This most dangerous of all vine pests (Daktulosphaira vitifoliae, Viteus vitifoliae) is an insect of the order Phylloxera (Homoptera), suborder Aphidina (Aphidina) and family Phylloxeridae (Phylloxeridae). The phylloxera only attacks the grapevine, sucking on the leaves and/or roots and releasing its saliva into the sap ducts, causing galls (growths) which then serve as oviposition and food.
The picture shows the development cycle of phylloxera from the Humboldt University in Berlin (Germany) around 1880.
Phylloxera vastatrix (devastating louse)
Different species are suspected due to different behavioural patterns towards the vine. The German biologist Dr Carl Börner (1880-1953) distinguished between a less dangerous long-bodied phylloxera and a more harmful short-bodied phylloxera. From the initial infestation, it usually takes a maximum of three years for the vines to die and be completely destroyed due to subsequent effects such as nutrient deficiency and root rot. The French scientist Jules Émile Planchon (1823-1888) therefore gave phylloxera the apt name "Phylloxera vastatrix" (devastating louse) when it was identified in France in 1868.
Different life cycles
The life cycle is different in Europe(Vitis vinifera) and America(Vitis cinerea, Vitis riparia, Vitis labrusca and many others), which is related to the respective vine species and their resistance to phylloxera. This takes place either in the form of a complete cycle (cycle) between vine (above ground) and root (underground) or only on leaves (only above ground) or only roots (only underground) and thus a shortened cycle. There are parthenogenetic (young production from unfertilised egg cells) and sexual generations.
A distinction is made between the yellow-green 1.5 mm long leaf aphid (Gallicola = leaf gall aphid, Daktulosphaira vitifoliae) and the yellow-brown 1.35 mm long root aphid (Radicicola = root aphid, Eriosoma lanigerum) according to the site of infestation. The latter is much more dangerous as it damages the vascular tissue, which leads to a lack of water and nutrients. Infestation of the leaves, on the other hand, is not usually life-threatening. Among the vine species there are some that form both leaf and root galls, root galls but no leaf galls, and leaf galls but no root galls. The group of completely resistant vine species forms neither leaf nor root galls.
In Europe, propagation usually only takes place through the root aphids, while the full cycle only takes place in America. Only the above-ground cycle produces offspring with new genetic material, as there are only males and females here. Root lice only have females, which reproduce parthenogenetically and lay 600 eggs. Young hatchlings do not immediately infest the roots, but overwinter deep in the soil.
Root phylloxera (Radicicola)
In Central Europe, there are usually four to six generations of vine aphids per year. The young aphids of the last generation (hiemales) form the overwintering form. The newborn nymphs at the end of the summer usually have wings. Some of them, especially the females, develop winged forms to disperse to the host plants and establish new colonies. However, most male aphids remain wingless.
The winged females (sexuparae) lay eggs on the bark of the vine. These eggs hatch into sexuals with regressed mouthparts (proboscis) and non-functional intestines, as they cannot and do not need food. Both live for only about 8 to 10 days. The males (Aptera) only search for females and mate. The females (ovipara) then lay eggs from which new aphids (nymphs) hatch. With these, a new life cycle starts all over again (see above).
The picture on the left shows the different stages of development and the picture on the right shows a winged female phylloxera.
Damage to the roots
In spring, the roots of the vine are pierced with the long proboscis (half the length of the body) and saliva is injected into the tissue. As a defence reaction of the vine, nodosities (on young roots) or tuberosities (on older roots ) are formed. The root aphids feed on these soft formations by sucking them up. The pest can only survive by forming galls, as the hard roots themselves cannot be gnawed directly. The picture on the left shows some root aphids, the picture on the right shows an egg laying on the roots.
Leaf aphid (Gallicola)
The mated females lay a single fertilised olive-green winter egg in a crack in the bark. In spring, the May gall aphids hatch from these eggs, which only develop on American grapevine species leaf gallenGallen ausbilden (Vitis vinifera ist an den Blättern resistent). Diese Maigallenläuse legen bis zu 1.200 Eier. Nach etwa acht bis zehn Tagen schlüpfen aus diesen Eiern zwei verschiedene Larvenarten. Die erste Art bildet vor allem an jüngeren Blättern erneut Blattgallen aus und vermehrt sich parthenogenetisch mit sechs bis acht Generationen pro Jahr.
Die andere Art wandert zu den Rebwurzeln im Boden und vervollständigt oder startet dort den unterirdischen Entwicklungszyklus neu. Eine überwinterte Reblaus mit 1.000 Eiern kann bis zum Herbst etwa 25 Billionen Nachkommen hervorbringen. Das Bild links zeigt die Blattgallen und das Bild rechts die von der Reblaus dort abgelegten Eier.
Gesamter Lebenszyklus
Den komplexe Kreislauf zeigen die zwei Graphiken. Beim oberen Zyklus werden die Blätter, beim unterer Zyklus die Wurzeln des Rebstocks befallen. Der oberirdische Zyklus mit (Vitis vinifera is resistant on the leaves). These mealybugs lay up to 1,200 eggs. After about eight to ten days, two different types of larvae hatch from these eggs. The first species forms new leaf galls, especially on younger leaves, and reproduces parthenogenetically with six to eight generations per year.
The other species migrates to the vine roots in the soil and completes or restarts the underground development cycle there. An overwintered phylloxera with 1,000 eggs can produce around 25 trillion offspring by autumn. The picture on the left shows the leaf galls and the picture on the right shows the eggs laid by the...
