INTERESTING INSECTS

By N A Martin (2019)

New Zealand spinach planthopper, NZ spinach planthopper

This species of planthopper (Delphacidae) has not been identified. All known adults are brachypterous (short winged) and were breeding on New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae).

This endemic planthopper has been found around Auckland on its coastal host plant, New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae). It may also occur on New Zealand spinach, Tetragonia tetragonioides.

Conservation status: Probably widespread on its host plant.

The New Zealand spinach planthopper has been found breeding in spring and early summer. It may continue breeding over the whole summer.

So far the only adults found have been brachypterous, short-winged and are therefore not able to fly. Fully winged adults may also exist. They have two pairs of wings, three pairs of legs and one pair of antennae. The adults are mid brown with pale and dark markings. The legs are pale brown with irregularly shaped darker areas. The undersides of the abdominal segments are mainly dark with pale cuticle between the segments. The compound eyes are on the side of the head. A rostrum that holds the feeding stylets projects from the lower side of the head and when not being used is held between the legs. At the base of the rostrum is an almost black segment.

At the end of the female abdomen is the ovipositor for laying eggs. The eggs are probably inserted into a plant stem or leaf.

Young nymphs have not been observed. The large nymphs have a pale background colour with dark lateral areas of the upper side body that may meet on the thorax (middle part of the body). They have dark antennae and pale legs with dark mottling. Like the adults the nymphs have a rostrum with the stylets for feeding, three pairs of legs and a pair of antennae. Nymphs go from one stage to the next by moulting. During moulting, the skin on the dorsal side splits and the next stage pulls itself out of the old skin. Older nymphs have wing buds.

Walking and flying

The nymphs and adults have three pairs of legs and when disturbed they can jump (hop). The adults have two pairs of wings held over their body. The short-winged, brachypterous, adults cannot fly.

Feeding

Like other Hemiptera, the New Zealand spinach planthopper has piercing and sucking mouth parts. The long stylets, special shaped rods, are held in the rostrum. When it wishes to feed, the planthopper moves the tip of the rostrum to a suitable part of the plant. 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 plants juices are sucked up into the insect. The New Zealand spinach planthopper feeds on the phloem, one of the two systems for distributing nutrients in plants. The planthoppers excrete excess liquid as honeydew.

Adult female New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the short wings. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FT]

Side view of an adult female New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the short wings. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FS]

Underside of an adult female New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae). Creator: Darren Snaith. © Plant & Food Research. [Image: 31FV]

Adult male New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the short wings. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FR]

Underside of an adult male New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae). Creator: Darren Snaith. © Plant & Food Research. [Image: 31FQ]

Nymph of a New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the wing buds. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FW]

Underside of a nymph of the New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae). Creator: Darren Snaith. © Plant & Food Research. [Image: 31FX]

Nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) on a leaf of New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae): note the wing buds. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G2]

Planthoppers require special procedures and taxonomic knowledge to identify specimens. However, the New Zealand spinach planthopper is the only species of planthopper found on New Zealand spinach. Only short-winged, brachypterous, adults are known, though fully winged adults are likely to exist. The adults are mid brown with pale and dark markings. The large nymphs have a pale background colour with dark lateral areas of the body and dark antennae.

Adult female New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the short wings. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FT]

Side view of an adult female New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the short wings. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FS]

Nymph of a New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae): note the wing buds. Creator: Darren Snaith. © Plant & Food Research. [Image: 31FW]

Nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) on a leaf of New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae): note the wing buds. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G2]

The only natural enemy reported is a parasitoid, but New Zealand spinach planthoppers are likely to be preyed upon by other insects, spiders and birds.

Parasitoids

A wasp, Gonatopus alpinus (Gourlay, 1954) (Hymenoptera: Dryinidae) is an ectoparasitoid of the NZ spinach planthopper. The wasp larva lives on the outside of the planthopper nymphs and possibly brachypterous (short-winged) adults. Its head is under the nymph’s wing buds and it sucks nutrients from the nymph. When the wasp larva is fully grown it leaves the dying planthopper nymph and spins a long thin cocoon in which it pupates. When the adult wasp has emerged from its pupa and its body had hardened, it chews an exit hole in the cocoon. The adult wasps may be wingless and have muscular legs.

Nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) with a larva of the Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) attached to its back. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31FY]

Side view of a nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) with a larva of the Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) attached to its back. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31FZ]

Side view of a nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) with a larva of the Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) attached to its back. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G0]

Left, the skin of a nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) and right, a newly spun cocoon of a Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) on a stem of New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G5]

A newly spun cocoon of a Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) on a stem of New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G6]

The skin of a nymph of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae) with the skin of a larva of the Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) attached to its back. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G7]

A cocoon of a Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) with an exit hole made by the adult wasp. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G8]

Side view of a winged adult male Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) whose larva was a parasite on a nymph of Kiwi spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31G9]

Winged adult male Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) whose larva was a parasite on a nymph of Kiwi spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31GA]

Underside side of a winged adult male Delphacid parasitoid wasp, Gonatopus alpinus, (Hymenoptera: Dryinidae) whose larva was a parasite on a nymph of Kiwi spinach planthopper, Delphacidae sp. (Tetragonia), (Hemiptera: Delphacidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 31GB]

The only known host plant is New Zealand climbing spinach, Tetragonia implexicoma (Aizoaceae). However, it may also occur on New Zealand spinach, Tetragonia tetragonioides.

Adults and juveniles feed by inserting their stylets into the phloem of the plant. They excrete excess liquid as honeydew.

A plant of New Zealand climbing spinach, Tetragonia implexicoma, (Aizoaceae), host plant of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia) (Hemiptera: Delphacidae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 31GC]

Plants of New Zealand climbing spinach, Tetragonia implexicoma, (Aizoaceae), host plant of New Zealand spinach planthopper, Delphacidae sp. (Tetragonia) (Hemiptera: Delphacidae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 31GD]

Research Project

Delphacidae are in desperate need of revision. There are 18 named species. Since the last review in 1965, a lot of specimens have been collected that probably contains many undescribed species. Also the host plants of most described species are unknown.

Fennah, R.G. 1965. Delphacidae from Australia and New Zealand. Homoptera: Fulgoroidea. Bulletin of the British Museum (Natural History), Entomology 17: 1-59.

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