Pulvinaria regalis

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Pulvinaria regalis
Pulvinaria regalis in Llanelli.jpeg
P. regalis in Llanelli, Wales
Scientific classification
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P. regalis
Binomial name
Pulvinaria regalis
Canard, 1968

Pulvinaria regalis is a species of scale insect in the family Coccidae. Although it is commonly known as the horse chestnut scale, it affects other trees besides horse chestnuts as well as many species of woody shrubs. Adults are normally all female and produce eggs by parthenogenesis. The insects are thought to have originated in Asia but arrived in Europe in the second half of the twentieth century.

Contents

Host species

Pulvinaria regalis is known to be hosted by 65 species of plant from 25 families. [1] The main species of tree which act as hosts for this scale insect are horse chestnut, sycamore, maple, lime, elm, magnolia, bay and dogwood. [2]

Distribution and habitat

Pulvinaria regalis is thought to be native to Asia. [1] It was first detected in Europe in the 1960s when it became established in London, [2] it arrived in Paris by 1968 and had spread to Germany by 1989, where it has since been detected in many cities. [1] The female insects have no wings and are therefore unable to fly, and their means of transportation is thought to be either with tree prunings, or on nursery stock. The nymphs at their crawler stage may be transported by wind and it is possible that they, or the eggs, are sometimes carried on the legs of birds. [1]

Scale insects can occur in both rural and urban environments, but town trees are usually less healthy and pest burdens tend to be higher in towns. This is thought to be due to various habitat differences in urban settings; higher temperatures, more air pollution, lower availability of nutrients, and more stress caused by lack of moisture (more run-off and less water penetrating the ground). [3] P. regalis is primarily a pest of urban trees; its sap-sucking activities reduce its hosts' vigour, and the excess honeydew produced by the insects encourages the growth of sooty mould, which is unsightly. [1]

Biology

P. regalis infecting horse chestnut in Denmark Pulvinaria regalis (7439920846).jpg
P. regalis infecting horse chestnut in Denmark

The adult scale insect resembles a limpet and remains stationary on the bark of its host tree where it feeds on sap. Although males can occur, the insects are normally all female, and reproduce by parthenogenesis. [4] In early summer, the mature female lays white, circular egg masses which become visible as they protrude slightly from under her brown scale. The eggs hatch into nymphs which crawl away from the mother along the branches to find foliage, where they start to suck sap. In the autumn, they return to the trunk and larger branches where they spend the winter as flat scales about 1 mm (0.04 in) long. They resume feeding in spring and are fully grown by early summer. There is a single generation each year and the adults die after reproducing. [2] This insect has glands that produce several forms of wax; some glands produce water-repellent wax that keeps the air passages leading to the spiracles open. Other glands produce long white filaments of wax that serve a function in the construction of the sac that surrounds the eggs. To avoid getting contaminated by its own honeydew, the scale insect has a six-bristled mechanism close to the anus, with which it can flick away its excrement. [5]

Related Research Articles

Hemiptera Order of insects often called bugs

The Hemiptera or true bugs are an order of insects comprising some 50,000 to 80,000 species of groups such as the cicadas, aphids, planthoppers, leafhoppers, bed bugs and shield bugs. They range in size from 1 mm (0.04 in) to around 15 cm (6 in), and share a common arrangement of sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera. Many insects commonly known as "bugs", especially in American English, belong to other orders; for example, the lovebug is a fly and the May bug and ladybug are beetles.

Scale insect Superfamily of insects

Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the superfamily Coccoidea. Adult females typically have soft bodies and no limbs, and are concealed underneath domed scales, extruding quantities of wax for protection. Some species are hermaphroditic, with a combined ovotestis instead of separate ovaries and testes. Males, in the species where they occur, have legs and sometimes wings, and resemble small flies. Scale insects are herbivores, piercing plant tissues with their mouthparts and remaining in one place, feeding on sap. The excess fluid they imbibe is secreted as honeydew on which sooty mold tends to grow. The insects often have a mutualistic relationship with ants, which feed on the honeydew and protect them from predators. There are about 8,000 described species.

<i>Icerya purchasi</i> Species of true bug

Icerya purchasi is a scale insect that feeds on more than 65 families of woody plants, most notably on Citrus and Pittosporum. Originally described in 1878 from specimens collected in New Zealand as pests of kangaroo acacia and named by W.M. Maskell "after the Rev. Dr. Purchas who, [he] believe[d], first found it". It is now found worldwide where citrus crops are grown. The cottony cushion scale originates from Australia.

<i>Psylla pyri</i> Species of true bug

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Cinara cupressi, the cypress aphid, is a brownish soft-bodied aphid. It sucks sap from twigs of conifers, and can cause damage to the tree, ranging from discoloring of the affected twig to the death of the tree. This insect appears to have originated in the Middle East and has been increasing its range and is considered to be an invasive species in Africa and Europe. It has been included in the List of the world's 100 worst invasive species.

<i>Aphis gossypii</i> Species of insect

Aphis gossypii is a tiny insect, an aphid ("greenfly") in the superfamily Aphidoidea in the order Hemiptera. It is a true bug and sucks sap from plants. It is a widely distributed pest of a variety of agricultural crops in the families Cucurbitaceae, Rutaceae and Malvaceae. Common names include cotton aphid, melon aphid and melon and cotton aphid.

