INTERESTING INSECTS

By N A Martin (2016, revised 2017)

Citrus whitefly ladybird

Serangium bicolour Blackburn, 1895

This adventive ladybird comes from Australia and was first found in New Zealand by Stephen Thorpe in Auckland Domain in 2005. It is present in Northland and Auckland, and spreading south. It feeds on several kinds of insects including of Australian citrus whitefly, Orchamoplatus citri (Takahashi, 1940) (Hemiptera: Aleyrodidae).

Conservation status: This small shiny black ladybird is present in Northern New Zealand and still spreading. It feeds on native insects as well as adventive species. It may be useful for biological control of Australian citrus whitefly.

Annual cycle

There have not been any detailed observations of the annual cycle of this ladybird in New Zealand. Adults and larvae have been found with prey in late spring, and adults have been found with prey in summer. Like other ladybirds, the adults may overwinter and become active in the spring. There are likely to be several generations per year. In Auckland in late spring time from egg to adult is about 6-8 weeks.

Life stages

The adults are tiny, less than 3 millimetres long. The head, prothorax (first part of the middle body) and elytra (wing covers) are shiny black with a dull red spot on each elytra. The elytra, prothorax and head are covered with a few short hairs. The legs and antennae are pale brown, though the top segments of the middle and hind legs are dark brown. Under the elytra is a pair of wings used for flying. The small head has a pair of compound eyes and two short antennae. Female ladybirds lay eggs probably near infestations of prey. A long, pale grey larva hatches from each egg. They are covered with long fine hairs. The three pairs of legs are used for walking. They don’t appear to be used for holding prey. As the larva grows, it moults (changes skin). There are four larval instars (stages). When the fourth larval instar is fully grown, it attaches itself to a sheltered place on a plant and moults into a pupa. The white pupa remains partly inside the moulted larval skin and is itself covered with long fine hairs. Adults hatch from pupae and mate. The length of time of each life stage depends on temperature, being shorter at higher temperatures.

Walking and flying

Both adult and larval stages of this citrus whitefly ladybird have three pairs of legs that can be used for walking. Adults have wings and can fly. In warm weather, they fly readily if disturbed.

Feeding

The adult and larval ladybirds eat psyllids, whitefly and probably other insects and gall mites. The jaws are the primarily structures used for holding and chewing the prey. Legs do not appear to be used for holding food.

Adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 163X]

Underside of an adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 1649]

Adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 164A]

Adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), feeding on nymph of Ctenarytaina sp. (Hemiptera: Psyllidae ). Creator: Tim Holmes. © Plant & Food Research. [Image: 163Y]

Pale adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 164D]

Pale adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 164E]

Two eggs of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on a citrus whitefly, Orchamoplatus citri (Hemiptera: Aleyrodidae), infested leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 164J]

Two first instar (stage) larvae of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) in a citrus whitefly, Orchamoplatus citri (Hemiptera: Aleyrodidae), infested leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 164K]

Larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 1642]

Larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 1641]

Large larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), on leaf of Acmena, Syzygium smithii. Creator: Tim Holmes. © Plant & Food Research. [Image: 1646]

Large larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), on leaf of Acmena, Syzygium smithii. Creator: Tim Holmes. © Plant & Food Research. [Image: 1647]

Large larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), on citrus leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 164F]

Underside of larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Minna Personen. © Plant & Food Research. [Image: 164M]

Pupa of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on a citrus whitefly, Orchamoplatus citri (Hemiptera: Aleyrodidae), infested leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 164G]

Pupal skin of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on a citrus whitefly, Orchamoplatus citri (Hemiptera: Aleyrodidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 164H]

White pupa of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), in moulted larval skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 1644]

White pupa of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), in moulted larval skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 1645]

Adult citrus whitefly ladybirds are easily recognised; they very small, shining black and have two dull red spots on the elytra (wing covers). Larvae are tiny, pale grey and covered in dense, fine, long hairs. The pupae are also distinctive being white and covered in long fine hairs, and partly covered by the moulted larvae skin.

Adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 163Z]

Adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 163X]

Larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 1641]

Larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae). Creator: Minna Personen. © Plant & Food Research. [Image: 164L]

White pupa of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), in moulted larval skin. Creator: Tim Holmes. © Plant & Food Research. [Image: 1644]

No natural enemies of the citrus whitefly ladybird are known in New Zealand. They are probably preyed upon by birds, spiders and predatory insects.

