Mulberry tukra mealybug Photo: Ministry of Textiles · GODL-India · source ↗

Mulberry tukra mealybug

Mulberry tukra is the leaf-crumpling, shoot-stunting condition caused by the pink hibiscus mealybug Maconellicoccus hirsutus on Morus species. It is the single most economically damaging pest of commercial mulberry gardens in Karnataka, Andhra Pradesh and Tamil Nadu, where outbreaks routinely cut leaf yield by 25-40% and degrade leaf quality enough to depress cocoon weight and shell ratio in the silkworm rearing that follows.

Identification

Adult females of M. hirsutus are 2-4 mm long, pinkish-red bodies covered with white waxy filaments and located in clusters on shoot tips, leaf axils and the underside of young leaves. Males are smaller, winged and rarely seen. Egg masses are loose pinkish-white ovisacs lodged in leaf folds and bark crevices. Affected shoots show the diagnostic tukra symptom: tightly bunched, crumpled, distorted young leaves at the growing tip, with internodes shortened and the apical bud bent or knotted. Sooty mould develops on the honeydew secretion that drips onto leaves below.

Hosts and lifecycle

The mealybug is highly polyphagous — its known hosts include cotton, hibiscus, okra, guava, grape, mango and many ornamentals — but mulberry is one of its preferred hosts in South India. The female lays 300-600 eggs in a single ovisac; eggs hatch in 3-9 days and the crawler stage spreads by wind, contact with workers and tools, and through nursery cuttings. Three nymphal instars complete development in 25-30 days at 25-30°C; eight to ten overlapping generations occur per year, with population peaks in February-May and after the south-west monsoon ebbs in October-November. Cool-humid pockets with shaded, dense gardens are favoured.

Damage and economic impact

Toxic saliva injected during feeding distorts cell division at the shoot apex, producing the characteristic tukra crumpling. The crumpled leaves are unfit for silkworm feeding — they are dehydrated, secondary-metabolite-loaded and contaminated with honeydew and sooty mould. Worms fed even diluted tukra-affected leaf show reduced larval weight, longer larval duration and lower shell ratio. CSRTI Mysore on-station and field surveys put commercial-garden leaf loss from tukra at 25-40% in unmanaged plots and 5-12% under integrated management. Bivoltine rearings on V-1 (Mulberry Variety V1 Victory 1) — the dominant variety — are particularly exposed because V-1 is highly susceptible.

Management

Standard integrated package (CSRTI, Central Silk Board, Karnataka State Sericulture Department):

Cultural: Prune and burn affected shoots at first detection; do not compost. Avoid dense, low-pruned gardens that retain humidity at the canopy base. Use only mealybug-free stem cuttings for new gardens; quarantine and inspect incoming planting material.
Biological: Field release of the Australian ladybird beetle Cryptolaemus montrouzieri at 250-500 beetles per acre is the foundation tactic. The parasitoid Anagyrus dactylopii (released at 500-1,000 per acre) supplements predator action. CSRTI maintains both as multiplication starter cultures.
Chemical: Where biological agents have not yet established or outbreaks are severe, dichlorvos 76% EC at 2 ml per litre, OR dimethoate 30% EC at 2 ml per litre, OR profenofos 50% EC at 2 ml per litre is sprayed on affected shoots with a 20-day pre-harvest interval before silkworm feeding. Repeated chemical use disrupts Cryptolaemus and is to be avoided once the predator is established.
Sanitation: Remove sooty mould-encrusted leaves; wash worker hands and tools between gardens to avoid mechanical carry-over.

Sources

Tukra Disease of Mulberry. Central Sericultural Research and Training Institute, Mysore.
Maconellicoccus hirsutus. CABI Plantwise Knowledge Bank.
Pests of Mulberry. Central Silk Board.