Psyllid (Pittosporum) Trioza vitreoradiata
Species: Trioza vitreoradiata
Common name: Pittosporum psyllid
The family of Psyllidae are small plant-feeding insects (jumping plant lice) that tend to be very "host specific", i. e. they only feed on one plant species (monophagous) or feed on a few related plants (oligophagous). Together with aphids, phylloxerans, scale insects and whiteflies they form the group called Sternorrhyncha, which is considered to be the most "primitive" group within the "true bugs" (Hemiptera). They have traditionally been considered a single family, Psyllidae, but recent classifications divide the group into a total of seven families; the present restricted definition still includes more than 70 genera in the Psyllidae.
Trioza vitreoradiata is a New Zealand native psyllid (jumping plant louse) that causes damage to Pittosporum crassifolium (karo) and other Pittosporum naturally occurring and cultivated varieties.
Pittosporum psyllid adults are winged, yellowish-green to black, with a size range of 3-4mm in length . They closely resemble winged aphids, and may be mistaken as such. However, on close inspection, psyllids do not bear cornicles on their abdomen, and do not tend to congregate in colonies, as aphids do. The nymphs and adults secrete copious amounts of honeydew. The eggs are irregular, apically spined, white or yellowish structures about 0.35mm long. They have a short basal stalk for attachment to leaf surfaces.
Adult psyllids lay eggs and when they hatch the nymphs attack the leaves, The plants react by creating a blister or gall (Leave bumps) or scar best described as pitting of the leaf. When the nymphs feed they excrete honeydew, a form of “sugars”. Often there is a development of sooty mould on the sugary excreta.
Nymphs are at first appearance look like scale insects because young forms are flattened and usually live stationary lives attached to the surface of leaves. Tey are small sucking insects which feed by penetrating the leaf tissue with their piercing and sucking mouthparts, allowing plant nutrients to be taken up by the insect.
New spring growth is particularly susceptible to attack, and retains the scars throughout life. Five generations may be possible in a year, varying according to location and environmental conditions. All life stages may be present at one time and throughout the year. There are population peaks in spring and autumn, coinciding with the flush of new foliage on the host plants. A life cycle can be completed in 60 days.
Note the yellow raised areas on the leaf in the photo below. Although recorded primarily from Pittosporum species, it has also been found on Discaria toumatou (Matagouri) and Geniostoma ligustrifolium (hangehange). It has also been seen infecting a grapefruit tree that was growing close to apsyllid-infested Pittosporum. This psyllid species is now also recorded in England, Ireland and France.
Photos below are of the damage to Pittosporum crassifolium (karo) caused by Trioza vitreoradiata.