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Mealybug in orchard fruit crops

Mealybugs are sap-sucking scale insects covered with a white mealy wax. Several species damage Indian orchard fruit crops, most notably Maconellicoccus hirsutus (pink hibiscus mealybug) and Planococcus citri (citrus mealybug). ICAR-NBAIR and ICAR-NCIPM coordinate research on biological control of these pests in horticulture.

Identification and symptoms

Adult females are 2-4 mm long, oval, soft-bodied and coated in a white waxy secretion. Colonies appear as fluffy white masses on leaf undersides, shoots, fruit calyces and stem crevices. Feeding causes leaf curl, stunted shoots and honeydew secretion, which supports a sooty mould layer that further reduces photosynthesis and downgrades fruit quality.

Host crops and life cycle

M. hirsutus is extremely polyphagous, recorded on more than 200 plant genera including guava (Guava Allahabad Safeda, Guava Taiwan Pink), mango, sapota, mulberry, hibiscus, cotton and grapes. P. citri is the principal mealybug on citrus and is also found on guava and grape. Both species reproduce year-round in tropical regions, with multiple overlapping generations and frequent ant-tended colonies on tender shoots.

Damage and economic impact

Severe infestations in guava cause leaf and shoot distortion, premature fruit drop and unmarketable, mould-stained fruit. Heavy outbreaks on sapota and mango can defoliate young trees. Cosmetic damage from sooty mould alone causes substantial price loss in commercial orchards.

Management

ICAR-supported integrated management combines:

  • Cultural: orchard sanitation, pruning out infested shoots after the standard pruning cycle (Guava Pruning Cycle), and ant management to break the mutualism.
  • Biological: release of the encyrtid parasitoid Leptomastix dactylopii and the Australian ladybird beetle Cryptolaemus montrouzieri, both produced commercially by NBAIR-affiliated bio-control labs.
  • Mechanical/chemical: high-volume sprays of horticultural oil emulsions; spot applications of approved insecticides where bioagents are insufficient.

See also: Guava Allahabad Safeda, Guava Taiwan Pink, Guava Pruning Cycle.

References

  1. Mealybugs and their management. ICAR-NCIPM bulletin.
  2. Compendium of insect bioagents. ICAR-NBAIR.