FEEDING AND OVIPOSITION INJURY TO FLOWERS AND DEVELOPING FLORAL BUDS OF NAVEL ORANGE BY FRANKLINIELLA-BISPINOSA (THYSANOPTERA, THRIPIDAE) IN FLORIDA

Larvae and adults of Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae) feed on the ovary, style, floral disk, petals, and anthers of swollen buds and open flowers of 'Navel' orange (Citrus sinensis (L.) Osbeck). Evidence from scanning electron micrographs suggest stylar punctures in floral tissues ranged from 2.5 to 5-mu-m in diameter, and depth of injured areas into interior cells ranged from 12 to 84-mu-m (xBAR, 44-mu-m; n = 36). Measurements of injured areas in transmission electron micrographs (TEM) of the floral disks and pistils were up to 96-mu-m (xBAR, 63-mu-m; range, 37-96-mu-m; n = 20). Measurements of TEM micrographs were considered more accurate than light micrographs because of the higher magnification and resolution obtained. Thrips feeding resulted in cellular evacuation, necrosis, plasmolysis, and cellular collapse of floral or bud tissues frequently extending one to five cells deep. Thrips oviposition and subsequent eclosion were recorded from the pistil, calyx, petals, and filaments of both flowers and swollen buds of 'Navel' orange. Seventy-three percent of the thrips eclosed from the pistil-calyx units of open flowers followed by 15% from the petals and 12% from the filament-anthers. Plant cell injury due to oviposition was highly localized and, unlike feeding injury, adjacent cells were minimally affected by cellular collapse.