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Daktulosphaira [Phylloxerini]There does not seem to be a recent description or diagnosis of the genus Daktulosphaira (frequently given as the junior synonym Viteus), so we will confine ourselves to detailing the differences between Daktulosphaira and the other genus to which the single species in this genus was previously assigned - namely Phylloxera.
Daktulosphaira vitifoliae (Grape phylloxera) CosmopolitanThe grape phylloxera (Daktulosphaira vitifoliae) is an important pest of commercial grapevines. When on its native vines in America, its life cycle takes two years to complete and includes a sexual stage. The single overwintering egg on vine hatches in spring to give the fundatrix. As the immature fundatrix feeds, she injects saliva into the leaf which induces a hairy, scabrous gall on the leaf underside (see first picture below) which opens on the upper surface. On reaching maturity the fundatrix lays eggs parthenogenetically in the leaf gall (see second picture below). The nymphs that hatch from these eggs move to other leaves where they produce 3-4 asexual generations of grape phylloxera.
Both images above copyright Claude Pilon, all rights reserved. The adult apterae of Daktulosphaira vitifoliae are yellow (see third picture above). The body is pyriform (=pear-shaped) with the broadest part anterior. The antennae are very short, with only 3 segments. As the season progresses, some of the wingless females move to feeding on the roots. On vine roots the grape phylloxera induce bird's head-like galls, termed 'nodosities', on young expanding roots and cause hyperplastic growth (=excessive cell division) of lignified roots, termed 'tuberosities'. (The first picture below shows both the galls and white tuberosities.) Their offspring (see second picture below) spread to other roots of the same vine, or to the roots of other vines through cracks in the soil. Successive asexual generations of apterae persist on roots. The generation of nymphs which hatch in the autumn hibernate in the roots and emerge next spring when the sap begins to rise.
Both images above copyright Joachim Schmid under a Creative Commons Attribution 3.0 Germany License. In the eastern US the root-feeding wingless females then produce winged individuals (alate sexuparae) from mid-summer to late autumn. These emerge from the soil to migrate and produce non-feeding sexuales: males, and oviparae (females), which in turn mate. The ovipara then lays the single overwintering sexual egg in the bark of the vine's trunk and then dies. It is this egg that gives rise to the leaf-inhabiting forms. The grape phylloxera was introduced to Europe in the late 1850s where it destroyed many vineyards growing the common grape vine (Vitis vinifera). However, the life cycle of the phylloxerid is much simplified on the European vine. The sexual stage is lost, so there are no leaf galls and the grape phylloxera is anholocyclic on these vine roots. Forneck & Huber (2008) review the varied life cycles of the grape phylloxera. Leaf galls can occur in Europe on cultivars derived from hybrids between Vitis vinifera and American vine species. Daktulosphaira vitifoliae is now found in many parts of the world including North, Central and South America, Europe, the Mediterranean, the Middle East, Africa, China and Australia.
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