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Black pepper pollu beetle (Longitarsus nigripennis) Photo: placeholder pending image-fill pass

Black pepper pollu beetle (Longitarsus nigripennis)

The pollu beetle (Longitarsus nigripennis Motschulsky), a small chrysomelid flea-beetle, is the most damaging insect pest of black pepper (Piper nigrum) in India and is responsible for the "pollu" or hollow-berry defect that downgrades pepper to lower trade grades. ICAR-IISR Calicut documents pollu beetle as the principal yield-quality limiting pest of the Kerala pepper belt.

Identification and life cycle

The adult is a small (2.5-3.0 mm) shiny dark blue-black flea-beetle with enlarged hind femora that flips away when disturbed. Eggs are laid singly on tender spikes and immature berries. The grub is creamy white, 4-5 mm long, and bores into the immature berry, feeding internally for 25-30 days. Pupation occurs in soil. The total life cycle takes 35-50 days; six to eight overlapping generations occur per year in the Western Ghats. Adults feed on tender leaves and spikes.

Hosts and damage

The pest is monophagous on Piper nigrum and a few wild Piper species. Grub feeding hollows out the developing berry, which dries up and turns black — "pollu" berries in trade parlance. Adult feeding shows pinhole punctures on tender leaves and shed of spikes. Damage is severe under shaded, moist conditions and in plantations bordering forest with wild Piper.

Economic impact

Pollu berries downgrade the lot from Malabar Garbled MG-1 to MG-2 or lower, with proportionate price discounts. Quality losses of 30-40% in heavily infested vines are recorded by ICAR-IISR Calicut, especially in shaded gardens with poor canopy management.

Management

ICAR-IISR Calicut and the Spices Board India recommend an integrated package:

  • Cultural: regulate shade — heavy shade favours the pest; remove wild Piper hosts from borders.
  • Mechanical: hand-pick and destroy infested ("pollu") berries during the spike-formation stage.
  • Biological: spray neem oil 0.5% during spike emergence and berry-formation stages; conservation of larval parasitoid Pediobius spp. is encouraged.
  • Chemical: two prophylactic sprays of quinalphos 0.05% or dimethoate 0.05% — first at spike emergence and second 25-30 days later, before berry-hardening, on the spikes and tender shoots.
  • Variety: among ICAR-IISR releases, IISR Sreekara, IISR Subhakara and Panniyur 5 are recorded as relatively less preferred by adults — see [[black-pepper-iisr-thevam-girimunda|IISR Thevam and Girimunda]] and [[black-pepper-panniyur-1-to-9|Panniyur series]].

See also: Black Pepper Karimunda Traditional, Black Pepper Panniyur 1 To 9, Black Pepper Iisr Thevam Girimunda, Black Pepper Foot Rot Phytophthora Capsici.

References

  1. Pollu beetle of black pepper - ICAR-IISR Calicut. https://www.spices.res.in/research/pepper
  2. Black pepper pest management - Spices Board India. https://www.indianspices.com/sites/default/files/blackpeppercultivation.pdf