Black bean aphid Species of true bug

The black bean aphid is a small black insect in the genus Aphis, with a broad, soft body, a member of the order Hemiptera. Other common names include blackfly, bean aphid, and beet leaf aphid. In the warmer months of the year, it is found in large numbers on the undersides of leaves and on the growing tips of host plants, including various agricultural crops and many wild and ornamental plants. Both winged and wingless forms exist, and at this time of year, they are all females. They suck sap from stems and leaves and cause distortion of the shoots, stunted plants, reduced yield, and spoiled crops. This aphid also acts as a vector for viruses that cause plant disease, and the honeydew it secretes may encourage the growth of sooty mould. It breeds profusely by live birth, but its numbers are kept in check, especially in the later part of the summer, by various predatory and parasitic insects. Ants feed on the honeydew it produces, and take active steps to remove the aphid's enemies. It is a widely distributed pest of agricultural crops and can be controlled by chemical or biological means. In the autumn, winged forms move to different host plants, where both males and females are produced. These mate and the females lay eggs which overwinter.

<i>Coccus viridis</i> Species of true bug

Coccus viridis is a soft scale insect in the family Coccidae with a wide host range. It is commonly known as green scale or sometimes coffee green scale because it is a major pest of coffee crops throughout the world.

Cryptococcus fagisuga, commonly known as the beech scale or woolly beech scale, is a felted scale insect in the superfamily Coccoidea that infests beech trees of the genus Fagus. It is associated with the transmission of beech bark disease because the puncture holes it makes in the bark allow entry of pathogenic fungi which have been identified as Nectria coccinea var. faginata and sometimes Nectria galligena.

Euceraphis betulae, the birch aphid or silver birch aphid, is a species of aphid in the order Hemiptera. It is a tiny green insect with a soft body and wings. It is found living on the European silver birch tree where it feeds and multiplies on the buds and leaves by sucking sap.

<i>Euceraphis punctipennis</i> Species of true bug

Euceraphis punctipennis, the downy birch aphid or European birch aphid, is a species of aphid in the order Hemiptera. These aphids are tiny green insects with soft bodies and membranous wings. They are found living on downy birch trees where they feed and multiply on the buds and leaves by sucking sap.

<i>Planococcus citri</i> Species of true bug

Planococcus citri, commonly known as the citrus mealybug, is a species of mealybugs native to Asia. It has been introduced to the rest of the world, including Europe, the Americas, and Oceania, as an agricultural pest. It is associated with citrus, but it attacks a wide range of crop plants, ornamental plants, and wild flora.

Aleurodicus dispersus, the spiralling whitefly, is a species of small, white sap-sucking insect, a true bug in the order Hemiptera. It originated in Central America and the Caribbean region and has spread to many of the world's tropical and subtropical regions, where it has become a major pest of agricultural crops.

<i>Coccus hesperidum</i> Species of true bug

Coccus hesperidum is a soft scale insect in the family Coccidae with a wide host range. It is commonly known as brown soft scale. It has a cosmopolitan distribution and feeds on many different host plants. It is an agricultural pest, particularly of citrus and commercial greenhouse crops.

<i>Eriosoma lanigerum</i> Species of true bug

Eriosoma lanigerum, the woolly apple aphid, woolly aphid or American blight, is an aphid in the superfamily Aphidoidea in the order Hemiptera. It is a true bug and sucks sap from plants.

Saissetia coffeae, known generally as hemispherical scale, is a species of soft scale insect in the family Coccidae. Other common names include the helmet scale and coffee brown scale.

Hemiberlesia lataniae, the latania or palm scale, is a species of armored scale insect in the family Diaspididae. It was first described by the French entomologist Victor Antoine Signoret in 1869 using Latania lontaroides, a species of palm tree endemic to Réunion as its host; since then, it has been found on avocado trees growing in South Africa, Australia, Israel, the United States, and on a range of other plants in many parts of the world.

<i>Saissetia oleae</i> Species of true bug

Saissetia oleae is a scale insect in the family Coccidae. It is considered one of the three main phytophagous parasites of the olive tree, together with the olive fruit fly and the olive moth. Although it is a common parasite which occurs most often in olive trees, it is a polyphagous species, also attacking citrus trees as well as various ornamental shrubs such as oleanders, pittosporums and euonymus.

<i>Protopulvinaria pyriformis</i> Species of insect (pyriform scale)

Protopulvinaria pyriformis, commonly known as the pyriform scale, is a species of soft scale insect in the family Coccidae. It is a pest of avocado and is found in many countries around the world where avocados grow.

<i>Ceroplastes ceriferus</i> Species of scale insect

Ceroplastes ceriferus, the Indian wax scale, is a species of scale insect in the family Coccidae. It is native to southern Asia and has spread to many other parts of the world.

References

  1. 1 2 3 4 5 Trierweiler, P.; Balder, H. "Spread of horse chestnut scale (Pulvinaria regalis) in Germany".
  2. 1 2 3 "Horse chestnut scale". Royal Horticultural Society. Retrieved 5 March 2016.
  3. Speight, M.R.; Hails, R.S.; Gilbert, M.; Foggo. A. (1998). "Horse Chestnut Scale (Pulvinaria regalis) (Homoptera: Coccidae) and Urban Host Tree Environment" (PDF). Ecology. 79 (5): 1503–1513. doi:10.2307/176772.
  4. "Horse chestnut scale – Pulvinaria regalis". Oak Leaf Gardening. Retrieved 5 March 2016.
  5. Foldi, Imre; Pearce, Michael J. (1985). "Fine structure of wax glands, wax morphology and function in the female scale insect, Pulvinaria regalis Canard. (Hemiptera : Coccidae)". International Journal of Insect Morphology and Embryology. 14 (5): 259–271. doi:10.1016/0020-7322(85)90041-8.