Tea Tortrix

📖 Description

Tea tortrix, Homona coffearia — sometimes called the ‘Japanese tea tortrix’ in older literature, though the species is widely distributed across tropical and subtropical Asia — is a major lepidopteran defoliator of tea (Camellia sinensis) cultivation in India, particularly in the nursery and young-plantation stages. Adult moths emerge at dusk, mate, and females lay 200–400 eggs in overlapping scale-like masses of 30–80 on the undersides of mature tea leaves. The pale green larvae hatch in 5–7 days and immediately begin to web the edges of young tea leaves together with silk, forming a characteristic ‘folded’ or ‘rolled’ shelter within which they feed on the leaf tissue, leaving only the cuticle. The roll protects the larva from predators and from contact insecticides, making control particularly challenging. A single larva can roll 3–5 leaves during its 18–25-day larval stage, and a heavily infested tea bush can show 30–60% of its young leaves rolled, browned, and unproductive. In tea nurseries (6–18 month old seedlings), heavy infestations can delay transplantation by 4–8 weeks, disrupting the entire planting schedule. In established tea plantations, the leaf roller attacks the young ‘plucking table’ leaves (the top 2–3 leaves that are harvested for tea), reducing both yield and quality — rolled, damaged leaves must be discarded at plucking, and damaged bushes produce fewer usable leaves. Yield losses of 10–20% in tea nurseries and 5–15% in established plantations have been reported from Assam and South India. Even lightly infested leaves are downgraded at tea manufacture — quality tea requires undamaged ‘two-leaves-and-a-bud’ plucking, and any rolled or silk-webbed leaves are rejected at the factory, with the grower receiving a lower price for the consignment. The pest is most severe in the Assam and Dooars tea tracts of North-East India (which together produce over 50% of Indian tea), where the warm humid climate (May–October, 25–32 °C, >80% humidity) is ideal for larval development. Outbreaks are most frequent during the main tea harvest season (April–November), when tea is in its active vegetative phase and conditions are ideal for larval development. The pest is polyphagous, attacking coffee, cocoa, citrus, jackfruit, mango, and many other plantation and orchard crops — making it one of the most widespread lepidopteran pests in tropical plantation agriculture. The pest is difficult to control with chemical insecticides because tea faces strict pesticide residue limits for export (the EU MRL for most insecticides on tea is 0.01–0.05 mg/kg, among the strictest in the world), and the 7–10-day plucking cycle means that even short-PHI insecticides like spinosad (3-day PHI) effectively prevent spraying during the harvest season. Integrated management combines Btk sprays (effective on young larvae and residue-free), NPV application (highly specific and residue-free), Trichogramma egg parasitoid releases, pheromone traps for adult monitoring and mating disruption, hand-collection of rolled leaves, and rigorous crop sanitation. Tocklai Tea Research Institute (Jorhat, Assam) and UPASI Tea Research Institute (Coonoor, Tamil Nadu) have developed IPM packages for tea tortrix that have been adopted by tea growers in Assam, West Bengal (Darjeeling, Dooars), and South India. In the major tea growing states of Assam (Cachar, Dibrugarh, Tinsukia, Sibsagar), West Bengal (Darjeeling, Dooars, Terai), Tamil Nadu (Nilgiris, Anaimalai), Kerala (Idukki, Wayanad), and Karnataka (Chikmagalur, Coorg), H. coffearia is one of the top 3 insect pests of tea, alongside the tea mosquito bug (Helopeltis theivora) and the red spider mite (Oligonychus coffeae). Annual losses to tea tortrix are estimated at ₹60–90 crore in Indian tea plantations.