Influence of aster yellows phytoplasma on the fitness of aster leafhopper (Homoptera : Cicadellidae)

This study revealed that feral aster leafhoppers, Macrosteles quadrilineatu s Forbes, exposed to aster yellows phytoplasma live longer and may lay more eggs than nonexposed leafhoppers. Aster leafhoppers were reared on asters infected with either of 2 strains of aster yellows phytoplasma or uninfecte d asters. After eclosion, adults were placed on uninfected healthy lettuce or oat plants and transferred periodically. The life span of test leafhoppe rs and the number of offspring they produced were compared. Females reared on noninfected aster plants lived for an average of 19 d, those reared on ' severe' and 'bolt' strain aster yellows phytoplasma-infected plants lived 2 6 and 28 d, respectively. The mean number of offspring produced by females reared on the belt strain of aster yellows phytoplasma-infected asters was almost twice the number produced by nonexposed leafhoppers. The life span o f feral leafhoppers or the number of eggs laid did not differ for leafhoppe rs maintained on either oats or lettuce after exposure to aster yellows phy toplasma-infected asters. Female leafhoppers lived twice as long as males. Our results suggest that the aster leafhopper may have had a long associati on with aster yellows phytoplasma. The longer life and higher fecundity of phytoplasma-infected leafhoppers may influence disease dynamics of aster ye llows in lettuce.