Ladybirds in the genus Serangium are reported to be associated with whitefly (Hemiptera: Aleyrodidae). In New Zealand the citrus whitefly ladybird has been found feeding on native and adventive species of whitefly including Australian citrus whitefly, Orchamoplatus citri (Takahashi, 1940). It has a much wider range of prey including two species of psyllid and a native soft scale (Coccidae). It appears to feed on gall mites though this needs to be confirmed. Several adults were found on tree leaves with numerous free living gall mites, Lambella cerina (Lamb, 1953) (Acari: Eriophyoidea: Diptilomiopidae) on Carpodetus serratus (Grossulariaceae). At present this ladybird has only been found on trees, shrubs and a tree fern.

In New Zealand it has been found breeding in association with peppercorn scale, Epelidochiton piperis (Hemiptera: Coccidae). While in Australia this ladybird has been recorded feeding on soft wax scale, Ceroplastes destructor Newstead, 1917, and Chinese wax scale, Ceroplastes sinensis Del, Guercio, 1900 (Coccidae).

Adult citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), feeding on nymph of Ctenarytaina sp. (Hemiptera: Psyllidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 163Y]

Large larva of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae), on leaf of Acmena, Syzygium smithii. Creator: Tim Holmes. © Plant & Food Research. [Image: 1646]

Two eggs of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on a citrus whitefly, Orchamoplatus citri (Hemiptera: Aleyrodidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 166V]

Pupa of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on a citrus whitefly, Orchamoplatus citri (Hemiptera: Aleyrodidae), infested leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 164G]

Pupa and larval skin of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on a pittosporum whitefly, Asterochiton simplex (Hemiptera: Aleyrodidae), infested leaf. Creator: Tim Holmes. © Plant & Food Research. [Image: 164I]

Larvae of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) feeding on pittosporum whitefly, Asterochiton simplex (Hemiptera: Aleyrodidae). Creator: Tim Holmes. © Plant & Food Research. [Image: 29QM]

Larvae of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) feeding on first instar (stage) peppercorn scale, Epelidochiton piperis (Hemiptera: Coccidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 29QN]

Larvae of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on leaves with juvenile Karo felted scale, Eriococcus pallidus (Hemiptera: Eriococcidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 29QP]

Larvae of citrus whitefly ladybird, Serangium maculigerum (Coleoptera: Coccinellidae) on leaves with juvenile Karo felted scale, Eriococcus pallidus (Hemiptera: Eriococcidae). Creator: Nicholas A. Martin. © Plant & Food Research. [Image: 29QQ]

Biological control of pests

Biological control of whitefly and other herbivorous pests can reduce the impact of the pests and the need to use insecticides. The citrus whitefly ladybird may contribute to the control of Australian citrus whitefly in the home garden and commercial crops. If pesticides are needed to control other pests, it is advisable to use chemicals that will have minimal harmful effects on the ladybirds or to use them at a time when the ladybirds are not present.

Diverse habits of 'ladybirds'

Not all ladybirds eat insects; some feed on mites. Other species eat plant leaves and are pests especially in some tropical countries, whereas other ladybirds feed on fungi. One of these, Illeis galbula (Mulsant, 1850) from Australia, feeds on powdery mildew fungi. In New Zealand it is common on pumpkins and other cucurbits, plants that are commonly infected by powdery mildews. A plant feeding ladybird, hadda beetle (Epilachna vigintioctopunctata (Fabricius, 1775)) recently established in Auckland feeds on plants in the Solanaceae (potato family).

Slipinski A, Burckardt D 2006. Revision of the Australian Coccinellidae (Coccinellidae). Part 5. Tribe Serangiini. Annales Zoologici (Warszawa) 56(1): 37-58.

Slipinski A, Hastings A, Boyd B 2007. Ladybirds of Australia. Retrieved April 2011. ento.csiro.au/biology/ladybirds/ladybirds.htm

Waterhouse DF, Sands DPA 2001. Classical Biological Control of Arthropods in Australia. Canberra, CSIRO Entomology. 560 p.

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

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

1 August 2017. NA Martin. Prey table updated. Biostatus paragraph corrected.