Phylloxera

1. Very complex life cycle: from roots to leaves

Phylloxera is a small winged aphid from North American, it lives on different trees including oak or pear. The species was first described by Fitch in the E.U.A. in 1855, and the English entomologist Westwood recorded it in London greenhouses in 1863.

 

In France, as early as 1863, the first damage of an unknown predator was observed on the commune of Pujaut, near Roquemaure in the Gard. It was a veterinarian from Arles, Mr. Delorme, who was also the manager of an estate in the Camarguaise region, who first reported this strange decline in vines in a letter sent on the 8th of November 1867 to the Agricole Comice in Aix-en-Provence. The expansion by proximity, was of a disturbing gravity.

 

 

A commission consisting of three members: Jules-Emile Planchon - Professor of Botany at the Faculty of Science and the Ecole de Pharmacie de Montpellier, Gaston Bazille - winemaker and President of the Société d'Agriculture de l'Hérault, soon appointed politician and future Senator, and Félix Sahut - horticulturist and founder of the Société d'Horticulture et d'Histoire Naturelle de l'Hérault.

 

This commission was covered with glory when, on July the 15th, 1868, it went to the Lagoy Castle near Saint-Rémy-de-Provence, and distinguished the evil insect.

 

It was F. Sahut who first observed the aphid on dried roots, and handed the vine to his colleagues J.E. Planchon and G. Bazille. This primacy of a few seconds in the discovery of the pest aphid will result in inextricable conflicts between Sahut and Bazille, since the latter, the group’s only true scientist, has written an investigation note on this discovery, and took sole ownership of it and named the aphid "Phylloxera vastatrix". Official history has validated this thesis, as always, for the one of the best communicator.

 

It is a stinging bug characterized by long antennae; two pairs of wings and biting oral parts with a long articulated rostrum. 90% of the known species are phytophagous. Its existence dates back to 250,000 years. The species Phylloxéra vastatrix attacks the vine. This is the one we’re looking at.

The reproduction cycle of Phylloxera is absolutely complex, with several generations of parthenogenesis reproduction per year (for those who have not been studying in school, this is a mode of self-reproduction), and a sexual reproduction cycle.

 

The eggs can give winged Phylloxera which fly with the help of the wind, but also wingless and root-lesion, which bury themselves underground where, with the help of their suckers absorb the sap of the roots. The insect can experience several moults in a few days, to become winged.

In most cases, this adaptive phylloxera descends on the roots of the vine, at the expense of which it lives, hence its name of phylloxera root-lesion; but it can sometimes go on the leaves, giving birth to galls (we then refer to phylloxera gallicole).

 

The infestation of a vine stock with Phylloxera results in its death in three years. It is the root-lesion generations – who live on the roots – that are dangerous. Gallic generations – which live on the leaves on which their bites cause the formation of galls – result in yellowing of the foliage, which is not fatal for the plant (even if at high infestation levels, the photosynthetic action of the foliage may be damaged).

 

Within a few months, aphids multiply by millions. Because of its complexity, the aphid is difficult to control. In any case, it was one hundred and fifty years ago.

Today in the 21st century, no one is interested in the fight against Phylloxera, and that’s too bad because modern technology and ecology should be able to stop the yoke of a tiny insect, whose consequences are immeasurable and still lasting.