Studies on penetration of sugar beet leaves by stylets ofMyzus persicae

Abstract

The feeding habit of the aphid, Myzus persicae, that transmits the virus of the beet yellows disease of sugar beet, was studied by examining the course of the insect’s mouth parts in sugar beet leaves. Of the 150 penetrations that were identified by the saliva sheaths left by the insects in the leaf tissues, 50 per cent terminated in the phloem tissue, the others in the mesophyll or other parenchyma. The frequent penetration of the phloem by the feeding insects suggests that the insect could release the beet yellows virus into and pick it up from the phloem. This manner of virus transmission would agree with the previously obtained evidence that the virus affects the phloem tissue primarily.