06 Oca 2025 Pazartesi
Biology, seasonal incidence, and damage of the Cotton Leaf Roller, Sylepta derogata Fabricius (Lepidoptera: Pyralidae) on Hibiscus rosa-sinensis
Abstract : The cotton leaf roller, Sylepta derogata Fabricius (Lepidoptera: Pyralidae), is a major pest affecting Hibiscus rosa-sinensis and various other plants within the Malvaceae family. This study, conducted in Dharmadam Panchayat, Kannur, Kerala, examines the pest’s biology, seasonal occurrence, and damage on H. rosa-sinensis, a widely cultivated ornamental plant known for its vibrant, large flowers and cultural, medicinal, and ecological significance. Female moths lay 250-300 eggs on the lower leaf surface, with larvae emerging in 2-9 days. These larvae deskeletonize leaves, spinning silk to form protective rolls. Fully grown larvae measure 20.75±0.43 mm, progressing through five distinct instars before pupating within the leaf rolls. Adult moths are nocturnal, with white bodies marked by brown. The study recorded 60-70% infestation during heavily infested monsoon months (June to September), with about 90% of host plant foliage typically rolled by larvae, leading to significant foliage reduction and decreased productivity. Infestations were lower during winter (December to February), with a significant correlation (Pearson’s r = 0.787) between rainfall and infestation rates. Understanding these factors is crucial for effective pest management in hibiscus cultivation.