Epidemiology of Tomato Spotted Wilt Virus Disease on Crisphead Lettuce in Hawaii. J. J. Cho, Department of Plant Pathology, University of Hawaii, Maui Research, P.O. Box 269, Kula 96790. W. C. Mitchell, R. F. L. Mau, and K. Sakimura. Department of Entomology, University of Hawaii, Honolulu 96822; and B. P. Bishop Museum, Honolulu, HI 96813. Plant Dis. 71:505-508. Accepted for publication 24 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0505.

Tomato spotted wilt virus (TSWV) causes a devastating disease of lettuce in Hawaii. TSWV disease and thrips species surveys were conducted on Maui during 1981–1984. TSWV disease incidence and thrips numbers were greatest at a low elevation (366 m) farm compared with higher elevation farms. Three known insect vector species of TSWV were found on Maui: Frankliniella occidentalis, F. schultzei, and Thrips tabaci. F. occidentalis was the predominant species at both low (366 m) and middle (643 m) elevation farms. T. tabaci was the predominant species at the highest farm, located at 701 m. Twenty-three other thrips species were found in Kula. Three are new records for Hawaii: Neohydatothrips gracilipes, Baileyothrips limbatus, and Scirtothrips inermis. A lettuce isolate of TSWV was transmitted to Emilia sonchifolia plants by F. occidentalis. There were significant correlations between mean number of thrips trapped per week for each month sampling was done and tomato spotted wilt disease incidence in lettuce, total monthly rainfall, mean monthly temperature, minimum monthly temperature, and (at P?10%) maximum monthly temperature.