Psylla pyri

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Pear psylla
Psylla pyri.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Sternorrhyncha
Family: Psyllidae
Genus: Psylla
Species:
P. pyri
Binomial name
Psylla pyri
Synonyms
  • Cacopsylla pyri, Linnaeus [1]

Psylla pyri, commonly known as the pear psylla or pear psyllid, is an insect in the family Psyllidae. Originating in Europe and Asia, it has spread to North America. It is a pest of pear trees, sucking the sap, damaging the foliage, flowers and fruit and diminishing the crop. [2]

Contents

Description

The adult Psylla pyri is between 2 and 3 mm (0.08 and 0.12 in) long. The colour is variable, ranging between orange-red and black, the thorax having whitish longitudinal stripes on its upper surface. The wings are transparent, with dark veins and sometimes a smoky appearance near the base. Later instar nymphs are purplish-brown or reddish-brown, with white longitudinal stripes and black patches; the developing wing-pads each bear a single knobbed bristle. The younger nymphs are yellowish with red-purple eyes. [3]

Distribution

The species is found in Europe, including Scandinavia, and in Asia. [3] In Britain it used to be very rare, with only one record before 1969, but since then it has become much more common, especially in the southeast of the country. [4] It was introduced accidentally into North America, being observed in Connecticut in 1832 and arriving in Washington State by 1939, soon becoming a serious pest of pears in the Pacific Northwest. [5]

Life cycle

This psylla overwinters as an adult, concealing itself in a crack in the bark. In spring it leaves diapause, and the female starts laying eggs round the base of the swelling buds. Later in the summer, the eggs are laid beside the midribs of the leaves, on the petioles and on the flower buds. The nymphs moult five times, and both nymphs and adults insert their mouthparts deep into the phloem tissue to suck the sap, secreting the excess fluid as honeydew. [5]

Ecology

Research in an untreated orchard in Turkey found 32 predator and three parasitoid species of insect associated with this psylla. The predators included the predatory bugs Anthocoris nemoralis and Deraeocoris spp., the green lacewing Chrysoperla carnea and several ladybirds. The wasp Trechnites psyllae was the main parasitoid. [1] In a research study in the United States, a single developing nymph of the predatory bug Deraeocoris brevis took 25 days to mature during which time it consumed about 400 eggs and nymphs of the pear psylla. [6]

Another predator, the running crab spider Philodromus cespitum, preys on this species in European fruit orchards. [7]

Damage

Psylla pyri damages pear trees by sucking the plant sap; leaves are yellowed and distorted and flower buds and fruitlets are shed. The excess honeydew produced by the insects coats the leaves, covering up the stomata, and encourages the growth of sooty mould. The size of fruit is decreased and tree growth is diminished. [2] Honeydew can cause discolouration of fruit, leading to its being downgraded. Heavy infestations can result in "psylla shock", caused by toxins in the saliva and resulting in defoliation or fruit drop, which may also affect the following year's crop. [5]

The psyllia can also carry mycoplasma in their saliva which can cause disease of the conducting cells in the tree's phloem. Failure of nutrients to be translocated downwards can cause root starvation, with trees either declining slowly or suffering from sudden collapse. Trees grafted onto Pyrus pyrifolia or Pyrus ussuriensis rootstocks are more susceptible to this disease than those on Pyrus communis . [5]

Related Research Articles

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Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A typical life cycle involves flightless females giving live birth to female nymphs—who may also be already pregnant, an adaptation scientists call telescoping generations—without the involvement of males. Maturing rapidly, females breed profusely so that the number of these insects multiplies quickly. Winged females may develop later in the season, allowing the insects to colonize new plants. In temperate regions, a phase of sexual reproduction occurs in the autumn, with the insects often overwintering as eggs.

<span class="mw-page-title-main">Hemiptera</span> Order of insects often called true bugs

Hemiptera is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, 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 piercing-sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera.

<span class="mw-page-title-main">Whitefly</span> Family of insects

Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described.

<span class="mw-page-title-main">Aphididae</span> Family of true bugs

The Aphididae are a very large insect family in the aphid superfamily (Aphidoidea), of the order Hemiptera. These insects suck the sap from plant leaves. Several thousand species are placed in this family, many of which are considered plant/crop pests. They are the family of insects containing most plant virus vectors with the green peach aphid being one of the most prevalent and indiscriminate carriers.

