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Tea mosquito bug (Helopeltis theivora) Photo: placeholder pending image-fill pass

Tea mosquito bug (Helopeltis theivora)

The tea mosquito bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae), is the most damaging insect pest of tea in Assam, Dooars, Terai, Tripura and the south-Bengal foothills. A second species, H. antonii, is the dominant TMB on south Indian tea, cashew and neem. In Assam alone, untreated bushes can lose 30-50% of the harvestable flush in a single TMB outbreak.

Identification

Adults are slender, gnat-like mirids 6-8 mm long with long thread-like antennae and a characteristic dorsal pin-like "scutellar process". Body colour varies by sex and species: H. theivora females have a reddish-orange thorax with a black abdomen and pale-green legs. Nymphs are wingless, ant-like and bright orange-red. Eggs are inserted singly into tender shoots, leaving a pair of fine white filaments protruding.

Damage and symptoms

Both nymphs and adults feed by inserting stylets into young leaves, buds and tender stems and injecting toxic saliva. Each feeding puncture forms a dark-brown, water-soaked spot that later turns necrotic. Heavy feeding scorches whole flushes, distorts the leaf lamina, kills growing tips, causes shot-hole-like perforations and triggers secondary fungal infection. The result is a "stag-headed" bush that flushes erratically. Made-tea quality also drops because damaged leaf processes poorly.

Hosts and life cycle

Camellia sinensis is the primary host; alternate hosts include guava, neem, cashew, cocoa, Mikania micrantha and several weed shrubs around tea sections. One generation takes 21-31 days at 25-28 °C; 6-8 overlapping generations occur annually, with population peaks in May-June and again September-October on the heels of monsoon flushes. Shaded, moist, weedy sections favour build-up.

Management

The Tea Board's Plant Protection Code prescribes an integrated approach because indiscriminate spraying selects for resistance and elevates residues above export MRLs.

  • Cultural: hard plucking on a 7-day round to remove eggs with the leaf; pruning out infested wood; thorough removal of Mikania and other alternate hosts; rationalised shade to break the humid microclimate.
  • Biological: conservation of reduviid predators (Sycanus, Endochus), spiders and the parasitoid Erythmelus helopeltidis; field releases of Mallada boninensis.
  • Botanical/biorational: neem-based azadirachtin 1500 ppm at 2-3 mL/L, Beauveria bassiana at 2 × 10⁹ cfu/g.
  • Chemical (only PPC-approved molecules with strict pre-harvest intervals): thiamethoxam 25 WG @ 100 g/ha, clothianidin 50 WDG @ 120 g/ha, flubendiamide 480 SC @ 100 mL/ha, or thiacloprid 21.7 SC. Rotation across mode-of-action groups is mandatory.
  • Resistant clones: TV23 and TV26 from [[tea-tv-1-tocklai-vegetative-clone|Tocklai]] are rated moderately tolerant.

See also: Tea Camellia Sinensis Assamica, Tea Blister Blight Exobasidium, Tea Grey Blight Pestalotiopsis, Tea Tv 1 Tocklai Vegetative Clone, Tea Orthodox Vs Ctc Processing.

References

  1. Tea Research Association Tocklai — Plant Protection Code. https://www.tocklai.org/
  2. Tea Board India — Plant Protection Code (PPC). https://www.teaboard.gov.in/