Palm thrips - Parthenothrips dracaenae

By N A Martin (2017 revised 2018)

Caption:

Classification

Phylum

Arthropoda

Class

Insecta

Order

Thysanoptera

Family

Thripidae

Subfamily

Panchaetothripinae

Scientific name

Parthenothrips dracaenae (Heeger, 1854)

Common names

Palm thrips, Dracaena thrips

Synonyms

Heliothrips dracaenae Heeger, 1854

Parthenothrips concolor Uzel, 1895

Thrips dracaenae Regel, 1858

Taxonomic notes

Palm thrips, Parthenothrips dracaenae (Heeger, 1854) is one of four species of the subfamily Panchaetothripinae in New Zealand. The other three species are Greenhouse thrips, Heliothrips haemorrhoidalis (Bouche, 1833), Banana silvering thrips, Hercinothrips bicinctus (Bagnal, 1919) and an endemic species, Hangehange thrips, Sigmothrips aotearoana Ward, 1970. This subfamily is distinguished from other Thripidae by the dorsal surfaces of the head and prothorax being covered in reticulate sculpture. The maxillary palp is two segmented and the forewing having the first vein more or less fused to the costa. Another distinguishing feature of the four species in New Zealand is that they feed on mature or almost mature plant leaves.

Biostatus and distribution

This adventive species of thrips is widespread in the tropics and subtropics and lives on mature plant leaves. It was first found in New Zealand on passion fruit leaves in June 1935 by W. Cottier. In New Zealand it is in the North Island and Nelson in the South Island. In some areas it may be restricted to pot plants and greenhouses. It is mainly found on adventive plants, but in the Auckland Region it is often seen on Pigeonwood, Hedycarya arborea (Monimiaceae) in native forests.

Conservation status: Widespread in the North Island and present in the North of the South Island; mainly on adventive plants, but also on a few native species in and out of native habitats.

Life stages and annual cycle

Life cycle of a plant feeding Terebrantia thrips. © Plant & Food Research Figure 8 from Crop & Food Research Infosheet No3-16. [Image: 2J2N]

The Palm thrips appears to breed all year outdoors in Auckland and they can also breed all year on indoor plants. In a greenhouse the full life cycle may take 7 days, but it will be longer on outdoor plants. They live mainly on the mature leaves of their host plants as do the other three species of the subfamily Panchaetothripinae found in New Zealand.

Adults

Adults, like the other active stages of Palm thrips, are relatively long and thin. The body is brown and its head and prothorax is strongly sculptured and reticulate. The head has two antennae, two compound eyes and on the underside the mouth cone contains a pair of short maxillary stylets and a single stout mandible. There are three pairs of legs and two pairs of wings that when not used for flying are held over the abdomen. The relatively broad white forewings have a dark band near their base and other darker areas nearer the tip. The tip of the abdomen contains the genitalia. The end of the female abdomen also has an ovipositor for inserting eggs into leaves.

Eggs, Larvae and Pupae

Eggs are laid in either the upper or underside of the leaf depending on the plants species. A thin larva hatches from the egg. It is the shape of a tiny white wingless adult. Like the adult it has three pairs of legs, a pair of antennae and the same structures for feeding. There are two larval stages and two non-feeding stages, a prepupa and a pupa. The juvenile thrips go to the next stage by moulting. This involves the dorsal skin splitting and the next stage pulling itself out of the old skin. The second larva looks like the first larva. Many of the body setae (hairs) have widened tips. The tips of the setae on the two non-feeding stages are not as obviously wide as on the larvae. The first non-feeding stage, the prepupa, differs in appearance from the larva by having short wing buds. The next stage, the pupa, has longer wing buds and the antennae are folded back. The prepupa and pupa also live on the leaf with the larvae.

Feeding and plant damage

Palm thrips feed on mature leaves rather than young leaves. Larvae and adults use the stylets in their mouth cone to feed. They puncture plant cells with their single mandible and suck up the plant cell contents with their maxillary stylets. Their feeding kills the surface cells of the leaves creating distinctive pale areas of dead cells. Unlike other species of the subfamily Panchaetothripinae in New Zealand, Palm thrips larvae do not carry a dark faecal droplet at the tip of the abdomen.