<span class="mw-page-title-main">Eriosomatinae</span> Subfamily of aphids

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<span class="mw-page-title-main">Greenhouse whitefly</span> Species of true bug

Trialeurodes vaporariorum, commonly known as the glasshouse whitefly or greenhouse whitefly, is an insect that inhabits the world's temperate regions. Like various other whiteflies, it is a primary insect pest of many fruit, vegetable and ornamental crops. It is frequently found in glasshouses (greenhouses), polytunnels, and other protected horticultural environments. Adults are 1–2 mm in length, with yellowish bodies and four wax-coated wings held near parallel to the leaf surface.

<i>Aonidiella aurantii</i> Species of true bug

Aonidiella aurantii or red scale is an armored scale insect and a major pest of citrus. It is thought to be a native of South China but has been widely dispersed by the agency of man through the movement of infected plant material. In the United States it is known as California red scale. It was first found in California between 1868 and 1875, apparently brought there on planting material imported from Australia.

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.

<span class="mw-page-title-main">Black bean aphid</span> 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.

<i>Trioza erytreae</i> Species of true bug

The African citrus psyllid is a sap-sucking insect, a hemipteran bug in the family Triozidae. It is an important pest of citrus, being one of only two known vectors of the serious citrus disease, huanglongbing or citrus greening disease. It is widely distributed in Africa. The other vector is the Asian citrus psyllid, Diaphorina citri.

<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>Aphis pomi</i> Species of true bug

Aphis pomi, commonly known as the apple aphid, or the green apple aphid, is a true bug in the family Aphididae. It is found on young growth of apple trees and on other members of the rose family where it feeds by sucking sap. Reproduction is mainly by parthenogenesis, in which unmated females give birth to live young.

<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.

<i>Anthocoris nemoralis</i> Species of true bug

Anthocoris nemoralis is a true bug in the family Anthocoridae. The species is native to Europe and is introduced in North America. It is a predator of aphids, spider mites and jumping plant lice, and is therefore used as a biological pest control agent.

Deraeocoris brevis is a species of predatory plant bug in the family Miridae. It is native to North America where it feeds on plant pests in apple and pear orchards.

Cacopsylla pyricola, commonly known as the pear sucker, is a true bug in the family Psyllidae and is a pest of pear trees (Pyrus). It originated in Europe, was introduced to the United States in the early nineteenth century and spread across the country in the next century.

Rhynocoris marginatus is a species of assassin bug in the family Reduviidae. It is a predator of other insects and is found in Asia. Crops in India on which it has been found feeding on pests include sugarcane, pigeon pea, cardamom, cotton, tea, and peanuts. The insects are potentially useful in biological control because they are more resistant to pesticides than are the pests on which they feed.

Pyrilla perpusilla, commonly known as the sugarcane planthopper, is a planthopper in the family Lophopidae. It is native to Asia where it feeds on grasses and other plants and is a major pest of sugarcane and sorghum.

<i>Toumeyella parvicornis</i> Species of true bug

Toumeyella parvicornis is a soft scale insect in the family Coccidae with a wide host range. It is commonly known as pine tortoise scale because of the characteristic appearance of the mature females, which look like tiny tortoises up to 1/4 inch in diameter.

References

  1. 1 2 Erler, F. (2004). "Natural enemies of the pear psylla Cacopsylla pyri in treated vs untreated pear orchards in Antalya, Turkey". Phytoparasitica. 32 (3): 295–304. doi:10.1007/BF02979824. S2CID   35159190.
  2. 1 2 Berim, M.N. "Psylla pyri Linnaeus - Pear Psylla". AgroAtlas. Retrieved 19 April 2018.
  3. 1 2 Alford, D.V. (2007). Pests of Fruit Crops: A Color Handbook. Elsevier. p. 60. ISBN   978-0-12-373676-5.
  4. "Psylla pyri". British Bugs. Retrieved 20 April 2018.
  5. 1 2 3 4 "Pear psylla". Orchard Pest Management Online. Washington State University. Retrieved 20 April 2018.
  6. "Deraeocoris". Orchard Pest Management Online. Washington State University. Retrieved 20 April 2018.
  7. Michalko, Radek; Dvoryankina, Viktoriya (1 June 2019). "Intraspecific phenotypic variation in functional traits of a generalist predator in an agricultural landscape". Agriculture, Ecosystems & Environment. 278: 35–42. doi:10.1016/j.agee.2019.03.018.