New Zealand flower thrips - Thrips obscuratus

By N A Martin (2019)

Caption:

Classification

Phylum

Arthropoda

Class

Insecta

Order

Thysanoptera

Family

Thripidae

Subfamily

Thripinae

Scientific name

Thrips obscuratus (Crawford, 1941)

Common names

New Zealand flower thrips

Synonyms

Isoneurothrips obscuratus Crawford, 1941

Biostatus and distribution

The endemic species, New Zealand flower thrips, is probably the commonest species of native thrips. It is found on plants throughout New Zealand from sea level to alpine areas. As its name suggests, it mainly found associated with flowers. As well as native plants, it lives on naturalised and cultivated plants. It can be a pest on some cultivated plants.

Conservation status: common, not threatened.

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]

New Zealand flower thrips may be found on its host plants from early spring to late summer. It is usually only seen on plants that have young growth and flowers and young fruit on which it can feed and breed. Adult females are believed to over winter in plant litter or other suitable hiding places.

Adults

Adults, like the other active stages of New Zealand flower thrips, are relatively long and thin. The appearance of adults can be variable. Adults are usually dark brown to black with a white base to its wings. They have two pairs of wings and three pairs of legs. The head has two antennae (with 7 or 8 segments), two compound eyes and on the underside the mouth cone contains a pair of short maxillary stylets and a single stout mandible. When not used for flying the wings are held over the abdomen. The tip of the abdomen contains the genitalia. The end of the female abdomen also has an ovipositor for inserting eggs into leaves.

Some adults a pale coloured, others have short non-functional wings (microptera). Wingless adults tend to live on alpine flowers.

Eggs, Larvae and Pupae

The female uses her ovipositor to insert Eggs singly into soft plant tissue such as flowers and young expanding leaves. A thin larva hatches from the egg. It is the shape of a tiny pale 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. 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 over the head. The prepupa and pupa may be found hiding on the plant, but may also live off the plant.

Feeding and plant damage

The thrips feed and breed on leaves, in flowers and on young fruit. 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, fruit and flowers. Leaves that have been fed on by the thrips exhibit scarring and distortion.

Adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: DSIR Photographers. © Plant & Food Research. [Image: 2ZNS]

Drawing of an adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Des Helmore. © Landcare Research. [Image: 2ZJT]

Drawing of an adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae) showing the names of the parts of the body. Creator: Annette K. Walker. © Landcare Research. [Image: 2ZJU]

Drawing of large and small antennae of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). The antennae usually have seven segments, but sometimes has eight. Creator: Annette K. Walker. © Landcare Research. [Image: 2ZJV]

Drawings of full sized and reduced wings of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Annette K. Walker. © Landcare Research. [Image: 2ZJX]

Drawing of a side view of the ovipositor of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Annette K. Walker. © Landcare Research. [Image: 2ZJW]

Photograph of a microscope slide of the tip of the abdomen showing the ovipositor of a female New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Landcare Research. [Image: 2ZJQ]

Photograph of a microscope slide of the tip of the abdomen with the genitalia of a male New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Landcare Research. [Image: 2ZJR]

Adult and larval New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae) on the inside of a flower bract of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the feeding damage to the bract. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJK]

Prepupa (left) and pupa (right) of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae): note the different length of the wing buds and the way the antennae is curled back over the head of the pupa. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJP]

Inside of a flower bract of New Zealand flax, Phormium tenax (Hemerocallidaceae) with feeding damage caused by adult and larval New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJH]

Old leaves of Black matipo, Pittosporum tenuifolium (Pittosporaceae) damaged when young by feeding of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJ8]

Recognition

While the typical adult New Zealand flower thrips is dark brown to black with a white base to its wings, the species can vary considerably. Identification of this thrips requires special procedures and taxonomic knowledge.

The thrips is easily recognised under the flower bracts and amongst the buds of New Zealand flax, Phormium species. It is often present in other flowers, even in alpine areas. The damage to young leaves such as those of Black matipo, Pittosporum tenuifolium is less commonly observed.

Adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: DSIR Photographers. © Landcare Research. [Image: 2ZJS]

Adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae) on the inside of a flower bract of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the feeding damage to the bract. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJF]

Young leaves of Black matipo, Pittosporum tenuifolium (Pittosporaceae) damaged by feeding of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJD]

Natural enemies

Several natural enemies of New Zealand flower thrips have been found.

