<i>In vitro</i> propagation of <i>Dactylosphaera vitifolii</i> SHIMER (Homoptera: Phylloxeridae) on shoot and root cultures of a <i>Vitis</i> hybrid

Abstract

Using a Vitis hybrid, methods of long-term micropropagation of shoots and culture of hairy roots (transformed by Agrobacterium rhizogenes) were developed. The growth of these organ cultures was characterized. The cultures were used as feeding substrates for grapevine phylloxera. Starting with eggs, at 23.6°C the parthenogenetic life cycle of the aphid proceeded in vitro.
Within 2 weeks after inoculation, more than 80 % of the shoot cultures responded with the formation of galls on young leaf blades and swellings on petioles, and, exceptionally, young shoots. At about the same time new eggs were deposited. Gall formation and propagation of phylloxera could be perpetuated for 2.5 years by aseptical transfer of eggs to freshly micropropagated shoots every 1-3 weeks.
Within 1 week after inoculation, more than 90 % of the younger parts of root cultures harboured larvae and responded with curvatures and thickenings. After 2 weeks, phylloxera oviposited and during the following weeks the number of eggs and animals increased considerably.
Thus, both forms of dual culture enable leaf and root gall formation and propagation of phylloxera excluding further organisms.