EFFECTS OF DENSITY, STAGE, AND SEX OF THE POTATO LEAFHOPPER,EMPOASCA FABAE(HOMOPTERA: CICADELLIDAE), ON SEEDLING ALFALFA GROWTH

Abstract

AbstractPotato leafhopper,Empoasca fabae(Harris), early-instar nymphs (1–2 instar), late-instar nymphs (3–5 instar), adult males and adult females were caged at various densities on seedling alfalfa cv. Vernal and allowed to feed for 6 days. Feeding by adult females, late-instar nymphs, and adult males retarded plant height, leaf number, and dry weight, about 20 to 50% more than did the early-instar nymphs at most of the leafhopper densities tested, over 6 days. Protein content was affected differently from the other plant parameters; it was reduced most by adult males. This was apparently due to premature death of the plants caused by late-instar nymphs and adult females. The percentage reduction for each of the plant parameters was highly correlated with leafhopper density and was nonlinear, except with the early-instar nymphs. Alfalfa plants exposed to two or four late-instar nymphs or two adult females, significantly increased in height and leaf number during a 7-day recovery period. Plants exposed to four adult females did not recover.