Pathogens

In Auckland an unidentified bacterial pathogen has been found on adult and juvenile thrips living amongst unopened flowers of New Zealand flax, Phormium tenax. An unidentified species of insect pathogenic fungus has been found once on adult thrips. The swellings of the intersegmental membrane in the adult thrips and the dorsal swellings on the larval thrips are probably a result of the breakdown of the internal body tissue. The appearance of the adult New Zealand flower thrips is similar to that of adult onion thrips, Thrips tabaci, infested by a fungal pathogen.

Parasites

A nematode, Thripinema sp. has been found living in the gut of New Zealand flower thrips. It is not known how commonly this happens or if the nematode kills its host.

Predators

An Australian jumping spider on a flax plant was observed feeding on an adult New Zealand flower thrips. A predatory sucking bug from another country has been observed feeding on New Zealand flower thrips on outdoor plants and in a laboratory.

Adults of the predatory wasps, Spilomena species catch adult and larval thrips. The adult wasp approaches a thrips from behind, grasps it behind the head in its mandibles, then stings it on the ventral surface. It puts the thrips in cells made in old wood borer beetle tunnels. The numbers of thrips per cell varies between 28 and 72. An egg is laid in each cell and after hatching the wasp larva feeds on the thrips.

Mound and Walker in their 1982 major work on New Zealand Thrips in the group, Terrebrantia, report that the predatory thrips, Desmidothrips walkerae (Aeolothripidae) is believed to feed on New Zealand flower thrips.

Adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae) on a flower bud of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the swelling of the white intersegmental membrane associated with a bacterial infection. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJL]

Two images of larva of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae) on a flower bud of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the swelling of the top of the abdomen that is associated with a bacterial infection. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJM]

Larva of New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae) on a flower bud of New Zealand flax, Phormium tenax (Hemerocallidaceae): note the swelling of the top of the abdomen that is associated with a bacterial infection. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJN]

An adult Aussie Bronze Jumper, Helpis minitabunda (Araneae: Salticidae) that was seen feeding on an adult New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2ZJI]

Table: Natural enemies of New Zealand flower thrips, *Thrips obscuratus* (Thysanoptera: Thripidae), from Plant-SyNZ databas e (2 December 2018). The reliability index shows the quality of evidence for the host association (0-10, 10=high quality).
Scientific Name	Common Name	Classification	Enemy Type	Reliability Index	Biostatus
Thripinema sp.	(Eelworm)	Tylenchida: Allantonematidae	parasitoid	7	unknown
Bacterial pathogen sp. thrips		Bacteria	pathogen	5	unknown
Entomophthora sp.		Fungi: subphylum Entomophthoromycotina: Entomophthorales: Entomophthoraceae	pathogen	7	unknown
Helpis minitabunda (L. Koch, 1880)	Aussie Bronze Jumper (Spider)	Araneae: Salticidae	predator	10	adventive
Orius vicinus (Ribaut, 1923)	(Sucking bug)	Hemiptera: Anthocoridae	predator	10	adventive
Spilomena earlyi Harris, 1994	(Wasp)	Hymenoptera: Crabronidae	predator	10	endemic
Spilomena elegantula Turner, 1916	(Wasp)	Hymenoptera: Crabronidae	predator	10	native
Spilomena nozela Vardy, 1987	(Wasp)	Hymenoptera: Crabronidae	predator	10	native

Host plants

New Zealand flower thrips feeds and breeds on many native plants as well as naturalised and cultivated plants. It breeds in flowers of many of its host plants as well as on the developing seeds and fruit. On some plants it feeds and breed on young leaves while buds are expanding. They may also feed on young fruit of trees such as peaches, Prunus persica (Rosaceae).

Adult and larvae feed by inserting their stylets plant cells at or near the surface of a leaf or flower. They suck out the cell contents. Their feeding may have no obvious effect on some plants, while on most the dead plant cells discolour the affected parts of the flower. Feeding on young expanding leaves may cause distortion of the leaf.