Adult Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on leaf of Three Kings cabbage tree, Cordyline obtecta (Asparagaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J2S]

Adult Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on a leaf of Tecomanthe speciosa (Bignoniaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J34]

Dorsal (upper) side of head of an adult of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae): microscope slide preparation showing the reticulate sculpturing. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2JDL]

Drawing of the forewing of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) showing the veins, setae (hairs) and pigmentation. © Drawing published in Fauna of New Zealand Number 1. Figure 152. [Image: 2JDP]

Microscope slide of the end of the abdomen of an adult male of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) showing the genitalia. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2JDM]

Microscope slide of the end of the abdomen of an adult female of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) showing the curved and toothed ovipositor. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2JDN]

Larvae of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on the upper side of a leaf of Pigeonwood, Hedycarya arborea (Monimiaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J2W]

Larvae and a prepupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on the upper side of a leaf of Pigeonwood, Hedycarya arborea (Monimiaceae): note the wing buds on the prepupa. Creator: Tim Holmes. © Plant & Food Research. [Image: 2J30]

Pupae of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on leaf of Three Kings cabbage tree, Cordyline obtecta (Asparagaceae): note the long wing buds and the folded antennae. Creator: Tim Holmes. © Plant & Food Research. [Image: 2J2Z]

Leaf of Three Kings cabbage tree, Cordyline obtecta (Asparagaceae) with feeding damage by Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J2Q]

Upper side of a leaf of Pigeonwood, Hedycarya arborea (Monimiaceae) with feeding damage by Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2J3E]

Dorsal (upper) side of larva of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae): microscope slide preparation showing the setae (hairs) with expanded tips. The black arrows point to the stigmata (opening to breathing tubes) of the first abdominal segment (left) and the thorax (right). Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J37]

Dorsal (upper) side of head of a larva of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae): microscope slide preparation showing the setae (hairs) with expanded tips and the antennae. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J38]

Dorsal (upper) side of the tip of the abdomen of a larva of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae): microscope slide preparation showing the setae (hairs) with expanded tips and the round stigma (opening to breathing tube) on abdominal segment 8 (black arrow). Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J39]

Ventral (under) side of the tip of the abdomen of a larva of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae): microscope slide preparation showing the small setae (hairs) and ornamentation on the abdominal segments. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J3A]

Wing buds of a pupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) in a microscope slide preparation: note the long setae (hairs) on the forewing bud. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J3B]

Dorsal (upper) side of the abdomen of a pupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) in a microscope slide preparation: note the round stigma on abdominal segment 1 (black arrow) and the setae (hairs) with expanded tips. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J3C]

Recognition

Palm thrips are found on mature or almost mature leaves of host plants with typical thrips feeding damage. With the aid of a strong magnifying glass, they can be distinguished from the other three species in the subfamily Panchaetothripinae. The dorsal surface of the head and prothroax of adults of the New Zealand species in this subfamily is strongly sculptured and reticulate.

Adult Palm thrips body is dark brown and it has broad wings. The forewings have a strong dark band near the base and paler dark areas nearer the wing tip. The banana silvering thrips, Hercinothrips bicintus, and Hangehange thrips, Sigmothrips aotearoana, have banded wings, but the wings are much narrower.

If adults are absent, colonies of Palm thrips are easily distinguished from those of the other Panchaetothripinae. The larvae, prepupae and pupae may all be found on host plant leaves and they are a brilliant white. If you have access to a binocular microscope, you will see that the setae (hairs) on the body of the larvae have enlarged tips. It is the only species to have setae with enlarged tips. They are not so obvious on the prepupae and pupae. The larvae do not carry faecal droplets on the tip of the abdomen whereas the larvae of the other three species carry faecal droplets most of the time.

Colonies of Greenhouse thrips, Heliothrips haemorrhoidalis, may also have pupae and prepupae on leaves, but they are a greenish-yellow. The larvae usually carry dark faecal droplets. Colonies of banana silvering thrips, Hercinothrips bicintus, and Hangehange thrips, Sigmothrips aotearoana, never have prepupae or pupae in them. Their larvae also carry faecal droplets at the tip of the abdomen.

Adult Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on the upper side of a leaf of Pigeonwood, Hedycarya arborea (Monimiaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J2U]

Adult and prepupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on leaf of Three Kings cabbage tree, Cordyline obtecta (Asparagaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J2R]

Pupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on a leaf of Tecomanthe speciosa (Bignoniaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J33]

Side view of the abdomen of a pupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) in a microscope slide preparation: note the setae (hairs) with expanded tips. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J3D]

Recently moulted Adult Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) on the underside of a leaf of Small-flowered mistletoe, Ileostylus micranthus (Loranthaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2JUU]

Larvae of Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) on the underside of a leaf of Small-flowered mistletoe, Ileostylus micranthus (Loranthaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2JUV]

Adult and juvenile Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) on the underside of a leaf of Puka, Meryta sinclairii (Araliaceae): note the colour of the larvae, prepupae and pupae. Creator: Tim Holmes. © Plant & Food Research. [Image: 2JUY]

