INTERESTING INSECTS

By N A Martin (2018)

Golden mealybug, Araucaria mealybug

Dactylopius aurilanatus Maskell, 1890

Pseudococcus aurilanatus (Maskell, 1890)

Erium aurilanatum (Maskell, 1890)

This distinctive adventive mealybug comes from Australia. It has also been found in California, USA. It lives on trees in two genera of the family Araucariaceae, Agathis and Araucaria, but it has not been found on New Zealand Kauri, Agathis australis.

Conservation status: This Adventive mealybug is found trees cultivated and naturalised trees in the genera Agathis and Araucaria.

Diagramme of the life cycle of a typical mealybug (Hemiptera: Pseudococcidae). Creator: JM Cox. © Drawing published in Fauna of New Zealand 11:1-228, Fig. 1. [Image: 2F19]

Golden mealybugs have a typical mealybug life cycle. After mating the adult female lays eggs into a wax covered sac that extends from under her abdomen out the back of her body. The eggs hatch into tiny nymphs that after feeding moult into other feeding nymphal stages. The adult female emerges from the third instar nymph. The male has two nymphal stages that are followed by two non-feeding stages in white wax cocoons. The winged adult male emerges and looks for and mates with a female. There may be more than one generation per year.

The adult female is deep purple, with tufts of golden wax down midline and around margins of upper side of the body. The body is broadly oval to spherical and about 2-4 mm long. On the underside it has a pair of antennae and three pairs of legs. Also on the underside of the head is a rostrum that holds the stylets used for feeding. After mating the female lays eggs under the rear of her abdomen. The eggs are a dark purplish grey and accumulate under a layer of white flocculent wax that varies greatly in its thickness. The wax may have a base of golden wax.

First instar (stage) nymphs hatch from the eggs and crawl out of the egg sac. Like the adult, the nymph has antennae, legs and a rostrum. The first instar nymph is dark purple and has tufts of white wax on its body and a short wax tube at the end of the abdomen for excretion. When the first instar is fully grown it moults to the second instar. During moulting the nymphs skin splits in the front and it pulls its body out. The second instar nymph is similar in shape, but has tufts of golden wax like the adult female. The third and final female nymphal stage is like the second, but larger.

The male only has two nymphal instars. It is followed by two non-feeding stages, the prepupa and pupa. When the second instar male is fully grown, it moults into a prepupa which produces a flocculent white wax cocoon. Several males may make cocoons close to each other. The pupa has long wing buds and does not have walking legs. The adult male emerges from the pupa and its wings (1 pair) expand and harden. It also grows a pair of wax tails. It is presumed that the wax tails help balance the insect in flight. The adult male does not have a rostrum or stylets and does not feed. The male may mate with females of the same colony or fly to another colony to mate.

Feeding and honeydew.

Mealybug adult females and nymphs have sucking mouthparts. Specially shaped rods called stylets are held in the short sheath-like rostrum. When it wishes to feed, the mealybug moves the tip of the rostrum onto the surface of the plant leaf or stem. The stylets are then gradually pushed into the plant and manoeuvred into the phloem (nutrient transport vessels) of the plant. The mealybugs suck the plant’s sap, which is high in sugars and low in other nutrients. Mealybugs excrete the excess sugary liquid, which is called honeydew, through a short white wax anal tube.

Walking, flying and dispersal.

The adult male has legs and one pair of wings. It can walk around the stems where its cocoon was and it can fly to other stems or to different trees. Adult females and nymphs also have legs and can walk. They may move about the group of stems where they were born. In other insects with a none flying adult female, the first stage larvae or nymphs are able to disperse to new trees. They usually do this using the wind. It is likely that some first instar nymphs climb to a prominent place on a leaf or branch and await a gust of wind.

Female Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDU]

Female Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note the large egg sacs. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDV]

A female Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note the large egg sac. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDI]

Exposed eggs of a female Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDJ]

Opened egg sac of a female of Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Norfolk Island pine, Araucaria heterophylla (Araucariaceae): note the many first instar (stage) nymphs that are about to leave. Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDC]

First instar (stage) nymphs on an egg sac of Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDG]

First instar (stage) nymphs at the base of the egg sac of a female Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note all the eggs in the egg sac. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDK]

First instar (stage) nymphs of Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDN]

First instar (stage) nymphs of Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note that one is moulting to a second instar (top left) and one is a recently hatched ‘crawler’ (bottom left). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDM]

Moulted nymphal skins and second and third instar nymphs of Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on an Araucariaceae species: note the white first instar moulted skins and yellow second instar skins. Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDF]

Moulted nymphal skins and third instar nymph and adult female Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note the white first instar moulted skins and yellow second and third instar skins. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDQ]

Moulted nymphal skins and adult female Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note the dark moulting adult females Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDR]

White wax cocoons of male Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDP]

An opened cocoon of Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) with a winged male, dark pupae in wax and dark prepupae. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDX]

Two winged adult males and dark prepupae pupae of Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) in an opened cocoon of white wax. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDW]

Two images of adult male Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae): note the wings and wax tails. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDY]

The Golden mealybug is the only species of mealybug in New Zealand found on cultivated and naturalised species of Agathis and Araucaria (Araucariaceae). No species of mealybugs have been found on New Zealand Kauri, Agathis australis.

