Processionary caterpillar of the pine

The Thaumetopoea pityocampa is a Insecte of the order of the Lépidoptère S, of the Notodontidés, subfamily of the Thaumetopoeinae. It is called processionary pine in its form caterpillar and bombyx pityocampe in its form Imago (butterfly). The Larve S are known for their mode of displacement in Indian file, nourish needles of various species of pine S, causing an important weakening of the trees.

Recent classifications raise Thaumetopoeinae with the row of family.

Description

The adult insect is a butterfly from 35 to 40 mm of scale, with the pectinate antennas . The former wings are gray, with two parallel dark bands, the posterior white ones marked of a dark spot at the posterior end.

The larva is a caterpillar from 30 to 40 mm length, brown noirâtre with reddish spots on the top and the sides. Its ventral face is yellow. The body is strongly hairy and cover of irritant hairs and allergisants. The predatory ones at this stage are mainly the titmouse and other insectivorous birds, nonsensitive to the irritant hairs. The caterpillars go in procession in a curiously jerked way.

Biology

The butterflies, which hatch during the summer, between June and September according to the climate, lay their eggs deposited in lines parallel per packages from 150 to 320 on the branches or the needles of various species of pine. The blossoming takes place five to six weeks after the laying.

It gives rise to caterpillars which moult three times before the winter on dates varying according to the latitude and altitude and probably related on moisture, the temperature like with the thermal amplitude, like total radiation and the photoperiod. The peaks of temperature (heat or cold) can stop the food of the caterpillar temporarily.

More one goes up towards north and in altitude, more the larva develops slowly, by shortening the diapause nymphale. The caterpillars spend the day, and all the winter, sheltered in a bulky nest built at the fourth larval stage (southern part to benefit from the rays of the sun). It leave during the night there to feed, moving in “procession” according to a silk wire which enables them to return to the nest. The cohesion of the file in displacement is ensured by the contact of the head of a caterpillar with the hairs of the abdomen of that which precedes it.

In spring, the colony, led by a female, leaves the nest, always in procession to gain on the ground a well shone upon place and to hide in a hole where each caterpillar will weave its Cocon to start its process of transformation into Chrysalide.

At the end of several months, even several years, the chrysales are transformed into butterfly which leave ground. The cycle can then begin again by coupling of the female and the male which dies one or two days after, whereas the female flies away towards a branch to lay its 70 to 300 eggs before dying too. The small caterpillars hatch 30 to 45 days after the laying.

Damage

The caterpillars nourish needles of the pines, involving a defoliation partial and a deformation of the branches, and in the event of massive infestation, an important weakening of the trees opening the way with other ravageurs and parasites.

The attacked species are especially the Pin of Alep, the Maritime pine, the black Pin of Austria, the Pin laricio and the woodland Pin. The Cèdre is also parasitized.

The caterpillars can have until a million tiny very irritant hairs which are released in the air. Their long hairs break easily and are transported by the drafts. Their strong irritant character can cause at the man of the reactions of Démangeaison on the level of the neck, the hands and the eyes, but also of the edema S, the ocular and respiratory disorders.

Natural enemies

Various species of insects parasitize the processionary catarpilar of the pine or are the predatory ones, in particular eggs and caterpillars.

Means of fight

For small surfaces:

mechanical Fight: for reduced surfaces (parks and gardens), it consists in removing and destroying the layings and the nests. In this case, it is advisable to be protected from any contact with the irritant hairs of the caterpillars. It is advised to use a tree pruner which is shears at the end of a length handle.
the triangular trap, containing phéromone of synthesis suspended in height, attracts in June the male butterflies believer to find a female. This trap is effective for several trees.

For large surfaces:

chemical Fight: by air insecticide pulverization, is increasingly abandoned.
biological Fight: the most used method is the toxin pulverization produced by a Bactérie, the Bacillus thuringiensis VAr. kurstaki , which is effective against the caterpillars of Lépidoptère S. the ingestion of these toxins causes the death of the larvae by Septicémie. Unfortunately, this toxin also acts on other larvae of lépidoptères. The commercial spceialities approved in France have a persistence of very short action, but also a very good effectiveness on old stages. the use at the end of the autumn thus allows a good protection against this important ravageur of the forests while having an impact mimimum on other caterpillars because of their nonpresence.

Sources

DEMOLIN G., 1987: The processionary catarpilar of the pine, Thaumetopoea pityocampa Schiff., with the Ventoux Mount. Studies vauclusiennes; Bull. sem. dépt. of history and géo. of the faculty of Avignon 3 : 157-173.
DEMOLIN G., ABGRALL J.F., BOUHO-DELDUC L., 1996: Evolution of the surface of the processionary catarpilar of the pine in France. books of the DSF , 1-1996: 26-28.
DEMOLIN G., FREROT B., CHAMBON J.P., MARTIN J.C., 1994: Biosystematic reflections on all the processionary catarpilars of the kind Thaumetopoea (Lepidoptera Thaumetopoeidae), considered as important ravageurs of the cedars Cedrus libani Barel and Cedrus atlantica Manetti on the circumference of the Mediterranean basin. Ass. Rech. For. Morocco, 27 (1): 578-591.
MARTIN J.C and MAZET R., 2001. Winter fight against the processionary catarpilar of the pine. Use potential of Bacillus thuringiensis K. Phytoma. 540: 32-35.
MARTIN J.C and BONNEAU X., 2006. Bacillus thuringiensis: 30 years of fight against the caterpillars défoliatrices in forest. Phytoma. 590: 4-7.
MARTIN J.C and FREROT B., 2006. Evolution of the fight against the processionary caterpillar of the pine: towards the use of the phéromone of synthesis. Books of the DSF.2006 (1): 29-31.

See too

Processionary List of the ravageurs of the crop plants
of the oak

External bonds

entomological Memories of Jean-Henri Fabre on the Processionary catarpilar of the pine.
the Processionary catarpilar of the pine in France in 2006.
Evolution of the surface of the Processionary catarpilar of the pine in France of 1981 to 2004.
treatments against the processionary catarpilar of the pine of 1992 to 2005.
Futura science on the processionary catarpilar of the pine

MARTIN J.C., 2007: Processionary file INRA it of the pine http://www.avignon.inra.fr/les_recherches__1/liste_des_unites/ue_forestiere_mediterraneenne/dossier_la_processionnaire

Random links: