Colorado beetle

The Colorado beetle ( Leptinotarsa decemlineata ), of the Latin doryphorus , is a Insecte Coléoptère S, of the Chrysomelidé S, with the élytre S yellows striped of devastating black, of the Feuille S of potatoes and others Solanacées. This insect was imported the United States at the end of the First World War.

Description

Adult: insect from 10 to 12 mm length, oval form, strongly bent on the top. The yellow head carries a frontal spot in the shape of V. the thorax, brown russet-red, presents some black spots. The élytres yellow clearly have each one five characteristic black bands.

Larva: orange red with the birth, it becomes darker thereafter. At the end of the growth, it measures 11 to 12 mm length. The body arched, soft, carries two rows of black spots on the sides.

Biological cycle

The adults hibernate in the ground and leave in spring when the ground was sufficiently heated. One finds them at once on the potato sheets of which they are nourished.

The eggs, ovoid, of yellow color orange, are deposited by small packages from 20 to 30, stuck to the lower face of the sheets. The young larvae, very voracious, are born at the end of 10 to 15 days and nourish sheets. In the absence of potatoes, the Colorado beetle can tackle others solanées cultivated (Tomate, Eggplant…) or savages (Morelle black, Soft-bitter, Datura). After three moults, the larva finished its development; it goes down then in the ground to transform itself into nymph, then in adult insect.

The complete cycle requires one month of one month and half. According to the climate, there can be two or three generations per annum. The cycles superimposing itself, one can simultaneously find individuals at various stages in the cultures.

At the end of the summer, the surviving adults are inserted in the ground to hibernate to 30-40 cm of depth.

Damage

The adults, like the larvae, devour the sheets of potato, even the stems, and possibly of the others solanées like tomato. In the event of strong infestation, the damage can be very important.

Means of fight

A " Opinion important" direction of agriculture gone back to September 1877 recommends in particular the following provisions:

ships: " the crews of the ships coming from the one of the ports of America or the Germany must destroy all the insects which they will find on board. They must also burn the dry straws, grasses or potato fans, instead of throwing them to the sea or to deposit them with ground. "
elementary Schools: " the teachers can, by their zeal and their devotion, to contribute on the whole preventing the Colorado beetle from being propagated if it penetrates in France. They must be essential the mission of drawing the attention of their pupils to colored engraving and the instruction placarded in the classes, and which make known characters, manners and the damage which this Coléoptère causes. Moreover, they must commit them to bring back to the school all the insects which they will find in the fields of Potatoes, in their showing the need for noting the pieces in which they will have collected them.

It is with the teacher whom will fall the task to know if the Colorado beetle made its appearance in the commune. The schools, by accepting this mission, will become true station control rooms. " Thus, several hearths of Colorado beetles were discovered in Germany by pupils belonging to the elementary schools. The method of eradication consisted in digging a small ditch around contaminated surface, of approximately 50 cm of depth and 33 cm broad in which one was to place straw soaked with Pétrole at which one put fire. the insects collected being put in a bottle containing is Bleach, Hydrochloric acid or sulphuric, or of the Spirits of turpentine. - end of the extract of the ministerial directive of September 1877.

Collecting and destruction of the adults, the larvae and the layings (method valid for small surfaces (gardens) and at the beginning of spring);
Pulling up and destruction by the fire of the contaminated feet;
preventive Disinfection of the ground to destroy the hibernating adults;
Insecticidal Treatment using S of synthesis;
Culture of solanaceous with fragmented Wood raméal (BRF).

History

Until the middle of the 19th century, the Colorado beetle remained confined with the foot of the Rocky Mountains, where it lived sparely at the expense of one solanée wild, Solanum rostratum . When towards 1850, the Potato was introduced into this area, the Colorado beetle adopted it and was propagated through all the the United States. It reached the Atlantic coast in 1874.

Several introductions in Europe, in particular in Germany in 1877 and 1914, in England in 1901, were controlled; but in 1922, a new hearth was discovered with Bordeaux, consequence probable of the deliveries to the American army in 1918-1919, but too wide, it was not possible any more to destroy it. From there, it was propagated quickly in France, arrived in Belgium and Spain in 1935, Germany and Holland in 1936, in Suisse in 1937, in Italy in 1941.

Simple: Colorado potato beetle

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