Seasonal incidence of mango leaf webber (Orthaga spp.) and correlation with abiotic factors

Abstract

The seasonal incidence of mango leaf webber was studied during 2022-23 and 2023-24. Web formation was absent during the first fortnight of June and from the second fortnight of March to May. The pest first appeared during the second fortnight of June (1.76 and 0.80 webs/tree in 2022-23 and 2023-24, respectively). The population gradually increased and reached a peak in the first fortnight of December, recording 27.66 and 20.63 webs/tree, respectively, and thereafter declined to negligible levels by the first fortnight of March. Larval incidence in the local variety followed a similar trend, first appearing in the second fortnight of June (2.18 and 1.22 larvae/tree in 2022-23 and 2023-24, respectively) and attaining maximum levels during the first fortnight of December (50.18 and 37.17 larvae/tree, respectively). The larval population declined thereafter and remained negligible from March to May. Correlation analysis revealed a significant positive association with morning relative humidity (r = 0.683**), while other abiotic factors showed a negative correlation with leaf webber population. The south-facing canopy recorded the highest number of webs and larvae per tree, followed by the west-facing side in both years. Among the varieties evaluated, Totapari showed the highest web and larval infestation, followed by Baneshan and Dashehari, whereas Langra recorded the lowest infestation, followed by Swarnrekha and Neelum, during both years.