Table: Host plants of the New Zealand flower thrips, *Thrips obscuratus* (Thysanoptera: Thripidae) from Plant-SyNZ database (2 December 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
Yarrow, Milfoil, Nose bleed, Sanguinary, Thousand seal, Common yarrow	Achillea millefolium L.	Compositae	10	naturalised
Horse chestnut	Aesculus hippocastanum L.	Sapindaceae	10	naturalised
Indian horse chestnut	Aesculus indica Colebr. ex Wall.	Sapindaceae	10	naturalised
Marsh mallow, White mallow	Althaea officinalis L.	Malvaceae	10	naturalised
Aromatic aniseed, Common aniseed, Kopoti, Pinakitere	Anisotome aromatica Hook.f.	Umbelliferae	10	endemic
Goats beard	Aruncus dioicus (Walter) Fern.	Rosaceae	10	cultivated
Coastal astelia, Shore kowharawhara, Horahora, Kōwharawhara, Pūhara, Pūwhara, Pūwharawhara, Wharawhara	Astelia banksii A. Cunn.	Asteliaceae	10	endemic
Cabbage	Brassica oleracea L. var. capitata	Cruciferae	10	cultivated
Buddleia, Butterfly bush, Summer lilac	Buddleja davidii Franch.	Scrophulariaceae	10	naturalised
Maori onion, Bog lily	Bulbinella hookeri (Hook.) Cheeseman	Asphodelaceae	10	endemic
Leafy broom, Scented broom, Maukoro	Carmichaelia odorata Benth.	Leguminosae	10	endemic
Cigar tree, Eastern catalpa, Indian bean tree, Indian cigar	Catalpa bignonioides Walter	Bignoniaceae	10	naturalised
Common mountain daisy, Cotton daisy, Cotton plant, Mountain daisy, Matua-tikumu, Puakaito, Pūharetāiko, Pūheretāiko, Pūwharetāiko, Tikumu	Celmisia spectabilis Hook.f.	Compositae	10	endemic
Tagasaste, Tree lucerne	Chamaecytisus palmensis (H.Christ) F.A.Bisby & K.W.Nicholls	Leguminosae	10	naturalised
Mexican orange blossom	Choisya ternata Kunth	Rutaceae	10	cultivated
Cabbage tree, Giant dracena, Grass palm, Palm lily, Sago palm, Ti, Kāuka, Kiokio, Kōuka, Tī, Tī awe, Ti kōuka, Tī para, Tī pua, Tī rākau, Whanake	Cordyline australis (G.Forst.) Endl.	Asparagaceae	10	endemic
Dwarf cabbage tree, Short-stemmed cabbage tree, Ti rauriki, Kōpuapua, Korokio, Mauku, Tī awe, Tī kapu, Tī koraha, Tī kupenga, Tī papa, Tī rauriki	Cordyline pumilio Hook.f.	Asparagaceae	10	endemic
	Corokia ×virgata Turrill	Argophyllaceae	10	endemic
	Crataegus ×lavallei	Rosaceae	10	cultivated
Quince	Cydonia oblonga Mill.	Rosaceae	10	cultivated
Broom, English broom, Scotch broom, Wild broom	Cytisus scoprarius (L.) Link	Leguminosae	10	naturalised
Dahlia	Dahlia sp.	Compositae	7	unknown
Bridal wreath, Wedding bells	Deutzia sp.	Hydrangeaceae	7	unknown
Hauama, Houama, Whau, Whauama, Whauma	Entelea arborescens R.Br.	Malvaceae	8	endemic
Fuchsia	Fuchsia ×hybrida Vilm.	Onagraceae	10	cultivated
	Gaultheria rupestris (L.f.) D.Don	Ericaceae	10	endemic
Mountain lacebark, Narrow-leaved houhere, Houhi, Houhi-puruhi, Puruhi	Hoheria angustifolia Raoul	Malvaceae	10	endemic
Graceful lacebark, Lacebark, Houhere, Houhiongaonga	Hoheria sexstylosa Colenso	Malvaceae	10	endemic
White tea tree, Kānuka, Kōpuka, Manuea, Mānuka, Mānuka-rauriki, Mārū, Rauiri, Rauwiri	Kunzea ericoides s.l. (A.Rich.) Joy Thomps.	Myrtaceae	10	indigenous, non-endemic
