Cacopsylla pyricola

Cacopsylla pyricola
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hemiptera
Suborder:	Sternorrhyncha
Superfamily:	Psylloidea
Family:	Psyllidae
Genus:	Cacopsylla
Species:	C. pyricola
Binomial name
	Cacopsylla pyricola; (Foerster, 1848)
Synonyms
	Psylla pyricola

Last updated March 17, 2019

Cacopsylla pyricola, commonly known as the pear sucker,^[1] 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.

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, 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 sometimes limited to the suborder Heteroptera. Many insects commonly known as "bugs" belong to other orders; for example, the lovebug is a fly, while the May bug and ladybug are beetles.

Description

The eggs are tiny, stalked, oval, and cream to yellow, darkening before they hatch. The first instar nymphs are yellowish or pinkish and flattened, but later instars are greenish to dark brown, with distinctive red eyes and developing wing buds. The edges of the buds bear three to five knobbed bristles. The nymphs are largely immobile and tend to be found on the underside of leaves. In summer the adults are a fairly pale colour but in winter they are reddish-brown to black, the transparent wings being dusky. These psylla rest with their wings folded roof-like over their abdomens.^[2]^[1]

An instar is a developmental stage of arthropods, such as insects, between each moult (ecdysis), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After moulting, i.e. shedding their exoskeleton, the juvenile arthropods continue in their life cycle until they either pupate or moult again. The instar period of growth is fixed; however, in some insects, like the salvinia stem-borer moth, the number of instars depends on early larval nutrition. Some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars.

Distribution

Cacopsylla pyricola is native to Europe but was introduced into the eastern United States with nursery stock in the early 1800s; it had spread to the fruit-growing regions of the Pacific Northwest by the early 1900s.^[3] Along with the codling moth (Cydia pomonella), it is considered one of the most important pest of pears in the United States.^[3] Host plants are restricted to pear and quince.^[2]

The Pacific Northwest (PNW), sometimes referred to as Cascadia, is a geographic region in western North America bounded by the Pacific Ocean to the west and (loosely) by the Cascade Mountain Range on the east. Though no official boundary exists, the most common conception includes the Canadian province of British Columbia (BC) and the U.S. states of Idaho, Oregon, and Washington. Broader conceptions reach north into Southeast Alaska and Yukon, south into northern California, and east of the Continental Divide to include Western Montana and parts of Wyoming. Narrower conceptions may be limited to the coastal areas west of the Cascade and Coast mountains. The variety of definitions can be attributed to partially overlapping commonalities of the region's history, culture, geography, society, and other factors.

The codling moth is a member of the Lepidopteran family Tortricidae. They are major pests to agricultural crops, mainly fruits such as apples and pears. Because the larvae are not able to feed on leaves, they are highly dependent on fruits as a food source and thus have a significant impact on crops. The caterpillars bore into fruit and stop it from growing, which leads to premature ripening. Various means of control, including chemical, biological, and preventative, have been implemented. This moth has a widespread distribution, being found on six continents. Adaptive behavior such as diapause and multiple generations per breeding season have allowed this moth to persist even during years of bad climatic conditions.

The quince is the sole member of the genus Cydonia in the family Rosaceae. It is a deciduous tree that bears a pome fruit, similar in appearance to a pear, and bright golden-yellow when mature. Throughout history the cooked fruit has been used as food, but the tree is also grown for its attractive pale pink blossoms and other ornamental qualities.

Life cycle

Adult C. pyricola overwinter on the bark or twigs of a pear tree, or on other trees and shrubs near pear orchards. In the spring, the female lays eggs on twigs and expanding shoots of host trees, attaching them by means of short stalks on their ventral surfaces. On hatching, the nymphs feed on the buds and flowers of the host tree, inserting their mouthparts and sucking out the sap. Later in the year, the eggs are laid beside the veins on the upper surface of leaves. The nymphs pass through five instars before becoming adult in a few weeks. There may be up to six generations each year and numbers of insects can build up fast. The nymphs produce copious honeydew which attracts ants, flies, bees and other insects.^[1]

In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis (hemimetabolism) before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult, except for a lack of wings. In addition, while a nymph moults it never enters a pupal stage. Instead, the final moult results in an adult insect. Nymphs undergo multiple stages of development called instars.

Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. When their mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the anus of the aphid. Honeydew is particularly common as a secretion in hemipteran insects and is often the basis for trophobiosis. Some caterpillars of Lycaenidae butterflies and some moths also produce honeydew. Honeydew can cause sooty mold—a bane of gardeners—on many ornamental plants. It also contaminates vehicles parked beneath trees, and can then be difficult to remove from glass and bodywork. Honeydew is also secreted by certain fungi, particularly ergot.

Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the Cretaceous period, about 140 million years ago, and diversified after the rise of flowering plants. More than 12,500 of an estimated total of 22,000 species have been classified. They are easily identified by their elbowed antennae and the distinctive node-like structure that forms their slender waists.

Related Research Articles

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<i>Maconellicoccus hirsutus</i> species of insect

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References

1 2 3 Alford, D.V. (2007). Pests of Fruit Crops: A Color Handbook. Elsevier. pp. 60–61. ISBN 978-0-12-373676-5.
1 2 Alston, Diane (2007). "Pear Psylla (Cacopsylla pyricola)". Utah Pests. Missing or empty |url= (help); |access-date= requires |url= (help)
1 2 Horton, David (2008). "Pear Psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae)". Encyclopedia of Entomology, in: Capinera J.L. (eds). doi:10.1007/978-1-4020-6359-6_2818.

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[Alford-1] 1 2 3 Alford, D.V. (2007). Pests of Fruit Crops: A Color Handbook. Elsevier. pp. 60–61. ISBN 978-0-12-373676-5.

[Alston-2] 1 2 Alston, Diane (2007). "Pear Psylla (Cacopsylla pyricola)". Utah Pests. Missing or empty |url= (help); |access-date= requires |url= (help)

[Horton-3] 1 2 Horton, David (2008). "Pear Psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae)". Encyclopedia of Entomology, in: Capinera J.L. (eds). doi:10.1007/978-1-4020-6359-6_2818.