluta in tomato crops. We compared triangular traps, planar traps, and colour sticky boards (blue, yellow, and white), quantified the effects of trap position (basal, mid-canopy, and apical) and diel time window (08:00-12:00, 12:00-16:00, 16:00-20:00, 20:00-08:00), and tested three protected cultivation systems over two consecutive seasons. Blue triangular traps deployed at the basal position consistently outperformed other configurations, with mean catches exceeding 40 adults per trap - more than twice those at mid-canopy or apical placements. Night-time deployment (20:00-08:00) captured over 60% of the total daily catch, confirming the predominantly nocturnal activity of T. absoluta. Across three cultivation systems and two seasons, blue triangular traps maintained stable monitoring efficiency and consistently outperformed yellow and white traps, while achieving a better balance between target catches and non-target interception than planar traps. These findings demonstrate that optimising trap colour, placement height, and deployment period substantially enhances T. absoluta monitoring. The optimised triangular trap configuration provides a practical, low-cost tool for precision IPM in protected tomato systems, with clear potential to support reductions in insecticide use and associated environmental contamination.