Spatial and Seasonal Distributions of Leafhopper Vectors of Peach X-Disease in Connecticut

Abstract

Adults of 6 leafhopper vectors of peach X-disease were captured on yellow sticky traps hung on peach trees and on wild host plants at 18 sites including 16 peach orchards in Connecticut. They were Scaphytopius acutus (Say) (comprising 61.7% of the total leafhoppers; n = 13131), Colladonus clitellarius (Say) (18. 1%), Paraphlepsius irroratus (Say) (15.8%), Gyponana lamina DeLong (3.7%), Norvellina seminuda (Say) (0.4%), and Fieberiella florii (Stal.) (0.3%). The seasonal distributions of these leafhoppers indicated that G. lamina and F. florii are univoltine, that S. acutus, C. clitellarius and N. seminuda are bivoltine, and that P. irroratus is trivoltine. The trapping period during which the greatest number of leafhoppers was caught occurred at least 2 wks earlier on wild host plants at the orchard edge than on peach trees even though leafhoppers matured simultaneously on both. On wild hosts, fewer leafhoppers were trapped in autumn than in summer while on peach trees more were trapped in autumn than in summer. These data indicate that leafhopper vectors invade the peach orchard from bordering wild host plants. Orchards that had ground cover comprised of wild host plants had the largest populations of leafhoppers and the highest incidence of X-disease. The percent of peach trees showing disease symptoms was correlated with leafhopper densities which indicates the role of wild host plants in the epidemiology of peach X-disease.