Grape phylloxera external morphology observations under scanning electron microscopy

Abstract

Grape phylloxera is a major viticulture pest present in most grape-growing regions of the world. Radicicolae grape phylloxera feed on the root system of grapevines, and may result in the death of susceptible vines. During an investigation into the biology of grape phylloxera, scanning electron microscopy was used to examine the insects' external morphology. During incomplete metamorphosis, grape phylloxera moult four times with a sequential increase in size with each instar. Parthenogenetic egg production in adult grape phylloxera result in the swelling of the abdomen and the posterior region near the gonopore. A posterior opening appears to be present for excretion, however honeydew production has not been observed during feeding. The stylet length of grape phylloxera indicated that the insect feeds on non-vascular parenchyma tissue. This high protein and low sugar food source is the basis for the differing morphological and physiological traits between grape phylloxera and the closely related Aphididae.