“CandidatusPhytoplasma pyri” Affects Behavior ofCacopsylla pyricola(Hemiptera: Psyllidae)1

Abstract

Abstract Pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae), is a key pest of pear and is a vector of “Candidatus Phytoplasma pyri”, the pathogen associated with pear decline disease. Although commercial pear trees are grafted to Phytoplasma-resistant rootstock, a recent report indicated that many C. pyricola in Washington and Oregon harbor this bacterium. Using fluorescence in situ hybridization, we confirmed that Phytoplasma invades internal tissues of C. pyricola, suggesting the pathogen is persistently transmitted. Because many persistently transmitted plant pathogens alter the flight behavior of their insect vectors, we examined the effects of Phytoplasma infection on dispersal of C. pyricola. Flight behavior was investigated using greenhouse bioassays, which demonstrated that Phytoplasma-infected psylla were less likely than uninfected psylla to emigrate from trees and become captured on yellow traps. Pear psylla occurs as two seasonal morphotypes—summerform and winterform—and the ef...