Management of Pests
Acknowledgment:
This guide is adapted from the Coffee Industry Corporation (CIC) PNG Coffee Handbook 2016. We have simplified the content for easier understanding by farmers.
Pest 1: Scale Insects
- Introduction
- Green scales (Coccus spp.) feed on coffee and other plants in PNG.
- Occur in most coffee-growing areas; attack both Arabica and Robusta.
- Ants are always associated, feeding on honeydew.
- Two species: C. celatus (dark green) and C. viridis (pale green); field identification requires a specialist.
- Natural enemies: Coccinellid beetles, fungi, parasitic wasps (seldom control heavy infestations).
- Description and Damage
- Adult females oval, flat, up to 4 mm long × 2 mm wide.
- Favor young shoots and lower canopy; citrus is an important alternative host.
- Sap-sucking; excrete honeydew promoting sooty mold.
- Severe infestation → 21% flower loss, 16% fruiting node loss, ~50% cherry loss.
- Ants protect scales, remove honeydew, transport scales, build shelters.
- Control
- Chemical:
- Ants: Dursban EC, Losban EC, Cislin 25, Bifenthrin EC, Amdro bait (2 applications before & after flowering).
- Green scales: White Oil (dry season) or White Oil + Malathion 500 EC (3 applications monthly).
- Biological: Parasitic wasp Metaphycus baruensis, Coccinellid beetles, Verticillium lecanii, native wasps.
- Cultural: Prune lower branches during peak adult scale population (Nov–Dec).
- Integrated: Combine chemical, biological, and cultural methods.
- Chemical:
Pest 2: Coffee Berry Borer
- Introduction
- Hypothenemus hampei (small black beetle 1.5–1.8 mm).
- Females bore into berries, lay eggs inside beans.
- Not yet in PNG; present in nearby Indonesia and New Caledonia.
- Description and Damage
- Eggs: 30–120 per tunnel; larvae feed inside beans.
- Crop loss: 30–80% in severe infestations.
- Damaged beans affect grading and market quality.
- Host Range
- Monophagous on Coffea species: Arabica & Robusta susceptible; Liberica resistant.
- Other plants used only for feeding, not supporting life cycle.
- Ecological/Cultural Factors
- Influenced by altitude, temperature, rainfall, and cultural practices.
- Favored by heavy shade, close planting, unpruned trees, continuous flowering, fallen cherries.
- Dispersal
- Females fly to new cherries; long-distance assisted by wind.
- Spread by humans (beans, clothing, packing materials).
- Control
- Sanitation: Remove all cherries (on tree & ground), off-season flowers.
- Host Plant Resistance: Use Liberica as barrier crop.
- Chemical: Confidor (Imidacloprid).
- Biological: Parasitoids: Cephalonomia stephanoderis, Prorops nasutu, Phymastichus coffea, Beauveria bassiana.
Pest 3: Coffee Ring Borer
- Introduction
- Meroleptus cinctor attacks coffee in nurseries & smallholder fields; common host is sweet potato.
- Description and Damage
- Adults: brown/black, ~7 mm; larvae off-white with dark heads.
- Larvae tunnel around trunk, feed on inner bark & outer wood.
- Young trees: wilting & dieback; older trees: damage often repaired.
- Control
- Remove sweet potato from planting areas.
- Cut & burn infested uprights.
- Brush-on Lorsban 0.5% on trunk effective; foliar sprays usually ineffective.
Pest 4: Leafhoppers
- Introduction
- Leafhoppers (Hemiptera: Cicadellidae) feed on coffee sap.
- Common species: Batrachomorphus spp., Archeguina spp.
- Description and Damage
- Small, slender, long-bodied insects; females brown, males dark green/blue.
- Eggs in internodes; nymphs black → green, feed on sap.
- High populations → reduced vigour, stunted growth, yellowing, wood warping.
- Control
- Natural enemies: parasitic wasps, predatory insects.
- Chemical: Basudin, Actellic 50 EC, Orthene 75 (foliar spray when population high).
Pest 5: Coffee Centre Borer
- Introduction
- Zeuzera coffeae attacks coffee, citrus, cocoa, tea, kapok, ornamentals.
- Description and Damage
- Adults: grey/white with black dots; females larger (5 cm wingspan), males smaller (4 cm).
- Larvae bore into branches, cylindrical tunnels, reddish-brown frass; killed branches.
- Control
- Prune & burn infested branches.
- Parasitic wasps & predatory insects help regulate populations.
Pest 6: Coffee Leaf Roller
- Introduction
- Hamona coffearia feeds on coffee leaves; alternate hosts: Crotalaria, Dahlia, Albizzia, wild hops, silky oak.
- Description and Damage
- Larvae dull green/blue-green; pupate in rolled leaves.
- Eggs laid in scale-like masses of 20–40.
- Life cycle ~8 weeks; up to 80% defoliation in severe attacks.
- Control
- Natural parasitism up to 60%.
- Chemical: Orthene or Karate 75 (0.25% spray on leaves at larval stage).
Pest 7: Cicadas
- Introduction
- Occasionally problematic; numbers increase with shade removal, litter loss, insecticide use.
- Description and Damage
- Adult females lay eggs in primaries; nymphs drop to soil & feed on rootlets.
- High populations reduce nutrient uptake, mimicking dieback.
- Control
- Natural enemies: Cordiceps spp., Metarrhizium spp., Rhipiphoridae larvae, ants.
- Long-term: plant shade trees, maintain litter layer.
Pest 8: Army Worms
- Introduction
- Spodoptera exempta seasonal; affects coffee, grasses, some fruit & root crops.
- Description and Damage
- Adults robust, light brown, ~40 mm; larvae ~40 mm, cream-yellow stripe.
- Larvae feed on leaves & immature cherries; life cycle 21–30 days.
- Density 16–25 larvae/tree → significant defoliation.
- Control
- Monitor fields for feeding larvae.
- Chemical: Orthene 75 or Maldison 500 (foliar spray at larval stage, rotate if needed).
Pest 9: Shot Hole Weevil
- Introduction
- Oribius spp. minor pest; found in most coffee-growing regions.
- Description and Damage
- Adults ~5 mm, dark brown/black; feed on leaves causing small holes.
- Control
- Weed control to reduce host plants.
- Chemical only if severe: Dursban, Malathion, Imidacloprid.
- Biological: Beauveria bassiana (spray on foliage, branches, base; 2 applications Oct–Nov).