Further Study of the Transmission of Citrus Huanglungbin by a Psyllid, Diaphorina citri Kuwayama

Abstract

The huanglungbin agent was successfully transmitted from diseased citrus plants to healthy Ponkan mandarin seedlings by fourth and fifth instar nymphs of Diaphorina citri Kuwayama and not by first to third instar nymphs. The effect of number of adults on transmission showed that a single adult could transmit the pathogen very efficiently. In serial transmissions to healthy Ponkan mandarin seedlings by single adults, the minimum latent period of the pathogen was 1-2 days, and the maximum latent period was 25 days after acquisition feeding. The infected adult retained infectivity throughout its life. When the adult was newly emerged from an infected nymph, it could transmit the pathogen to healthy seedlings without an acquisition feeding. In ultrathin sections of salivary glands and other organs of infected adults under electron microscope, the pathogen was found in the cells of salivary gland, the filtration chamber of the foregut, and the cells of midgut and hindgut.