INTERESTING INSECTS

By N A Martin (2016, revised 2017)

Australian solanum psyllid

This adventive psyllid comes from Australia where it was recently discovered. It was found breeding on some non-native Solanum plants. It has since been found on native plants and other plants in the family Solanaceae. It was found in New Zealand in 2012 and is only known from non-native Solanaceae in New Zealand.

Conservation status: Known in Auckland, living on Solanaceae crops and weeds.

The Australian solanum psyllid appears to breeds all year, though the time from egg to adult (generation time) is longer in the winter when it is cold, than in the summer or in a heated greenhouse.

Adult Australian solanum psyllid are small insects similar in size to aphids. The two pairs of transparent wings are held over their abdomen making the adults look like small cicadas. There are three pairs of legs and sucking mouthparts. When the adults first emerge, they are light yellow in colour. After 2-3 days they develop their full colour. Adult males have a black head and thorax, and pale abdomen with darker transverse bands on the abdomen. The tip of the abdomen is broad and upturned. Females have a slender tip to the abdomen. Female colouration is variable. They may have a black head and thorax like males or have a pale head and thorax. The paler females have brown markings on their thorax and abdomen that vary in intensity. Both males and females have long antennae. The distal two thirds are black and the basal third is white.

When seen from above, usually only the first two pairs of legs can be seen. The last pair is kept under the body ready to make the adult hop if it is disturbed.

The broad end to the male abdomen includes structures used for grasping the female during mating. During mating the male sits alongside the female, facing in the same direction, and the end of the abdomen curls under the female and tip of the female abdomen. The male sometimes rubs the end of its abdomen on plant leaves. The tip of the female abdomen is slender and houses a narrow blade-like ovipositor that assists with egg laying.

Australasian solanum psyllid eggs are brown and inserted in between the hairs on host plant leaves. Nymphs hatch from the eggs. They are flat and scale like, and have three pairs of legs and sucking mouth parts. They settle on young leaves amongst the hairs. Although they can walk, they spend much of their time motionless with their stylets inserted into the plant and feeding on the sap. There are five nymphal stages, 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. The nymphs are white and hairy. The large nymphs have small black spots on their body and later instars develop wing buds. Adults emerge from fifth instar nymphs.

Feeding and honeydew

Like other Hemiptera, the Australian solanum psyllid has sucking mouth parts. The long stylets, special 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 inner pair of 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 Australian solanum psyllid inserts its 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. It excretes the excess water and sugar, which is called honeydew. The Australasian solanum psyllid coats the droplet of honeydew with white wax before ejecting it. The white wax coated droplets are called psyllid sugars and can be seen on host plant leaves.

Adult male Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), are black and yellow. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0G]

Adult male Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the upturned end of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B11]

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0W]

Underside of an adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0Q]

Underside of an adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0H]

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0U]

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B15]

An egg (left) and small nymph of Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0L]

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0P]

A small and large nymph of Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0K]

Two nymphs of the Australian solanum Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae), note the wax encased honeydew. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0I]

Nymph of Australian solanum Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0J]

Large nymph of the Australian solanum Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae), note the wax encased honeydew. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0N]

A recently moulted adult Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae) and a nymphal skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0M]

In New Zealand two species of psyllids live on Solanum species, the Australian solanum psyllid and the tomato potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae). They are easily distinguished. Mature adult male Australian solanum psyllids have a black head and thorax and yellow abdomen. The female may have a black head and thorax, but also may have a pale head thorax and abdomen. The adult tomato potato psyllids have a dark abdomen as well as dark coloured head and thorax. The nymphs of the Australian solanum psyllid are hairy and very pale with a few dark spots, while the tomato potato psyllid nymphs are smoother and tan coloured. The tomato potato psyllid has distinctive yellow eggs on stalks.

Adult psyllids are similar in size to winged aphids also seen on tomato potato psyllid host plants. Psyllid wings cover the body when folded and look like small cicadas, whereas aphid wings are held above the body. TIP: psyllids often waggle their abdomen and will hop when touched.

Australian solanum psyllid nymphs can easily be distinguished from whitefly nymphs. Whitefly nymphs stay in the same place once the first stage larva (crawler) has settled on the leaf. The first three larval stages are oval and flat, while the fourth stage and the puparium and raised up. No juvenile stage has wing buds.

Adult male Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), are black and yellow. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0G]

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0P]

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae), note the pointed tip of the abdomen. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0Z]

Nymph of Australian solanum Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0J]

Adult tomato potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae), with moulted skin of nymph and yellow eggs on stalks. © Plant & Food Research. [Image: 2BBP]

Tomato potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae), nymph with wing buds and white 'psyllid sugars', the wax coated excess sap excreted by the insects. © Plant & Food Research. [Image: 2BBQ]

An aphid holding its wings above its body; melon aphid (Aphis gossypii Glover, 1877 (Hemiptera: Aphididae). Creator: DSIR photographers. © Plant & Food Research. [Image: 3HB]

Larvae of greenhouse whitefly, Trialeurodes vaporariorum (Westwood, 1856) (Hemiptera: Aleyrodidae). Young larvae are flat, while the fourth stage larvae swell up and form puparia. Creator: DSIR Photographers. © Plant & Food Research. [Image: 2B16]

No natural enemies of the Australian solanum psyllid are known in New Zealand. They are probably preyed upon by birds, spiders and predatory insects.

The Australian solanum psyllid breeds only on plants in the Solanaceae (potato family). In New Zealand it has been found breeding on a weed, Solanum mauritianum and two crops. In Australia it has also been found feeding on species of Brugmansia and Datura.

Plant feeding, honeydew and psyllids sugars

Like other Hemiptera, the Australian solanum psyllid has sucking mouth parts. The long stylets, special 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 inner pair of 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 Australian solanum psyllid inserts its 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. It excretes the excess water and sugar, which is called honeydew. The Australasian solanum psyllid coats the droplet of honeydew with white wax before ejecting it. The white wax coated droplets are called psyllid sugars and can be seen on host plant leaves.

Adult female Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae) on Solanum mauritianum leaf. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0R]

Adult male Australian solanum psyllid, Acizzia solanicola (Hemiptera: Psyllidae) on Solanum mauritianum leaf. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2B0S]

Two nymphs of the Australian solanum Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae), note the wax encased honeydew. Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0I]

Nymph of Australian solanum Acizzia solanicola (Hemiptera: Psyllidae), on underside of leaf of cape gooseberry, Physalis peruviana (Solanaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2B0J]

Commercial growers should consult their professional organisation for up-to-date advice on control of the psyllid. Populations on outdoor plants in Auckland are usually low and control is unlikely to be needed for home garden plants.

Kent, D.; Taylor, G. 2010: Two new species of Acizzia Crawford (Hemiptera: Psyllidae) from the Solanaceae with a potential new economic pest of eggplant, Solanum melongena. Australian journal of entomology, 49(1): 73-81.

Taylor, G.S.; Kent, D.S. 2013: Potential economic pests of solanaceous crops: a new species of Solanum-feeding psyllid from Australia and first record from New Zealand of Acizzia solanicola (Hemiptera: Psyllidae). Zootaxa, 3613(3): 257-273.

Pam Dale for psyllid identifications.

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

1 December 2018. NA Martin. Changed symbol used for apostrophes.

1 August 2017. NA Martin. Paragraph on Natural Enemies added. Host plant table updated.