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Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

Malay apple gall psyllid (366)

Photo 1. Galls on uppersurface of leaves of Syzgium malaccense, caused by Trioza vitiensis.

Photo 2. Heavy incidence of galls on uppersurface of leaves of young Syzgium malaccense plants, caused by Trioza vitiensis.

Photo 3. Close-up of galls on uppersurface of leaves of Syzgium malaccense, caused by Trioza vitiensis.

Photo 4. Close-up of galls on uppersurface of leaves of Syzgium malaccense, caused by Trioza vitiensis.

Photo 5. Nymph of Trioza vitiensis, in the 'cup' of a gall on the underside of a leaf of Syzgium malaccense.

Photo 6. Galls on underside of leaves of Syzgium malaccense, caused by Trioza vitiensis, from which adults have emerged.

Photo 7. Nymph of Trioza vitiensis, removed from a gall on the leaf of Syzgium malaccense. Note the obvious eyes and the fringe of short white hairs around the body.

Photo 8. Adult (and nymph) of Trioza vitiensis, removed from a gall on the leaf of Syzgium malaccense. Note the prominent wing veins of the adult.

Summary

Restricted distribution. South and Southeast Asia, Oceania. Present in Fiji, FSM, French Polynesia, Samoa.
Cosmetic problem on mature trees; may set back seedling growth. Eggs laid on new leaves and shoots. Nymphs suck sap from underside of leaf injecting a toxin. Galls form around the nymphs. Adults emerge from gall, 2 mm long, winged with dark veins.
Spread in wind, and plants in horticultural trade.
Natural enemies: ladybird beetles, lacewing larvae. Possibly, parasitoid wasps.
Cultural control: prune plants in nurseries or trees used as hedges (then apply insecticides).
Chemical control: synthetic pyrethroid, malathion to protect new growth. Imidacloprid not recommended because of effect on bees (unless used outside time of flowering).

Common Name

Leaf gall psyllid, Eugenia psyllid, Malay apple gall psyllid, rose apple psyllid. Psyllids are often referred to as "jumping lice".

Scientific Name

Trioza vitiensis; previously, known as Metatrioza vitiensis.

AUTHOR Grahame Jackson & Mani Mua
Information from Hodkinson ID The biology and ecology of the gall-forming Psylloidea (Homoptera). In: TN Ananthakrishnan Biology of gall insects. Oxford University Press. (https://www.researchgate.net/publication/270284681_The_biology_and_ecology_of_the_gall-forming_Psylloidea_Homoptera); and Au S (2013) Succession in galls on Syzygium malaccense and their impact on leaf aging. UC Berkeley. (https://cloudfront.escholarship.org/dist/prd/content/qt847704sb/qt847704sb.pdf); and from Swaine G (1971) Agricultural Zoology in Fiji. Her Majesty's Stationery Office. London. Photos 3&8 Gerald McCormack & Maja Poeschko, Cook Islands Biodiversity & Natural Heritage. (http://cookislands.bishopmuseum.org/).

Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/185: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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