Trioza panacis Maskell, 1890
Lancewood psyllid, Lancewood jumping plant louse
Powellia panacis (Maskell, 1890)
Biostatus and distribution
This endemic psyllid lives in the North and South Islands of New Zealand. It occurs in city gardens and parks as well as native ecosystems on its host plants, lancewood, Pseudopanax crassifolius, and closely related, Pseudopanax species.
Conservation status: Widespread, not threatened, a minor pest in gardens.
Life stages and annual cycle
In Auckland, adults and juveniles may be found all year. In colder areas the insect probably overwinters as adults, probably females that were mated the previous autumn. Adults each have three pairs of legs and two pairs of transparent wings that are held partly covering their abdomens. The body is green. The head has a pair of antennae, a pair of compound eyes and a ventral rostrum that holds the stylets used for feeding. The male has a complex apparatus at the tip of the abdomen that is used for grasping the female during mating. While mating the male sits alongside the female, facing in the same direction, and the end of the abdomen curls under the female and the tip of her abdomen. The tip of the female’s abdomen is slender and houses a narrow blade-like ovipositor that assists with egg laying.
Females lay eggs on the surface of leaves. They are laid on the underside of older leaves amongst a psyllid colony or on young expanding leaves. Eggs are shining, smooth and tear drop-shaped. The egg base has a short stalk that may be inserted into the plant. The eggs are a pale cream. A few days before hatching red eyespots are present. Eggs are about 0.35 mm long.
Nymphs hatch from the eggs. First instar (stage) nymphs are small, pale brown, flat and oval shaped. They have three pairs of legs and sucking mouthparts. They settle on the upper side of young expanding leaves or on the underside of older leaves. There are five nymphal stages, and each is called an instar. Nymphs go from one stage to the next by moulting (changing their skin). During moulting, the skin on the dorsal side splits and the next stage pulls itself out of the old skin which in many Lancewood psyllid nymphs remains attached on the tip of the abdomen. Older nymphs may have two or three moulted skins attached. Adults emerge from fifth instar nymphs.
As the insects progress through the nymphal stages their colour and shape changes. The second, third and fourth instar nymphs are usually pale while the fifth instar has brown marking that are almost black centrally. Some early instars also have dark markings. The older instars have progressively larger wing buds.
The length of time needed for egg and nymphal development depends on the temperature.
Walking jumping and flying
Adults and all nymphal stages possess three pairs of legs that are used for walking. When the adults are at rest and walking the last pair of legs are held under the body (see photo of underside of an adult male). These hind legs are used make the adult jump if it is disturbed. And hence a common name for psyllids, jumping plant lice. The adults also possess wings and can fly, which aids dispersal and location of new host plants.
Feeding and honeydew
Like other Hemiptera, the lancewood psyllid has sucking mouthparts. The long stylets, which are specially shaped rods, are held in the rostrum. When it wishes to feed, the psyllid moves the tip of the rostrum to the surface of a leaf or stem. The stylets are then gradually pushed into the plant. The stylets form two tubes, one through which saliva is injected into the plant and a second through which plant juices are sucked up into the insect. The lancewood psyllid inserts the stylets into the phloem (the plant vessels for transmitting sap from the leaves to other parts of the plant). The sap has a high volume of water and sugars, more than the insect needs. The psyllid excretes the excess water and sugar, which is called honeydew.
There are several kinds of psyllids in New Zealand, the adults of which look very similar to the lancewood psyllid and can only be distinguished through microscopic examination. However, the Lancewood psyllid, Trioza panacis, is the only species that breeds on Lancewood, (Pseudopanax crassifolius), Fierce lancewood (Pseudopanax ferox) and Coastal five finger (Pseudopanax lessonii).
Aphids could be confused with Lancewood psyllids on Pseudopanax lessonii. Winged aphids are similar in size to adult psyllids, but have globular bodies and the round ended wings are held above their bodies. Psyllids are more like tiny cicadas, slender with point ended the wings that cover the body when they are at rest. Furthermore, the abdomen of the adult psyllid often twitches from side to side.
Juvenile lancewood psyllids are flat and scale like, unlike globular long legged aphids. The presence of moulted skins on nymphs is a distinctive feature.
The presence of pits in host plant leaves and associated chlorotic (yellow or red) areas on leaves is an indication of the presence of Lancewood psyllid.
