San Jose scale insect

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San Jose scale insect
San José scale insect, illustration in the Encyclopædia Britannica, 1911. A: male, B: female, C: larva, D: shield of the female, E: shield of the male

San José scale insect, illustration in the Encyclopædia Britannica, 1911. A: male, B: female, C: larva, D: shield of the female, E: shield of the male

Systematics
Class : Insects (Insecta)
Order : Schnabelkerfe (Hemiptera)
Superfamily : Scale insects (Coccoidea)
Family : Lid scale insects (Diaspididae)
Genre : Comstockaspis
Type : San Jose scale insect
Scientific name
Comstockaspis perniciosa
( Comstock , 1881)
Book from 1898

The San José scale insect ( Comstockaspis perniciosa ) is an insect from the family of the cap scale insects (Diaspidiae). This pest occurs on numerous fruit plants and can cause great damage and crop failures.

Origin and Distribution

The San José scale insect originates from East Asia , probably from North China , and was imported into the USA in 1873 on peach trees , where it spread in the orchards of San José ( California ). The entomologist John Henry Comstock recognized the scale insect there as a new species, described it in 1880 and thus gave its name. The spread was driven by trade, it is now one of the most dangerous pathogens to fruit trees. It can be found worldwide, with the exception of arctic areas. Originally a thermophilic insect, it is also increasingly conquering cooler and maritime climates . The scale insect lives on numerous deciduous trees, a total of over 150 host plants from numerous families are known, including apples , pears , cherries , plums , currants and citrus plants .

The species was first discovered in Switzerland in 1946. In Germany, where it has been known since 1898, the species has been more common since around 2000 and spreads further north. It was first found in Brandenburg (Frankfurt / Oder area) in 2000 and in Thuringia for the first time in 2005. Their occurrence is notifiable in Germany ( Section 1 (1) of the Ordinance on Combating the San Jose Scale Insect).

Features and life cycle

The San José scale insect normally produces three, under unfavorable climatic conditions (like in Central Europe) only one or two generations per year. The female gives early summer in a birth period 6 to 8 weeks viviparous about 100 to 400 movable larvae (crawlers, English "crawler") indicates the tightly eyes located close to the dam and begin to turn, forming a separate plate from Analsekretionen and wax filaments. Alternatively, they are able to cling to the tarsi of other insect species and allow them to spread ( phoresy ). Under the shield, the animals go through their larval development in several stages, two for the females, four for the males. The males develop wings and are able to leave their shield. Their mouthparts are stunted, so their lifespan is usually limited to a few hours. The females remain immobile under the shield and are visited there by the males for mating . Its body is clumsy in shape without any externally recognizable segments and without wings. The shield is whitish at the beginning of larval development, gray-brown at the end and has a diameter of approx. 2 millimeters, the animal sitting underneath is yellow. The shield of the females is almost circular, that of the males oblong.

The scale insects usually suckle on the bark of their woody host plants , but rarely can they also appear on the fruits, especially on apples. They overwinter in the first larval stage.

The type can be roughly assigned based on the shape of the shield; an exact determination is only possible for specialists under the microscope. A very similar species, with which it often occurs together, is the common oyster scale ( Quadraspidiotus ostraeformis ). The species are difficult to distinguish, characteristics are the formation of a few pores and bristles on the abdomen.

Combat

Because of its shield, the San José scale insect is very difficult to control with chemical measures. Oil -based preparations with rapeseed oil or mineral oil are used here, which are applied to the plants via shoots. Another measure is biological control with the parasitoid ichneumon fly (in the broader sense) Prospaltella perniciosi (syn. Encarsia perniciosi , family Aphelinidae ), which lays its eggs in the louse's shield and thus kills them. Parasitic wasps are able to control an infested population.

Taxonomy

Within the family of the cap scale insect , almost all species, including the San José scale insect, were assigned to a broad genus Aspidiotus . Later, several genera were traditionally distinguished, which were differentiated from one another according to a morphological characteristic, the number and formation of several lobe-like processes (lobes) near the tip of the abdomen. The San José scale insect was assigned by numerous authors to the genera Diaspidiotus or Quadraspidiotus , so that it is listed in numerous scientific publications under the synonymous names Diaspidiotus perniciosus or Quadraspidiotus perniciosus , there are also a number of other synonyms. The Japanese entomologist Sadao Takagi recognized these groupings as artificial and separated the species group around the San José scale insect, following an older suggestion by Alexander Dyer MacGillivray , as the genus Comstockaspis . This proposal has been widely accepted.

The genus Comstockaspis includes two species, the second species Comstockaspis macroporana (Takagi) is endemic to Japan.

swell

  • Heinrich Schmutterer: The scale insects, Coccina and their natural antagonists. Plant sap sucking insects - Volume 4. Die Neue Brehm-Bücherei Vol. 666. Westarp, Hohenwarsleben, 2008.
  • Comstockaspis perniciosa (Comstock) in García Morales M, Denno BD, Miller DR, Miller GL, Ben-Dov Y, Hardy NB. 2016. ScaleNet: A literature-based model of scale insect biology and systematics. Database. doi : 10.1093 / database / bav118 . http://scalenet.info .

Web links

Individual evidence

  1. ↑ a b San José scale insect. KOB Competence Center Fruit Growing Bodensee , accessed on May 25, 2016.
  2. ↑ It is small, yellow and dangerous: the San José scale insect - Industrial Association of Agriculture. In: iva.de. Retrieved May 23, 2016 .
  3. ↑ a b Sadao Takagi (1974): An approach to the Hemiberlesia problem (Homoptera: Coccoidea). Insecta Matsumurana New Series 3: 1-33.
  4. ↑ Deutscher Reichsanzeiger No. 37 of February 11, 1898
  5. ↑ a b Comstockaspis perniciosa (Comstock) in García Morales M, Denno BD, Miller DR, Miller GL, Ben-Dov Y, Hardy NB. 2016. ScaleNet: A literature-based model of scale insect biology and systematics. Database. doi : 10.1093 / database / bav118 . http://scalenet.info .
  6. ↑ San José scale insect and similar species. Leaflet 156 from the Agroscope Research Station of the Federal Department of Economic Affairs. PDF ( Memento of the original from May 25, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.agroscope.ch
  7. ↑ Imperial Health Department : The San José Scale Insect. Memorandum, second reprint 1898. Springer Verlag, Heidelberg.
  8. ↑ Ute Schönfeld: Cocciden species in Brandenburg . In: Journal for Cultivated Plants . tape 67 , no. 10 , 2015, p. 337–341 , doi : 10.5073 / JfK.2015.10.02 ( PDF ).
  9. ^ Thuringian State Research Center for Agriculture: Leaflet San José Scale Louse - a new pest in Thuringia. PDF
  10. ↑ RC Henderson: Diaspididae (Insecta: Hemiptera: Coccoidea). Fauna of New Zealand 66, 2011. 275 pp. ISBN 978-0-478-34726-5