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Panicle mite (kanki nalli) in paddy

The panicle rice mite, Steneotarsonemus spinki Smiley, known locally as kanki nalli, is a tarsonemid sheath and panicle mite of rice. Feeding inside the flag leaf sheath and on developing reproductive structures causes empty and discoloured grains, brown sheath rot symptoms and reduced milling recovery.

Identification and symptoms

Microscopic mites (under 0.3 mm) live concealed inside the boot. Visible field symptoms are blackened or empty grains at maturity, brown-grey sheath lesions on the flag leaf and uneven panicle exsertion. Diagnosis combines symptom recognition with microscopic examination of sheath scrapings. The mite is also implicated as a vector or facilitator of sheath fungal pathogens.

Host crops and life cycle

The species is essentially monophagous on cultivated rice with very rapid generations under warm humid conditions. Populations explode inside the boot before panicle exsertion, then decline as the panicle dries. Spread between fields is largely by movement of infested seed, straw and equipment.

Damage and economic impact

Reported yield losses range from about 5% in light infestations to 45% in severe outbreaks. Quality losses are large because discoloured and chaffy grains are discounted at procurement and screened out at milling. S. spinki is listed on the USDA-APHIS pest alert list as a quarantine-significant invasive.

Management

  • Cultural: clean seed, avoid carry-over of infested straw, manage stubble between crops.
  • Chemical: spiromesifen 22.9% SC, propargite 57 EC, fenpyroximate and diafenthiuron + propiconazole combinations have been validated in Indian and global field trials as effective when applied preventively at the boot stage (Paddy Panicle Stage Management).
  • Integration: treat alongside boot-stage fungicide sprays for sheath rot (Paddy Sheath Stem Rot) and sheath blight (Sheath Blight Paddy) because the same window addresses both pest and disease.

See also: Paddy Panicle Mite, Paddy Sheath Stem Rot, Sheath Blight Paddy, Bacterial Panicle Blight Paddy, Paddy Panicle Stage Management.

References

  1. Bio-efficacy of pesticides against rice panicle mite. Biochem Journal.
  2. Steneotarsonemus spinki: Rice panicle mite. USDA APHIS NPAG.