Three pupae of Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) on the underside of a leaf of Whau, Entelea arborescens (Malvaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2JUD]

Microscope slide preparation of a larva of Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae): note the short terminal segment of the abdomen and short anal setae (hairs). Creator: Nicholas A. Martin. © Landcare Research. [Image: 2JVK]

Wing buds of a pupa of Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) in a microscope slide preparation: note short setae (hairs) on the forewing bud. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2JVR]

Terminal segments of the abdomen a prepupa of Greenhouse thrips, Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) in a microscope slide preparation: note the simple bristle-like setae. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2JVS]

Adult Banana silvering thrips, Hercinothrips bicinctus (Thysanoptera: Thripidae) on underside of a leaf of Night-scented Jessamine, Cestrum nocturnum (Solanaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J5K]

Drawing of the forewing of Banana silvering thrips, Hercinothrips bicinctus (Thysanoptera: Thripidae) showing the veins setae (hairs) and pigmentation. © Drawing published in Fauna of New Zealand Number 1. Figure 150. [Image: 2J62]

First and second instar (stage) larvae of Banana silvering thrips, Hercinothrips bicinctus (Thysanoptera: Thripidae) on underside of a leaf of Tecomanthe speciosa (Bignoniaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J61]

Second instar (stage) larvae of Banana silvering thrips, Hercinothrips bicinctus (Thysanoptera: Thripidae) on underside of a leaf of Night-scented Jessamine, Cestrum nocturnum (Solanaceae): note the conical shape of the segments at the tip of the abdomen (black arrow). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J5I]

Microscope slide preparation of a larva of Banana silvering thrips, Hercinothrips bicinctus (Thysanoptera: Thripidae): note the short conical terminal segments of the abdomen. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J67]

Adult Hangehange thrips, Sigmothrips aotearoana (Thysanoptera: Thripidae) on upper side of a leaf of Hangehange, Geniostoma ligustrifolium (Loganiaceae): note the sharp lateral projections on the head (white arrow). Creator: Tim Holmes. © Plant & Food Research. [Image: 2J3X]

Drawing of the forewing of Hangehange thrips, Sigmothrips aotearoana (Thysanoptera: Thripidae) showing the veins setae (hairs) and pigmentation. © Drawing published in Fauna of New Zealand Number 1. Figure 153. [Image: 2J4Q]

First and second instar (stage) larvae of Hangehange thrips, Sigmothrips aotearoana (Thysanoptera: Thripidae) on upper side of a leaf of Hangehange, Geniostoma ligustrifolium (Loganiaceae): note the long anal setae in the faecal droplet of the thrips on the right. Creator: Tim Holmes. © Plant & Food Research. [Image: 2J40]

Microscope slide preparation of a larva of Hangehange thrips, Sigmothrips aotearoana (Thysanoptera: Thripidae): note long setae at the tip of the abdomen. Creator: Nicholas A. Martin. © Landcare Research. [Image: 2J4G]

Natural enemies

Only one natural enemy of Palm thrips in known in New Zealand, a tiny wasp parasitoid of thrips eggs, Megaphragma sp. (Hymenoptera: Trichogrammitidae).

Host plants

Palm thrips mainly feed on mature leaves of trees, shrubs and climbers. The adults and larvae often feed on the upper side of leaves.

Adult and larvae feed by inserting their stylets plant cells at or near the surface of the leaf. They suck out the cell contents. Their presence can be recognised by the distinctive appearance of their feeding damage on leaves.

Adult Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on leaf of Three Kings cabbage tree, Cordyline obtecta (Asparagaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J2P]

Upper and underside of leaf of leaf of Pigeonwood, Hedycarya arborea (Monimiaceae) with feeding damage by Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J2T]

Upper side of leaf of Tecomanthe speciosa (Bignoniaceae) with feeding damage by Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J35]

Upper side of leaflets of Tecomanthe speciosa (Bignoniaceae) with feeding damage by Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J36]

Adult Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on a leaf of Pigeonwood, Hedycarya arborea (Monimiaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2J32]

Pupa of Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on the upper side of a leaf of Pigeonwood, Hedycarya arborea (Monimiaceae): the pupa is a non-feeding life stage. Creator: Tim Holmes. © Plant & Food Research. [Image: 2J31]

Upper side of leaf of Ngaio, Myoporum laetum (Scrophulariaceae) with feeding damage by Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). © All rights reserved. [Image: 2SAP]

Underside of leaf of Ngaio, Myoporum laetum (Scrophulariaceae) with feeding damage and Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae). © All rights reserved. [Image: 2SAQ]