Female Golden mealybugs are deep purple, with tufts of golden wax down midline and around margins of dorsum, body broadly oval to spherical. Female egg sacs are sometimes covered with white wax and males make cocoons of white wax.

Felted pine scale, Eriococcus araucariae (Eriococcidae) is found on Araucaria species and produces sacs of white, brittle wax that may be confused with Golden scale.

Female Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDU]

Female Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae): note the large egg sacs. Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDV]

Nymphs of Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Norfolk Island pine, Araucaria heterophylla (Araucariaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QD9]

Nymph of Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Norfolk Island pine, Araucaria heterophylla (Araucariaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QE0]

Nymphs and egg sac of a female of Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Norfolk Island pine, Araucaria heterophylla (Araucariaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QD4]

Stem of Norfolk Island pine, Araucaria heterophylla (Araucariaceae) with nymphs of Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) and white brittle wax sac of Felted pine scale, Eriococcus araucariae (Eriococcidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QD5]

Stem of Norfolk Island pine, Araucaria heterophylla (Araucariaceae) with an opened white brittle wax sac exposing a Felted pine scale, Eriococcus araucariae (Eriococcidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QD6]

No pathogens of the Golden mealybug, Nipaecoccus aurilanatus, are known.

Parasitoids

Adults of five species of wasps (Hymenoptera) have been reared from Golden mealybug in New Zealand.

Predators

Three predators of have been recorded feeding on Golden mealybug. Two are ladybirds and the other a lacewing. The commonest species in Auckland is the Mealybug ladybird, Cryptolaemus montrouzieri.

White fungus associated with Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Norfolk Island pine, Araucaria heterophylla (Araucariaceae). The fungus may be on dead females and empty egg sacs. Creator: Tim Holmes. © Plant & Food Research. [Image: 2QD8]

Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Araucariaceae species: note the parasitoid exit holes in the nymphal skin and the parasitised nymph (bottom centre). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDE]

Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Araucaria species (Araucariaceae): note the parasitoid exit hole in the nymphal skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDH]

Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Araucaria species (Araucariaceae): note the parasitoid exit hole in the nymphal skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDA]

Larva of mealybug ladybird, Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), on Queensland kauri, Agathis robusta (Araucariaceae) and feeding on first instar Golden mealybug, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2LSE]

Larvae of mealybug ladybird, Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), on Araucaria hunsteinii (Araucariaceae) and feeding on Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2LSF]

Larvae of mealybug ladybird, Cryptolaemus montrouzieri (Coleoptera: Coccinellidae), on Queensland kauri, Agathis robusta (Araucariaceae) and feeding on Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2LSG]

Adult gumtree scale ladybird, Rhyzobius ventralis (Coleoptera: Coccinellidae) with eaten gum tree scale Eriococcus coriaceus (Hemiptera: Eriococcidae) on Eucalyptus leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 2D5T]

Larvae of gumtree scale ladybird, Rhyzobius ventralis (Coleoptera: Coccinellidae) feeding on gum tree scale, Eriococcus coriaceus (Hemiptera: Eriococcidae) on a Eucalyptus leaf. Creator: Minna Personen. © Plant & Food Research. [Image: 2D5N]

The Golden mealybug is only found a cultivated and naturalised trees in the family Araucariaceae. Even though it breeds on Australian species of Agathis, it does not live on New Zealand Kauri, Agathis australis.

Feeding and honeydew.

Mealybug adult females and nymphs have sucking mouthparts. Specially shaped rods called stylets are held in the short sheath-like rostrum. When it wishes to feed, the mealybug moves the tip of the rostrum onto the surface of the plant leaf or stem. The stylets are then gradually pushed into the plant and manoeuvred into the phloem (nutrient transport vessels) of the plant. The mealybugs suck the plant’s sap, which is high in sugars and low in other nutrients. Mealybugs excrete the excess sugary liquid, which is called honeydew, through a short white wax anal tube.

Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Norfolk Island pine, Araucaria heterophylla (Araucariaceae). Creator: Tim Holmes. © Plant & Food Research. [Image: 2QD7]

Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Araucariaceae species. Creator: Tim Holmes. © Plant & Food Research. [Image: 2QDB]

Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Araucaria hunsteinii (Araucariaceae) and being fed on by larvae of mealybug ladybird, Cryptolaemus montrouzieri (Coleoptera: Coccinellidae). Creator: Nicholas A. Martin. © Nicholas A. Martin. [Image: 2QDZ]

Female Golden mealybugs, Nipaecoccus aurilanatus (Hemiptera: Pseudococcidae) on Queensland kauri, Agathis robusta (Araucariaceae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 2QDS]

Cox JM. 1987. Pseudococcidae (Insecta: Hemiptera). Fauna of New Zealand. 11: 1-230.

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

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