Effects of feeding on healthy and diseased corn plants on a vector and on a non-vector insect

Insect-transmitted plant pathogens can have positive, negative or no effects on the vector insect. Effects could be direct (caused by the pathogen) or indirect (mediated by changes in the plant). Pathogen effects on non-vector insects are less well known.Peregrinus maidis (Ashmead) (Homoptera: Delphacidae), an insect that is not a vector of the corn stunt spiroplasma (CSS), weighed less 15 days after feeding on CSS-infected corn plants relative to insects feeding on healthy corn plants. Fecundity of non-vector insects that were removed from diseased plants was higher than for insects coming from healthy plants. ForDalbulus maidis (DeLong & Wolcott) (Homoptera: Cicadellidae), an insect that transmits CSS, there were no differences in weight, longevity, eggs per day, weekly or total fecundity after feeding on healthy or on CSS-infected corn plants. Significant differences in some phloem amino acids were detected between healthy and CSS-infected plants. Infected plants also showed an increased phloem acidity as disease symptoms progressed. Feeding on CSS-infected corn plants by an insect that does not vector the pathogen infecting the plant can have favorable consequences as evidenced by an increased fecundity.Scientific aritcle no. 8819, contribution no. A-6605 of the Maryland Agricultural Experiment Station.