Juvenile and adult Palm thrips, Parthenothrips dracaenae (Thysanoptera: Thripidae) on underside of leaf of Ngaio, Myoporum laetum (Scrophulariaceae). © All rights reserved. [Image: 2SAR]

Table: Host plants of the Palm thrips, *Parthenothrips dracaenae* (Thysanoptera: Thripidae) from Plant-SyNZ database (15 July 2018). The reliability score shows the quality of evidence for the host association (1-10, 10=high).
Common Name(s)	Scientific Name	Family	Reliability Index	Biostatus
	Chamaedorea pochutlensis Liebm.	Palmae	10	cultivated
Three Kings cabbage tree	Cordyline obtecta (Graham) Baker	Asparagaceae	10	indigenous, non-endemic
Fatsia, Glossy-leaved paper plant, Japanese aralia, Rice paper plant, Yatsude	Fatsia japonica (Thunb.) Decne. & Planch.	Araliaceae	9	naturalised
Pigeonwood, Kaiwhir, Kaiwhiria, Kōporokaiwhiri, Pōporokaiwhiri, Pōporokaiwhiria, Porokaiwhiri, Porokaiwhiria, Poroporokaiwhiria	Hedycarya arborea J.R.Forst. & G.Forst.	Monimiaceae	10	endemic
Curly palm, Sentry palm	Howea belmoreana (C. Moore & F. Muell.) Becc.	Palmae	9	cultivated
Ngaio	Myoporum laetum G.Forst.	Scrophulariaceae	10	endemic
Black passionfruit, Purple granadilla, Purple passionfruit	Passiflora edulis Sims	Passifloraceae	10	naturalised
	Pennantia baylisiana (W.R.B.Oliv.) G.T.S.Baylis	Pennantiaceae	10	endemic
Queensland umbrella tree, Umbrella tree	Schefflera actinophylla (Endl.) Harms	Araliaceae	9	naturalised
Seven-finger, Kohi, Kotētē, Patate, Patatē, Patē, Patētē	Schefflera digitata J.R.Forst. & G.Forst.	Araliaceae	10	endemic
	Tecomanthe speciosa W.R.B.Oliv.	Bignoniaceae	10	endemic

Additional information

Reproduction and Parthenogenesis in Thysanoptera

In Thysanoptera, females are diploid (2 sets of chromosomes) and males are haploid (one set of chromosomes). Males are produced from unfertilised eggs. This type of reproduction is called Arrhenotoky. The proportion of males to females in a population is variable. In Palm thrips this appears to be related to temperature. In a warm greenhouse (25-28°C) there are very few males, 6-7 per 100 females, while in a cooler greenhouse (18-20°C) there are more males. Where there are very few or no males, females can reproduce without fertilisation. This is called Thelotoky, form of parthenogenesis. In populations where there are very few males there are probably two types of female present, Arrhenotokous and Thelotokous.

Palm thrips is the first species from the Thysanoptera order that was found to be capable of thelytokous parthenogenetic reproduction. This characteristic is contained in the Latin name of the genus, Parthenothrips.

Information sources

Lewis T. 1973. Thrips their biology, ecology and economic importance. Academic Press, London, UK. Pp. 1-349.

Martin NA. 2016. Distinguishing feature of immature stages of Panchaetothripinae (Thysanoptera: Thripidae) known in New Zealand. New Zealand Journal of Zoology 43 (4): 1-8.

Martin NA. 2017. Host plants of Panchaetothripinae (Thysanoptera: Terebrantia: Thripidae) in New Zealand. New Zealand Journal of Zoology 44 (1): 1-8.

Martin NA, Mound LA. 2004. Host plants for some New Zealand thrips (Thysanoptera: Terebrantia). New Zealand Entomologist. 27: 119-123.

Moritz G, Brant S, Triapitsyn S, Subramanian S. Identification and Information tools for thrips in East Africa. Parthenothrips dracaenae (Heeger, 1854) Accessed 27 June 2017

Mound LA, Walker AK. 1982. Terebrantia (Insecta: Thysanoptera). Fauna of New Zealand. 1: 1-113.

Plant-SyNZ: Invertebrate herbivore-host plant association database. plant-synz.landcareresearch.co.nz/

Acknowledgements

The New Zealand Institute for Plant & Food Research Limited (Plant & Food Research) for permission to use photographs.

Landcare Research New Zealand Limited (Landcare Research) for permission to use photographs.

Update history

1 August 2018. NA Martin. Updated host plant list, added photo of Myoporum.

INTERESTING INSECTS

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