Comparative Efficacy of Yellow and Blue Sticky Traps to Estimate the Population Density of Apple Blotch Leaf Miner (Leucoptera malifoliella) in the Kashmir Valley

Abstract

Apple is among the leading temperate fruit crops, which faces considerable losses due to diseases and insect pests annually. Amongst the recently reported pests on apple, Apple blotch leaf miner (ABLM) has caused severe outbreaks in parts of the Shopian district, located in the North-Western Himalayan region of Kashmir. To devise effective management strategies, seasonal monitoring was carried out using yellow and blue sticky traps at seven sites (Zainapora, Aglar, Babapora, Reshipora, Durpora, Mujimarg, and Sofipora) from the 13th Standard Meteorological Week (SMW) (26 March–01 April) to the 45th SMW (05–11 November). Results indicated a clear bimodal population trend of the pest. Weekly trap counts (adults/5 traps) revealed an initial outbreak in early spring, with the highest capture in yellow traps at Zainapora (334.66 adults/5 traps with mean of 66.93 adults/trap at the 13th SMW) and an overall mean of 242.37. This peak was followed by a sharp decline during May–June and a secondary increase in late summer, reaching a mean of 142.21 adults at the 35th SMW. Aglar recorded 262.33 adults /5traps (52.47adults/trap), Babapora had 335.16 adults/5traps (67.03 adults /trap), Reshipora showed 332.83 adults/ 5 traps (66.57 adults/trap), Durpora reported 194.83 adults/5traps (38.97adults/ trap), Mujimarg noted 135.00 adults/5 traps (27.00 adults/ trap), and Sofipora, which had a peak shifted to SMW 35, recorded 104.23 adults/5traps (20.85 adults/trap).Blue traps exhibited the same temporal pattern but recorded lower catches, with a maximum of 85.33 at Zainapora in the 13th SMW (mean 65.71) and a modest secondary rise in late September (mean 13.56 at the 39th SMW). Spatial variation was marked, with Zainapora and Aglar consistently showing higher pest densities than other locations. The findings suggest that while blue traps can serve as supportive indicators, yellow sticky traps provide greater sensitivity for early detection. Overall, the study underscores the value of integrating site-specific trap-based thresholds with local weather and crop growth data to fine-tune intervention timings, reduce unnecessary pesticide applications, and highlights two critical monitoring windows: late March–early April and late August–September. To reduce chemical inputs and improve early detection of ABLM outbreaks, the study supports the integration of yellow sticky traps into precision-based IPM frameworks.