Two fungal pathogens of the Lancewood psyllid have been found. A white fluffy fungus on nymphs is called Torrubiella confragosa Mains (Clavicipitaceae) (previously called Verticillium lecanii) and the fungus with spiky growths on an adult and nymph is Hirsutella saussurei (Cooke) Speare (Ophiocordycipitaceae).
Birds probably feed on the psyllid, but there are no specific reports. Spiders and several species of lacewings, ladybirds and mirid bugs are likely to pry upon adult and juvenile lancewood psyllids.
At least three species of parasitoid wasp (Hymenoptera) have been reared from Lancewood psyllid nymphs. One species is Tamarixia sp. A (Eulophidae), a parasitoid of several native psyllids. The adult female has a pale area on the top (dorsal) abdomen. This parasitoid lay an egg on the underside of the nymph, the wasp larva lives under the psyllid and feeds from the outside. When the larva is full grown, the wasp larva pupates under the psyllid nymph. The adult wasp, after emergence from the pupa, chews an exit hole in the top, dorsal, side of the dead nymph. Another the adult female of another apparent ectoparasitoid is all black on top, has dark hind legs and the middle pair of legs have a prominent tibial ‘spine’.
Endoparasitoids (Encyrtidae) lay an egg in the nymph and the wasp larva develops in the psyllid nymphs body. When it is fully grown the larva pupates within the nymph. Again the adult wasp chews an exit hole in the top of the nymph.
A sign that parasitoids have killed lancewood psyllid nymphs is a round exit hole made by the adult parasitoid, though this does not provide information about the kind of parasitoid.
|Scientific Name||Common Name||Classification||Enemy Type||Reliability Index||Biostatus|
|Encyrtidae sp.||(Wasp)||Hymenoptera: Encyrtidae||parasitoid||5||unknown|
|Tamarixia sp. A||(Wasp)||Hymenoptera: Eulophidae||parasitoid||9||unknown|
|Hirsutella saussurei (Cooke) Speare||Fungi: Ascomycota: Sordariomycetes: Hypocreales: Ophiocordycipitaceae||pathogen||10||naturalised|
|Torrubiella confragosa Mains||Fungi: Ascomycota: Sordariomycetes: Hypocreales: Clavicipitaceae||pathogen||10||indigenous, non-endemic|
The lancewood psyllid, Trioza panacis, breeds on leaves of three species of Pseudopanax, Lancewood, Fierce lancewood and Coastal five finger (Araliaceae).
Feeding and plant damage
When the psyllid nymph settles and feeds on a young expanding leaf, a pit gall is formed. This happens when the nymph settles on the upper or lower side of the leaf. Very young leaves may also develop areas of chlorotic (yellow or red) tissue as a result of psyllid feeding. In a heavy infestation a leaf can become badly distorted and in lancewood, the edge of the leaf may roll over. The presence of dimples and yellow or red areas on leaves makes it easy to recognise plants that have been infested by this insect.
|Common Name(s)||Scientific Name||Family||Reliability Index||Biostatus|
|Lancewood, Hoheka, Horoeka, Koeka, Kokoeka, Ohoeka||Pseudopanax crassifolius (Sol. ex A.Cunn.) K.Koch||Araliaceae||10||endemic|
|Fierce lancewood||Pseudopanax ferox Kirk||Araliaceae||10||endemic|
|Coastal five finger, Houmāpara, Houpara, Houparapara, Kokotai, Oho, Parapara, Whauwhau||Pseudopanax lessonii (DC.) K. Koch||Araliaceae||10||endemic|
Plant-SyNZ: Invertebrate herbivore-host plant association database. plant-synz.landcareresearch.co.nz/
Sommerfield KG 1984. Greenhouse and ornamental pests. In: Scott RR ed. New Zealand pest and beneficial insects. Canterbury, New Zealand, Lincoln University College of Agriculture. Pp. 65-92.
Tuthill LD 1952. On the Psyllidae of New Zealand (Homoptera). Pacific Science 6(2): 18-125.
Pam Dale for psyllid identifications and information about the psyllid.
Peter Workman for information about the psyllid, especially its natural enemies, and photographs.
The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.
1 October 2019, NA Martin. Recognition: changed ‘continually twitches’ to ‘often twiches’.
1 August 2018, NA Martin. Photos added of nymphs and galls on lancewood.