Koebele's ladybird - Rodolia koebelei
By N A Martin (2016)
Biostatus and Distribution
This Australian ladybird is found in the North Island of New Zealand. It was first recognised in New Zealand by Peter Maddison in 2003 when he found it in Mangere, Auckland. The earliest known specimen was from a bait trap, used in Papakura in 1991. All known specimens have been found in Auckland. In New Zealand it is a predator of a species of cottony cushion scale, Icerya purchasi Maskell 1879 (Hemiptera: Monophlebidae).
Conservation status: The Koebele’s ladybird is present in low numbers in Auckland and may contributes to the biological control of cottony cushion scale, Icerya purchasi Maskell, a pest of citrus and native trees.
Life Stages and Annual Cycle
The adults are small, about 3-4 millimetres long. The head, prothorax (first part of the middle body) and elytra (wing covers) are covered in short setae (hairs). The head and prothorax are brown and the elytra are red and black. Sometimes the elytra are only red. The legs are black with brown tarsi (feet) and antennae are tan, while the underside of the body is red. 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 larva hatches from each egg. They are grey and have long hairs (setae) on lateral tubercles of the abdomen. The head is small. The three pairs of legs are used for walking. As the larva grows, it moults (changes skin). There are four larval instars (stages). The larvae may have an underlying red colour. The last instar is grey-brown with a dark head and two long dark stripes. The lateral tubercles are prominent and bear long hairs. All these features may be obscured by white wax. The legs are dark and the feet (tarsi) are covered in white hairs (setae).
When the fourth larval instar is fully grown, it attaches itself to a sheltered place on a plant and moults into a pupa. The pupa, which is mostly enclosed by the larval skin, is covered in short setae and coloured shades of brown. Adults hatch from pupae and mate. The adults may stay in the pupal skin for a short time while their skin hardens. The length of time of each life stage depends on temperature, being shorter at higher temperatures.
The ladybird probably overwinters as adults. There may be two or three generations per year in Auckland.
Walking and flying
Both adult and larval stages of this ladybird have three pairs of legs that can be used for walking. Adults have wings and can fly.
The adult and larval ladybirds eat cottony cushion scale. They will burrow into the egg sacks of mature females pulling the white wax away to get to the eggs underneath. The jaws are the primarily structures used for holding and chewing the prey. Legs do not appear to be used for holding food.
Adult Koebele’s ladybirds are usually red and black, but the elytra (wing covers) may be all red. The dorsal (top) side of the beetles are covered by short hairs which gives them a mat appearance. The other similar species is the cardinal ladybird, Rodolia cardinalis (Mulsant, 1850). It has larger areas of black on the elytra. Other red and black ladybirds have a glossy appearance.
The larvae of the cardinal ladybird and Koebele’s ladybird have prominent lateral abdominal tubercles with many very long hairs (setae) and the lateral margin also have similar long hairs. Also larvae of both species may have underlying red colour. Koebele’s ladybird larvae have a pair of dark abdominal strips and may also be covered in white wax. Whereas larvae of the cardinal ladybird are grey and/or red and no photographs on the internet show any white body wax. The pupae of the two species are red and black and within the larval skin. The larval skin of Koebele’s ladybird is usually is covered in white wax.
No natural enemies of the Koebele’s ladybird are known in New Zealand. They are probably preyed upon by birds, spiders and predatory insects. There is some evidence that the larvae will eat each other.
In New Zealand, the only known prey of the Koebele’s ladybird is the cottony cushion scale, Icerya purchasi Maskell, 1879 (Hemiptera: Monophlebidae).
There is one report that when Koebele’s ladybirds were fed on different species of Icerya, in captivity they only completed development to adults on Icerya koebelei. The species on which they could not complete development included Icerya purchasi. Different in populations of the ladybird may have different preferences for prey species.
Biological control of pests
Ladybirds contributes to the control of mites, aphids, psyllids, scale insects and other insects on trees, shrubs and herbs. Some species of ladybirds eat many kinds of insects, but the only known prey of the Koebele’s ladybird are species of cottony cushion scale, Icerya species (Hemiptera: Monophlebidae). While they can feed on several species of Icerya, they are only known to complete development on two species, Icerya purchasi (in New Zealand) and Icerya koebelei (unspecified country).
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).
Sands, D.P.A.; Van Driesche, R.G. 2004: Using the scientific literature to estimate the host range of a biological control agent. Pp. 15-23 in: Van Driesche, R.G., Murray, T. & Reardon, R. (eds.), Assessing host ranges of parasitoids and predators used for classical biological control: a guide to best practice. Morgantown, W. Va.: Forest Health Technology Enterprise Team, U.S. Dept. of Agriculture, Forest Service. http://www.invasive.org/hostrange/ch3.pdf.
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.