Red tea tree, Tea tree, Kahikātoa, Kātoa, Mānuka, Pata, Rauiri, Rauwiri	Leptospermum scoparium J.R.Forst. & G.Forst.	Myrtaceae	10	indigenous, non-endemic
Privet	Ligustrum sp.	Oleaceae	7	naturalised
Japanese honeysuckle	Lonicera japonica Thunb.	Caprifoliaceae	5	naturalised
Russell lupin	Lupinus polyphyllus Lindl.	Leguminosae	10	naturalised
Crab apple, European apple, Wild crab	Malus sylvestris (L.) Miller	Rosaceae	10	cultivated
Alfalfa, Lucerne	Medicago sativa L.	Leguminosae	10	naturalised
Large-leaved muehlenbeckia, Pōhuehue, Puka	Muehlenbeckia australis (G.Forst.) Meisn.	Polygonaceae	10	indigenous, non-endemic
Ngaio	Myoporum laetum G.Forst.	Scrophulariaceae	10	endemic
Black passionfruit, Purple granadilla, Purple passionfruit	Passiflora edulis Sims	Passifloraceae	10	naturalised
Coastal flax, Mountain flax, Kōrari-tuauru, Wharariki	Phormium cookianum Le Jolis	Hemerocallidaceae	10	endemic
Flax, Lowland flax, New Zealand flax, Swamp flax, Harakeke, Harareke, Kōrari	Phormium tenax J.R.Forst. & G.Forst.	Hemerocallidaceae	10	endemic
Black matipo, Kaikaro, Kōhūhū, Kohukohu, Koihu, Kōwhiwhi, Māpauriki, Pōhiri, Pōwhiri, Rautāwhiri, Tāwhiri	Pittosporum tenuifolium Sol. ex Gaertn.	Pittosporaceae	10	endemic
Apricot	Prunus armeniaca L.	Rosaceae	10	naturalised
Nectarine	Prunus persica (L.) Batsch. var. nucipersica (Suckow) C.K. Scheider	Rosaceae	10	naturalised
Nectarine, Peach	Prunus persica (L.) Batsch.	Rosaceae	10	naturalised
Tokyo cherry, Yoshino cherry	Prunus yedoensis Matsum.	Rosaceae	10	cultivated
	Pterostyrax hispidus Siebold & Zucc.	Styracaceae	10	cultivated
European pear, Pear	Pyrus communis L.	Rosaceae	10	naturalised
False acacia, Bastard acacia	Robinia pseudoacacia L.	Leguminosae	10	naturalised
Rose	Rosa sp. 'cultivated'	Rosaceae	7	cultivated
Rosemary	Rosmarinus officinalis L.	Labiatae	10	naturalised
Blackberry	Rubus fruticosus L.	Rosaceae	10	naturalised
Black elder, Elder, Elderberry	Sambucus nigra L.	Adoxaceae	10	naturalised
White mustard	Sinapis alba L.	Cruciferae	10	naturalised
Apple of Peru, Peruvian apple, Tomato	Solanum lycopersicum L.	Solanaceae	10	naturalised
Large-leaved kowhai, North Island kowhai, Kōwhai	Sophora tetraptera J.S. Miller	Leguminosae	10	endemic
Red clover	Trifolium pratense L.	Leguminosae	10	naturalised
White clover	Trifolium repens L.	Leguminosae	10	naturalised
Gorse	Ulex europaeus L.	Leguminosae	10	naturalised
Purple hebe, Napuka, Tītīrangi	Veronica speciosa R.Cunn. ex A.Cunn.	Plantaginaceae	10	endemic
Hebe	Veronica vernicosa Hook.f.	Plantaginaceae	10	endemic
Laurustinus	Viburnum tinus L.	Adoxaceae	10	naturalised
Broad bean, Field bean, Horse bean, Tick bean	Vicia faba L.	Leguminosae	10	naturalised
Grape	Vitis vinifera L.	Vitaceae	6	naturalised

Control

Commercial growers who need to control New Zealand flower thrips should consult their professional organisation for up-to-date advice.

Information sources

Mound LA, Nielsen M, Hastings A. 2017. Thysanoptera Aotearoa - Thrips of New Zealand. Lucidcentral.org, Identic Pty Ltd, Queensland, Australia.

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.

INTERESTING INSECTS

and other invertebrates