RESISTANCE AMONG LYCOPERSICON SPECIES TO FRANKLINIELLA-OCCIDENTALIS (THYSANOPTERA, THRIPIDAE)

The response of Western flower thrips, Frankliniella occidentalis (Per gande) to several species of Lycopersicon was evaluated. In thumbtack bioassays for antixenosis, L. Hirsutum Muller, L. hirsutum f. glabratu m Humb. and Bonpl., and L. pennelli Corr. were all highly antixenic to thrips nymphs, and L. chilense Dun. was moderately antixenic. Thrips nymphs readily moved onto leaves of L. peruvianum (L.) Miller, L. parv iflorum Rick, L. esculentum Miller 'Anahu' and 'Rey de los Tempranos', and L. chmielewskii Rick, indicating that these plant accessions lack ed antixenosis to the western flower thrips. Feeding damage by adult w estern flower thrips varied significantly among leaves of Lycopersicon species. The greatest amount of feeding occurred on L. peruvianum and L. parviflorum. The least amount of feeding occurred on L. hirsutum. Adult western flower thrips feeding on accessions that had strong anti xenosis caused shriveled and distorted epidermal cells with no apparen t damage to internal mesophyll cells. Among those accessions that lack ed antixenosis, adult thrips feeding resulted in severely damaged epid ermal, palisade, and spongy parenchyma cells. In these accessions many mesophyll cells were destroyed and cell contents scattered in the int ercellular space between spongy parenchyma cells. Adult western flower thrips fed on flowers of all the Lycopersicon species evaluated witho ut significant differences in feeding damage among plant accessions. T he importance of these findings to breeding programs for resistance to the thrips transmitted virus, tomato spotted wilt tospovirus, is disc ussed.